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technical supplement no.1 IAIAnd ~~Ioureo$ 'oundatton, Inc: 1718 P 8"tt6Ct, ttV'J., Suite Ti04 Wasfi.nit~n, j.),C, .NoH MARINE ENVIRONMENTS OF THE VIRGIN ISLANDS technical supplement no.1 prepared by ISLAND RESOURCES FOUNDATION for Government of the Virgin Islands of the United States VIRGIN ISLANDS PLANNING OFFICE COASTAL ZONE MANAGEMENT PROGRAM Cyril King GOVERNOR Thomas R. Blake DIRECTOR OF PLANNING August, 1977 The preparation of this report was financed in part through a Coastal Zone Management Program Development Grant as provided by Section 305 of the Coastal Zone Management Act of 1972, administered by the Office of Coastal Zone Management, National Oceanic and Atmospheric Administration. ISLAN'D RESOURCES F"OUNDATION P.O. BOX 4187, ST. THOMAS, U.S. VIRGIN ISLANDS 00801 • (809) 775-3225 Mr. Thomas R. Blake, Director of Planning V.I. Planning Office, Office of the Governor Government of the U.S. Virgin Islands Dear Mr. Blake: April 8, 1976 The Virgin Islands constitute a unique island system - a place of value, beauty, and inspiration, possessing a rich history, spectacular marine life, diverse coastlines and a salubrious climate. They also have a promising future as a habitat for resident faunal, floral, and human species, living in a balanced, natural beauty. There is, however, mounting evidence that the human component of our islands' population has, through oversight, uncontrolled expansion, and ill conceived actions, induced a broad spectrum of stresses that threaten the natural viability of the island system and could destroy what Alexander Pope referred to as "th e gen i us of the place." Th is process is especially apparent in the coastal zone of the Virgin Islands where competing human interests and dynamic components of natural ecosystems interface and interact. The present effort to develop a management plan for this critical zone of man-environment inter- relationship offers the promise of minimizing environmental conflict, improving resource allocation decisions, preserving our insular heritage and restoring the intricate balance with natural systems. Our mission was to establish a point of departure in assessing the marine segment of the endangered coastal zone, reviewing what is known, preparing an inventory and classification of component subsystems and defining their inter-relationships. Lastly, we have sought to suggest preliminary guidelines for the planner who bears the ultimate responsibility for devising procedures and making t"ecommendations to our government on how to improve upon management of the coastal zone. This has been an exciting, awesome and inspiring project. Thank you for the opportunity to under- take this study. I take great pleasure in submitting this report. We trust you will find it useful in the tasks which lie ahead. Sincerely yours, ,d~~·--'-~ Edward L. Towle, Ph.D. President COASTAL ZONE MANAGEMENT STAFF Darlan Brin, Assistant Director of Planning and Program Director Edward H. Lindelof, Project Coordinator Walter L. Stewart Steven L. Colman William F. Newbold, Jr. Marsha McLaughlin Roy E. Adams Katina Coulianos ISLAND RESOURCES PROJECT STAFF STAFF Edward L. Towle, Project Director David I. Grigg, Senior Biologist William E. Rainey, Ecologist CONSU L T ANTS Maynard Nichols, Oceanographer John McEachern, Resource Planner James A. Dobbin, Landscape Planner ACKNOWLEDGEMENTS The following people were helpful in identifying existing resource information: E.A. Bertrand Lagoon Marina St. Thomas, Virgin Islands John R. Clark The Conservation F ou ndation Washington, D.C. Arthur E. Dammann Virgin Islands Department of Conservation and Cultural Affairs Robert Dill West Indies Laboratory St. Croix, Virgin Islands Johnny Harms Lagoon Marina St. Thomas, Virgin Islands Robert S. Mathes Virgin Islands Department of Conservation and Cultural Affairs iv David Olsen Virgin Islands Department of Conservation and Cultural Affairs Timothy B. Still Virgin Islands Department of Conservation and Cultural Affairs Robert T eytaud Virgin Islands Department of Conservation and Cultural Affairs Robert P. VanEepoel Virgin Islands Department of Conservation and Cultural Affairs Werner Wernicke Virgin Islands Department of Conservation and Cultural Affairs John A. Yntema Virgin Islands Department of Conservation and Cultural Affairs Ervin H. Zube University of Massach usetts CONTENTS INTRODUCTION v SYNTHESIS - COASTAL ZONE 80 PLANNING GUIDELINES INVENTORY OF NATURAL RESOURCES 1 Regional Context 80 Oceanography and Climatology 1 Planning Concept: 80 Tides and Currents 1 Ecosystems Approach Waves and Swell 9 Water Quality 11 GUIDELINES FOR RESOURCE 81 Prevailing Winds 22 MANAGEMENT Storms and Hurricanes 24 Precipitation and 27 Vital Areas 81 Evaporation Areas of Environmental Concern 81 Geophysical Factors 29 Areas of Normal Concern 82 Bathymetry 29 Seismic Activity 31 Areas of Regional, National 82 and I nternational Concern Marine Ecology 33 Guidelines for Ecosystem 82 Fisheries 33 Management Other Coastal Wildlife 39 Coastal and Submarine 39 RECOMMENDATIONS FOR 88 Habitats FURTHER STUDY Beaches 44 SUMMARY 90 Rocky Shores 52 Salt Ponds 54 SELECTED BIBLIOGRAPHY 101 Mangroves 56 Coral Reefs 63 Sandy Bottoms 67 Grass Beds 68 Offshore Cays 70 Other Marine Resource 72 Elements Other Marine Resource 72 Elements ANAL YSIS OF BIOPHYSICAL 75 RELATIONSHIPS Classification of Coastal 75 Ecosystems Critical Areas 77 Areas of High Productivity 77 Areas Under Stress 78 IlninllP Arp;:J<; 79 FIGURES AND TABLES FIGURES 1. Predicted and observed tidal ranges in St. Thomas harbor, March - April, 1972 2. Variations in the character of the tide displayed in time-height curves in Christiansted harbor, June 29- July 19,1971. 3. Annual prevailing currents in the Caribbean. 4. General current patterns on the island platforms. 5. Mean surface current, speed and direction for Christiansted harbor currents and for littoral currents, August 1971. 6. Maximum bottom currents recorded at ten points in Can eel Bay, St. John. 7. Surface currents near Great St. James Island in August. 8. Water movement in Jersey Bay and Mangrove Lagoon, St. Thomas. 9. Average sea and swell conditions for Virgin Islands coasts. 10. August surface temperatures. 11. January surface temperatures. 12. Winter-Spring (December-April) inshore water temperatures, St. Croix. 13. Summer-Fall (J une-October) inshore water temperatures, St. Croix. 14. Winter-Spring (December-April) inshore water temperatures, St. John. 15. Summer-Fall (J une-October) inshore water temperatures, St. John. 16. Winter-Spring (December-April) inshore water temperatures, St. Thomas. 17 . Summer-Fall (J une-October) inshore water temperatures, St. Thomas. 18. Contours of equal salinities (isohalines) in Jersey Bay and Mangrove Lagoon. 19. Diurnal variation of dissolved oxygen, salinity, pH and temperature measured at one foot depth in south Jersey Bay, St. Thomas, 1970. 20. Wind direction and speed frequency, central Caribbean, January-June. 21. Wind direction and speed frequency, central Caribbean, July-December. 22. Tropical cyclone frequencies: latitude 150 - 200 N. 23. Hurricane paths that have affected the Virgin Islands since 1876. 24. One hundred year frequency and standard project tidal flood stage hydrographs. 25. Bathymetry of Virgin Islands basins and plateaus. 26. Profiles of bottom topography across the Virgin Islands shelf south of St. Thomas and St. John. 27. Distribution of Caribbean seismic and volcanic activity. 28. Coastal and submarine habitats, St. Croix 29. Coastal and submarine habitats, St. Thomas and St. John 30. Beach profile showing beach terminology and component parts in relation to high and low water. C 31. High energy winter profile and moderate energy summer (beach) profile. 32. Summer and winter beach profile in relation to beach roc~. 33. Representation of sand transport in an enclosed bay. 34. Profile of a beach indicating physical zonation and characteristic organisms. 35. Typical rocky shoreline of eroded volcanic rock with boulder and rubble bottom. 36. Cross-section of a salt pond. 37. Salt River, St. Croix, showing drainage patterns and protective reefs. 38. Profile of a mangrove forest showing typical zonation and associated habitats. 39. Marine ecological zones of Jersey Bay and Mangrove Lagoon, St. Thomas. 40. Benthic communities of Salt River estuary. 41. Diagrammatic profile of an offshore reef system. 42. Profile of a sand-dominated bottom. 2 2 4 4 6 6 7 8 10 13 14 14 15 15 16 16 18 20 22 23 25 26 27 29 30 32 40-41 42-43 45 45 47 47 48 53 54 56 58 59 60 64 68 43. Typical shallow water sea grass bed. 44. Rocky shoreline and associated sea bottom. 45. Typical sand beach ecosystem showing relationship of component habitats. 46. Mangrove dominated ecosystem with lagoonal flats and protective reef. 47. Man-dominated bay ecosystem. TABLES 1. Major element composition of sea water. 2. Occurrence of tropical storms and hurricanes within 240 nautical miles of St. Croix. 3. Location of Virgin Islands salt ponds, excluding cays. 4. Partial list of birds from Jersey Bay mangrove lagoon including cays. 5. Inventory of offshore cays. vii 68 74 76 77 78 17 25 57 62 71 Introduction The coastal zone is an area that, far from separat- ing land from sea, brings the two together in a complex interaction of living and physical features. It is an area of constantly active forces that makes it probably the most dynamic portion Qf the earth's surface. Some of the interplay of forces are constant, even subtle (currents, evaporation, tides, biological processes); while others can be sudden, destructive and catastrophic (hurricanes, earthquakes, drought, flooding). Between these extremes, one finds a continuum of natural pro- cesses which are ongoing and interactive, often poorly understood and some, no doubt, yet un- known. The complexity of processes in the coastal zone is amplified and modified by human activities but continues nevertheless, sometimes shunted or tem- porarily obstructed as a result of man's activities along inexorable patterns dictated by natural evolutionary systems. Thus, while man has further complicated the kaleidoscope of coastal interac- tions, he finds it necessary (more so because of his intrusion to identify and understand the pieces of the pattern and their mechanations. Increasing human modification and exploitation of coastal resources demand an identification and under- standing of these resources, their attributes, inter- relationships, constraints and limits. Only from such a starting point can workable plans be de- veloped for maximum multiple-use mc..nagement of coastal resources. Some level of resource protection and conserva- tion is imperative, at the very least for self-serving, short-term development related reasons. However, protection and preservation of portions of the environment can also be compatible 'Nith other valuable functions including biological productivity, recreation, environmental diversity, aesthetics and cultural preservation. Perhaps the greatest value of preservation is the maintenance of options for further uses. Development and modification of natural resources are frequently destructive in the sense that resource attributes are permanently committed to a particular use and no longer available for alternative uses. Protection not only maintains natural productivity and aesthetic values, but preserves use options for future generations. The following compilation is intended as a first effort survey of Virgin Islands coastal resources, an interpretive summation of our knowledge of their interactive processes, values and capacities, and our needs for additional information. It is important to recognize the necessity for understanding the coastal zone - or any natural system for that matter - as a complex interaction of many pieces, processes and problems. It must be understood also that any modification of a single part or process will cause some response in other parts of the system. Natural systems as a whole maintain their integrity by a process of dy- namic equilibrium and must change in response to external stimuli. Sometimes this response is negli- gible, sometimes catastrophic. Often it is subtle and imperceptible to human scrutiny - assuming an effort at observation is even made. It is counterproductive, therefore, to approach problems of resource development and exploita- tion as separate, segmented actions dealing with in- d ividual resources or separate development schemes. Ignoring the interdependent aspects of natural systems and the additive and secondary effects of individual resource manipulations is unlikely to promote optimum sustained mUltiple-use manage- ment of these resources. The information compiled herein is the most com- prehensive treatment to date on the marine com- ponent of the Virgin Islands coastal environment. It should be noted that a great amount of esoteric detail has not been included, primarily because it is not suited to the scope of a general inventory, re- view and management document. More important is the fact that a yet greater amount of necessary information is simply not available. We have attempted at several points and in the Recommen- dations to identify these voids in our knowledge of the Virgin Islands coastal ecosystems and to sug- gest how some of these lacunae may be filled in. The final section of the report is an annotated bibliography to the marine component of the Virgin Islands Coastal Zone Management Plan, organized alphabetically by author and publica- tion date. An attempt has been made to distin- guish between documents which are of general or overview nature, those which have particular relevance to local coastal zone management, and those which are technical or specialized. The key word index refers to appropriate sections of the text and is cross-referenced to provide leads to related information. 1)( Inventory Of Natural Resources Oceanography and Climatology Tides and Currents Tides are regular cyclical rises and falls of sea level induced by astronomical forces. The gravitational pull of the moon, and to a lesser degree the sun, in effect, create a giant global wave system which pro- duces the earth's tides. Inshore, the tide height and time of occurrence is affected by coastal and bottom geography, but the magnitude of tides generally depends on the relative positions of the earth, moon and sun. Maximum gravitational attraction of the earth's oceans - and therefore maximum tides - occur when the three planets are in a straight line relationship. Thus, high tides are generated on the sides of the earth nearest to and furthest from the moon and maximum tides (as well as minimum - lowest- tides at tangential points) when the sun and moon are aligned in the same plane with the earth, i.e., at new and full moons. Tides of maximum ranges are called spring tides, when the water level reaches from the higher high water level to the lower low water level. When the planetary positions are such that a given point on the earth experiences only minimal tidal ranges (from lower high water to higher low water), the tides are called neap. Since the relative positions of the sun, moon and earth change constantly, but cyclically, on a daily and annual basis, the magnitude and locations of tidal maxima and minima also change. Tides are also complicated by such factors as winds, the cen- trifugal force of the earth and local geography and bathymetry. As a result, the times of high or low water and their heights can vary greatly along a large, complex shoreline. In the Virgin Islands, tidal ranges are not great, and tidal currents, except in some inshore locali- ties, are not significant. The small islands, lacking complex shoreline physiography, do not restrict changes in water level. The sea flows around the islands relatively unimpeded, resulting in tidal fluctuations of only a few inches to a foot. Fur- ther, the steep slopes of the islands rising out of the water means that the intertidal zone - the part of the shoreline regularly covered and un- covered by the tides - is very narrow. We therefore do not have large areas of tidal flats uncovered at low tides as in other places in the world, especially along continental coastal zones. One of the consequences of this small tidal action is that water exchange in bays due to tidal action is usually very small. For example, it is estimated that 24 to 40 tidal cycles alone would be necessary to exchange "all the water in the main part of St. Thomas harbor (Percious, et ai, 1972) Fortunately, waves, swells and oceanic currents usually do a good job of flushing most bays. However, these forces are considerably reduced by the time they reach the heads of deep embayments. As a result, circulation may be poor in the inner reaches of some of our larger embayments. The innermost portions of the mangrove lagoon on St. Thomas, of Salt River, St. Croix and of Coral Bay, st. John are like this. To a lesser extent, similar conditions have been observed at the head of Vessup Bay (Redhook), st. Thomas and Cruz Bay Cr.eek, St. John, and probably occurs in other similar locat- tions. For the planner and decision maker, these condi- tions are important because it means that pollu- tants introduced to these calm areas will be very slowly dispersed. For the same reason, such quiet areas will be very slowly dispersed. For the same reason, such quiet areas are sites of relatively rapid deposition. Sand transported naturally through these bays, as well as silt and debris from the land, tend to settle out in the quieter areas, filling the bottom and eventually extending the shoreline. Because of different exposures to open ocean water on one side and modified circulation of Caribbean water on the other, the north and south coasts of st. Thomas and st. John experience dif- Figure 1. Figure 2. r----------------------------------------------------------------- 1.0 o. o. 0.5 PRillICl'ED heights in Feet, referenced to ~1FlIN rru Wl\TF;R Ul\1U1 OBSERVED heights in l'ElIT alxJve arbitrary reference level, fran gauge in llaroor Mas ter' s Dock = referenced to DATUM 3_5 3.0 2.5 2.0 1.5 () E N 3.5 \ , moon phas,es position o fun E-equator S-south 2.0 • new N-north () last quarter 1.5 12 13 14 IS 16 Time- days 0 e- O> ~ ~ ~ Co I :3 0 e- rn ~ ~ " Co :§ Predicted and observed tidal ranges in St. Thomas harbor, March-April, 1972. From Percious, van Eepoel, and Grigg, 1972. 12.0 E u. fo- 6.0 :x: (!) w :x: 0.0 -6.0 29 30 JUNE JULY VANISHING 12.0 / E u fo- 6.0 :x: (!) w :x: 0.0 -6.0 9 10 II 12 13 14 15 16 17 18 19 J U L Y Variations in the character of the tide displayed in time-height curves, from predicted tables and from observed tides in Christiansted harbor, June 29 - July 19, 1971. From Nichols, et. at, 1972. 2 ferent tidal activities. On the north, tides are simi- lar to the north coast of Puerto Rico, being semi- diurnal (two cycles of high and low water per 24 hours. The time of tide stages in the Virgin Islands are earlier than in Puerto Rico, however. On the south coasts of St. Thomas and St. John, and for all of St. Croix, tides are primarily diurnal (only one high and low water per day). The second cycle is reduced to very slight ebbs and floods, and on some days is not measurable at all. The mean range of local tides is 0.8 - 1.0 feet (0.24 - 0.30 meters). The mean range of spring tide is about 1.3 feet (0.4 meters). Changes in tidal height with time can be displayed graphically by a marigram, a chart which plots the water level as measured by a tidal gauge. Such marigrams have been constructed for Lameshur Bay, St. John (Dammann, et. 01.1969), St. Thomas harbor (Percious, et. 01, 1972) and Christiansted harbor (Nichols, et. 01, 1972)' The latter two clear- ly show the vanishing semi-diurnal (second cycle) component of south coast tides (Figures 1 and 2). CURRENTS Currents are defined as horizontal movement of water as a result of any of several driving forces. In actual practice it is often difficult to determine what the causative forces are, and for most purposes it does not matter. Thus, tidal currents are water flow resulting as changes in sea level drive water through channels or embayments. Density currents are generated by differences in dissolved solids (salinity) and/or temperature. Currents are also generated by the rotation of the earth and the resulting wind stress at the surface. Density and pressure account for the general large- scale currents of the ocean, including the North Equatorial Current which pushes water through the Caribbean Basin (Figu re 3) to the west-north- west to eventually join the Gulf Stream. Ocean water from the Tropical North Atlantic (North Equatorial or Canary Current) enters the Caribbean Basin between the islands of the Lesser Antilles. In most localities, the submarine ridge on which the islands lie is less than 1,000 meters deep, therefore admitting primarily upper water from the Atlantic. This water flows west-northwest past the Lesser and Greater Antilles, entering the Gulf of Mexico and Florida Straits through the Yucatan Channel. Atlantic water from south of the equator also enters the Caribbean between Trinidad and Grenada and eventually joins the north equatorial water in the Yucatan Basin. However, this southern current, with a velocity about twice that of the Northern Caribbean current does not impinge directly on the West Indian archipelago. The major bottom features (ridges and troughs) of the Caribbean, described in the section on Bathymetry, act to restrict movement of deep water through the Caribbean. Movement of the upper layer water is complicated when it flows over the shallow island platforms. For most pur- poses, these are defined as the submarine shelf from the shoreline to 100 fathoms (183 meters) depth. Here, coral reefs, other bottom irregulari- ties, winds, shoreline configurations and tides act to divert and diverge the prevailing ocean currents. On the Virgin Islands platform, while the pre- vailing mass flow of water is still dominated by the west-northwest drift, passage of water between islands and in bays varies depending on location and exposure to the open sea. Generalized flow on the islands' shelves has been plotted by Dam- man, et. 01. (1969) and is shown as Figure 4. Because of seasonal changes in wind direction, water is driven across the shelf from the east in the winter and from the southeast in the summer. In individual bays, unless they have eastern expo- sures, water movement is controlled primarily by wind and swell. If the bay's exposure and shape permits access of offshore current driven water, then often bays on the north exhibit a clockwise movement of bay water, while in those on the south, the circulation is counter clockwise. Many factors interact to determine the direction of water flow in a bay however. Some of these are relative strength of tides, winds, wave, swell, and external currents in addition to the bay's bathymetry, shoreline shape and size, It is therefore not surprising that patterns of water movement in bays, especially the larger more complex ones, change as the rela- tive strength of the various determinants change, For the planner, this is important because it points to the need for site specific studies of currents when these are important for decision making, Furthermore, such studies should be conducted during a long enough period and under various conditions to determine not only prevailing condi- tions, but variations that may occur, . Figures 5 through 8 show some available current information for specific bays and point to the var- iety of circulation patterns which can be encoun- tered locally, '" '" 70' ". 58' 67' LEGEND ARROW SHOWS CURRENT DIRECTION. 65' ro' NUl'>lBER ABOVE ARROW SHOWS MEAN SPEED IN KNOTS. '" NUMBER BELOW ARROW SHOWS PERCENT FREQUENCY OF CURRENT. OPPOSING ARROWS !N SOt>lE QUADRANGLES ADJOINING THE COAST '" ''' iO' ~ .. 60'-- ~ --.Q.L 35 33 "'-.Q .• 6 ...... INDICATE PREDOMINANCE OF FLOOD AND EBB TIDAL CURRENTS. '-1.1 .-;-.. ~ '" -.L.L 48 EXAMPLE: "-.E .• 6>'--- ANNUAL PREVAILING CURRENTS g' 00' CURRENT SETS NW AT A MEAN SPEED OF 0.7 KNOT AS SHOWN BY 42 PER· CENT OF ALL OBSERVATIONS. THE REMAINING 58 PERCENT OF OBSER· VATIONS INCLUDE CALMS AND ALL OTHER CURRENTS REPORTED. ""·6 S""" ~--~74'~--~71~'----;'''~'----;'1l7'----~ro~'----C''~'----~58~'----C67~'----:'65~'----;,65~'----~"~,----;~~'-----6r,'~--~'~,'~~~OO~,-----S~"----~ ro' 13' iO' g' Figure 3, Annual prevailing currents in the Caribbean. From U.S. Naval Oceano~raphk Office, Sailing Directions, 1963. 4 <;- = / 100 1athOrn droP _01\. ... / _._._._.-._._._._.-. tJ • II savana i I / ;' ,. ".;---.' - / ._. vi rgin Figure 4. General current patterns on th . I e IS and I p atforms F . rom Dam mann,eta!,1969. c ~,. ", " /1 .... <j'barracuda :""'/ bank <: JANUARY islands N Figure 5. Figure 6. LITTORAL CURRENTS Measured ......... ;.. Inferred Scotch Bonk - Mean surface current, speed and direction for harbor currents and for littoral currents, August, 1971. Length and width of arrow indicates speed in meters per second. Harbor currents based on anchor station measure- ments; littoral currents on dye patch measurements. * indicates two alternating predominate directions. From Nichols, et at, 1972. 0 427 ' ,.362 KT. ~ 7' :.246 KT . . 270KT. .. 05 t4' CANEEL BAY, ST. JOHN 01 12' 0211' .228 KT. .. .246 KT. .. N + Maximum Bottom Currents Recorded at Ten Points in Caneel Bay, St. John. Recording Depths (feet) shown at each station. From Dammann, et at, 1969. 6 ST. THOMAS . .,.~ ,- ..... : ~. --... 1._. , .. . ,.. . •• v •• .- ,.- {M: .. ' "". o+- ,.,. e I GREAT ST. JAMES ~ •.• ~'t . \ .. ... ; N --I Figure 7. Surface currents near Great St. James Island in August. Determined by dye diffusion. Data from Brody in . Dammann, et ai, 1969. 19 67 Figure 8. \ :;'2 -'-'- fi .. 37 ~.­ .-.- '2. .10 '" s .' <29. .... ' 59 ,...1' 71 .. b 7 , 4 8 : : : : 9 3 5 .12 67 II II ,c'ii" .. ' .. '/ 16 21··· .. '2 1& .. · .. '.1& "'"'' :. '2( .... ··.16 13 '(8 '2 " . ..... J ... £. 1 14"" ". ' ... 33 .. ., '. . II '~ . .8 '. , .... ~ 65 70 34 ", " ..... , '". 16'; ~ 3 ;~.3 .. ", ". , . "\I~.3.;·>. ::. ····W .. 70 I< d) • :f,)- Water movement in Jersey Bay and the Mangrove Lagoon, St. Thomas. From McNulty, Robertson and Horton, 1968. 8 Waves and Swell Waves are the main source of energy that move beach sediment and that affect shipping and shore- line structures during storms. Waves differ widely according to their heights, length, period and speed. Their energy depends mainly on height and period. The deepwater wave regime of offshore waters is driven by the northeast trade winds most of the year. On the average, wave heights of one to three feet approach from the east 42 percent of the time throughout the year. For short periods, 0.6 per cent of the time, these easterly waves reach 12 feet. Intermediate wave heights and corresponding frequencies of occurrence (Figure 9) are summarized in Deane, et aI, (1973). In addition to the normal easterly swell that affects the windward coasts of the islands, there are two seasonal modes of wave approach that affect leeward coasts: a south- easterly chop and swell and a northern swell. The southeasterly swell with waves one to twelve feet high becomes significant in late summer and fall when the trade winds blow from the east or when tropical storms and hurricanes pass the islands at a distance to the south. The east-south- easterly wind and wave regime is associated with the doldrum belt located over the interior of Venezuela and with an intensive high pressure area over Bermuda. By contrast, during winter when the doldrum belt is located farther south along the equator and the Bermuda High is weak, a long length and long period northern swell develops. Although the swell offshore is only one to five feet high and occurs only four percent of the time, it is significant because it gains heights of ten to twelve feet nearshore. By refracting around the west coasts of the islands, this swell affects leeward coasts for short periods. Variations in the depth of water and orientation of the coast nearshore greatly modify the height and length of approaching swells. As a result of refraction, wave energy is concentrated on seaward projecting points and, at the same time, it is diffused with in the bays. Th us, waves tend to straighten the north coast of St. Croix by erosion of headlands and deposition of sand in the bays. Straightening along the north coast of St. Thomas and St. John is opposed by the variations in re- sistance to erosion of different rock types. For example, the projecting points on the north side of Magens Bay, St. Thomas, at Mary's Point, St. John and of Thatch and Grass Cays owe their origin to the Tutu rock formation which is more resistant than the Brass limestone. Commonly, on the north coasts, waves approach the shore from two principal directions. Short period waves and chop approach from the east and northeast, and, at the same time, long period swells approach from the north. However, in the winter, from November through March, the north- ern swells are larger than in summer, and they are refracted and redirected more around points and islands. Because of their high angle of approach and large size, such waves create strong longshore currents. Around islands like Dutchcap Cay, St. Thomas and Buck Island, St. Croix, the two wave types produce very complicated patterns of cross- ing sea and swell which can be observed on aerial photographs. Along coasts fronted by partly submerged reefs, waves playa significant role in circulating back reef water. As demonstrated in Christiansted harbor (Nichols, van Eepoel, Grigg, et al 1972), the mass transport of waves breaking over Long Reef drives a harbor-wide circulation (Figure 5) that flushes most of the harbor water through the entrance in about fourteen hours. Consequently, the response of waves to reefs and nearshore bathy- metry is significant in reducing pollution and im- proving water quality. In many harbors and bays, periodic surging of the water surface, called "seiching" or "surging", has been recorded. Although the seiches are usually less than 15 centimeters high, they create oscil- lations within a harbor that induce horizontal movements that can drive ships sideways against the dock. Such movements have not been observed in Virgin Islands harbors, but they need to be taken into account when evaluating proposed changes in harbor geometry. 73' 12' 11' 20' fillS FIGUq[ :s t'lESIGNED TO (;jVF: Telf. PEIl.CErH FRcOUU1CY O~ SEA AND SWELL ~y [l1"Fr::TION AND qO:Ir,IH FOR VARIOUS COASTAL AU ... FHFN1S. THE [lArA ARE APf'lICA8lE TO NE/lI'IS"Or.E WATEP5 ',","HI'N ~F.N MIl.ES or THE COAsr; r::O'IOITIOfI5 rnn THE fl[A'lSHonf w",TI=;R5 OF ElA.q6A[1~S ARE Vl'qy SIMILAR TO T'"'OSE SHDWN 0"1 HIE F:Asr ANn wr.sr FXPOSURES OJ: THE" l.£F.WARD ~IIO WINDWARO SI A'H)S TlfE A~I"EMF.Nrs HA'IE RFE'j ~EU:r.rEO O.'J THE A .... S1S OF SIMILA'1'TY OF E~r>OS!JRr '-1f.TE· COOt-OGIO'L CONI)ITIO>.!S. AND OR"iI"R'JEO SF.A AND SWELl. DATA. whvE ("01-l01110"'S AT SPECIFIC co~sr"L I r)CATIO'IS MAY VARY 1'1'1(""1 TlIF PRE· SfNTEO DA"A BI:':AIj"iF or "lCtICO"l""ORMlrY TO 'HE r.[IIEI1Ai. CIl",f"lAr;TFRISTICS O' T~I F. AL,NE· JJoJ Mf'.~4T. T"f GE~~.I'lAL "IArun[ 0_ THIS STUDY DOES 12' Nor PF.R"1IT AN M4ALYSIS OF SEA, ~NO SWELL CON. f1ITIO~IS -OR E,o\CI~ SPECIFIC COASTAL LOCAliTY. ·ME .... NS LESS THAN 0.5 II'.~ 10'· 13' 10' WINTER SEA ~ .. ~" ~;:..-t ..... VlHGIN IF; (SOPTH EXPOSURF.:) SUMMER - Figure 9, Average sea and swell conditions for Virgin Islands coasts, From U,S, Naval Oceanographic Office, 1963, 10 18' II' I" 15' I 1 l4' 13' II' II' Water Quality The discussion below has been limited to major parameters most commonly used to describe water quality. While the oceans contain at least traces of almost every chemical element known, obvious- ly the discussion of all of them is impossible and inappropriate to this document. Furthermore, little or nothing is known about the levels of most of the elements in local waters. Oceanographic parameters treated are those commonly used to characterize bodies of water. For most purposes, they reflect the general quality of water and in- directly suggest something about the presence or absence of other broad quality determinants and give inferences about the biota. Physical and chemical properties are important as they affect the behavior and physiology of the sea's inhabitants from the lowliest to the most complex. Only a relatively small amount of infor- mation exists on the biological implications of water quality for tropical organisms. Much of it is general and qual itative. Quantitative data on the effects of specific parameters on specific tropical organisms is particularly scarce. Even such defini- tive information is not universally and readily transferable to situations outside the closely defined limits of the experimental setting within which it was determined. Part of the enormous complexity of biological relationship is that there are interacting effect relationships among the many component para- meters of the environment. For example, the re- sponse of a given organism, including its tolerance, to temperature may vary with salinity. Further- more, this variable response relationship may be different for different life stages (i.e., egg, larva, juvenile, adult). Levels of turbidity and sedime.nta- tion which permit the survival of established coral colonies may not allow settlement of larvae and development of new colonies. Acclimatization also affects an organism's response. For example, an organism accustomed to a relatively high tem- perature, salinity, turbidity, etc. may often exhi- bit a higher upper limit of tolerance to said para- meter than the same species which is acclimatized to a lower prevailing level of the same parameter. Acclimatization responses are also related to other factors in the organism's environment. Given such innumerable complex relationships governing the establishment and survival of marine life, it is no wonder that we are, in the main, ignorant of most details of marine ecology. This fact explains why biologists are unable to specify, in fine, cause-effect relationships of observed phe- nomena and why they are hesitant to make une- quivocable predictions about specific effects of particular environmental modifications. Our present knowledgeof biological responses to a few variables is simply too inadequate to extend without reser- vations, even to the same organism at another time in another setting. Even naturally occurring environmental compon- ents can assume pollution roles when increased beyond normal levels. Thus, thermal pollution can result from heated industrial discharges which raise water temperature beyond the tolerance limit of organisms. Hypersaline effluents or those abnormally high in other natural sea water consti- tuents can likewise be lethal. Sewage, even treated sewage effluents, can add a variety of chem icals which are directly or indirectly antagonistic to marine life. Organic matter remove.s oxygen from the water directly or in the course of its degrada- tion by micro-organisms. Nutrients (nitrogen, phosphorous, silicon), when elevated above their normally low concentration can increase the growth of nuisance species of algae, molds, diatoms, etc. Explosive growth of such forms can smother normal organisms, produce toxins, remove oxygen from the water and may eventually, if conditions persist, change the entire ecosystem. There is always a normal background amount of suspended matter in the sea and fine particulate matter is constantly settling to the bottom at a slow rate, even in the cleanest water. In some inshore areas, turbidity and siltation may be nat- urally high, but in both extremes the local biota is composed of species adapted to or tolerant of the prevailing conditions. Chronic increases in turbidity and the rate of siltation will stress and fipally extirpate the more sensitive organisms, and their place will be taken by more tolerant ones. However, even the most tolerant organism has a finite ability to endure a given stress. Organ- isms inhabiting turbid, muddy areas will perhaps survive longer under greater increases of suspended and settleable matter than those inhabiting relative- ly clear water, but can ultimately be destroyed by chronic, extremely severe conditions. The effects of pollution are less damaging, in the direct sense, to motile forms than to fixed (sessile) forms. While several environmental modifications (diversity, predator-prey relationships, fishery yield, etc.) may result from the loss of mobile organisms, they can leave an unsuitable area for better sur- roundings. Fixed forms - plants, corals, sponges, oysters, etc. - must perish if they cannot tolerate the induced stresses. In the larger sense, this loss of sessile organisms has much greater implications than the displacement of mobile ones. Fixed organ- isms are not simply living components of an en- vironment; they, in large measure, are both phy- sically and biologically the determinant structure of the ecosystem. The corals on a reef - apart from their roles as living members of that diverse community - are the actual physical material of the reef. They provide food, shelter and anchorage for all of the thousands of other species living there. The same is true of sea grass and algae pastures and mangrove forests. If these basic determinant elements of the ecosystem perish, then the rest of the associated biota - even if not directly af- fected by particular stress factors - will be ad- versely affected. The parameters most frequently used to describe basic water quality are temperature, salinity, dissolved oxygen, transparency and sometimes color. For more critical definition of a water body, especially where pollution is present, bac- teria, oxygen demand, pH and nutrients ("fertili- zers" important for algae growth) are often measured. For assessment of water quality rela- tive to other specific problems, there is an almost unlimited list of other chemical and physical measurements which may be made. Selection of specific ones depends on the information that is needed and on the nature of factors which may be influencing water quality (i.e., the type and sou rce of poll ution). The following discussion treats the more common quality determinants and our knowledge of their natural levels and man-induced variations in local waters. 12 TEMPERATURE Most frequently reported in degrees Celcius (or centrigrade) in technical literature, water temper- ature is a function of radiation at the surface. Insolation (exposure to the sun) warms the water; radiation of heat from the surface results in cooling by a loss of "excess" heat (roughly the difference between the water temperature and the night- time air temperature). Water is more heat stable than the land. Thus, while the land surface heats up rapidly under the sun and cools rapidly at night, the sea is able to absorb considerable heat without a resulting large increase in temperature and to hold that heat without rapid loss. The result is that ocean temperatures are much more stable than air or land temperatures and do not show the same wide daily fluctuations. The larger the volume of the water, the more tem- perature stable it is. Therefore, shallow headwat- ers, tidal flats and ponds tend to reach very high temperatures during the day (sometimes 300 C and higher). At night they may cool to air tem- perature or lower if a stiff breeze promotes evapor- ation. In contrast, offshore water measured at perhaps one foot below the surface may fluctuate as little as 2-3 0 C diurnally. Mixing of the water by waves, swell and current improves temperature stability by reducing local- ized areas of anomeolous temperature and by distributing heat energy more evenly throughout the water mass. Biologically, temperature is important because every organism has a limited range of temepr- ature within which it can survive. There is usually an even narrower range within which the organism will flourish, exhibit optimum growth and repro- duce. Frequently these narrow temperature optima are not the same; organisms may grow faster and reproduce better at different temperatures. Very often optimum temperatures are different for juveniles and adults. Temperature is also biologically important for several other reasons. Generally, warmer water can hold larger quantities of dissolved salts, but less dissolved gases, including oxygen, than colder t) savana I / ) "@"- I 27.S·C i IZl i 27.~·C II) virgin N ~~<b? d \~: arracu a ..... bank : ..... islands 10. ':Xugust Surface Temperatures. Temperatures are the average of the number of separate-day samples given in ~ 11_ .. () savana i i " I N '.~~".? 0:'barracuda .. ' ". bank I ••• t' virgin islands January Surface Temperatures. Temperatures are the average of the number of separate-day samples given in parenthesis. From Dammann, et aI, 1969. Sf. CrQix ::;;'oufh Coosl Aver""ges 25.3 ~ - 2G.5~C Monthly Figure 12. Average Winter-Spring (December-April) inshore water temperatures. Data from the Division of Natural re- sources Management, Virgin Islands Department of Conservation and Cultural Affairs. Sf. Croix $. fl s.-,. C-" A_...".. "5- -.,. .• -C _'My ! i.j.$ i ~;Ics Figure 13. Average Summer-Fall (June-October) ..inshore water temperatures. Data from the Division of Natural Resources Management, Virgin Islands Department of Conservation and Cultural Affairs. 14 4 N gure 14. Winter-Spring (December-April) inshore water temperatures around St. John. From data of the Virgin Islands Department of Conservation and Cultural Affairs. 1973·74. I i __ . .0 2.OUO' &QoOQ' jl"~~-J""""F_t ure 15. Summer-Fall (June-October) inshore water temperatures around St. John. From the data of the Virgin Islands Department of Conservation and Cultural Affairs, 1973-74. SI: Thorn .... 5o~'" Coosl .11.-....,.8<".. 25_&" - 27.Z"C Monl,,& ~----------------------------------~------------------~~--~---------------~ Figure 16_ Winter-Spring (December-April) inshore water temperatures around St. Thomas. Data from Virgin Islands Department of Conservation and Cultural Affairs, 1973-74. ~ N o .. ..... ""1"'"' .. ;,--..-_. N, ... Figure 17. Summer-Fall (June-October) inshore water temperatures around St. Thomas. From data of the Virgin Islands Department of Conservation and Cultural Affairs, 1973-74. water. Organisms, as a rule, tend to be more active as temperature increases within their range of tolerance, although near their upper limits many exhibit behavioral or physiological maneuvers to curtail energy loss and heat exhaustion. The lowered oxygen capacity of very warm water can result in anoxia or death for oxganisms if they cannot leave the area or reduce their activity and oxygen demand. Offshore surface water around the edge of the northeast Virgin Islands platform is in the range 27.5 - 27.9 0 C in August (Dammann, et aI, 1969; Figure 10). In january, offshore surface water on the north was measured at 24.0 - 25.5 0 C, but on the south was red uced on I y to 25.5 - 27.0 0 C (Figure 11). This is undoubtedly a result of the southerly encroachment of colder Atlantic water in the winter, while the shallower, warmer Carib- bean water to the south is less affected by this seasonal cooling. Inshore temperatures are more variable and generally warmer than offshore. This is perhaps to be expected from the shallower depth and greater variety of water characteristics inshore. Part of the wider temperature range, however, may also be due to the larger number of inshore measurements made. The Virgin Islands Division of Natural Resources Management (for- merly Division of Environmental Health) has been making inshore water quality measurements monthly since November, 1972. Their temperature data from bays on St. Thomas show minima of 24.6 - 26.7 0 in january-February and maxima of 27.1 - 29.00 C between june-October. Average winter-spring and summer-fall temperatures for the three islands are given in Figures 12-17. During the three years from November, 1972 to September, 1975, a cooling trend is apparent with winter minimum falling from about 26.7 0 C to 24.6 0 C and summer maximum falling from 29.00 C to 28.40 C. These data are from clean open- coast bays; areas such as Benner Bay and St. Thomas harbor have been excluded. Data from St. john show the same cooling trend over the past three years. SALINITY The saltiness of sea water results from the various minerals dissolved in it. The most abundant is sodium chloride. The relative proportions of the 1.., constituents is almost constant regardless of sa- linity. Significant departures from constant compo- sition ratios occurs as a result of pollution. Table 1 indicates the relative abundance of the 11 major constituents in sea water. In determining salinity, the chloride content is determined and salinity derived from it by an empirical relationship. Sal- inity can also be derived from measurement of conductivity and temperature. Table 1. Major elem~nt composition of sea water gm./kg. of water of Constituents salinity 350/00 Chloride ........................... 19.353 Sodium ............................. 10.76 Sulphate ............................ 2.712 Magnesium ...........•.............. 1,294 Calcium ............................. 0.413 Potassium ........................... 0.387 Bicarbonate .......................... 0.142 Bromide ............................ 0.067 Strontium ........................... 0.008 Boron .............................. 0.004 Fluoride ............................ 0.001 Salinity is reported in parts per thousand or grams per litter of salts, more often represented as 0.00. Offshore sea water around the islands has a rather constant salinity of 35 .. 5 to 36.2 0/00 in winter-spring and 34.0 to 35.2 0/00 in summer- fall (Wust, 1964). Inshore salinity varies from place to place around the islands depending on the relative rates of evaporation, fresh water addition and renewal by offshore water. Inshore salinity can also vary considerably over the year for the same reasons. In protected inshore localities where circulation is poor, evaporation during hot, dry periods cz,n increase salinity to 40 0/00 or more. On the other hand, heavy rains can reduce it to 20 0/00 or less. I n fact, for short periods in pro- tected bays, an almost pure fresh water layer or "lens" may lie on top of the sea water. I n most localities, however, wind, waves and currents constantly exchange the water for offshore water of relatively "constant" salinity and so dampens salinity fluctuations. Under these conditions, water in most local bays is almost or exactly the same salinity at all depths, shows only small annual variations and, following torrential rain, can re- '20 19 . .. 1'1 S3 - - -'-. ,,'2 --'- - --. 67 .. 0 . ... 37 ""i . .. ~ .. - ".-,- -' .-' 7 4 .....-. 67 71 II II S.3- ; I~' ..... . , \6 ('ii" '. ,.... '(:: I~·," ".16 I) ...' ~._ "ROTTO CAY f .. ' !I. I ~ '. ". 2'0.... '20 ". 3 S ;13 '. t8 8 ' .. J'''r 14'·. " . .. }.r ~ ..... '. . ". '. .~. .... ~ .... ·ti~I:j·OO .' IS',. Ii····· ... 34 '" 5 ...... ~ ~\ ". 16'; ~ ~ ~3 70 70 .,..- .... Figure 18. Contours of equal salinities (isohalines) in Jersey Bay and Mangrove Lagoon, St. Thomas. From McNulty, Robertson and Horton, 1968. 18 cover to pre-flood salinity within a few days af- ter runoff stops. Oceanographers frequently measure salinity to de- fine bodies of water and identify circulation patterns. The areal distribution of salinity in a bay, for example, can be contoured to produce isohalines - lines of equal salinity. These distribu- tions can reveal sources of water, mixing zones and paths of water flow. Isohalines constructed for Jersey Bay mangrove lagoon on St. Thomas (McNulty, Robertson and Horton, 1968) show the increasingly higher salin- ities of the inner areas where poorer circulation and evaporation promote salt concentration (Figure 18). DISSOLVED OXYGEN Oxygen, dissolved in the water, is necessary for life support. At the sea surface, oxygen may be ab- sorbed from the air, a process which is aided by surface agitation of waves. The largest part of sea water oxygen, however, is produced by marine plants on the sea bed and floating planktonic algae (phytoplankton).. This production is the source of most oxygen in the lower layers of in- shore water. The oxygen hold ing capacity of sea water is inversely proportional to temperature and salinity. Cold, fresh watercan hold more oxygen than warm, salty water. Excess oxygen produced beyond the ability of the sea to dissolve it diffuses into the atmosphere. In fact, marine production accounts for a major proportion of atmospheric oxygen, a factor which contributes to some of the serious concern about the effects of increasing global pollution of the oceans. Plants produce oxygen as a by-product of photo- synthesis, a process which requires light. There- fore, oxygen is not produced at night, but animal requirements for respiration continue. in addition, plants respire (use oxygen) in the dark. Therefore, it is necessary, during sunlight hours, for a net surplus of oxygen to be generated to carry life processes through the night. Diurnal oxygen pro- duction cycles have been measured locally at Cruz Bay and Chocolate Hole, St. John (Brody, 10 Grigg, Raup and van Eepoel, 1970), at Vessup Bay (Grigg, vanEepoel, and Brody, 1970) and in Ben- ner Bay-Mangrove Lagoon, St. Thomas (Grigg, van Eepoel and Brody, 1971). Figure 19 repro- duces characteristic oxygen curves from a highly productive site in Jersey Bay, St. Thomas on two different days. Oxygen production begins at about 6 A.M. and the concentration in the water increases rapidly to a peak at 3 P.M., after which it begins to fall and reaches a minimum, below the saturation level, at about 3 A.M. The open-circled points on the graph represent the oxygen saturation capacity of the water based on its temperature and salinity which also vary diurnally, the latter in response to changes in circulation and the volume of offshore water entering the area. During peak production hours, an observer in the water in such areas can see bubbles of oxygen rising from the sea grasses to the water surface. Under such conditions, the water is super-sat- urated with oxygen and is passing the excess to the atmosphere. Oxygen is removed from the water by organ- isms, including aerobic bacteria feeding on wastes. It is also removed by chemical reaction with waste products and pollutants. I ncreased amounts of organic pollutants remove more oxygen by chemi- cal reaction and by the life processes of bacteria and other micro-organisms which feed on it. Surface waters around the islands are usually oxy- genated at or near saturation during the day. In very productive areas, such as over dense turtle grass beds, supersaturation may occur during mid-day. Because of generally prevailing temper- ature and salinity, saturation values are about 6.0-6.6 milligrams per litre (mg/1). Because of this, annual variations in dissolved oxygen (d.o.) tend to follow annual variations in temperature; salinity varies much less than temperature. At night, es- pecially near the bottom, d.o. may be reduced to 5.0 mg/1 or less, depending on local conditions of the sediments, water and biota. Point sources or concentrations of pollutants also depress oxygen concentration by utilization and can further de- press local production by destruction of plant life. ~ r <>.0 ~ ,-- ----~ " /' ........ ~ .... 0 /' ----0-- - -0----0--- / -- --- VI VI ~ 1- It.: /'" / " ----- -$ / ------~~ , ~--~~-- , ~ 87 C II) ~ .. 'r t ~ __ ~c:~----~~>>_~ __ ~ __ ~--~~--~~ ____ =:~~-------------- --..- - --- 29 }J J 26 27 ~ ..! ~ 2" 0600 Figure 19. Diurnal variation of disolved oxygen, salinity, pH and temperature measured at one foot depth in south Jersey Bay, St. Thomas. Solid lines March 21-22, 1970; broken lines April 20-21, 1970. Open circles represent dis- solved oxygen saturation. Redrawn from Grigg, vanEeopel, and Brody, 1971. However. in areas of good water circulation, these effects may be masked by oxygen transport from other areas. In shallow, polluted inshore parts of the St. Thomas harbor, surface d.o. as low as 4.3 mgj1 have on occasion been measured in the past (Percious, van Eepoel, and Grigg, 1972). TRANSPARENCY Clarity and. transparency of the water is a function of suspended matter. It may be estimated in several ways. The more common are Secchi disk depths, turbidity units, and concentration (weight/volume) of suspended solids. The first two give estimates of light penetration, while the third is difficult to relate to actual clarity except in the extremes because it depends considerably on the size and nature of the suspended particles. Many small particles will cloud the water more than the same weight of larger, but fewer particles. Suspended solids concentrations cannot be related or con- 20 verted to Secchi depth or turbidity, but under some conditions Secchi depth and turbidity may be quantitatively related. Secch i disc depth is the depth to wh ich a wh ite or black and white disk can be distinguished when lowered into the water. Turbidity is a measure of light scattering by sus- pended particles in a water sample. It is reported in Jackson or Formazin turbidity units, depending on the method of calibrating the measuring instru- ment. The units are interchangeable. Suspended solids concentrations are determined by filtering a water sample through a fine membrane, generally with nominal pore sizes of 0.45 micron, drying and weighing to determine the suspended solids concentration in mg/1. Transparency in most local waters is excellent. A secchi disk can easily be seen to depths of 30 feet, frequently more, in normal water. This means that in most bays the bottom is visible from the surface, i.e., Secchi depth is 100 percent of the water depth. Three years of data from the Division of Natural Resources Management reveals that turbidity in undisturbed bays generally is 0.3 - 0.7. Formazin Turbidity Units (F.T.U.). The St. Thomas harbor, an example of a turbid bay, had Secchi Disk depths only 50-60 percent of the water depth. Since sewage has been removed from the harbor, Secchi depths have increased to 80-90 percent of the water depth. Turbidity in the harbor formerly was as high as 4.5 F.T.U., but since 1973 has fallen to 1.0-2.5 F.T.U. Turbidity of the water is important primarily because it reduces the amount of light reaching plants on the bottom. It is also associated with increased siltation of the bottom because many particles eventually settle out of the water in calm areas. Both effects place stresses on living systems. WATERCOLOR The apparent color of clear sea water is a result of absorption and reflection of light and of the color of sand or organisms on the bottom. As light penetrates the water, the longer wave lengths (red, yellow) are absorbed rapidly. Shorter, higher energy spectra (Violet, blue) penetrate farther and therefore dominate the light that finally reaches the bottom and is reflected. Therefore, deeper water appears to be blue or dark blue, while shallow water is greener. Very shallow water will appear clear or colorless if the bottom is sandy, or green if it is covered with seagrasses and green algae. Water color can also be affected by phytoplankton which may be red, green, brown or yellow-green. Turbidity makes the water brown while dissolved materials can produce a variety of colors. Water color may sometimes be of interest in describing local sites or characterizing a particular pollutant, but in most cases color alone is not particularly meaningful. OTHER QUALITY PARAMETERS Frequently it is valuable to estimate the density of some type of bacteria in the sea. Since this is most often done to monitor pollution by sewage in coastal waters, one of the common indicator species is usually monitored. Eschereschia coli, the most characteristic bacteria in feces of warm- blooded animals, including man, is most often tested for. New methods of analysis are simple and rapid and give results in 16-24 hours. Bacterial density in the water is useful for pin-pointing sources of pollution, evaluating public health acceptability and efficiency of sewage treatment facilities. '11 Chemical ions such as nitrate, phosphate, silicate and their related compounds are often studied as means of assessing the productivity or eutro- phication ("enrichment") of the water. These compounds are highly concentrated in sewage, even treated sewage effluents, and also occur in floodwater from the land. High concentrations of these compounds promote increased growth of plants, particularly phytoplankton and filamentous types. Rapid growth of these plants, which require or can tolerate high nutrient concentrations, can smother normal clean water forms or produce toxins which are harmful to other organisms. Organic matter in the water is frequently estimated indirectly by measuringbiochemical oxygen demand (B.O.D.) or chemical oxygen demand (C.O.D.). The first is a bioassay which measures the consump- tion of oxygen by micro-organisms feeding in a water sample under standard conditions, usually for five days. Chemical oxygen demaFld measures the oxygen uptake of a sample using strong oxi- dizing agents. Since many substances not easily attacked by bacteria (as in B.O.D. test) are thus oxidized, the C.O.D. value of a given sample is higher than the B.O.D. It is also a more rapid test than B.O.D. Prevailing Winds The Virgin Islands lie in the belt of "Easterlies" or "Trade Winds" which traverse the southern part of the "Bermuda High" pressure area. The trade winds approach the islands with great con- stancy of direction, primarily from the east- northeast and east. The trade winds vary in magni- tude and direction as the position of the sun changes seasonally in relation to the earth's surface. Major seasonal changes relate to the normal variations in position and intensity of the "Bermuda High" and "Equatorial Trough." In contrast to the Ber- muda High, the Equatorial Trough is a zone of low pressure south of the islands between the sub- tropical high pressure belts in the southern and 20' 19' '" /3' /2' II' /0' ", '" LEGEND DIRECTION FREQUENCY: 8ars represent percentage frequency of wind observed from each direction. Each circle equals 10%. 51' _ ... _~---'--- '''''' oJ all wi"d. ..... ,It (ram N.; Nil"'''.' 01 -,,"":.:'_--- (P~ ., OI!I_ .".J wi'" to f.o~CI I: no ./irltctiorr') 01.,."..11,,11. 17(~ I I wind observN front Nd dlrtet*, _Ithl" .. eh 'PHd interval: UI~ northern hemispheres (which includes the Bermuda High). Since the wind blows around the low pres- sure zone as a counterclockwise inflow in the northern hemisphere, the Equatorial Trough directly affects the easterly winds of the islands. The average percentage frequency of wind speeds for different directions is illustrated in the monthly wind roses of Figures 20 and 21 (U.S. Navy Hydro- graphic Office, 1963). The annual wind regime can be broadly divided into four seasonal modes: (1) December to February; (2) March to May; (3) June to August; (4) September to November (Brown and Root, 1974). Characteristics of each seasonal mode are discussed below. '" '" '" II' 10' 20' 19' ~ ......... / SP£EO FREQUUfC"'t! Prlnt.4 flturllS f'BII'resenl percentage frequency of G " __ (."JoII ..... _"-S"""..-s-t." 1 ,., ,., l 2 : ':3 of 1',.;""..... F_ .. -JI'I-".....,~) BNllfoli !:~-----1·1·.1:1 ~ 15 4 ) J+. /Table below wind rOM provides percentage frequency of wind Fore. 8.,::::::21.)1 \'l'!)llU!l l '!2,G! , 1" 1" 1" 15' 13"0 11' 10". Figure 20. I .., speed of each Buufllrl Force Irom 2 throullh 9: "12_· -'" .'·~ANUARY 1" ~ll3r9r;;-,-;-;~-"""'''''.... I ! I I I I r I I (p,,.!:lfnt.,. clwiflrlJ, abo"i/,'".) 13£5&789 "', ........ . ..... ____ ",2)"58 1 89 (S .. uIorlForn,b.lo .... I;, .. ) -----~ (191- 0' ,II ",mrJ • .... r. e..uforl Fore. II) +indicales less Ihan I percent t> "-. FEBRUARY 17' U' 15' MARCH 1" IJ' .. ;.: .•.. II' JUNE 10' SURFACE WINDS ". 11' ro' Wind Direction and Speed Frequency, Central Caribbean, January - June, From U,S. Naval Oceanographic Office, 1963, 22 December-February. During the winter the trade winds reach a maximum and blow with great regularity from the east-northeast. Wind speeds range eleven to twenty-one knots about sixty percent of the time. Speeds greater than twenty knots occur about twenty-five percent of the time in January. This is a period when the Bermuda High is intensified with only nominal compensating pressure changes in the Equatorial Trough. The trade winds during this period are interrupted by "Northerners" or "Christmas Winds" which blow more than twenty knots from a northerly direction in gusts from one to three days. Such outbreaks average about thirty each year. They are created by strengthening of high pressure cells w l\2,2Y~~~;ii--'",,, 2 J'~ ~ 1 e 'l .... LLLLJ_L-LLJ (P .. 'crnIIlQ~ of wind., .. bn"" I;~,,) 2 1 • 5 <; 1 ~ " (B~~uro" Force, bel"", /ine; 17" - - - - - -::: (29% of ~I/ .... 'nd. ~". B" .. ui .. ,t r O.C~ /j) +indica!eslesslhllnj J)'!'Cf!"! ". ". 13', 11', over the North American continent, which, in turn, allows weak cold fronts to move southeastward over the entire Caribbean region. These storms are accompanied by intermittent rains, by clouds and low visibility for mariners. March-May. During the spring, the trade winds are reduced in speed and blow mainly from the east. Winds exceed twenty knots only thirteen percent of the time in April. The change in speed and direction mainly result from a decrease in pressure of the Equatorial Trough. June-August. Trade winds reach a secondary maximum during this period and blow predom- inantly from the east to east-southeast. Speeds ". ". 59', Figure 21. Wind Direction and Speed Frequency, Central Caribbean, July - December. From U.S. Naval Oceanographic Office, 1963. exceed twenty knots twenty-three percent of the time during July. The trend for increasing winds results from the strengthening of the Bermuda High and a concurrent lowering of pressure in the Equatorial Trough. Trade winds during this period are interrupted by occasional hurricanes. September-November. During the fall, winds mainly blow from the east or southeast and speeds reach an annual minimum. Only seven percent of the winds exceed twenty knots in October. The low speeds result from a decrease in pressure in the Bermuda High with only a slight compensating pressure decrease in the Equatorial Trough. During this period, especially during late August through mid-October, the normal trade wind regime is often broken down by easterly waves, tropical storms and hurricanes. Storms and Hurricanes The major disturbances affecting normal trade wind circulation are caused by the passage of squalls, easterly waves, tropical cyclones and hurricanes. SQUALLS AND THUNDERSTORMS The islands are affected by numerous squalls which are often accompanied by thunder and lightening. In the vicinity of land, where the squalls are most frequent, cold air rushe~ down the mountain sides and moves out over harbors and bays with substantial force. These disturbances are most common in the summer months during periods of sultry weather and light variable winds. Because the squalls last only a few hours, they do not cause a pronounced change in the trade wind speed or direction over large areas. 24 Thunderstorms are localized wind storms associated with cumulus cloud types that may occur in all months but are most common between June and January. TROPICAL CYCLONES AND HURRICANES These storms are of great significance to the wind regime although they occur infrequently. When tropical cyclones sustain wind speeds that exceed 74 miles per hour, they are termed hurricanes. Tropical cyclones form or pass through the eastern Caribbean mainly from August through October. Peak activity is during September (Figure 22). The probability of tropical storms and hurricanes occuring in the islands at different seasons is given in Table 2 (Brown and Root, 1974). Annually there is an expected probability of one cyclone in sixteen years (Bowden, 1974). Since 1900, 24 hurricanes have passed within fifty miles of the Virgin Islands (U.s. Army, 1975.) Of these, the hurricanes of 1916, 1924, 1928, and 1932 caused the most damage. Hurricane paths that have affected the islands since 1876 are shown in Figure 23. STORM WAVES AND TIDAL FLOODING Tidal flooding, created by major hurricanes having a frequency on the average of once in 33 years, raise water levels in St. Thomas from five to twelve feet above normal. A six foot tide height would flood lower parts of Charlotte Amalie for 800 feet landward from the shoreline. A graph prepared by the U.s. Army Corps of Engineers (1975), showing the height of a hypothetical hurricane flood having a frequency of occurence of once in 100 years, is reproduced as Figure 24. Also presented is the height of the "standard project flood" which is defined as the largest tidal flood that can be reasonably expected to occur as a result of the most critical combination of con- d itions that are considered characteristic of the region, excluding extremely rare events. Besides flooding, damage to waterfront facilities and erosion of shores by storm waves can be heavy. Moreover, passing hurricanes may create a minus tide of as much as 1.0 feet below mean-'Iow water that can temporarily cause grounding of vessels in shoal water and exposure of tidal flats. 0 Catego,ies 1 and 11 ( 5forms) 14 ~ Categories III and IV C Hurricanes) 12 ...... 10 ~ ~ ~ ~ 8 ~ } 1 6 ~ ~ 4 "-r ~ 2 0-J 0 June July Aug Sept Oel Nov Figure 22. Tropical Cyclone Frequencies: Latitiude 150 - 200 N. From Deane, Thom,and Edmunds, 1973. TABLE 2 Occurrence of Tropical Storms and Hurricanes within 240 nautical miles of St. Croix. TROPICAL STORMS HURRICANES PERIOD OF HURRICANE SEASON July 6- Aug. 5 (31 days) (Inactive Early Season) Aug. 6- Sept. 30 (56 days) (Active Mid-Season) Oct. 1- Nov. 30 (61 days) (Inactive Late Season) Entire Season (148 days) Avg. No. Per Year 0.16 0.70 0.20 1.05 Avg. Interval Between Storms: Years 6.4 1.4 5.1 0.95 Occurrence Probability On Any Day In Period 0.50% 1.24% 0.32% 0.70% Avg. No. Per Year 0.05 0.85 0.13 1.03 Maximum number of Hurricanes and Tropical Storms in any year: 9 (1933) Avg. Interval Between Storms: Years 20.4 1.2 7.8 0.97 Occurrence Probability On Any Day In Period 0.15% 1.52% 0.20% 0.69% Minimum number of Hurricanes and Tropical Storms in any year: None (occurred in several years) Source: Brown and Root, 1974. N A T ~J 1908 .1960 19~ o C E AN 1931 1916 --------1932 A 1900 .1903 Figure 23. Hurricane paths that have affected the Virgin Islands since 1876. From U.S. Army, 1975. Nole ; To/",,/ heigl.hi. i,.."",ll..IcI. ; 1. A6frono"",~1 h. z.. Wind /-ide !S.W_ dr_J Figure 24. One hundred year frequency and standard project tidal flood stage hydrographs. From U.S. Army, 1975. Precipitation and Evaporation Rainfall in the islands is limited and variable. The amount of rain varies monthly, annually, by island and with areas on a given island. Average rainfall data, compiled from several years records at various stations, can be misleading in that it probably poorly represents the available precipi- tation at a particular area even over a year's time. The U.S. Virgin Islands receive an average of 41 inches of rain per year (Bowden, et ai, 1970). The wettest months are September to December. The dry season is February to July. St. Thomas, including Water Island and Hassel Island, receives about 42 inches. St. John receives about 47 inches. The larger cays probably average between 30-35 inches. A small area of Crown Mountain, St. Thomas averages slightly more than 50 inches. The eastern and southern lowlands of the islands generally are the driest and the central higher elevations wetter. Most of St. Croix receives 35-45 (average about 40) inches of rainfall a year. The northeast hills receive slightly more and Annaly, the wettest area, receives on the average 52 inches a year (Bowden,etal, 1968). In addition to sparse rainfall, dryness of the islands is heightened by rapid evaporation of surface and soil water by intense solar radiation and constant breezes, most marked on exposed coastal ridges. Spil retention of the sparse rainfall is hampered by the steep slopes which promote rapid runoff instead of infiltration and by the shallowness of most topsoils and their paucity of moisture-holding organic matter. In addition, plants remove mois- ture from the soil, pumping part of it back to the atmosphere by transpiration. Rainfall and evaporation are important in the coastal marine environment as they affect salinity, turbidity and other pollutants carried to the sea with stormwater. Most of the light, brief showers which fall are not sufficient to run off the land. This is primarily because the soil is almost always dry and rapidly absorbs these brief showers. During rainy periods when frequent showers may bring soil moisture to saturation, further rainfall runs off the steep slopes to the sea. I n flat areas, excess soil water may be able to percolate into the ground before running off. Vegetation, in addition to slope, is also important in determining the speed and extent of runoff. Plants help by in- terrupting the sheet flow of surface water, reducing its velocity and allowing more time for it to in- filtrate the soil. Plants can also absorb and tran- spire water back into the atmosphere. In addition, their roots help to hold the soil in place. Areas which have been stripped, cut or burned do not offer these advantages, and much less rai n is re- quired to promote runoff, which carries soil with it. Local bays receiving drainage from highly developed watersheds (St. Thomas harbor, Chris- tiansted harbor, Benner Bay and Water Bay, St. Thomas) are now subject to discoloration and siltation following good rainfall of an hour or more, while most other drainages do not shed water as readily. Historically, flooding of the coastal zone was infrequent and probably had negligible conse- quences for marine organisms. The lack of rivers was fortunate in the sense that coral growth was not hampered by low salinity, turbidity and other terrestrial contaminants which restrict reef growth around larger islands and continental coasts. Without constant or frequent pollution by fresh water, silt and other pollutants, clean-water com- munities were able to develop almost everywhere around the islands and could recover from the brief impact of periodic torrential rains. Today, fresh water (and a wide variety of transported pollutants) reaches the coastal sea quicker, more frequently, and in greater amounts than in the past. The frequency and severity of these occur- rences has begun to be reflected in the condition of the affected environments. In Christiansted and St. Thomas harbors, as well as Benner Bay and Water Bay, and to a lesser degree Cruz Bay, St. John and Stumpy Bay, St. Thomas, turbidity_ and bottom silt have increased noticeably in the past several years, and areas of coral and marine plants have been reduced. These trends in the en- vironment result from essentially permanent changes in water quality, in part, as a result of frequent rain induced runoff. However, most of 28 these areas are also subject to stress from other sources, i.e.,. dredging, marinas, boat traffic, sew- age). Rare inundation by fresh water, even without large amounts of other pollutants, can damage or kill most marine organisms. Natural forces usu- ally return normal salinity levels in a matter of days in most localities, and the biota can recover. However, increasing frequency and severity of these episodes will eventually modify the impacted ecosystem. Geophysical Factors Bathymetry The northern Virgin Islands lie on the Puerto Rican Plateau, a submerged plateau defined by the 100 fathom (183 meter) depth curve. This plateau is like a small continental mass surrounded by steep slopes and deep water (Dammann, 1969). The Puerto Rican Trench, with depths to 27,500 feet (9,166 meters) lies to the north, the Virgin Islands Basin with depths reaching 13,500 feet (4,500 meters) lies to the south, and the St. John ~" .. ~' and Anegada Passages with depths of about 6,000 feet (2,000 meters) lies to the east (Figure 25). The plateau mainly consists of an insular shelf with depths less than 300 feet. St. Croix lies on a submerged ridge which is se- parated from the Puerto Rican Plateau by the Vir- gin Islands Basin. The ridge is broken by the J ungfern Passage to the west and by the St. Croix passage to the east. The sill depths in these pas- sages reportedly control the movement of deep water between the Atlantic Ocean and the Carib- bean Sea. \ Figure 25. Bathymetry of Virgin Islands basins and plateaus. Depths in meters. From vanEepoel, et aI, 1971. The slopes that border the plateau and ridge and lead down into the adjoining basins or passages are commonly long and relatively straight. Several are more than ten miles long. Locally, there are occasional offsets on the slopes more or less at right angles to the slopes, e.g., off the north coast of St. Croix. Topographic evidence suggests the slopes are offault origin. They are relatively straight, steep and parallel known major faults on land. Despite the relatively smooth form of the depth curves in Figure 25, the slope contains many local irregularities on its surface. Relief of the slopes is known mainly from a study (van Eepoel, et af., 1971) to determine the feasibility of laying sub- marine cables between the islands. Reportedly, the slopes are a region of great relief with thick sedimentary deposits filling the valleys between peaks. The steep slopes and probably existence of a westerly bottom current have contributed to deposition in the valleys. These deposits are be- lieved to consist of turbidities, i.e., deep sea de- posits laid down by action of turbidity currents. The records also show evidence of slumping. A detailed description of downslope movement in submarine channels off Cane Bay, St. Croix is given by Multer and Gerhard, 1974. shelf edge Bathymetry of the insular shelf is' best known from a reconnaissance study of the shelf south of St. Thomas and St. John (Garrison; et aI, 1971). This shelf has an average width of 22 miles (14 kilometers), and it slopes about 16 meters per kilometer from the shoreline to 30 meters depth. West of Charlotte Amalie, the pro- file is smooth and regular (Figure 26). By contrast, profiles to the east are broken by a few hills and ridges that rise about 36 feet (12 meters) above the floor. Most of these features are oriented northeast-southwest and represent fault scarps and partly buried reef masses. Some of the faults are associated with faults mapped on the islands. Another prominent feature of the shelf profile is the serrated ridges and valleys that run along the edge of the shelf with a relief as great as 90 feet (30 meters). These features represent drowned reef masses believed to be active during Pleistocene low sea levels. Their relief is greatest on the eastern portion of the shelf particularly along segments that are oriented northeast-southwest. This orienta- tion probably allowed optimum exposure to nutrient-bearing currents which were from the southeast essentially as they are today (Garrison, etal, 1971). charlotte amalie > --------------------.. - ... - .... ----.... ---.---------------1 Figure 26. st. james bay> shelf edge o I n.m . . _---------_._--- Profiles of bottom topography across the Virgin Islands shelf south of St. Thomas and St. John. From Gar- rison,etal, 1971. For location, see Figure 25. Sediments of the shelf surface mainly consist of calcareous sands inshore and carbonate nodules plus coral rubble offshore, below 34 meters. The nodules are less common at shallow depths because wave action tends to break them down into sand. In a few locations, the underlying igneous base- ment rocks protrude above the shelf surface in the form of small islands or shoals. According to Garrison, et ai, (1971), blanketing sediments are relatively thin, and thus the subsurface struc- ture "shows through" as lines of low escarpments or reef-capped shoals. Inner parts of the shelf that surround St. Thomas and St. John exhibit a flat floor or terrace at about the 60 foot depth. On the south coast of St. Thomas, the terrace extends about 0.8 mile offshore, whereas on the north coast and elsewhere, it is narrow, less than 0.3 mile. The relatively flat surface most likely was formed by wave ero- sion during Pleistocene lower sea levels. Inner parts of the shelf are extensively broken by reef masses or dotted with heads of living coral. Many of these inshore reefs merge with living fringing reefs on island headlands. Consequently, most of the in- shore bathymetric curves of minus 30 feet or less tend to follow the shoreline. Along. the south coast of St. Croix, the inner shelf is very shoal, less than 36 feet, and varies from 0.5 mile wide in the east to two miles wide in the west. Reefs form elongate barriers in the eastern part and large patch reefs oriented in lines paralling the coast in the central and western part. Elsewhere, the inner shelf consists of coral sand interspersed with grass beds. Seismic Activity Since the Caribbean island arc marks a transition zone between continental and oceanic crustal masses, it is a nearly continuous belt of shallow focus earthquakes. Although seismic activity was more frequent in the vicinity of Hispaniola durin!?: 1950-1964, most shallow focus earthquakes in the region are distributed at random throughout the belt. Figure 27 shows the location of earthquake epicenters in the region together with related volcanic and storm surge activity as recorded by the U.s. Naval Oceanographic Office (1963). Earthquakes are generally more frequent in the vicinity of volcanically active islands such as Guadeloupe and Martinique. In the Virgin Islands region, Sykes and Ewing (1965) located the hypo- centers of earthquakes occurring between 1950 and 1964 with a magnitude greater than 3.5 Richter. At this magnitude, which is low to moderate, one earthquake occurs once every three years. Most of these probably occur along the Anegada fault which trends northeast from a position south of Puerto Rico, continues north- east through St. John Passage and Anegada Passage and terminates in the Puerto Rican Trench. Large sea waves of extraordinary length, often called tsunamis, .have been reported for the area. In deep ocean water they reach 100 miles in length from crest to crest, but their height from trough to crest is only a few feet. When a tsunami enters shoal waters around coasts, the speed decreases but the wave height increases, especially in broad bays. Tsunamis are associated with submarine seismic disturbances, either an earthquake along a fault or an explosion of a volcano. Although most local tsunamis originiate in the Caribbean earth- quake belt, a few arrive from the mid or eastern Atlantic Ocean. The Lisbon, Portugal earthquake of 1755 created a damaging seismic sea wave throughout the West Indies. Observations are spot- ty, but small waves seem to occur about every ten or fifteen years (van Eepoel, et aI, 1971). A preliminary study of tsunami frequencies by Deane, et al (1973) for the period 1965-1969 indicates a tsunami wave having a maximum two meter wave height will occur once in 75 years. 15' 13' 12' Figure 27. BY EARTHQUAKES AREAS IN WHICH EARTHQUAKES HAVE BEEN FELT AREAS IN WHICH SEAQUAKES MAY BE EXPECTED ISLAND VOLCANOES LOCALS OF REPORTED SUBMARINE VOLCANOES 'MUD VOLCANOES AND DISAPPEARING ISLANDS COASTAL SECTORS ~ROM WHICH TSUNAMIS AND STORM SURGES HAVE BEEN REPORTED< ". 65' 20' ". II" 11" 15' 12' II' .64' 63' 61' 61' Distribution of Caribbean Seismic and Volcanic Activity. From U.S. Naval Oceanographic Office, 1963, 32 Marine Ecology Fisheries The striking similarity of various studies of fishing in the Virgin Islands going back over forty years emphasizes how fisheries have been relatively static in a period of generally rapid change. The outboard motor, galvanized mesh fish pots, and nylon nets have largely replaced sails, woven wicker pots, and cotton or hemp nets. Diving has acquired greated importance as a fishery method. Catches have climbed gradually in association with improved technology. Fishery resources particularly, high value semi-sedentary organisms such as conch, whelk, mangrove oyster, etc. - have been reduced to very low densities in accessible area near popu- lation centers. As the economy and population have burgeoned, the demand for fish and the price per pound have climbed, but the number of fishermen has not changed significantly, except for slight temporary increases during periods of slack in major economic activities (tourism, construction). Personnel from the Virgin Islands Bureau of Fish and Wildlife report such an increase in local fishermen currently. The retarded growth (or decline in some locales) of fishing is part of the general decline of fisheries and agriculture in the West Indies, but specific constraints on fisheries will be treated herein. FISHES The limited pelagic fish resources (billfish, tuna, wahoo, etc.) of the northern Virgin Islands support a sport fishery along the edge of the shelf, but repeated exploratory fishing has made it clear that stocks are not sufficient to support an indus- trial fishery. The primary commercial resources are demersal fish ( and invertebrates) associated with coral reefs and other, usually irregular, "live bottom." A secondary finfish resource is inshore schooling fish, generally jacks, which are tradition- ally taken with haul seines. Fish tend to be concentrated around small irregu- larities at the bottom which provide refuge. Many of the irregularities in the open shelf and its elevated margin are coral reefs produced at lower sea levels during the Pleistocene and now only veneered with living coral or other organisms. 33 Even though primary productivity of these deeper reefs (below 20 fathoms) is lower than shallower reefs, the areas are extensive and currently little exploited. Thus, substantial stocks of fish are present. On deeper reefs, the herbivores (surgeon fish, damsel fish, parrot fish, etc) which may dom- inate shallow water trap catches are less common, and catches are more often snappers and groupers which bring a higher price. Beyond the shelf edge reefs, the bottom drops to 100 fathoms or more before becoming gently sloping again. On the south side of the Virgin Islands plateau, the "drop-off" is often a sheer wall from 40 to 100 fathoms, but there are areas, particularly along the northern edge, where the slope is relatively gradual down to 80 fathoms or more. The resources of the shelf edge zone are considerable (primarily several species of red shapper and grouper), but the rough seas and the greater working depths demand a substantial increase in capital investment in gear and boats for effective fishing. Finfish stocks alone among the living marine resources offer long-term potential for increased yields, primarily by fishing stocks which are now only lightly exploited. Bar Jack or Carang (Caranx ruber) OTHER VERTEBRATES Two other groups make up a small part of the biomass of marine vertebrates on the Virgin Islands shelf-sea turtles and marine mammals. Marine mammals (here whales, dolphins, and por- poises) are not currently regarded as an exploitable resource by Virgin Islanders, but the establishment of a system for reporting sightings or strandings would be of scientific interest. Among these large marine mammals, hump backed whales, pilot and bottle-nose dolphins migrate through our waters in the spring. Sea turtles have been a traditional fishery in the Virgin Islands, and, although relatively few people still fish for them regularly, any turtle encountered incidentally is caught. Islanders still seasonally monitor beaches where turtles are known to nest in order to collect eggs and perhaps capture the nesting female. Unlike lobster or other animals with pelagic larvae, once a sea turtle nesting colony is extirpated, it is probably, in human time frame, gone forever. Sea turtle species in probable order of abundance in local waters are: Hawksbill, green turtle, logger- head. Despite its relative abundance in the Vir- gin Islands, the hawksbill turtle is seriously endan- gered world wide, by a combination of hunting for food and shell. A UNDP-sponsored (United Nations Development Programme) crafts training project in Tortola, British Virgin Islands has contributed to the general resurgence of sales of hawksbill shell artifacts. In the U.s. Virgin Islands, the hawksbill and leatherbacks are completely protected (and the green and loggerhead may be shortly) under the federal Endangered Species Act. Consequently, it is illegal for a tourist to purchase hawksbill products in the British Virgin Islands or elsewhere and import them into the United States. Seizure of endangered species products in U.S. Customs is becoming increasingly likely. The stocks of hawksbill shell being sold in St. Thomas shops were confiscated years ago. Black Grouper (Mycterouerc~ bonaci) SPINY LOBSTERS In the Virgin Islands, the spiny lobster fishery is second only to finfish in economic importance. 34 The current fishery is a relatively young one which has developed in response to tourist demand and with improved transportation providing access to more distant markets. Conversations with older Virgin Islands fishermen suggest that spiny lobsters were not formerly relished as food by most of the residents of the English-speaking Caribbean, but, like conch, they were abundant and easily caught and made excellent bait for traps or handline fish. Currently, lobsters are fished by traps and by divers using wire snares. Relatively small amounts of lobster per haul are caught in traditional fish traps, but specialized lobster traps catch virtually no fish, and there is no clear evidence that they are superior for catching lobsters in this region. For most fishermen, it is a better strategy to set fish traps. A few Virgin Islands fishermen, who have made a substantial investment in large boats and power hauling equipment, have also tried using substantial numbers of lobster pots. Many have eventually rejected them. The average annual catch per boat of lobster by St. Thomas-St. John fishermen using fish traps and fishing 5.8 days/ month is reported at 200 pounds (Olsen, 1975) - a yield of 0.17 pound/lobster/trap/haul. Free diving for lobsters requires relatively little capital investment (in addition to a boat) and can provide substantial cash rewards for even weekend efforts. Diving for lobster is the primary employment for only a few Virgin Islanders. For a relatively small sample of boat days (21) distributed over nine months, the mean catch by St. Thomas fishermen. diving for lobsters was 44.7 pounds/boat/day (Olsen, 1975). Lobster landings in the U.S. Virgin Islands in 1967 were 85,900 pounds from U.s. Virgin Islands fishermen and 18,640 pounds worth $15,844 (at $0.75/pound) from British Virgin Islands fishermen (Swingle, et ai, 1969). Most local lobster were and are sold whole. If 1967 imports from non- Virgin Islands sources of lobster tail are multiplied to approximate live weight, local lobster made up approximately one-fourth of the total consumed. Thus, a substantial demand exists, but marketing problems, as usual, are serious. In the U. S. Virgin Islands and elsewhere, contractual buying by commercial consumers of lobsters (restaurants, hotels) assures a steady source of supply in the face of fluctuating availability of local product, but this means that the local fisherman, parti- cularly the one who dives for lobster on occasional days-off, has no assured market and may actually lose his catch to spoilage before he can sell it. A substantial (but unknown) proportion of the de- mand in St. Thomas is now supplied by small- scale entrepreneurs flying lobsters in from nearby islands. Kingfish (Scomberomorus cavalla) QUEEN CONCH Aboriginal conch shell mounds on Anegada and elsewhere in the Caribbean attest to a long history of exploitation, but despite its continuing impor- tance, relatively little is known about the status of conch populations in the Virgin Islands. Most of our limited knowledge of the biology of the queen conch (Strombus gigas) is contained in a paper by Randall (1964) based on work on St. John. Adult conchs generally occur in areas of low wave energy in beds of sea grass (admixed or some- times dominated by algae), on open sand, and on rocky pavements veneered with sediment and an algal mat. Adult queen conchs are not frequently encountered below 80 feet, roughly the lower depth limit of sea grasses. Juvenile conchs generally occur in shallow, rel- atively quiet water (less than 40 feet deep) on coral rubble, sand or sediment with sparse growths of sea grasses. Juveniles smaller than about three inches are rarely, if ever, found and are presu med to be buried in bottom sediments most of the time. Conchs feed on plant material (prim.uily soft algae) aoo organic detritus. Female conchs deposit large masses of eggs in open sandy areas. These hatch releasing larvae with a pelagic life of about three weeks. Like Virgin Islands lobsters, unless larval adaptations to local water circulation patterns deposit them back more or less where they hatched, conch populations in one area are probably dependent for recruitment on larvae produced in some distant unknown area and more directly on the vagaries of water mass movements. For reasons and in patterns as yet un- known; conchs are migratory and seem to move in groups. High catches may be made one year in areas which yielded increasingly fewer conch for the preceding several years. Therefore, any efforts at monitoring the fishery must be suffic- iently prolonged to differentiate low yields from natural causes and those from over exploitation. Queen conch are collected in the Virgin Islands almost exclusively by diving, generally without compressed air. Where conch populations have been more or less exhausted in free diving range (to 50 feet), a few people have found it profitable to dive for them with compressed air. These deeper areas are less productive, and probably conch growth rates are lower. I n the past, they consti- tuted a refuge which by migration probably provided some gradual input into the more heavily lexploited inshore waters. Thoroughgoing extraction by SCUBA diving bodes ill for anyone still engaged in low technology, subsistence fishing in the same or adjacent areas. In 1974 the four major food wholesalers in St. Thomas were importing 35,000 pounds per year from dealers in Florida or Puerto Rico at roughly $0.65 per pound delivered. At that time, little or no local conch appeared to be moving through commercial channels (Stott ms .• 1974). Most of the imported conch in 1974 and the local conch in 1967 was used by commercial outlets (restaurants, hotels). There is clearly a strong market for conch, but consistent availability is important for large scale commercial outlets. The quantitative data are not available, but there are numerous instances in the Caribbean of eco- nomically serious local depletion of conch popu- lations (e.g., the Grenadines). There are suggestions of similar trends in the Virgin IsJana$, with ex- ploitation converging on An.egada, the only island with fairly extensive habitat and remaining stocks of conch. Intensification of the existing conch fishery should not be contemplated until a serious eval- uation of stocks is undertaken. This may require an investment of man days seemingly dispropor- tionate to the commercial value of the fishery, but it should be remembered that conch have some traditional subsistence role. The indirect costs (in imported food purchased, for instance) of eliminating (or at least making inaccessible) the resource for some years are rarely properly tallied up against the small gains in cash income. Bh:.e Runr.er (Caranx fusus) WHELKS The whelk, wilk or West Indian topshell (Cittarium pica) is a large marine snail formerly common on exposed rocky shores in the Virgin Islands and elsewhere in the West Indies. It is a traditional food in the Virgin Islands and is the only gastropod, other than the queen conch, of any general eco- nomic importance. The narrow habitat zone occupied by whelk extends from the upper limit of rocks constantly wetted by wave splash to perhaps five feet (gen- erally less) below the surface. The upper limit of whelk distribution probably is controlled by Jessic'ation and availability of algae for food, and the lower limit by predation. Generally, smaller animals occur in the upper tidal zone, and the largest animals (four to five inches basal diameter) occur below the low tide mark in crevices in areas of heavy surge. Whelks are harvested by walking along rocky shores and picking them from the rock surface or by snorkelling near steep rock shores. The ease and lack of equipment required for gathering whelks partly accounts for their virtual disappear- 36 ance near populated areas. Whelk larvae are pro- bably at least briefly planktonic, but marking experiments suggest that after juveniles settle out of the plankton, they move only short dis- tances. More mobile animals (fish, lobsters, and even conch) may disperse from unexploited areas into those which have been heavily fished and. conse- quently maintain an exploitable population. But in areas depleted of whelk, it will take a number of years for newly recruited juveniles to grow to exploitable size. The only paper on whelk biology useful to manage- ment is by Randal (1964), which includes studies on distribution, diet, size structure, growth and reproduction in a population on the south shore of St. John, U.S. Virgin Islands. Using boats and/or snorkel ling gear to collect in previously unexploited areas (rocky cliffs inacces- sible from land or the shores of isolated cays), it is possible to collect commercially significant quantities of whelk. Swingle, et aI, (1969) reported that 22,305 pounds of whelk ($8,900 at $0.40 per pound) were sold to commercial outlets in the U.S. Virgin Islands in 1968. No whelk were imported from outside the Virgin Islands. Presently, at least one retailer is importing from other islands. Probably collection for home use is of equal or greater magnitude. In terms of catch per unit effort, each of six U.S. Virgin Islands fishermen reported collecting a mean of 500 pounds/day of whelks for a total of 15 days (Olsen, 1975). Again, without some stock assessment and moni- toring of catch, whelk collecting should be dis- couraged as a means of diversifying the fishery. The pelagic phase of the life cycle, secretiveness and a preference for rough water on rocky coasts means that some whelks will always be present, if unexploitable, but some decision needs to be made whether whelk are to be viewed as a subsis- tence or "recreational)) resou rce or one to be exploited commercially. In the event of the develop- ment of a regulatory mechanism, any number of arrangements are possible, but the simplest for optimizing yield will probably be a minimum. size. If the subsistence aspect is important, a catch limit is also useful. CIGUATERA FISH POISONING Fish poisoning is a relatively common event in the Virgin Islands and, in addition to the public health problem, constitutes a major impediment to fishery development, particularly in expanding marketing to the tourism sector. In St. Thomas, any mass poisoning resulting from sales of toxic fish to residents temporarily depresses the market for local fish. The general strategy of fishermen is to avoid certain localities, or particular species in particular localities, which are traditionally known to harbor poisonous fish. Incidental poisonings of non-residents unfamiliar with ciguatera are relatively common (bare-boat charterers, down-islanders, etc). Fishermen are also poisoned by taking a chance eating a fish they are unwilling to sell. However, toxic local- ities are subject to little fishing pressure, and a somewhat unscrupulous fisherman can readily make a good catch and substantial income if he is willing to risk poisoning his customers. As popu- lations rise in the Virgin Islands and community cohesiveness declines, this problem is likely to increase. Any middleman (e.g., a cooperative marketing operation) can fall victim to this unless some system of fisherman accountability is estab- lished. Many potential commercial consumers of local fish in 51. Thomas avoid it not only because of high price for unprocessed fish, but because of concern about poisoning their guests. Presumably part of this is reputation and other concerns about liability. The Island Resources Foundation of St. Thomas maintains an epidemiological register of intoxi- cation incidents, and a laboratory at Bitter End, North Sound, Virgin Gorda in the British Virgin Islands is surveying the distribution of toxic fish and collecting them in order to extract and charac- terize the toxin. Work is also going on in other parts of the world, but despite considerable effort ':).7 (Brody, 1972), a summary of ciguatera in the Vir- gin Islands including lists of toxic species}, there is no simple way to determ ine if a fish is toxic. Great Barracuda or Barra (Sphyraena barr8.cuda) PRODUCTION AND HARVESTABLE YIELDS The preceding pastiche of biology, ecology, exploi- tation history and qualitative recommendations are intended to give a predominantly biological overview of the primary fishery resources of the Virgin Islands shelf which are accessible to current fishing gear and methods. The basic objective of fishery management could be described as ob- taining the greatest yield of useable product at the least effort over some extended period of time. It is also desirable that the yield be, if not uniform, at least predictable through time so that large amounts of effort are not wasted at the wrong time looking for resources that are not there. As pointed out in the individual resource discus- sions, the life histories and primarily the lower reproductive potential of marine mammals and turtles make their management very different from that of most fish and marine invertebrates. This latter group, including virtually all of the species exploited in the. Virgin Islands, produce large numbers of planktoni~ larvae which drift for weeks or months before transforming into some- thing resembling the adult form. In the case of reef associated organisms, they then may establish themselves in some possibly permanent abode on the bottom. The survival of the dispersing planktonic larvae is related to nutrient availability, temperature, and related physical parameters in the waters in which they drift. Thus, the number of new recruits annu.ally to a fish or lobster popu- lation is not dependent on local egg production. There are some unexplained activities of tropical fish which make one .somewhat uneasy about the completeness of the picture presented b,y these assertions, but they are, in the main, true. Though over-exploitation of a fish stock is possible, planktonic larvae and wide distribution make biological extinction of a species by traditional fishing methods extremely unlikely. However, the substantially lower reproductive potential of marine mammals (for many one young/2 years) and sea turtles (a few hundred eggs/3-4 years) make it quite possible that continued or expanded harvesting will lead to biological extinction within a region. Geographic extent of habitat, mobility and/or site fixity of a species also affect the vulnerability for local stock depletion by exploitation. Contrast the restricted habitat and low mobility of whelks with coral reef fish which are relatively rapidly recruited from adjacent areas to occupy desirable habitats from which other fish have been caught. Hagfish (Lachnolaimus maxi~) The growth of most animals asymptotically ap- proaches an upper limit; thus, growth per unit time decreases. Any fish population is also subject to some mortality, largely through predation and fishing pressure. The mortality is reflected in the size structure of a population (many small fishes versus few large ones). Using basically this infor- mation and some assumptions which are reason- ably well founded, it is possible to calculate a minimum size limit which will provide a maxi- mum yield. Market preferences ar}d available gear may require modifying the figure somewhat, but it may also turn out that some fisheries are, in a sense, self-regulating, in that fish are caught only at or above the recommended minimum. The issue that then remains is whether the regulatory agency proposes to control the number of fisher- 38 men between whom the available catch is dis- tributed or will permit economics to take its course. In a mUlti-species fishery, like a coral reef trap fishery, interactions may develop, i.e, if heavy selective fishing removes large predatory species like snapper and grouper, their prey species, including smaller herbivorous species and lobster, may increase in numbers. PECULIAR LOCAL RESTRICTIONS Basic restrictions on the development of large- scale fisheries are imposed by the size of the Vir- gin Islands Plateau and its geological irregularities. While improvements in technology can no doubt increase the yield of various commercial species, the relatively small plateau areas available for fishing precludes sustained production of vast quantities of most species. Also, while most of our fishery is associated with reefs, the irregular, hard bottom of most of the Virgin Islands shelf and the concentration of fish in areas of rugged physiographic relief makes trawling impractical and interferes with the use of bottom setlines, mUltiple traps on a single ground- line, and stationary nets of various sorts. The low productivity of the fishery (both in total. catch and catch per unit effort) is also a reflection of the naturally low primary productivity (little growth of phytoplankton, the base of oceanic food chains) of Virgin Islands waters. Most primary production inshore is benthic - coral reefs, algae and grass beds - and most fish are caught in these areas. Much of the open shelf of the Virgin Islands is relatively flat but too deep (thUS the light is too dim) for sea grasses or vigorous coral reef growth. Thus, while there is room for improvement in fisheries, local conditions which limit production and harvesting do not allow development of a fishing industry akin to that of continental shelf areas. OTHER COASTAL WILDLIFE In addition to strictly marine species, other typical Virgin Islands wildlife are found in coastal areas. Many of our birds depend heavily on mangrove areas and offshore cays as feeding and nesting grounds. The mangroves are apparently the major nesti ng areas of the van ish i ng wh ite crowned pigeon. Most of the doves which feed and are hunted on St. Thomas nest on the off-shore cays. The common brown pelican - a permanent resident - is in danger of extinction but nests on some of the cays. Other permanent resident sea birds are brown boobies and frigate birds. Laughing gulls, terns, bluefaced boobies and tropic birds come here to nest on the cays. Coastal mangroves provide pro- tective habitats for several other birds and reptiles (lizards and snakes) which are infrequently seen elsewhere. Some offshore cays appear to be the last outposts of rare lizards, skinks, and snakes. Coastal salt ponds are feeding areas for several kinds of wading birds, especially when they are closed from the sea and the birds do not have to compete with invading fishes for food organisms living in the pond. Queen Triggerfish or Old Wife (Balistes vetula) COASTAL AND SUBMARINE HABITATS These natural systems, separately and in combin- ation, perform countless valuable functions for man at no cost, drawing energy from the sun. They buffer storm winds and waves, stabilize and pro- tect the shoreline with its expensive manmade infrastructure and facilities, purify water and offer an immense variety of diverse vistas and interesting wildlife and vegetation. The habitats 39 and their associated processes support the safety, health and welfare of every Virgin Islands resident and must be preserved. Different segments of each island contribute in varying degrees to each parti- cular function, and these elements are treated separately. The following sections describe the major coastal and shallow water marine habitats of the Virgin Islands (to 10 fathoms depth). These include beaches, rocky shores, salt ponds, mangroves, coral reefs, sandy sea beds, grass beds, and the offshore cays. Cays, more than other small oceanic islands including the three larger Virgins, are "coastal" in entirety. Because of their very small size, the entire area of acay is continually subjected to the influences of oceanic winds and salty air. Also because of their small size, a much higher percentage of their area is bathed by the sea in comparison with larger land masses. Almost all have salt ponds which often occupy a large per- centage of their acreage. These factors are strongly determinant of the physiography, hydrology, soil, vegetation and fauna of the cays. Therefore, it is important to include them in the discussion of the coastal zone of the Virgin Islands. The discussion of each coastal unit procedes from description of characteristic physical and biological processes. Attributes, use options and use limita- tions are based on these natural characteristics. Figures 28 and 29 present the distribution of each habitat type and highlight other pertinent infor- mation. BEACHES Beaches are parts of the shore that are covered with sand, gravel or debris and which are covered and uncovered by the tide. Beach sediments are highly mobile, and thus beaches are constantly changing their form and dimensions. Beaches are mainly the end product of the inter- play of water movements and sediment supplied by cliff erosion or from coral reefs. Beach organ- isms, however, also contribute to the supply, erosion and consolidation of beach sediments. Beach sediments of the Virgin Islands consist of a variety of materials. They contain within them evidence of their origin, either terrigenous or marine. SOURCES OF BEACH SEDIMENT The tetTigenous material consists of minerals either eroded from cliffs or eroded from soils that are transported to the shore by streams. The terrigenous components typically consist of quartz and feldspar which are light-colored com- ponents. Coarse gravel and boulder material is usually of terrigenous origin, but cobbles often consist of coral debt·is. The marine components consist of fragments torn from coral reefs or fragments of shell and algal bits thrown up from the nearshore bottom. They are composed of calcium carbonate which imparts a light color to the sand, commonly white. Coral particles are the main component of island beach sand, but the rate of production of coral sediment supplied to a beach is generally low. Calcareous algal particles as Halimeda and Corallinacaea also conuibute to beach sand. Algal sediments are pro- duced faster, but they are exceedingly brittle, readily broken at each joint, and reduced to a fine sand or silt which is easily transported away from a beach. Beach stability, therefore, depends on a supply of sediment either from the land or from the sea which is the main source. Consequent- ly, most beach sands are a mixture of different types of material that varies in size and compo- sition according to its source and rate of supply as well as according to the wave and current pro- cesses acting on it. Beach Processes in Profile Most beaches are fashioned into a sloping foreshore and a flattened backshore or berm (Figure 30). The foreshore lies between the low water level and the berm crest, whereas the berm lies between the berm crest and the coastline beyond the reach of ordinary waves. The berm height gives an estimate of the height of storm waves that can be expected. The beach is backed by a cliff or low dune ridge whereas seaward it faces a shallow nearshore bottom fronted by a coral reef. The interplay of waves and currents with different types of beach materials produces distinct profiles. The high energy of wash and backwash acting on windward facing coasts or sides of projecting headlands produces steep beach foreshores and narrow berms. Sediments, too, respond to the high energy by accumulating as coarse sand, gravel or coral debris. Beach-rock is often exposed in lower parts of the profile. Beach profiles not only change from place to place but also with time at one place as wave energy changes from season to season. The foreshore is continually adjusting its shape in response to variations in wave height, wave length and direc- tion. Thus, high energy waves of "northerners" acting on a beach will erode the foreshore producing a steep slope and narrow berm (Figure 31). Erosion is also indicated by undermining of trees, exposure of beachrock and a steep beach face (Figure 32). When average waves of less intensity act on the same beach, they tend to deposit sand and build the berm seaward producing a gentle slope. These profile changes reflect the onshore-offshore shuttling or exchange of sand between the beach slope and the inshore. In the process, some of the sediment is lost to deeper water; some is pushed landward across the berm to form dunes or over- wash deposits. For another part, the sediment is carried laterally along the beach. Changes in the beach profile are indicated by the following features. Numbers refer to features in Figure 31. 1. The width of the berm is wider in summer than in winter. Accretion is indicated by several berms. I i "',:(fj) ,/:' ,. \ , I \ t" '"\ ./ // f \ \ i ,; / \ '. ,/ : i \ :' ,,/ I / 'Q ~ , ~ "" , \ \ \. " ", .... \ '\ ... .. '\ ..... \ , '"" III ,~ 1/1 j ~ j ~ tl i )\ It .:t. J. \I )\ e t It 1 ~ l ~ 1 ~ t 0.. ~ Q\ l } ::: i l \I) .3 ~ t \ \ @ \ 1 . \ ...... . \ ~\ 'lIJ' \ \ .. ' .t j ,~ ~ j j 1 ~ i ~ ..t l r 6 '0' ~ j ~ ~ 'f' ~ ~ 'q: ~ : " <)+0 i~~i Fig 29 Coastal and Submarine Habitats. St. Thomas and St. John L.send ".- 9!!! ~ ,-J ~ ~ ~~. <> + o Sle.t!p ~':I ...noires. i.e>- ~dle/ rocky 6100 ...... 5 S-IF F-"""''' Het17grov41S HClll7lnO<- ~_"., .. II~, ",ien.J I!Jee,ch !lee.! Ar_ of 17'517 roduc.:lrvity Unl'lus 0'-_'- ~ under 1S~reS$ nA 'V .shelf r'''''"3 <) 5"'-'f -.Ig- fl."'i"!'f v 'II' S .... ~ S"""'3 TORTOLA <> :5"'~1J ~ Ii""i,,:! 'V ~ <- coa.t ---1- backohor. _,....-, lo",.hore_l_ nearshore I ' I I , I ;">"'>~!Ii'OIo. I dune / breaker - - - _. - ~ ~~ --- -high wate water Figure 30. Beach profile showing beach terminology and component parts in relations to high and low water. Figure 31. High energy winter profile and moderate energy summer profile (dotted). Modified from Environment Con- sultants, 1969. 2. A sharp beach face or scarp indicates beach is undergoing erosion under prevailing waves. 3. The shoreline moves with each wave. Erosion varies with wave height and period. Steepness of the foreshore varies with wave height and permeability and coarseness of the sand. 4. Longshore troughs and bars develop in winter as beach sand moves off-shore. 5. Base of dunes is steep when beach undergoes eroison during high store tides. Trees and banks may be undercut and beach rock ex- posed in foreshore (Figure 32). By contrast, the moderate energy of swash and backwash acting on leeward coasts or heads of bays produces gentle beach foreshores and wide berms. Sediments are typically fine-grained carbonate sand. Beach Processes In Plan When waves approach the beach from an angle, the water runs up and over the sand at an angle, but then recedes at right angles to the shore. Consequently, sand which is carried by the re- ceding wave is transported downdrift of its origin. Called littoral drift, this transport is a major factor in determining beach width and slope. In the breaker zone, the residual angle of wave approach creates a current along the shore called a littoral or a longshore current. The combined I ittoral transport is sign ificant in beach stab il ity on relatively straight north and south coasts since these coasts are aligned approximately parallel to the direction of wave approach. As a result of waves approaching the west coast of St. Croix at an angle, particularly during "northerners", sand is continually transported southward by the littoral drift. Thus, the northwestern beaches are narrow and eroding while the southwestern beaches which receive the sand are broad and accreting. Along the south coast a littoral drift directed westward also contributes sand. The combined transport from the north and the east provides an excess amount of sand to the region and thus tend to extend Sandy Point seaward. Similar lateral movements of sand occur on a 46 single beach as the direction of predominate wave approach changes. For example, at Chenay Bay, which faces northwest on the north coast of St. Croix, swells from the north and northeast drive sand eastward along the beach, whereas local trade wind waves drive sand to the west (Environ- ment Consultants, 1969). During winter "northern- ers", when swells gain height and become more frequent, this change results in a reversal in the net direction of sand transport: east in winter and west the rest of the year. The lateral movements of sand result in a change in the width and type of sediment residing on a beach. In general, sediment becomes finer with distance away from a headland, i.e., downstream from its source of supply, and also away from the transporting energy source. Consequently, the beach sediments like those at Botany Bay (Clark, et 01, 1964 - 65) are graded along their length from relatively coarse gravel to coral rubble and finally to sand at the other end. Similarly, beach deposits are relatively narrow and thick on the coarse- grained end and wide and thin on the fine-grained end, i.e., away from the source. The deeply indented or pocket bays of St. Thomas and St. John display little change in plan. Most changes are onshore and offshore, and many of these beach faces show little seasonal change. Sand transport is largely within the bay itself, and the rates of sand input, transport and loss are more or less in equilibrium. There is little exchange of sediment from bay to bay around the enclosing headland. Typically, littoral drift and longshore currents along sides of the bays drive the sand inward where it accumulates near the current convergence at the bay head. Th is is the case for Magens Bay beach (Figure 33) where the convergence is marked by widening of the berm and seaward extension of the shoreline in central reaches of the beach. (Robin- son, T., et 01, 1970). Part of the sand may be carried toward the sea by rip currents directed offshore from the bay head. Another portion of the sand may be driven back ashore by waves acting on the central bay floor. Some bays show a long-term history of accretion at the bay head, particularly where streams contribute sediment to / winter storm erosion erosion level rock Figure 32. Summer and winter profile in relation to beach rock. Modified from Environment Consultants, 1969. the nearshore. zone. By contrast, bays having deep floors, as Cane Bay on the north coast of St. Croix, permanently lose sand from the beach by transport down submarine channels that terminate close to shore (Multer and Gerhard, 1974). Figure 33. Representation of sand transport in an enclosed bay. 47 Biological Processes Although physical processes acting on a beach are the most obvious, organisms are also active in the formation of Virgin Islands beaches. Cal- careous algae, coral and invertebrates not only supply most of the sediment to local beaches, but they buffer much wave energy and, in turn, promote accumulation on the beach. Once the sand is deposited, salt-tolerant plants may encroach on the backshore and stabilize the sand. In some places organic debris and grass which inhabits nearshore bottoms is torn loose and deposited on upper parts of the beach. This nearshQre grass bed contributes stability to beach sand, acting as a footing to control seaward loss of sand. Island beaches are not rich in animals, but neither are they sterile. A number of small crabs, clams, worms, and sand dollars live in the sand between the backshore and nearshore zones. Occasional schools of fish fry come close to shore. The off- shore grass beds, which may lie in water as shallow as three feet, are rich in plants and alJimals. Figure 34 relates biological features to the physical zona- tion of a beach. Beach Rock Many sand beaches of the Virgin Islands are broken by a ledge of rock that typically runs parallel to the beach and protrudes seaward to the low water line. However, the ledges may be found com- pletely submerged offshore or partly above the high water line or buried within the beach under a thick layer of sand. The rock layer itself is often two to five feet thick and mainly consists of cal- careous sand and shell debris that is held together by carbonate cement. Figure 32 shows the relation- ship of beach rock to erosion profiles on a beach at Chenay Bay, St. Croix. The mode of beach rock formation is not fully known, but it is generally believed to be formed in place, below the beach surface, by the natural cementing action of ground water as dissolved calcium carbonate precipitates. In a detailed study of beach rock at Boiler Bay, St. Croix, Moore and Haner (1974) indicated that biological activity contributes to cementation processes. Intermittent exposure in the intertidal zone also may enhance conditions for cementation. Since recent artifacts and debris are occasionally found in the rock, cementation evidently takes place quickly, within a few years. Most beach rock occurs on exposed windward coasts. Generalizations on Stability and Erosion Most Virgin Islands beaches are undergoing erosion at varying rates. Erosion rates are generally greatest Beaches on exposed windward coasts especially where the rate of sand supply from coral reefs, streams or cliff recession is low. Beaches on windward coasts are generally narrow and less stable than on leeward coasts inasmuch as they are affected by seasonal changes in wave direction and wave height created by "northerners" and passing hurricanes. Beaches along deeply indented bays on St. John and St. Thomas are more stable seasonally than those on open, exposed bays. Depositional beaches, which are relatively wide and often backed by dunes, occur on coasts having coral reefs that protect the beach and supply sand. A few are associated with intermittent stream deltas, a source of supply at some localities. The most rapid accretion occurs around Sandy Point along the southwest end of St. Croix where the beaches receive a dual supply of sand by littoral drifts from west and south coasts. Uses By Man Beaches benefit man directly in five ways: (1) they serve as a buffer zone between land and sea within an ocean island system; (2) they are a source of sand used in concrete aggregate; (3) they are sites for recreation; (4) they serve as terminals COASTAL DUNE BACKSHORE FORESHORE NEARSHORE Bare sand zone - OFFSHORE Seagrass zone- large variety of organisms Vegetation zone - Sand berm zone Surf zone - coconuts, sea grape, ghost crabs, mole crabs, dune grass',. . beach hoppers clams sea pur- slane sand dollars, burrow- ing crabs Figure 34. Profile of a beach indicating physical zonation and characteristic organisms. 48 for small boat transportation and sites for small boat repair; and (5) some serve as a place to dump wastes or to store sand. Many were also used for nesting by sea turtles in the past, but turtle nesting on Virgin Islands beaches is an extremely rare event now. As a buffer zone, beaches protect property from wave attack. This use becomes important where shorefront real estate has a high value and where dunes lie close to the beach. Instead of eroding coastal property, the beach has the ability to re- shape itself to the changing physical forces and thus to assimilate wave energy. If sand is temporarily lost offshore, it may be returned later under normal wave conditions. Similarly, if the beach is backed by dunes, sand is often replenished by long-term transfer from the dunes to the beach. Dunes are not only a reservoir of sand but act as a dike that prevents massive flooding of the land by storm tides. Beach sand has been a traditional source of fine construction aggregate in the Virgin Islands inas- much as there is no river sand. With rapid growth in construction during the 1960's, mining of sand by both government and private groups led to nearly complete stripping of some beaches. At Boiler Bay and East End Bay, St. Croix, sand was stripped down to the underlying beach rock. As shorefront property values increased and as detri- mental effects to recreation and conservation became realized, the Virgin Islands government prohibited mining of beach sand in 1971. When large quantities of sand are removed from the beach, the natural transport dynamics are af- fected in several ways: (1) the wave refraction pattern is changed so that sand from both sides of the excavation is moved into the void; (2) sand transported by littoral drift is trapped in the excavation. Therefore, less sand is available for nourishing the beach down coast. On exposed coasts, removal of large quantities of beach sand results in rapid erosion over the entire beach. The beach slope steepens and the sand results in rapid erosion over the entire beach. The beach slope steepens and the sand becomes coarser. However, on leeward coasts, only a slight local recession of the highwater line is experienced over long periods. A severe swell or hurricane wave attack may cause sudden recession over a wide stretch of beach. The rate of beach recovery from sand mining is reportedly slow, especially where the nearshore bed is excavated and the rate of sand supply to the beach is low as is partly the case for coral sand in Brewers Bay, St. Thomas (Herrick, 1966; Tabb, 1967; Grigg, et 01, 1972). Because production of coral beach sand is slow, erosion caused by sand mining is semi-permanent. Off- shore sources of sand on the insular shelf provide the best alternative for the longterm needs of an ocean island. As zones for recreational use, the beaches of the Virgin Islands have exceptional value. They are best used for short-term contact sports, fishing, beach combing, picnicking, camping, horse riding, sunbathing, viewing, and as sites of departure for swimming, surfing, skin diving, small boat launching and SCUBA diving. Recreational uses are described elsewhere in this report. Although most trans-shipment and boat repair is now accomplished at modern docks and berths, a few beaches in Charlotte Amalie, Christiansted (Nichols, Grigg, van Eepoel, et 01, 1972), and out- lying areas serve as sites for launching and off- loading small fishing craft. For early islanders, th is was the most useful aspect of the beach. Beaches were widely used by lighters and fishing craft as a trans-shipping area in preference to rocky coasts or distant harbors. Around the urban harbors, beaches have served as sites for waste disposal in an effort to fill and to extend low land. For example, a former bathing beach along Frederiksberg Point, Charlotte Amalie was eliminated prior to 1925 by solid wastes and landfill. A similar case existed along the shore at Truman airport and near Anguilla, St. Croix. Although most disposal is now contained on land, the former fill sites are subject to erosion. Release of former wastes by hurricane presents a potential for pollution of nearshore water. Structural Modification Engineering structures intended for the beneficial purpose of shore protection often cause deleterious effects when they interfere with natural pro- cesses. Effects similar to those caused by sand mining take place when indiscriminate alteration of the beach profile is made by developers. Shore protection structures are of three types: (1) jetties and groins intended to interfere with currents and drift that transport sand; (2) sea walls and bulk- heads intended to inhibit direct attack by waves, and (3) beach nourishment by emplacing sand. By interfering with littoral drift and longshore transport, groins (structures at right angles to the beach) are designed to build up beaches. However, they often cause a shortage of sand on the down- stream side of the structure and erosion sets in. A groin only fifty feet long at the Mill Harbor condominium on St. Croix created a wide and high beach but caused severe erosion at neighboring Turquoise Beach. Failure of groins attests to the lack of knowledge concerning the behavior of wave and current processes that they are intended to resist. Groins work best when (1) littoral drift is significant in volume; (2) the material is at least of sand size (between 0.062 and 0.5 milli- meter); and (3) when the downstream shore is considered expendable. By absorbing or reflecting wave energy, sea walls may protect the shore, but they do not prevent the loss of sand on the beach in front of them. In fact, they often accelerate the loss of sand by de- flecting wave forces downward onto the beach deposits. At LaGrande Princess, St. Croix, con- struction of a sea wall in front of the Cruzan Princess condominium not only caused the beach to recede 23 feet within one year, but also caused severe erosion on adjoining property to the east that received much deflected energy from the wall (Environment Consultants, 1969). In short, the structures are often as deleterious as they are beneficial. Artificial Beaches When sand is placed on a beach in an attempt to rebuild it artificially, the natural processes continue essentially unhampered. Beach nourishment not only checks erosion but also supplies sand to ad- jacent beaches. It is economical when large quan- tities of sand are available and when it does .not require long-term management commitment, as do 50 sea walls and groins. Moderately successful beach land fill and nourishment projects have been com- pleted at Protestant Cay and near Fort Louise Augusta, Christiansted (Nichols, et aI, 1972) and at Brewers Bay, St. Thomas (Grigg, et aI, 1972). With the sharp rise in beach property values during the late 1960's, there have been attempts to pump offshore sand onto the beaches at several resorts, notably at Grapetree Bay Hotel, St. Croix. Use Impacts As previously noted, mining of beach sand promotes rapid erosion over an entire beach. Often little sand is left to supply dunes or to buffer the shore against hurricane waves. Dredging of sand has caused moderate damage to reefs in Christiansted harbor (Nichols, et aI, 1972), in Brewers Bay (Grigg, et aI, 1972), but effects elsewhere are not well known. Although the best use for beaches seems to be for recreation, even these activities tend to destroy aesthetic and recreational values through littering and pollution. Since backshores are washed only during storm tides, trash and litter often accumulate in this zone. A critical factor for upper backshore dune stability is vegetative cover. Dune buggies, motorcycles and over-grazing by animals can be damaging since exposure of the sand to wind and waves can trigger erosion. Without sanitary faci- lities on a beach, recreational activities can have a degrading impact on future use. Together with the addition of sol id wastes, they present a potential for pollution of shallow ground water supplies and nearshore waters. Unregulated construction and improperly designed structu res present a potential th reat to life and property when they fail during storms. Besides accelerating erosion, such structures may result in a recreational hazard as well. Scour holes often develop at the toe of vertical walls and broken masses of concrete and steel rod often protrude from displaced sections. At Cinnamon Bay, St. John, a rock revetment constructed to protect an old Danish warehouse created wave reflections (rather than energy dissipation) that increased scour at the base of the wall and produced sedi- ment plumes extending offshore onto the reefs (Hoffman, et aI, 1974) The wall itself was under- mined and collapsed. Artificially nourished beaches display the following impact features: (1) a steep beach foreshore or scarp caused by disequilibrium of the beach profile with nominal wave forces; (2) beach material is often coarse-grained and contains coral debris; (3) lowering of the nearshore profile accompanied by erosion of the deposited sand, and (4) a lag deposit of coarse gravel or coral debris often ac- cumulates in the breaker zone, while fines are released from the nearshore bed or foreshore, cause a turbidity. These effects often extend to nearby marine communities as turbidity reduces light penetration and as the substrate becomes unstable for benthic organisms. Re-establishment of 'pioneer' species in dredge holes and beach fill areas is typically slow (Cronin, et ai, 1969; Grigg and van Eepoel, 1971). Additionally, beaches are increasingly subject to the impact of containerized or accidental dis- charges of wastes in the open ocean. Floatables found on island beaches include plastics, tar balls, and oil coatings. These typically accumulate on the upper berm and are deleterious to both the biota and aesthetic aspects of the beach environment. Besides long-term accretion of ocean wastes, island beaches are continually threatened by major oil spills from transfer facilities, refining storage and tanker wrecks. Although nearshore grass beds stabilize the beach by absorbing energy, they present problems for heavily used beach areas. Thick plant growth makes swimming uncomfortable, while heavy deposition of detached grass on the beach produces noxious odors and makes walking and sunbathing uncom- fortable. But when grass beds are eliminated near- shore, sands are subject to erosion. Plants compris- ing the beach litter mainly are Thalassia (turtle grass) and Syringodium (manatee grass). Beaches are subject to a variety of different impacts from time to time, and these may have cumulative effects over the years. For example, dredging or blasting of coral reefs off a beach often leads to a die-off of the reef. In turn, this reduces the rate of reef-borne sand supply and increases wave attack and erosion on the beach. In areas of high 51 ship and motor boat traffic, boat wakes cause erosion and turbidity of nearshore water. Large- scale reclamation of lowlands disturbs the natural equilibrium of the beaches over wide stretches of coast or throughout a coastal compartment. Along some coasts a small change in coastline geometry or the vitality of mangroves and near-shore grass beds can have a large effect as demonstrated at Estate Whim, 51. Croix (Environment Consultants, 1971). Human interference with natural processes is one of the major causes of beach erosion in the Virgin Islands. Effects of Dredging Channels and ditches dug aCl"oss beaches to drain and flush back beach lagoon or salt ponds have a history of self-healing closure shortly after they are opened. This is well documented at Altona Lagoon and to some extent at Southgate Pond (Environment Consultants, 1971). At Magens Bay, . St. Thomas, torrential rains occasionally overfill the mangrove pond behind the beach causing it to break through the middle of the beach. The resulting canal is reclosed naturally within a few days. Dredging nearshore beds too close to shore causes sandy beaches and dunes to either erode severely or to slump away into the dredged hole. The beach at Sugar Bay on the south shore of Water Bay, St. Thomas was lost in this way (Grigg and van- Eepoel, 1970). Dredging and extensions of the shoreline seaward through landfill in Gordon Bay, st. Thomas harbor allowed wave energy to extend farther landward than normal and caused erosion of the nearshore bottom by two or three feet in forty years. The effects of dredging may be extended to dis- tant beaches via near-shore transport. Serious erosion in Estate Whim, Long Point Bay, S1. Croix relates to dredging of the Hess Oil channel five miles to the east (Environment Consultants, 1971). In this case, turbidity generated by dredge spoil caused a reduction in the near-shore grass cover off the beach. Such grass beds normally absorb wave energy, but without them wave energy is entirely expended on the beach. This case illus- trates how beaches may be linked to a sequence of impacts in a chain of causes and effects. Attributes, Use Options * Highly desirable recreational areas. Besides swimming, provide easy access to snorkel ling, SCUBA diving, sailing, water skiing, etc. * Generally protected from heavy seas providing safety for recreational uses. * Plastic nature of sandy shore changes in response to seasonal sea conditions, absorbing wave energy and protecting back shore. Use Limitations * Sand dynamics make beach unstable for struc- tures. * Structures across beach usually interfere with natural sand movement, often having undesir- able effects. * Not suitable for sand mining which usually causes destructive redistribution of remaining sand. * Not suitable for discharge of wastes. Susceptible to aesthetic and micro-biological (public health) degradation. Inventory of Beaches Locations of beaches on the three islands are shown in Figures 28 and 29. St. Thomas and St. John, because of their more irregular shorelines, have more beaches than St. Croix. In addition, much of the gently sloping shoreline of St. Croix, physically described as beach, is poorly suited for swimming because of beach rock, nearshore reefs and, in some areas, highly turbid water or exposure to strong sea and currents. On the other hand, because of its straighter shoreline, St. Croix possesses longer stretches of beach than the other islands. The continuous sandy beach from Concordia to Frederiksted is unparalleled anywhere else in the Virgins. ROCKY SHORES Rocky shorelines are here defined as steep slopes or cliffs formed by weathering and wave action on rock outcrops or promontories. These are 52 distinguished from rocky beaches which have a gentle seaward slope but are covered with rock and/or coral rubble. Rocky shorelines vary from vertically exposed rock faces (parts of the windward slides of most islands and cays) to angular sloping blocks of bed- rock (northwest St. Thomas) to boulder strewn shorelines (occurring scattered on all coasts). Occasionally there are eroded outcrops of sandstone or fossil reef areas, particularly on southern St. Croix. The shoreline at the tidal level and some distance below is strewn with boulders derived from the land or eroded projections of the bedrock. Ecology Rocky shores are rigorous environments, but far from sterile. The area above the water supports a few specialized salt tolerant plants and related fauna but below the water there may be well , developed coral growth attached to the bed rock and boulder rubble (Figure 35). Hardy members of the adjacent terrestrial vegetation may cling to the uppermost rocky area where there are pockets of soil or fissures in the rock. Common types are Agave (century plants), barrel cactus, pipe organ cactus and grasses. On some re- mote rocky cliffs sea birds roost and nest. Lower down where sea spray occasionally hits the rock a few hardy marine animals can be found: peri- winkles and an occasional crab. Closer to the water, the numbers and kinds of organisms increase. In the splash zone oysters, small fish, sea urchins and a wide variety of mulluscs can be found, including the edible whelk (Cittarium pica). The underwater rocky substrate is perfect for coral attachment and the shallow, clear, turbulent water ideal for their growth. In these areas, coral usually follows the hard bottom contour around the land. Adjacent areas - where the shorel i ne slope is grad ual and wave attack is gentler - usually have sandy or intermittently rocky beaches. At the deeper subsea base of the rocky shore, the reef is often composed of sea fans, sea whips, etc. (gorgonians or "soft" corals). Here land- derived boulders and rock may also be found, but, frequently, the shoreline bedrock is exposed or Rocky Shores EATHERED OUTCROP Worn by wind, waves and rain usually to bed- rock. SPLASH ZONE Snails, chitons, seaweeds. Boulders and bed- rock. HARD CORAL ZONE Acropora corals dominate coral growth on bould- er and rubble substrate. SOFT CORAL ZONE Sea fans, Gorgonia on hard bott'om. Sand cover thin. water clear. Figure 35. Typical rocky shoreline of eroded volcanic rock with boulder and rubble bottom. lies under a very thin layer of sand. Both "hard" and "soft" corals require a hard, stable substrate for attachment. Further offshore, the sand layer becomes thicker, and beds of sea grasses and algae may develop if the water is not too deep. There is almost always a band of bare sand, one or more meters wide, separating the rock and reef area from the sea grass beds. This sandy strip is main- tained by browsing fishes and sea urchins which I ive on the reef and forage on the edge of the grass areas. Because of the steep slope into the water and their usual occurrence on headlands and points, rocky shores are areas of high wave energy and turbulence. This activitiy keeps the water well mixed and aerated and discourages siltation. Be- cause of the immediate shore topography, there is usually no local source of concentrated drainage discharge. Attributes, Use Options * Frequently good spots for hard line fishing. * Good spots for snorkelling and SCUBA - often have whelks and lobsters. * Because of turbulence and water movement, are relatively well suited to receive treated effluents but outfall must be some distance offshore. * Provide scenic vistas from sea and shore. Salt Ponds Inland man- groves and xe- rophi t scrub, land crabs Bay bean, port ul a- ca, sea purslane, fiddler crabs, wading birds. Turbid water, usually hypersaline, phyto- plankton, brine shrimp. Mud and silt bottom, algal mats, occasionally mullet. Dune or berm of Red and sea sand. Rock, black. gravel, coral man- rubble. Beach groves, morning glory, beach sesuvium, scrub vegeta- growth, hermit tion. crabs. Figure 36. Cross-section of a salt pond. Slopes to beach at right; landward at left. * Locally may be important rookeries for sea birds. Use Limitations * Usually rugged and inaccessible, making con- struction d iffic u It. * Because of exposure, sites face heavy sea and wind damage in storms. * Rock and coral bottom and turbulence pre- cludes safe boat docking and anchorage. * Lack of topsoil precludes use of septic tank and drain fields. Inventory of Rocky Shores Rocky shores are extensive on all islands, especi- ally on the north (windward) coasts. St. Thomas and S1. John are rockier and steeper than S1. Croix, even on their southern coasts. The south of St. Croix is mostly flat with beach shores, although these may be low level rocky or gravel beaches. The distribution of steep rocky coasts on the islands is included in Figures 28 and 29. 54 SALT PONDS Description (Figure 36) Most salt ponds are isolated former bays or parts of a bay. Over time, they have become closed by reef or mangrove growth across the bay. The closure may be accelerated by sand and rubble tossed up on the shallow closing bank by storms. They may receive outside bay water slowly by percolation through the berm if it is porous enough. Evaporation in a closed pond is very rapid so that the salinity increases and the pond, if not replen- ished from the bay or by rain water, will dry up completely leaving crystallized salt on the surface_ Occasionally, a pond berm will be breached by storm water from the land or sea. When this occurs, the pond can be reinvaded by marine animals, usually crabs and fishes. These will die off as the pond recloses and salinity increases again. Ecology The biota of a salt pond is very specialized and limited compared to that of the adjacent bay, but its ecology is complex and dynamic. Common animals are fiddler crabs and larger land crabs (Cardisoma guanhumi). Several kind of insects which prefer saline environments live or breed there, including a fly (Salina gracilis) and several kinds of midges. Mosquitoes may breed there during brief periods when heavy rains lower the salinity sufficiently. Several kinds of microscopic algae float in the water sometimes giving it a green, pink, orange, brown, or red color. Other micro- algae grow as mats on the shallow margins. A number of wading birds (stilts, sandpipers) feed along the edges of the ponds on crabs, insect larvae and other small animals. Ponds frequently contain large numbers of brine shrimp (Artemia) which is in great demand throughout the world as food for aquarium fish, aquaculture and research organisms. Thick blooms of Artemia can give the pond water a brownish-pink tinge. If the pond is or has been recently open, it will contain fishes (sen net, small barracuda, mullet, tarpon, snook) and marine crabs. These are fed upon by king- fishers, herons and ospreys. Kingbirds ("chincheri") martins and swallows frequently feed on flying insects over the water. The local animals and plants associated with salt ponds are not well known, and the complex eco- logy of the ponds can only be inferred in simple outline. They have never been studied properly. We do know that salinity changes over a very wide range. It may concentrate to more than three times that of sea water (over 100 parts per thousand) or be depressed by heavy flooding to almost fresh water (depending on the volume of flood water, the size of the pond and the permeability of the pond-bay barrier). Periodic changes of even one- third of this magnitude would cause significant changes in the types and numbers of organisms inhabiting the pond. Slow changes, as by evapor- ation concentrating the salt, would promote a grad ual d ie-off of some forms and a grad ual invasion and development of others. There would be a constant, slow modification of the natural com- munrty in response to this change. Sudden changes in salinity, as by flood water, causes catastrophic changes in the biota. Masses of halophilic (salt-loving) forms are killed while other types, suited to the new, less saline environ- ment, quickly invade the pond and become estab- lished. Following heavy flooding, many ponds contain great amounts of dead halophilic algae, 55 insects, etc. These often account for the occasion- ally bad odor of a pond. Other environmental characteristics of salt ponds are high concentrations of hydrogen sulfide, es- pecially in the sediments (from the decay of dead organic matter), high temperature (from isolation with lack of shade), low dissolved oxygen (from high temperature, salinity and B.O.D.), and high turbidity (from large concentrations of land and pond-derived solids). Although no specific data is available, it is safe to assume that ponds also contain higher con- centrations of most pollutants than, for example, their adjacent associated bays. This is likely because of the natural ecosystem function of salt ponds as buffer zones and sumps. As they are located between the bay and its upland watershed, they receive and trap most of the runoff from the land, thus protecting the bay. Sediment corings in several local ponds have re- vealed thick layers of terrigenous (land-derived) mud and silt interbedded with layers of organic muck, algal mats and occasional sand lenses. The latter may have been deposited when a hurricane or other violent storm broke open the pond or threw waves over the berm bringing sea sand into the pond. Somewhere at the bottom (depending on the age and depth of the pond) lies the original bay bottom and, below that, bedrock. Because most of the upper layers of pond sediment are highly organic and being anaerobically decom- posed, disturbing these sediments usually releases obnoxious sulfide orders. When these materials are dispersed, they use up the available oxygen rapidly. This can kill animals in the water. Attributes, Use Options * Act as natural catchment and settling basins to protect marine resources. * Provide feeding places for wading birds, insects and fish eating birds. * Low in dissolved oxygen, frequently less than 4 parts per thousand. * Biota limited to few organisms which are tolerant of high and changea~le salinity. Use Limitations Use constraints include, but may not be limited to, the following: * Sediments unstable for foundationsj pilings almost always required. * Sediments - fine, toxic, and with high B.O.D. and C.O.D. - can be dangerous to adjacent marine biota if released. * Modification may adversely alter drainage and runoff patterns. * If filled, weight of overburden may, depending on nature of pond sediments, extrude pond sediments at certain points. Overburden may be plastic. * Nature of sediments may limit use of deep- rooted vegetation on overfill. * Modification will alter or destroy habitat for associated birds. Tolerances of the system appear to be wide, but this appearance is largely because we know very little about the functioning of the system. All systems and their components have tolerance limits. Obviously, massive inputs of toxic materials will destroy the ability of the system to function. Filling a pond will completely destroy its function as a catchment basin and aquatic habitat. Opening it to the sea will significantly change its ecological function and perhaps that of the adjacent bay. Inventory of Salt Ponds The locations of salt ponds on the three main islands are given in Table 3 and shown in Figures 28 and 29. They have been identified from pers()nal knowledge, aerial photographs and various charts. some very small ponds may not have been ac- counted for, and some areas with only minimal topographic depressions which hold very shallow lenses of water for short periods after heavy rains have not been included. St. Thomas and St. John have many more ponds than 51. Croix and, like 56 the many pocket beaches, this is largely a conse- quence of the difference in shoreline irregularity. Most salt ponds form at the head of embayments, a setting which also favors beach formation. In fact, in most cases, beaches and salt ponds occur together - a characteristic association in the Vir- gin Islands coastal zone. MANGROVES Description Mangrove habitats are limited in the Virgin Islands, probably because of the lack of rivers or streams. The largest areas wh ich did exist have been destroyed by filling for land development. Mangrove plants, in narrow strips along the coast, are fairly common, but well developed mangrove forests and their associated marine nursery areas survive only at Salt River, St. Croix (Figure 37) and Jersey Bay, St. Thomas (Figures 8 and 18). Figure 37. Salt River, St. Croix, showing drainage patterns and protective reefs. From U.S.G.S. 1954 Topographic Chart. TABLE 3 Location of Virgin Island salt ponds, excluding cays. ST. JOHN Hawksnest Bay (west) ............... small Foot of More Hill ................... small Newfound Bay ................... " small Calabash Boom ................... " small Turner (Enighed Pond) ............. " large Chocolate Hole ............. 2 small, I large Hart Bay ........................ " small Europa Bay ..................... medium Great Lameshur Bay ............... " small Grootpan Bay. . . . . . . . . . . . . . . . . . . . .. large Kiddel Bay ...................... " small Salt Pond- Drunk Bay ............. medium Harbor Point, Coral Bay ............ " small Fortsberg ......................... small Turner Point ....................... small Elk Bay .......................... small Haulover Bay ...................... small Pond Bay ....................... medium Privateer Bay ,..................... sma II ST. THOMAS St. John Bay ............... 2 small, I large Smith Bay ...................... I (cove) Foster Point ...................... 2 small Mandahl Point ................ I very large Foot of Flag Hill .................. I small Frenchman Bay ................ I medium Little Coculus Bay ................. 3 small Coculus Point ..................... I small Bolongo Bay ...................... I small Cabrita Hill ....................... 2 small Water Point .. ; .......... I medium, 3 small Great Bay ..................... 2 medium Muller Bay .................... 2 medium Vessup Bay ....................... I large Krabbepan Point .................. Ismail Compass Point .... ~ ............ I medium Mandahl Bay ..................... I large Smith Bay ....................... 2 small St. John Bay ....................... small Red Bay. . . . . . . . . . . . . . . . . . . . . . . . .. large Vessup Bay. . . . . . . . . . . . . . . . . . . . . . .. large Great Bay (north) ............ small, medium Great Bay (south) ................... small Water Point Scott Beach small small Benner Bay. . . . . . . . . . . . . . . . . . . . . . .. large Mangrove Lagoon .................. 2 large Long Point ........................ small Bovoni Bay ........................ small Bolongo .......... , ............... small Little Coculus Bay ................. 2 small Frenchman Bay .................... small Cove between Frenchman & Morningstar, small Perservance . . . . . . . . . . . . . . . . . . . . . . .. small Fortuna .......................... small ST. CROIX Great Pond Bay ............ , .... very large Robin Bay ........................ large West End ...................... very large Coakley Bay ...................... , large Chenay Bay ....................... large Mangroves Red mangroves growing at edge of quiet shallow lagoon. Black mangroves on higher wet soil, white mangroves on drier inland soil. Red mangrove prop roots trap sediment, support and shelter organisms, extend shore. Litter contributes organic matter to water and sediments. Lagoonal grass and algae provide oxygen, food, shelter for other organisms. Nurseries for juvenile reef and pelagic fish. Figure 38. Profile of a mangrove forest showing typical zonation and associated habitats. The greatest mangrove lagoon systems in the islands - Krause Lagoon on St. Croix and Mosquito (Lindbergh) Bay on St. Thomas - have been filled for land development. Some of the remaining mangrove plants at Krause Lagoon are slowly succumbing to air and waterpollutionand continued construction. Mangroves are flowering trees which can live in salt or brackish water. Several different trees are referred to by the common name "mangrove", but the most common are Red Mangrove (Rhizo- phoro mangle), White Mangrove (Languncularia racemosa) and Black Mangrove (A vicenia nitida). (Rhizophora, known as "the plant that makes land," is the most typically recognized species. It grows at the water's edge, and new seedlings become established to seaward. Besides providing support and hiding places for a wide variety of marine animals, the prop root system of the plants traps sediments that accumulate from the plants or are washed down from the land. By this prpcess, 58 the shoreline is slowly extended. Once the sediment becomes rather firmly established, the red man- groves die off naturally and are succeeded by other plants, initially black and then white mangroves. This sequence of succession creates a pattern of zonation (Figure 38) in which the pioneer red mangrove is at the water's edge, black mangroves occupy a zone behind and white mangroves are more inland, but still in sand soil. Mangroves, therefore, by their dense coverage and complex root structures at the shoreline, interrupt runoff from the land and help to trap fresh water, sediment and debris at the shoreline, thus protecting offshore marine areas from these pollutants. Ecology Each year red mangroves drop large quantities of leaves and seedlings, all of which do not survive to become new plants. The natural decomposition of these materials sustains a complex food web beginning with micro-organisms and scavengers and culminating in such higher trophic members r---- =~~~~~~========~Y?a~rd~.======~~~========~ t>oo===o 500 1000 1500 ! MANGROVE LAGOON, J{ A I I Sr: THOMAS, v v y i V Y v r \ y Y Figure 39. Marine ecological zones of Jersey Bay and Mangrove Lagoon, St. Thomas. From McNulty, Robertson and Horton (1968) as snappers, barracuda, lobsters and birds. The nutrients and other food energy supplied by plant litter decomposition account for the large numbers and wide variety of plants and animals which are found in climax mangrove communities. Biotopic maps have been constructed for Jersey Bay Lagoon (Figure 18) by McNulty, et ai, (1968) and for Salt River (Figure 39) by Gerhard and Bowman (1975). Mangroves require certain conditions for establish- ment and sustenance and, in turn, modify the en- vironment in a characteristic way which further favors their proliferation. Red mangroves grow from a floating cylindrical seedling which may float miles from the pa"rent tree. As these mature, the root end becomes heavier so that it hangs downward with the future leaf end sticking up. EventuallYI the pod sinks. When it does, it must encounter a muddy or sandy bottom with suffi- en cient nutrients (fertilizer). The water' must be shallow enough to allow the seedling to reach air and sunlight. The water must be calm enoug~ to allow the seedlings to take root and grow. These requirements explain why mangroves do not usually establish on windward coasts except where some shoreline features offer necessary protection and substrate, Salt River, St. Croix, is a good example where protective reefs and the long channel~like embayment offer suitable conditions (Figure 37). By their development, mangrove areas further promote sedimentation and quiet waters, In turn, expansion of mangrove growth is fac il itated, Wildlif.e diversity in mangrove ecosystems is second. only to the coral reefs locally, Considering 'that both Jersey Bay and Salt River mangl'Ove areas are immediately adjacent to beautiful, rich reefs, these combined environments are incomparable I-esource pools_ But the mangl"Ove forests are by fal- the most noteworthy because only two such areas I-emain while we have hundreds of fine reefs. Perhaps because reefs have attracted more at- tention, we are now in the process of constructing additional artificial I-eefs. An attempt has not been made yet to constl-uct a mangrove lagoon. The large numbers of fishes, birds, crustaceans and other animals that live in a mangrove area are dependent basically on the nutrients and vegetable matter pl-oduced from the leaves of mangl"Oves and \ sea grasses. This material is eaten by vegetarian and omnivorous animals. Their excrement and the ol-ganic soup from rotting of other leaf litter pro- N vide food for plankton (single-celled plants, larval animals) and bactel-ia. These, in turn, are eaten by lal-ger animals, including those harvested by man. Natural development of mangrove forests tends towal-d the fOI-mation of closed ponds. As the plants continue to gl"Ow across a shallow bar or spit, they may eventually merge with other mangroves or a headland on the other side of a body of water. For a time the water behind the mangroves may have limited communication with the outside through the prop roots or via narrowing channels. Such channels may be maintained indefinitely if a sufficiently strong current runs through period- ically. This sweeps sedimentation out of the channels so that they are often surprisingly deep in relation to the general shallows within the lagoon. Current flow and depth also work to prevent new seedlings from rooting and thereby closing the channel. Under other conditions, however, mangrove growth eventually seals off a body of water. For a while, high tides may be able to wash water through the mangroves into the pond, but eventu- ally the pond is cut off from open water and a salt pond is formed. Salt ponds may also be formed through a similar sequence by the growth of a coral reef. They are· discussed in more detail in the section on salt ponds. Tidal ponds, flats and salt ponds, therefore, are frequently associated with mangrove forests, but they may also develop where there is little or no mangrove growth. Mangrove forests frequently develop at the mouths 60 e...11 .. _ C .. _In",."ff_ : ;~IoIJ ?IM,,,ilhI,,, HAt, H<#Jiffllkkl HAN, &1/~f"rlNd1:¥. "F. IlNI Figure 40. _20 KM_ Benthic communities of Salt River estuary. Source: Gerhard and Bowman, 1975. of streams and rivers. On larger tropical islands and mainlands where these occur, really spec- tacular mangrove estuaries can be found, Although historical records indicate that there used to be several perennial streams in the Virgin Islands, none exist now. Therefore, local mangrove areas are not estuaries in the usual sense except period- ically when the guts which terminate in mangrove bays discharge storm water. At these times, ex- tensive lenses of fresh water can be found in the lagoons. Salinity as low as 10.8 parts per thousand (ppt.) has been measured in the Jersey Bay Lagoon after heavy rains. The usual range is 35-37 ppt. Actually, under usual local conditions of low rainfall and intense radiation, the shallow, quiet inner regions of the lagoon experience considerable evaporation, and salinity in some places may increase above 38 ppt. to higher levels in the backwaters at the head of the lagoon. This con- dition has sometimes been described as a "hyper- saline estuary."At any rate, the lack of a regular brackish water zone has several consequences for local mangrove areas. One is that many organisms requiring low salinities for all or part of their life cycle and found in "true" estuaries are absent or rare here. Some of these are species of crabs, shrimp, fish and bivalve mollusks. Besides many commercially valuable, edible species, the relative- ly narrow salinity range precludes the establishment of a host of other organisms which are physio- logically dependent on low or variable salinity. This is a manifestation of a basic biological rule: habitat diversity - at any level - fosters biotic diversity. A further consequence of the local salinity regime is that since local lagoon inhabitants are adapted to normal or high salinity, when the salinity is suddenly reduced by flooding rain, many of the organisms perish. At such times, large amounts of plant and animal debris from dead and damaged organisms are released into the lagoon water. This organic material has been observed in Jersey Bay to reach a peak about a week following flooding, after most of the washed in mud had settled. At such times, also, phytoplankton blooms usually occur, probably triggered by the unusually high levels of nutrients coming from the land and the decaying plant and animal matter. Within weeks normal salinity can be re-established by a variety of forces, and the organisms begin to resume their natural mode of existence. Biotur- bation (the mixing of sediment by animals living in and on it) incorporates alluvial mud into the natural sediments. Organic debris is assimilated and water clarity improves again. Mangroves as Wildlife Habitats Large mangrove areas provide home and food for thousands of plants and animals. Numerous kinds of birds roost, feed and nest in and around the mangroves. Among the more important of these £:1 are doves and pigeons, pelicans and the osprey or fish hawk. The cattle egret also roosts and nests in mangroves although it makes a daily trip inland to feed on insects near cattle. Some of our rarer species of reptiles are also found in mangroves, very possibly because they are less accessible to predation by humans, mongoose and domestic animals. Iguanas find good protection there. The small local snake Alsophis occurs in the Jersey Bay area as well as ground lizards (Ameiva). Other than marine life, the main wildlife value of the mangroves is as a habitat for birds. Jersey Bay Lagoon is a major habitat for about twenty species of herons, egrets, dudes, gallinules, moun- tain doves, white-crowned pigeons and Bahama pintail ducks. Table 4 lists birds observed in the lagoon area. Several are rarely, if ever, seen else- where on the islands, and so the mangrove lagoon is critical for their survival locally. This list does not pretend to be complete. Observations of birds and other wildlife in the lagoon, as in most other locales in the islands, has been brief and at scat- tered times. Fish trapping In Jersey Bay, St. Thomas and Manning Bay, St. Croix (Olsen, Dammann, et af; 1972), produced 79 and 61 species, respectively, in addition to spiny lobsters. These are only types that enter traps - many species do not. For the species trapped, it was estimated these mangrove areas supported populations of more than 50,000 at Jersey Bay and more than 68,000 at Manning Bay. The majority of the fishes were ones also found on coral reefs. Many of the species trapped in the mangroves were juveniles or both adult and juvenile, indicating that the fishes use the areas as nursery grounds. Table 4. Partial list of birds from Jersey Bay mangrove lagoon including cays. SPECIES Great Blue Heron Common Egret Louisiana Heron Snowy Egret Clappel" Rail White Crowned Pigeon Mountain (Zenaida) Dove Osprey Bahama Pintail Duck Blue (scaly-naped) Pigeon Mangrove Cuc koo King Bil"d Kingfisher Bananaquit Antillean CI"ested Hummingbird Brown Pelican Cattle Egret White Tailed Tropic Bird Red Billed Tropic Bil"d Red Billed Tropic Bil"d American Oystercatcher Roseate Tern Least Tern SOURCE 1 1,2 1 1,2 1,2 2 2 2 2 2 2 2 1,2 2 SOUl"ces: (1) McNulty, Robertson, Horton, 1968; (2) personal observation. Environmental Characteristics of Mangrove Eco- Systems The following list attempts to identify some of the unique and characteristic physical and biolog- ical aspects of mangrove ecosystems that account for their high intrinsic value and productivity. 1. Energy production (food supply) is high from mangroves, grasses, and plankton. 2. Protection from strong waves and swell creates quiet water. 3. Relatively rapid sediment deposition via plant litter, biogenic sand, terrigenous silt. 4. Wide variety of habitats and niches, e.g., shoreline forest, prop root zone, bare sand, muddy areas, algal beds, sea grass meadows, 62 coral areas. 5. Usually receive some degree of periodic fresh water inflow. 6. Subject to greater spatial and temporal salinitv variation than other coastal zones (excepting salt ponds). 7. Shallow depths, quiet waters and secluded setting restricts larger predators (sharks, etc.) 8. Usually backed upland by flat flood plain or tidal marsh of black and white mangroves, buttonwood, marsh plants, etc., which affords protection from excessive siltation. 9. Because of the wide variety of environmental conditions and ecological niches in a rather small area, mangrove forests are characterized by an unusually wide variety of wildlife, particularly marine life and birds. Mangrove Areas in the Virgin Islands * Jersey Bay, St. Thomas - The most extensive system remaining in the Virgin Islands. In- cludes several cays, salt ponds, lowland marshes and reef areas in about 850 acres. * * * * * * Salt River, St. Croix - Second only to Jersey Bay in size and complexity. Manning Bay, St. Croix - South of the airport and racetrack. Small area stressed by effects of nearby open shoreline garbage dump (now closed) and heavy industrial area. Very rich fish population. Great Pond, St. Croix - Primarily black mangrove. Westend Salt Pond, St. Croix - Mostly black mangrove. Altona Lagoon, St. Croix Krause Lagoon, St. Croix - No longer exists. Lagoon filled. Some plants of all three species remain mostly in nearshore bands, but suf- Actually, under usual local conditions of low rainfall and intense radiation, the shallow, quiet inner regions of the lagoon experience considerable evaporation, and salinity in some places may increase above 38 ppt. to higher levels in the backwaters at the head of the lagoon. This con- dition has sometimes been described as a "hyper- saline estuary."At any rate, the lack of a regular brackish water zone has several consequences for local mangrove areas. One is that many organisms requiring low salinities for all or part of their life cycle and found in "true" estuaries are absent or rare here. Some of these are species of crabs, shrimp, fish and bivalve mollusks. Besides many commercially valuable, edible species, the relative- ly narrow salinity range precludes the establishment of a host of other organisms which are physio- logically dependent on low or variable salinity. This is a manifestation of a basic biological rule: habitat diversity - at any level - fosters biotic diversity. A further consequence of the local salinity regime is that since local lagoon inhabitants are adapted to normal or high salinity, when the salinity is suddenly reduced by flooding rain, many of the organisms perish. At such times, large amounts of plant and animal debris from dead and damaged organisms are released into the lagoon water. This organic material has been observed in Jersey Bay to reach a peak about a week following flooding, after most of the washed in mud had settled. At such times, also, phytoplankton blooms usually occur, probably triggered by the unusually high levels of nutrients coming from the land and the decaying plant and animal matter. Within weeks normal salinity can be re-established by a variety of forces, and the organisms begin to resume their natural mode of existence. Biotur- bation (the mixing of sediment by animals living in and on it) incorporates alluvial mud into the natural sediments. Organic debris is assimilated and water clarity improves again. Mangroves as Wildlife Habitats Large mangrove areas provide home and food for thousands of plants and animals. Numerous kinds of birds roost, feed and nest in and around the mangroves. Among the more important of these t:1 are doves and pigeons, pelicans and the osprey or fish hawk. The cattle egret also roosts and nests in mangroves although it makes a daily trip inland to feed on insects near cattle. Some of our rarer species of reptiles are also found in mangroves, very possibly because they are less accessible to predation by humans, mongoose and domestic animals. Iguanas find good protection there. The small local snake Alsophis occurs in the Jersey Bay area as well as ground lizards (Ameiva). Other than marine life, the main wildlife value of the mangroves is as a habitat for birds. Jersey Bay Lagoon is a major habitat for about twenty species of herons, egrets, dudes, gallin ules, moun- tain doves, white-crowned pigeons and Bahama pintail ducks. Table 4 lists birds observed in the lagoon area. Several are rarely, if ever, seen else- where on the islands, and so the mangrove lagoon is critical for their survival locally. This list does not pretend to be complete. Observations of birds and other wildlife in the lagoon, as in most other locales in the islands, has been brief and at scat- tered times. Fish trapping in Jersey Bay, St. Thomas and Manning Bay, St. Croix (Olsen, Dammann, et ai, 1972), produced 79 and 61 species, respectively, in addition to spiny lobster-so These are only types that enter traps - many species do not. For the species trapped, it was estimated these mangrove areas supported populations of more than 50,000 at Jersey Bay and more than 68,000 at Manning Bay. The majority of the fishes were ones also found on coral reefs. Many of the species trapped in the mangroves were juveniles or both adult and juvenile, indicating that the fishes use the areas as nursery grounds. Table 4. Partial list of birds from Jersey Bay mangl'Ove lagoon including cays. SPECIES Great Blue Hel'On Common Egt'et Louisiana Heron Snowy Egt'et Clapper Rail White Crowned Pigeon Mountain (Zenaida) Dove Osprey Bahama Pintail Duck Blue (scaly-naped) Pigeon Mangrove Cuc koo King Bird Kingfisher Bananaq u it Antillean Crested Hummingbird Bl'Own Pelican Cattle Egret White Tailed Tl'Opic Bird Red Billed Tl'Opic Bird Red Billed Tl'Opic Bird Amet'ican Oystercatcher Roseate Tern Least Tern SOURCE 1 1 1 1,2 1 1,2 1,2 2 1 2 2 2 2 2 2 1,2 2 Sources: (1) McNulty, Robertson, Horton, 1968; (2) personal observation. Environmental Characteristics of Mangrove Eco- Systems The following list attempts to identify some of the unique and characteristic physical and biolog- ical aspects of mangrove ecosystems that account for their high intrinsic value and productivity. 1. Energy production (food supply) is high fl'Om mangroves, grasses, and plankton. 2. Protection fl'Om strong waves and swell creates quiet water. 3. Relatively rapid sediment deposition via plant litter, biogenic sand, terrigenous silt. 4. Wide variety of habitats and niches, e.g., shoreline forest, prop root zone, bare sand, muddy areas, algal beds, sea grass meadows, 62 coral areas. 5. Usually receive some degree of periodic fresh water inflow. 6. Subject to greater spatial and temporal salinity variation than other coastal zones (excepting salt ponds). 7. Shallow depths, quiet waters and secluded setting restricts larger predators (sharks, etc.) 8. Usually backed upland by flat flood plain or tidal marsh of black and white mangroves, buttonwood, marsh plants, etc., which affords protection from excessive siltation. 9. Because of the wide variety of environmental conditions and ecological niches in a rather small area, mangrove forests are characterized by an unusually wide variety of wildlife, particularly marine life and birds. Mangrove Areas in the Virgin Islands * Jersey Bay, St. Thomas - The most extensive system remaining in the Virgin Islands. In- cludes several cays, salt ponds, lowland marshes and reef areas in about 850 acres. * * * * * * Salt River, St. Croix - Second only to Jersey Bay in size and complexity. Manning Bay, St. Croix - South of the airport and racetrack. Small area stressed by effects of nearby open shoreline garbage dump (now closed) and heavy industrial area. Very rich fish population. Great Pond, St. Croix - Primarily black mangrove. Westend Salt Pond, St. Croix - Mostly black mangrove. Altona Lagoon, St. Croix Krause Lagoon, St. Croix - No longer exists. Lagoon filled. Some plants of all three species remain mostly in nearshore bands, but suf- * * fering from effects of industrialization. Lameshur, Leinster, and Coral Bays, St. J oh n have small stands of mangroves. Miscellaneous small patches on the peri- meter of most remaining undisturbed salt ponds. These areas are located on Figures 28 and 29. CORAL REEFS A tropical coral reef is a complex association of hundreds of kinds of plants and animals. Corals are the dominant organism in terms of area coverage and, more importantly, they comprise the basic physical structure of the reef. Corals are colonial animals. The pores in a piece of coral each contain a small animal - a polyp. One of their life processes is extracting soluble calcium carbonate from the water and precipitating it in solid form to comprise the rock skeleton which surrounds the polyps. Coral colonies grow by asexual budding - polyps split into two. This increases the size of the colony laterally and upward. New growth piles up on top of old skeletal material, so that below the living part of the reef there may be hundreds of feet of fossilized coral rock from previous reef growth. Corals can also reproduce sexually. Periodically, the polyps expel I clouds of eggs and sperm into the sea. Fertilization results in a microscopic larva which is distributed by ocean currents. After a period of development in the plankton, the larva settles to the bottom. If they encounter suitably clean, hard, stable substrate, they attach and begin a new colony by budding. Many of the plank- tonic larvae are eaten by other animals, including coral colonies which feed by filtering a host of small plants, animals, eggs and larva from the water. Corals as a group require warm water and their global distribution is generally confined between the tropics of Cancer and Capricorn. They also require clean, clear water so that within suitable temperatures their occurrence is also locally interrupted in areas subjected to outpourings of large rivers and pollutants. Close relatives of the stony, reef building corals are the gorgonians or soft corals. These include such forms as sea fans, sea whips, and sea pens which are common on reefs. As a group, they tend to do better in deeper or murkier water than the hard corals, although there are numerous indivi- dual exceptions. Coral reefs are common characteristic features of the islands' coastal zone and are of fundamental environmental and economic value. Besides their intrinsic beauty which is apparent only to the relatively few who observe them directly, they are important as producers of sand for natural and manmade beach cover and for construction. As such, they represent one of the territory's few naturally replaceable resources available for extraction. Reefs also provide protection for harbors, shorelines and shore structures by abate- ment of waves and dissipation of their energy which otherwise would be expended on the shore with great force. Thirdly, reefs provide perhaps the largest portion of seafood presently harvested in the islands. Most species of fish consumed lo- cally either live on the reefs or depend on them in some measure for their food. Lobsters, too, are taken primarily from reef areas. The new sciences of mariculture and marine phar- macology promise to bring even more awareness of the productive capacity of reefs and probably greater pressures for their exploitation and the need for sound management. Reef Ecology Reefs are among the most diverse natural com- munities and in terms of productivity are com- parable to prime farm land. Productivity - the rate at which inorganic carbon (from the water in the case of marine plants and from the atmosphere in the case of land plants) is converted to plant tissue - is rapidly utilized by other reef organisms for community maintenance and growth. This primary productivity, or photosynthesis, also produces oxygen for the support of respiratory organisms both on land and in the sea. Most studies of reef productivity have been con- ducted in the Pacific, but the results are generally applicable to estimates of production on other tropical reefs. These studies indicate reef height increases at 8 - 13 millimeters per year. This actual net increase in reef height does not represent the total gross growth and production of the reef corals because their structures are constantly being reduced by living and physical forces. One Hawaiian study estimated that calcium carbonate (the mineral material of which coral skeletons - as well as shells and sand - is composed) is produced at the average rate of 0.32 pounds per square foot per year. Roughly half of this was in reef framework and half was sediment. Many fishes, crustaceans, echinoderms, sponges, mollusks and algae chew off pieces of coral or bore into it. Waves and other physical forces break off pieces. Physiological and physical factors slow down the rate of coral growth as the colony reaches the water surface. Coral Reefs LAGOONAL INSHORE LAGOONAL PATCH REEF Quieter water. Finger corals common forming large masses The surface experiences greater fluctuations in temperature, salinity and pollution levels. Corals near the surface are subject to wave destruction and at low tides may be exposed to drying and heating. These factors operate to slow down and finally stop reef growth as it reaches the water surface. One estimate indicated that rasping reef fishes alone (parrot fishes in particular), by feeding on the coral, redeposited about 108 grams of calcium carbonate per square meter per year. Th is is one route for sand production. Others are via wave breaking and grinding of coral and other plant and animal skeletons. Other organisms contributing to sand production are certain algae, mollusks, crustaceans, echinoderms and foraminifera. In short, an animal or plant with a hard shell or BARRIER REEF CREST Sand and grass areas leading to shore beach or mangroves. Abun- dant bottom fauna among plants. to four feet high. Numerous small fishes and invertebrates. Sea grasses often on surround- ing sand. Dominated by elkhorn and staghorn corals. Deeper face with organ pipe and other hard corals, sea fans, sea whips. Abundant fish and invertebrates. Figure 41. Diagramatic profile of an offshore reef system. Seaward barrier reef drops to deep water. 64 exoskeleton will contribute to the sand supply when it dies or is killed and its hard parts disin- tegrate. In some localities, species of green algae which deposit calcium carbonate in their tissues (e.g., Halimeda) can account for . large volumes of sand, sometimes piled in deep deposits where the plants are numerous and wave action does not rapidly disperse the resulting sediment. It is often possible by microscopic examination to de- termine the origin of sand particles and sometimes to estimate roughly the percentage contribution from various organisms. The biogenic origin of sand makes it a renewable natural resource which, provided proper manage- ment is employed, can be harvested indefinitely within rates which will allow for its replenishment. The problem in most cases - as it is with the utilization of any renewable resource - is that not enough is known about local rates of replenish- ment, sources of production or factors controlling it. Given other suitable conditions, reefs develop upon hard, stable substrates: rocks or other reef struc- tures. Small reef areas occur at the base of most rocky promontories. Patch reefs of various sizes occur scattered in many areas. Long offshore barrier reefs, roughly parallel to the shoreline, have developed on the edges of ancient island platforms now submerged (Figure 41). Attributes, Sensitivity and Constraints Attributes of reef areas include the following: * Valuable production of marine life including most species harvested for food. * Scenic value for underwater recreation. * Educational value. * * * Shore protection by sea abatement (energy absorption). Sand production. Produces other potentially valuable products, i.e., anti-biotics, other drugs, sea urchins, precious coral. 65 Tolerances are known mostly in a general sense relating to reef building corals as a group. Corals are generally acknowledged to have a narrow range of tolerances to many environmental variables. These limits vary, however, with species and with the setting. The following are some general de- scriptions of forms with differing sensitivities; blanket statements are difficult and at best broadly applicable. * * * Temperature tolerance 160 - 360 C, optimum development between 23 0 - 25 0 C. Salinity below 25 parts per thousand (ppt.) Optimum for most appears to be 34 - 38 ppt. Siltation - tolerances of various local species vary widely and has not been quantified for most. Reefs are generally considered to be relatively susceptible to continued heavy siltation. The definition of "heavy" is not available in the literature. Corals have a limited ability to cleanse themselves, but may expend too much energy in eliminating non-nutri- tive particles or may be literally smothered. Organic sediment, particulatly, can deplete the oxygen supply to lethal levels. Siltation is closely related to turbidity, being caused by solid particles, and their effects may be difficult to separate. A great deal of siltation occurs during most dredging operations as finer particles settle slowly and siltation, therefore, can continue for some time after dredging and may occur at far removed sites. I ts effects can be catastroph ic for sessi Ie organisms. If the rate of fallout is too great, many sedentary organisms, particularly corals, are literally smothered if they cannot cleanse themselves rapidly enough. Beyond this, the coating of the substrate by silt size particles is disadvantageous to the settling of most invertebrate larvae and so recolonization is obstructed. Such surfaces are favored by some species of algae which give the advantage of stabi- lizing the bottom, but also effectively exclude the establishment of reef-builders. In fact, such alteration of the environment has been known to banish corals forever from an area where they were formerly well-developed. * * * Turbidity - corals contain symbiotic algae which are critical to the life of the coral. These algae, if not the coral polyps themselves, require light. They apparently produce oxygen wh ich is used by the coral polyps. Because light is absorbed rapidly as it pene- trates the water, reef building corals are seldom found below 150 feet in clear water. Really good reef growth occurs in 90 feet or less. In turbid water the amount of light reaching the bottom is further reduced. Prolonged light reduction may alter the species composition of a reef or kill it com- pletely. Specific light requirements for cor- als are not known. It is reasonable to assume, however, that local reefs, accustomed to very clear water, are very sensitive to I ight red uction. This assumption seems proven by qualitative observations on reefs subjected to prolonged turbidity. Eutrophication - enrichment of water in the vicinity of reefs may be beneficial up to a point. Corals are filter feeding animals and take fine digestible organic matter and small organisms from the water. Enriched water may increase the supply of these items but will also increase the growth of algae and other forms which can overgrow, smother and compete with the corals for food and oxygen. In addition, enriching nutrients in excessive concentrations can be toxic or be accompanied by substances toxic even in low concentration. Artificial enrichment of naturally low-nutrient environments is a dan- gerous business and not to be recommended generally. Simple common sense dictates against eutrophying an ecosystem which has developed and flourished under native conditions. Use constraints and limitations for reefs derive primarily from their relatively stringent environmental requirements. The following are some representative activities inconsistent with the maintenance of healthy reef ecosystems Effluent Discharges - any discharge except almost pure sea water may be expected to have some detrimental effect on a reef. Fortunately, the location of most reefs in 66 active, flowing water, usually assures rapid dilution and dispersal of pollutants. Only a relatively small area immediately surround- ing the discharge may be affected, but this depends on the nature and rate of the dis- charge and the effectiveness of dispersal. Hot discharges, although they may be clean, are nevertheless destructive. Most tropical organisms exist near their upper temperature limits. Corals, made up of countless minute individual delicate polyps, have an extremely high surface to mass exposure. Heated effluents mounting water temperatures above 300 C will adversely affect many corals. Prolonged temperatures above 400 C will kill most corals. Prolonged exposure to hypersaline discharge elevating salinities above 40 ppt. is detrimental to reefs. Fresh water discharges lowering salinity below 30 ppt. can be ex- pected to affect reef composition. Sediment and other pollutants in the discharge can be harmful to reefs. Sewage discharges add a wide variety of ingredients to the water which have a number of effects. The more obvious contributions of sewage are lower salinity, high oxygen demand, high nutrients, turbidity, sediment and toxic compounds. Reef Inventory Shoreline reef areas and major offshore reef banks are shown in Figures 28 and 29. Reefs of various types and sizes are widespread and common around the islands. Most of the best examples of extensive reef development are on St. Croix where the submarine shelf is especially wide and relatively shallow. The more notable are Long Reef at Christiansted, Buck Island Reef, Tague Bay Reef, Long Bank on the east end, Great Pond Bay Reef and Long Reef on the south central coast. The latter has been extensive- ly damaged by industrial development. On St. Thomas large, well developed reefs occur at Long Point, fronting the mangrove lagoon, at Flat Cays off the southwest coast and at Triangle reef just east of the harbor entrance. On St. John large reefs occur at Ramshead on the southeast and Johnson reef on the northwestern coast. Sand Bottoms Dominated by sand, usually with worm and shrimp burrows and hummocks. Thin, slattered coverage of algae, grasses, sponges, occasional solitary corals and fish (mostly pelagic with few bottom-associated types). Figure 42. Profile of a sand-dominated bottom, usually grades into a reef or grass area. SANDY BOTTOMS Description Sandy bottoms are defined as areas with, at most, sparse sea grass or algal cover. Large areas of sandy sea bottom are scattered throughout the platform. Sometimes they occur in shallow bays without apparent reason, as most shallow bays are vegetated. The most extensive areas of essentially bare sand occur below 60 feet depth_ Even here, the lack of extensive plant growth is not easily explained, but may be due to low light intensity and/or the nature of the sediment Another possible explanation may be that the sand is shifting at a rate which prevents plant establish- ment. Ecology These areas are not, of course, barren_ They usu- ally support scattered algae and the flowering plant Ha/ophila. Occasional sponges, anemones, tunicates and small solitary corals are usually present (Figure 42) especially where there is some solid object - usually a piece of debris - for attach- ment. Bottom fishes are few, but lizard fish and tile fish are not uncommon. Conch, especially the small fighting conch, and hermit crabs may sometimes be numerous. The preponderance of animals in this habitat are infauna, burrowing or tube dwelling forms in the sand. Among the most numerous are several kinds of worms which may occur in densely packed beds. A large variety of mollusks, crabs and shrimp live in the sand. Most of these animals are rarely seen unless the sediment is dug up. Many are nocturnal feeders and when they emerge at night, fish, lobsters, rays, sharks and other predators from adjacent areas move in to feed on them. Attributes, Use Options Sandy areas are not well understood, and the ntcnt of thcilo significance to regional ecosystems is unf,;nowno It may be that they represent areas of active sand transport via which sediment is slowly moved insholoe and offshoreo They are potentially good sites to consider for sand mining pmviding the depth is not financially or technic- ally prohibitive and that adjacent, more sensitive resources will not be unduly affected. As a group the associated organisms are relatively tolerant of turbidity and siltation. This, coupled with the usual deeper open water location of sandy areas, makes them more suitable than most other habitats for effluent discharges. Limitations, Use Constraints Limitations on uses of sandy bottoms derive principally from their relative inaccessibility. Possible limitations deriving from their environ- mental importance are, at best, speculative because of the degree of their importance is unknown. Inventory of Sand Areas Sandy areas are mapped on separate charts avail- able from the Virgin Islands Planning Office. Grass Beds GRASS BEDS Description Grass beds are frequently referred to as marine pastures because they are areas of thick growth of sea grasses and algae resembling pastures on land and serving essentially the same functions. Most inshore bay bottoms are covered with such pastures as are some extensive areas outside of bays. The distribution of a marine pasture is controlled by by a number of factors including sediment quality and stability, depth, water clarity, currents, grazing by herbivorous animals and, in some in- stances, factors which are not apparent. The pas- tures usually do not extend below 60-70 feet depth. Their growth is interrupted in channels or other areas with swift currents or in surge areas when the sediment is constantly tossed, for example, close to a beach. Their edges are grazed away near reefs or other solid objects by fishes and sea urchins which live there and forage on the edge of the pasture. Thus, there is almost always a band of bare sand between a reef or rubble pile and the surrounding Primarily turtle grass with various green algae. High oxygen and biological productivity. Great diversity of inhabitants, many edible species: turtles, conch, fishes. Stabilizes and assimilates wastes, and absorbs wave energy thereby protecting adjacent beaches. Figure 43. Typical shallow water sea grass bed. 68 pasture. The dominant plant in local marine pastures is turtle grass (Tha/assia testudinum). The second most abundant is manatee grass (Syringodium filiforme) a grass with thin cylindrical blades (about one millimeter diameter). A third, less frequently encountered grass is Dip/anthera wrightii, various- ly called shoal grass or eel grass, although else- where these common names apply to other species. On some shallow banks with fine sand, Dip/anthera may form large beds as on the inshore south coast of St. Croix. The three plants are usually referred to as sea grasses. They are unlike the ma- jority of marine plants, which are algae, in that they are true flowering plants. Annually they pro- duce flowers and seeds. However, the prolific growth is mostly due to spreading via runners with emergent shoots. A fourth flowering plant, often found intermixed in small amounts in the grass beds is Ha/ophi/a baillonis, but it is more common in deeper water where it sometimes dominates the flora. Scattered among the sea grasses in the pasture is a large variety of algae in various shapes and colors (Figure 43). However, the largest and most numerous are staked greens. Com monly encountered genera are Penicillus (shaving brush), Vdotea (fan algae), several species of Cau/erpa and Ha/i- meda wh ich has hard calcareous blades and becomes sand when it dies. Ecology Marine pastures produce a significant amount - perhaps most - of the oxygen generated in local inshore waters. On a bright day dissolved oxygen over a healthy grass bed will exceed the saturation value (i.e., the water becomes supersaturated), and small bubbles rise from the leaves to the sur- face. Several species of small fish live in the pastures, but more important, a larger variety of others come here to feed on the plants and myriad creatures that live here. This is the habitat of the queen conch (Strombus gigas) arid feeding grounds of the sea turtles. A diverse group of animals live in the sand between the plants, and the bottom is often heaped into mounds marking the burrow KQ entrances of large worms and shrimp. Grass beds help to stabilize the sand, and where they front a beach it has been postulated that they act as a "footing" to retard seaward loss of sand from the beach. There is a very close knit relationship between the plants and animals in this habitat, both spa- tially and physiologically. The pasture is a low profile environment. The plants usually do not exceed eight inches in height, and all but a few of the associated animals live within this zone or in the sediment. Thus, except for visiting foragers and predators, the majority of community energy cycling goes on in close quarters. Wastes from the animals are utilized by the plants which produce oxygen and forage. Mild enrichments of the water as by small contin- uous sewage discharges can cause affected areas of grass to grow extremely rapidly and produce long leaves. Prolonged enrichment usually encour- ages atypical species of algae, indicative of pol- lution (V/va, Enteromorpha, Cladophora). For unexplained reasons, patches of grass removed by various means (dredging, boat anchors) may not be replaced for years. In most bays which have been dredged, the marine pasture has not become re-established in the dredged areas for many years. In the case of Lindbergh Bay, St. Thomas, 40 years have elapsed, and a barren hole remains off the western portion of the beach. Even small swatches cut by an anchor, a dredge or a boat's propeller may remain bare for a year or longer. Attrib.utes, Use Options * Grass areas have mild capabilities for assim- ilating wastes, but good flushing of the over- lying water is advantageous. * * Usually are associated with clear water, but can tolerate some increased turbidity; limit has not been quantified. Associated animals can remove silt from periodic flooding, incorporate it in sediment and "cleanse" the bottom. Limitations, Use Constraints * Once destroyed, marine pastures usually require a long time to recover. Deep holes may never recover. * Since the community is dominated by plants a critical minimum amount of light is needed. Chronic, heavy turbidity is destructive. Quantitative tolerances have not been deter- mined. Distribution of Grass Beds Shallow water sea grass beds are widely distributed in the islands. Major distribution patterns are shown on large scale charts available separately from the Virgin Islands Planning Office. OFFSHORE CAYS Description The small offshore islands vary in size from bare protruding rocks to over 170 acres. Most are 5 - 50 acres. A few are inhabited by one or two families - and many are difficult to get onto even by boat. Simple rock protrusions like Booby Rock, Sail Rock and Cricket Rock serve mainly as roosting and nesting sites for sea birds. The larger islets have beaches, rocky shores, cliffs, and some vegetation, mainly zeric scrub. Most have at least one salt pond and are surrounded by some degree of reef development. Most of the more than 60 emergent rocks and cays are around St. Thomas. Ecology Because of their remoteness, the cays are popular nesting sites for many local birds including migra- tory sea birds and are the last remaining local rookeries for several species. Although they usually harbor rats, with a few exceptions there are no mongooses. A major exception is Buck Island, St. Croix. The lack of these voracious predators per- mits ground nesting by many birds and the sur- vival of some lizards and snakes which have been extirpated on the main islands. However, con- siderable poaching of sea bird and dove nests as well as illegal hunting has been practiced by man, despite the prohibition of hunting on publicly owned cays at any time, a law which is difficult to enforce. The value of the cays as bird sanc- 70 tuaries has been stressed in the past (McNulty, Robertson and Horton, 1968) and Dr. Arthur E. Dammann of the Virgin Islands Department of Conservation and Cultural Affairs is presently preparing an atlas of the cays in an attempt to draw attention to their value and uniqueness. This document should be a useful management tool. Among the birds which nest on our cays is the brown pelican, a species which is in danger of extinction. Resident colonies breed on Whistling, Congo and Dutch Cap cays off 5t. Thomas and 5t. John and on Buck Island, 5t. Croix. A large colony of terns nests on Flanagan Island. The beautiful tropic birds nest on some cays, and mountain doves use mostcays,butfavorTurtledove, Saba, Buck, Capella and Flat Cays. Other impor- tant nesting sites are Little Hans Lollick, Cock- roach, 5ula, Sail Rock, French Cap, Kalkun and Dog Island. The salt ponds on most cays seasonally harbor some ducks, including the locally rare Bahama pintail. One attribute of the numerous cays around St. Thomas and St. John is their abatement of large ocean waves and swell and protection of the coastal areas of the main islands. TABLE 5 I nventory of offshore cays Elevation Beach Rocky Cay Acres (feet) Shore Shore Booby Rock 0.5 35 all Bovoni Cay 50 75 (all mangroves) Brass, Inner 128 256 E, S, W, NE N, NW Brass, Outer 108 412 all. Buck Island, St. Croix 179 330 S N Buck Island, St. Thomas 41 125 all Capella Island 22 121 all Carval Rock 0.5 67 all Cas Cay 16 99 NW E Cinnamon Cay 1 32 all Cockroach Island • c.lc.llo"cJ... 19 151 all Cocoloba Cay 1 36 S N Congo Cay 25 170 S N Cricket Rock 3 46 all Current Rock 0.4 13 all Dog Island 12 78 all Dutchcap Cay 32 278 all Fish Cay 3.5 21 all Flannagan Island 21.5 127 W N, E, S Flat Cay, Big 3 32 scattered scattered Flat Cay, Little 0.4 11 scattered scattered Frenchcap Cay 10.5 183 all Grass Cay 49 230 S N, S, E, W Green Cay, St. Croix 13 63 SE,E N, NW Green Cay, St. Thomas 0.7 24 W S, E Great Hanslollik Island 489 704 NE, SE N, S, E, W Little Hanslollik Island 100.5 204 5E N,S, E, W Hassel Island 139.5 267 W S, E, N Henley Cay 11.5 70 S NE,W Kalkun Cay 3.5 73 all Leduk Island 13.5 85 S N Lovango Cay 118 255 W,S N,E Mingo Cay 48 186 S N,W, E Patricia Cay 33.5 75 S (mangroves Elsewhere) Pelican Cay 4.5 15 all Perkins Cay 0.5 25 all Protestant Cay 4 33 W E Ramgoat Cay 2.7 30 all Range Cay 4.6 25 all Rotto Cay 2 33 (all mangroves) Saba Island 30.3. 202 N S, W, E Sail Rock 1.6 125 all Great St. James Island 156.8 175 N all Little St. James Island 68.7 142 scattered scattered Salt Cay 55;8 242 S N, E,W Savanna Island 173.3 269 all Shark Island 1.25 32 all Steven Cay 2 32 NW, rubble SE, SW Sula Cay 1.8 100 all Thatch Cay 236.8 482 S N Trunk Cay 1 48 N,NW E, NE,W Turtledove Cay 3.8 50 S N,E,W Two Brothers 0.4 10 all Water Island 491.4 294 scattered scattered Water Lemon Cay 0.7 35 SE S,W, N West Cay 40.3 121 scattered scattered Whistling Cay 18.6 202 S N Attributes, Use Options * Unique wildlife habitats, mostly mongoose- free. * * * Usually have unspoiled reefs. Provide coastal protection for main islands. Most are suitable and recommended as wild- life sanctuaries, others as recreational parks or multiple use resources in keeping with their fragile nature. Limitations, Use Constraints * Small size, easily subject to environmental damage. * Lack of fresh water resources. * Exposure to drying wind and salt spray. * Many poorly accessible. OTHER MARINE RESOURCE ELEMENTS Although the waters of the island shelves are noticeably low in dissolved nutrients {nitrates, phosphates, silicates} and of uniformly warm tem peratu res down to about 125 feet, the deep water of the submerged shelf faces and trenches is col.d and high in dissolved nutrients. This deep water is below the photic zone, the depth limit at which sufficient light is available for grass, algae and plankton growth which would use up nutrients. The lack of current upwelling prevents this water from reaching the photic zone and en- riching the upper levels of coastal water. Thus, this denser {colder, richer} water is stratified and essentially confined vertically. Temperatures in the deep basins are 5 - 100 C and nutrient concentrations are up to 200 times as high as surface water. These temperature. and nutrient differentials are a potentially valuable resource of enormous scale {Gerhard and Rohls, 1970}. Off the southeast coast of St. John and the north coast of St. Croix deep water occurs fairly close to shore. If drawn to the surface, this cold water is _potentially valuable for mariculture, 72 industrial cooling, fresh water production by con- densation, and power generation. Columbia University's mariculture research project at Rust-op-Twist on St. Croix's north shore has proven the technical, if not the financial, feasibility of the mariculture aspect. For other applications, considerable technological development is needed, but the possibilities are certainly worth exploring. Discharging the high nutrient water into the coast- al waters is an aspect that deserves to be monitored closely for adverse effects. Of the innumerable species of marine life around the islands, only a handful are presently used by man. A considerable number of others are suitable for food and other uses but have traditionally been ignored. Snails of the genus Astrea occur in similar habitats to Cittarium {the welk}, sometimes in large numbers. While they do not grow as large, they reach sizes comparable to that of harvested welk and are just as tasty. The small fighting conch (Strombus pugilus) frequently occurs in large aggregations at accessible depths, is similar to queen conch in taste and is larger than all but the largest welk, which are extremely rare. A crab of the family Portunidae, similar to the North American blue crab, but slightly smaller, has been taken incidentally in local fish pots for years but never considered as a food item. The Virgin Islands Division of Fish and Wildlife is now trapping selectively large numbers of these crabs from flat bottoms greater than 100 feet deep. Their work indicates that this crab is numerous on most of the deep, flat shelf areas around St. Thomas. Recently in California a commercial fishery has been developed for spiny sea urchins similar to our Diadema antillarum {sea egg}. The roe is extracted and used as a sort of "caviar". I n some other West Indian islands the roe of the larger short-spined sea urchin Tripneustes, which also occurs locally, is relished as a delicacy. Shark meat and by-products are in great demand allover the world. They are fished in other parts of the Caribbean and the world, and a small venture had been operating locally for a time. There is a market for virtually every part of a shark. The meat is used as human and pet food. The skin is used like leather for a variety of products, and vitamin rich oil is extracted from the liver. Other parts including fins and eyes are marketable for various uses. There probably are sufficient numbers of sharks in local offshore waters to support some commercial effort. Various kinds of precious coral occur locally, mostly at depths beyond 100 feet. These are bush or tree-like forms with hard horny skeletons which can be polished to a rich texture and color. The most popular is black coral Antipatharia) which occurs locally. Other precious corals are pink, rose or white, but their occurrence locally is un- known although possible. Precious corals are made into jewelery which brings a good price. Tradi- tionally it is harvested by SCUBA divers, but recently in Hawaii commercial collectors have begun using a submersible vehicle with mechanical arms. Black coral grows very slowly, and harvesting needs to be regulated to avoid extirpation. Re- search on growth rates of Antipatharia is currently being carried out in Curacao at the Caribbean Marine Biological Institute. Rocky Shoreline Associations CACTUS - AGAVE SCRUB Shoreline vegetation tolerant of salt and drying. Soil thin. CORAL COMMUNITY Bedrock and boulder substrate. Corals near surface. Sea fans, sea whips deeper. Figure 44. Rocky shoreline and associated sea bottom. SEA GRASS AND ALGAE Sand layer thin near- shore deepening off- shore, grading to grass or algae bed. ". :; Analysis of Biophysical Relationships Classification of Coastal Ecosystems The composition of coastal ecosystems varies considerably, but certain combinations of habi- tats occur frequently in the island areas. The Virgin Islands are no exception, and the following typical systems have been chosen for illustration. Rocky Shoreline Associations (Figure 44) Dom i nant featu res: shorel i ne of hard resistant, highly fractured rock extending under and resulting inactive coral growth on the rocky base along shore and extending onto hard substratum at greater depth. Characteristics: salt-tolerant plants on shore; turbulent, usually clean, clear well oxygenated water with tough hard and soft coral community and other living forms highly resistant to wave action. Bedrock usually lies beneath thin sand cover up to several meters offshore. Suitability: snorkelling, fishing, good dispersal for treated effluents, scenic value above and below the surface of the water. Restrictions: wave action precludes mooring, anchorage; light structures on shoreline rocks subject to wave, storm and corrosion damage. Salt Pond - Bay Associations (Fig. 45) Dominant features: protected bay with sea grass bottom and beach shoreline sometimes with near- shore patch reefs, hypersaline and separated from sea by sand or pebble beach and berm combinations, often surrounded by mangrove. Characteristics: very low energy water motion in bay, pond acts as catchment and filter for flood water from land, usually supports wading birds and other wildlife in associated mangrove. Suitability: low energy bay usually good for watersports, boat anchorage. Ponds may be filled for development or opened for marinas. Restrictions: structures on filled ponds need pil- ings, opening of ponds can release fine sediments and toxins to upset bay organisms and water quality. Filling or opening pond incurs water quality stresses on the adjacent bay. Sand Beach - Grass Beds Associations (Fig. 45) Dominant features: sandy beach, with gently sloping bottom leading to sea grass and algal pasture on bottom of protected bay. Characteristics: beach sediments, grain size and profile change constantly in response to wave and currents. Sea grass acts as stabilizing factor in offshore movement of sand. Plants oxygenate water, assimilate community wastes, provide food and shelter for wide variety of animals. Suitability: good swimming and recreation areas, usually suitable for small boat anchorages and moorings. Attractive areas for shoreline develop- ment. Frequently provide harvestable quantities of reef fish and conch. Restrictions: solid structures on the submerged beach act as barriers, interrupt sand transport, change beach shape and quality. Structures on pilings less so. Excessive development in the watershed can result in deterioration of water qual ity, affecti ng recreational potential. Excessive and/or poorly designed dredging for sand can severely damage beach, coral communities and marine vista. Mangrove - Lagoon - Reef Associations (Fig. 46) Dominant features: mangrove fringed shore or dense mUlti-species mangrove forest, mangrove mini-islands, landward salt ponds or tidal flats, quiet small lagoons between mangroves and pro- tective adjacent offshore reefs, usually shallow with narrow entrance channels. Characteristics: extremely high system productiv- ity and utilization of energy, rich in edible and other organisms, food chain based on mangrove leaf litter, quiet water with low flow promotes sedimentation. Area is important feeding and breeding ground for many birds, juvenile fishes and shellfish. Suitability: recreation, education, faunal pre- serves, fishing, marinas. Restrictions: low water flow makes areas unsuit- able for waste discharges. Filling land to shoreline will kill ecosystem base - the mangrove plants. Susceptible to turbidity and rapid sedimentation. While potentially good sites for marinas and sand dredging, they are generally intolerant of the impacts attributes condary tolerate. generated by these activities. Natural of mangrove areas subject them to se- environmental stresses they cannot Man-Made Shoreline and Structures (Fig. 47) Dominant features: developed shoreline with al- tered topography and drainage, high percentage of impermeable surface, unnatural shoreline (bulkhead, landfill, docks, etc.), usually low- energy quiescent protected bay. Characteristics: high use levels, increased addition of pollutants and toxins to the bay, abnormally high turbidity and pollutants, impoverished floral and faunal communities, increased sedimentation, subject to rapid runoff , frequent hydrocarbon Sand Beach - Grass Beds - Salt Pond - Reef Associations SALT POND Traps runoff, sediment, pollU- tants. Controls drainage. Figure 45. BEACH Dune Berm Foreshore Recreational sites. Vegeta- tion stabilizes shore. Berm and foreshore constantly changing in "dynamic equilib- rium." Filters water leaving the land. SEA GRASS BED Stabilizes sand. Provides oxygen. Assimilates wastes. Feeds and shelters diverse biota. REEF Protects shore from waves and s",ell. Sand and bio- logical pro- duction high. Typical sand beach ecosystem showing relationship of component habitats. 76 slicks, often develop colored phytoplankton blooms. Suitability: as previously modified natural systems, these areas could have priority consideration for sand dredging for channel maintenance or con- struction sand (if properly executed) to protect adjacent resources. Within limitations of the eco- system these bays should be considered first as sites for further development. Restrictions: because of limited circulation and existing pollution loading, should not be con- sidered for direct waste discharge of any type. Future development needs to be gauged carefully to avoid exceeding ecosystem capability and acceptable pollution loading levels. Mangrove - Lagoon - Reef Associations MANGROVE SEA GRASS SALT POND HORELINE FLAT MANGROVE CAY Critical Areas AREAS OF HIGH PRODUCTIVITY Few quantitative measurements of productivity have been made in the Virgin Islands. The follow- ing areas are listed because the site-specific environ- ment there is known generally, from research on similar sites, to be highly productive; or because it yields especially large amounts of seafood, although production may not be in situ. Thus, the list is conservative. Most reef banks are fished by traps and handlines. All grass beds sometimes contain harvestable quantities of conch. ST. THOMAS 1. Jersey Bay Mangrove Lagoon - breeding area, wildlife refuge. BACK REEF FLATS FRINGING REEF Traps run- Red man- Quiet wa- off. Black groves ter, silt and white seaward. sand sed- mangroves Black and iment, landward. white thick sea mangroves grass landward. growth, Trapped sediments and mangrove roots. Larger cays with mangrove zonation and terrestrial vegetation. Wild- life sanctuary. Sea grass, algae, scattered corals, clean sand, reef rubble. Typically Acropora near surface. Or- gan corals, sea fans, etc. seaward. Finger coral landward. A- bundant sea life. Wave protection. Sand produc-, tion. Figure 46. Traps abundant sediment sea life. expanding shore- line. Mangrove dominated ecosystem with lagoonal flats and protective reef. Food chain centered on sea grasses and mangrove litter. 2. Southern Shelf Edge (100 fathom d ropoff) high fish concentrations, heavily fished. 3. North Central and West Shelf - productive fishing areas. ST. CROIX 1. Sandy Point - traditional fishing area, apparent good sand source. 2. Manning Bay Mangrove Area - wildlife habi- tat, fish and bird breeding. 3. West Coast Shelf - heavily fished. 4. East End Reefs (Lang Bank) - biologically productive area ST. JOHN 1. South Shelf Edge - popular fish i ng area. Man-made Shoreline & Structures 2. Coral Bay and environs - heavily fished area, some mangroves. AREAS UNDER STRESS ST. THOMAS 1. St. Thomas Harbor and Crown Bay - urban runoff, sewage, dredging, marinas and ship traffic. 2. Lindbergh Bay - urban runoff, sewage, thermal- saline effluent, dredging. 3. Fortuna Bay - periodic stress by runoff from Estate Bordeaux and surround ing residential area. Apparently tolerating stress, recovers quickly from each episode but cumulative effects of continued increasing stress may produce long-term noticeable degradation. DEVELOPED SHORELINE STRESSED BAY Heavy use, altered drainage, high proportion of impervious surface, vegetation cleared, high runoff, pollution sources. .- - ~ Heavy use, increased turbidity, silty bottom, reduced bottom diversity and productivity, possible phytoplankton blooms, boats disturb bottom, con- tribute hydrocarbons, heavy metals, sewage, structures may reduce circulation. Often require maintenance dredging . :. : :. ,:::: .. :':::: ~ :J::: :~::::~. :::::: :':::::: :::::::: :::::::: :::::::: L:::: :L::: L::: i::;: i:;:;: ;:::;:;:./ ;. :i, :,b; :; :,:;;;.; .' Figure 47. Man-dominated Bay Ecosystem. 78 4. Stumpy and Santa Maria Bays - ambient tur- bidity appears to be increasing, caused by run- off from developing north shore mountain slope areas. 5. Water Bay - attrition of nearshore grasses and algal beds probably due to dredging, filling of salt pond and increasing siltation from residential development. 6. Vessup Bay - stress sources: marinas, boat traffic, sewage, runoff. 7. Jersey Bay Mangrove Lagoon - stress sources: marinas, boat traffic, sewage, runoff, filling of ponds, cutting mangroves, canalizing drainage. ST. CROIX 1. Christiansted Harbor - stress sources: dredging and filling, urbanization, runoff, sewage, ther- mal-saline effluents, marinas, boat traffic. 2. Altona Lagoon - stress sources: channel re- striction, urban runoff. 3. Canegarden Bay to Port Harvey -stress sources: dredging, filling, runoff, oil spills, air pollution, thermal-saline discharges, ship traffic. 4. Manning Bay-stress sources: garbage, dumping, periodic petroleum spills. ST. JOHN 1. Cruz Bay - stress sources: dredging, pond-fil- ling, marina, boat traffic, sewage. 2. Great Cruz Bay - stress sources: dredging, pond filling. 3. Enighed Pond - stress sources: garbage, solid wastes. UNIQUE AREAS ST. THOMAS 1. Jersey Bay Mangrove Lagoon - largest original surviving mangrove stand in the Virgin Islands. 2. Coki Point Peninsula-unique pretertiarymarine fossils. 3. Magens Bay Valley and Beach area - significant concentration of documented pre-Columbian archaeological sites. Superb public beach, ar- chaic botanical garden, publicly acknowledged as an aesthetically unique element of the Vir- gin Islands coastal zone. 4. Botany Bay Estate - deciduous forest, high diversity, adjacent patch and fringing reef, scen ic - high recreation potential for territorial park. , 5. Most offshore cays, especially Savana,Little Saba, Turtledove; Cockroach, Cricket Rock, Flat Cay, Whistling, Congo 'and Dutch Cap Cays - all are important nesting sites for d'oves and sea birds, the last three especially for pelicans which are an endangered species. ST. CROIX 1. Lang Bank - unusually large area of reefs ex- tending westward on both north and south sides of island. 2. Salt River - largest remaining mangrove estuary on St. Croix 3. Westend Salt Pond - unique combination of large pond, sand dunes, and xeric forest. 4. Great Pond - the largest remaining marsh area on St. Croix with fringing mangroves, partially dedicated to public use. ST. JOHN 1. Lagoon Point, Coral Bay - excellent well de- veloped fringing reef, broad coral flat, inner shallow lagoon with turtle grass stands, assoc- iated red mangrove and salt pond. Warrants inclusion in territorial park system. 2. Newfound Bay - ,excellent example of reef" choked bay combining classic fringing reef complex and coastal land-formation dynamics. 3. Carval Rock and Congo Cay - important nesting sites for sea birds, scenic. Miscellaneous Attention is directed to the published inventory of "Potential National Natural Landmarks" of the U.s. Virgin Islands, prepared by the West Indies Laboratory for the National Park Service (May, 1975); a priority rating system is used. Coastal Zone Planning Guidelines Regional Context Formulation of a Virgin Islands Coastal Zone Management Plan should reflect overall require- ments for services, facilities, environmental diver- sity, and the preservation of natural and cultural assets. We recommend that, in consonance with local requirements, an evaluation be made of the regional n for various resource allocations. There is probably no defensible basis on which to argue for the absolute protection of all of the approxi- mately 100 remaining salt ponds, but it is also indefensible to argue that they should all be filled for construction or opened as marinas, given the interdependent relationships of the U.s. Virgin Islands to adjacent island areas to leeward and windward. Local planning should be geared to providing rational resource allocation consistent with main- taining regional environmental diversity. The development of marinas, as one example, should not be limited only by current economic demand or the availability of suitable sites, but ultimately by the regional need for allocating available sites for alternate uses, given the pattern of small boat visitation in the eastern Caribbean. The need for this type of evaluation for many coastal resources is mounting and, in at least two site-specific cases, is long overdue. Of the several extensive mangrove forest areas originally found in the islands, only two remain. The majority have been committed to the single purpose of land develop- ment and virtually obliterated. The remaining two sites represent the Virgin Islands' only surviving opportunities to provide alternate allocations of these extremely important, highly threatened and presently unique resources. \I{\ A second example is the last remaining areas of native rainforest vegetation, primarily on St. Croix with a small area on St. Thomas. Although not coastal, they provide glaring examples of how individual resources may be decimated for a single purpose without thought to alternate uses. The foregoing descriptions of coastal and marine habitats have touched frequently on interactions between these component units. Future assessment of the Virgin Islands Coastal Zone and develop- ment of management strategies needs to keep the interactive perspective of natural systems in focus in understanding coastal processes for planning purposes. Management plans must be built on a comprehensive approach reflecting an appreciation of the interactions and interdependencies of the various physical and biological components within the larger scale. This ecosystem approach must consider the integrity of larger systems as related to singular manipulations of component parts. Inherent in this approach is the consideration of the secondary impacts of all resource manipula- tions, for whatever purpose. An "ecosystem" comprises a complete integrated unit of physical and biological components within which no part functions independently of the others. As such, coastal ecosystems can logically exclude neither the contributing inland watershed nor the adjacent marine area. Management of any ecosystem should have the fundamental purpose of maintaining the system at "best achievable ecosystem function" (Clark, 1974). Guidelines For Resource Management Concepts of resource management have been de- veloped along the lines of Clark's (1974) Coastal Ecosystems: Ecological Considerations for Manage- ment of the Coastal Zone, which is highly recom- mended for the planner and dec.ision-maker. The principles therein have been applied to specific local resources and their management require- ments so far as we now understand them. In this regard, it is necessary to broadly classify and identify coastal areas according to their needs for planning concern. Clark describes three cate- gories of concern: (1) Vital A reas are ecosystem elements of such high value and critical impor- tance that they must be set aside as preserves, protected intact from outside stresses. They must be encompassed within (2) an Area of Environ- mental Concern which serves as a buffer zone. Areas of Environmental Concern are conservation areas which require special conservation and man- agement protection because of broad environ- mental sensitivity. (3) Areas of Normal Concern are areas where only normal, but planned and en- forced, methods of utilization and exploitation are necessary. Vital Areas Cays Most offshore cays must be considered vital. Specifics on individual importance and manage- ment requirements should come out of work now being done by the Virgin Islands Department of Conservation and Cultural Affairs. These areas are extremely important to vanishing local as well as internationally migrating bird species. Because of their small size, the cays are very sus- ceptible to. man-made stresses, inadvertant or otherwise. Areas of Environmental Concern Mangroves Jersey Bay mangrove forest, St. Thomas, and Salt River and Great Pond on St. Croix represent ecosystems of proven importance to local com- mercial fish and lobsters as well as many birds. Much of their actual. and potential value is still not appreciated or understood. They are extremely critical also because they are the only remaining areas of their kind in the Virgin Islands. It may be necessary to set aside small, special sections as vital areas, and this is strongly indi- cated in the case of Cas Cay and Patricia Cay in the Jersey Bay lagoon. Rain Forest Remaining rain forest areas on St. Thomas and St. Croix are vital for the same reasons. Although not coastal, the protection of the large watershed areas wh ich they cover is important in the man- agement of the coastal receiving waters. Again, they represent the last remnants of original "coastal" vegetation and are a refuge for numerous plants and animals not found elsewhere in the extant coastal zone. Surface Water Caledonia Gut and Creque Dam on St. Croix are the most impressive fresh water habitats left in the islands and deserve special efforts for pro- tection and management. All remaining fresh water streams and perennial ponds in the islands need special status and enforcement of existing laws for their protection. Turpentine Run Gut on 51. Thomas formerly harbored a variety of fishes, crustaceans and water birds. It has been decimated by constant sewage and laundry waste discharges, and most of its biota has vanished. Again, these guts have significance for coastal water quality in addition to their own intrinsic value. These surviving areas are now unique in the Virgin Islands and require stringent, well planned protection and management. It is pro- bably not necessary to set them aside as inviolate preserves. They can be maintained as sanctuaries for important wildlife while providing properly controlled, multiple usage for recreation, educa- tion, research, water storage and agriculture. AREAS OF NORMAL CONCERN All other habitats and ecosystems in the islands are sufficiently extensive so that requirements for their protection are not yet critical. Some specific sites are approaching the point of needing special restricted management to insure their continued use, consistent with maintaining basic environmental quality. What is critical, however, is the need for regional' and local assessment of resource allocation re- quirements and a local management plan to insure proper allocation and environmental maintenance constraints. It should never be contrued that areas not specified as vital or requiring environ- mental concern do not warrant management controls. Uncontrolled resource exploitation will lead to crisis situations in all ecosystems eventually, and proper management of the entire coastal area is in order. AREAS OF REGIONAL, NATIONAL, and INTERNATIONAL SIGNIFICANCE The areas already cited as vital to the Virgin Islands and requiring special concern are significant in a larger sense, outside of their site-specific natural value. On one hand, they represent unique remnants of the islands' natural heritage and, as such, should be maintained for future generations. I n a larger frame, we suggest that mangrove areas, for example, may be significant to the production of regional populations of lobsters and several species of commercially important fishes. In an even larger sense, mangroves, cays, and rain forests are known to be critical habitats for many species of migratory birds, some in danger of extinction. In addition, they harbor many of our locally rarer reptiles and birds. Guidelines for Ecosystem Management The following general principles of coastal eco- system management are cited from Clark (1974). Ecologic Principles Eleven principles derived from ecology that under- lie major management functions are given below: 1. Ecosystem integrity - no one part of an ecosystem operates independently of any other. 2. Linkage - water provides the essential linkage of land and sea elements of the coastal ecosystem. 3. Inflow - the natural volume, pattern and seasonal rate of fresh water inflow provides for optimum ecosystem function. 4. Basin circulation - the natural pattern of water circulation within basin provides for optimum ecosystem function. 5. Energy - the flow and amount of available energy governs life processes within the coastal ecosystem. 6. Storage - a high capability for energy storage provides for optimum ecosystem function. 7. Nitrogen - productivity in coastal waters is normally governed by the amount of avail- able nitrogen. 8. Light - the natural light regime provides for optimum ecosystem function. 9. Temperatures - the natural temperature regime provides for optimum ecosystem function. 10. oxygen - high concentrations of dissolved oxygen provide for optimum ecosystem function. 11. Salinity - the natural salinity regime provides for optimum ecosystem function. Management Principles and Rules 1. Ecosystem integrity: each coastal ecosystem must be managed with respect to the related- must be managed with respect to the related- ness of its parts and the unity of its whole. 2. Drainage: A fundamental goal of shoreland management is to retain the system of land drainage as near to the natural pattern as possible. 3. Drainageway buffers: the need to provide vegetative buffer areas along drainageways increases with the degree of development. 4. Wetlands and tidelands: the need to preserve wetlands and vegetated tidelands increases with the degree of development. 5. Storage: storage components of ecosystems are of extreme value and should always be fully protected. 6. Energy: to maintain an ecosystem at optimum function, it is necessary to protect and optimize the sources and the flows of energy that power the system. Management Rules 1. Drainageways: alteration of any drainageway by realignment, bulkheading, filling, im- pounding, or any other process that short- cuts the natural rate or pattern of flow or blocks or impedes its passage is unacceptable. 2. Basin circulation: any significant change from the natural rate of water flows of a coastal water basin is presumed to be ecolo- gically detrimental and is unacceptable. 3. Nutrient supply: reduction (or increase) of the natural supply of nutrients to the coastal ecosystem by alteration of fresh water inflow is unacceptable. 4. Nitrogen: discharge of nitrogenous com- pounds into confined coastal waters is pre- sumed to have adverse effects througheutro- phication a~d is unacceptable .. 5. Turbidity: turbidity of higher than natural levels is to be presumed detrime'rltal to the coastal ecosystem and is unacceptable. 6.- Temperature: significant alteration of the natural temperature regime of the coastal ecosystem is presumed adverse and is un- acceptable. 7. Oxygen: any sign ificant red uction from th'e natural concentration of oxygen is presumed to be adverse and is unacceptable. 8. Salinity: any significant change from the natural salinity regime is presumed ecologi- cally detrimental and is unacceptable. 9. Runoff contam ination: any significant dis- charge of suspended solids, nutrients, or toxic chemicals is to be presumed adverse and is unacceptable. Controls Because both land and water use controls are necessary for best achievable ecosystem function, it is necessary to regulate' both the location and the design of projects in shoreland and coastal water provinces. Also, many types of human activities must be controlled to some degree. In addition, the construction of many types of projects and their operations will have to conform to certain performance standards. * * * * In addition to general principles applicable to specific types of environments, management guidelines should be flexible enough to allow for site-specific evaluations of control and management needs. The following guidelines are provided' as a preliminary basis for developing management plans for the ecological units described in this report. Management Guidelines for Beaches 1. Dredging in bays with beaches should not be allowed except under carefully designed plans to prevent loss of important sea grass b~as, the creation of deep depressions, water quality degredation and deleterious 'changes in sand transport mechanisms. 2. Beach restoration with dredged sand should hever be accomplished by simply pumping the sand onto the shore. It should be pumped into settling ponds and later spread on the beach mechanically, not hydraulically. 3. Structures (pipes, docks, groins, walls) should never be constructed across (or at right angles to) a beach unless carefull extensive study of alongshore sand transport regimes indicate they will be innocuous or advan- tageous. 4. Sand should not be removed from beaches. 5. Shoreward earth change and drainage modifi- cations must be controlled to protect beach areas from pollution by storm water. Management Guidelines for Rocky Shores 1. Structures on rocky shores should be secure- ly anchored to stable footings. 2. Soil and other land materials should not be pushed over the shore into the sea. 3. If effluent discharges are contemplated, site stud ies are needed to determ i ne where cu rrents will carry pollutants, perhaps to more sensi- tive adjacent communities. If so, alternate outfall locations should be selected. 4. On cliffs, a construction set-back require- ment may be advisable in some locations for safety and to avoid effects of erosion on near-shore resources. Management Guidelines for Salt Ponds Management and use allocations of salt ponds should be approached generally on an individual basis. Decisions need to be based on a fairly thorough understanding of the functions and relative importance of the salt pond in relation to its total ecosystem setting, that is, its impor- tance to surrounding resources and other use requirements. It is probably not necessary that every salt pond in the islands be preserved as is. Salt ponds vary in their relative importance to the surrounding watersheds and as wildlife habitats. The potential impact of pond mod i fi.cati on , there- fore, is a site specific function. However, the following considerations generally should be applied: 1. In any case where a pond is to be opened to the sea, or an existing opening enlarged or otherwise modified, an adequate descrip- tion of pond bathymetry and sediments based on soundings and borings should be available. 2. Sediments dredged from a pond should not be deposited directly in the sea or on the bay shoreline. Such disposal should only be considered if the sediments are clean sand or coarser material, a condition which usually does not occur under such circumstances. 3. Where a pond is deepened and opened to the sea, as for a marina basin, the connecting channel depth should be continuous with the depth of the pond basin. 4. Openings to the sea should not be made until all internal work in the pond is com- pleted. 5. Based on the sediment profile of the pond bottom, nature of the adjacent bay environ- ment and action of flushing currents, dredged pond and access channel depths should be designed to avoid releasing extremely fine, toxic pond sediments to dispersal in the sea. 6. The relationship of the pond to the surround- ing watershed should be determined. This consideration may determine whether or not pond modification is advisable and what alternate or restorative drainage provisions are required. 7. Because of the smallness and close spatial relationship of most Virgin Islands, the importance of a salt pond as a wildlife habitat should be determined in advance as it relates to the availability of similar habitats in the islands. 8. If the pond is to be opened to the sea, it is advisable to know something of the surround- ing marine environment, including water movement and biota. Management Guidelines for Mangrove Areas 1. The remaining large mangrove areas (espec- ially Salt River, St. Croix and Jersey Bay, S1. Thomas) should be placed in the terri- torial park system. Their development should be stringently restricted only for recreational, aesthetic and academic use. Only minimal, carefully planned construction, compatible with their protected status, should be per- mitted. 2. Dredging and filling as a rule should be pro- hibited except on a small, carefully controlled scale and only if thorough study has indicated its absolute necessity for some purpose consistent with protective management. 3. Collection of marine or terrestrial living or physical materials should be prohibited except under a carefully controlled permit system for educational or scientific purposes. Guidelines for such a permit system may be adapted from the similar National Park Service permit system. Commercial exploit- ation should generally not be allowed. 4. Sport fishing may be permitted, but it may be necessary to specify allowable areas, fishing gear and perhaps species, seasons and size limits. 5. Boat traffic within the area must be strictly controlled. Some portions may be opened to small outboard powered boats, while other areas (shallows, quiet waters, muddy bottoms) should be closed to all motor boats. 6. No anchorage for boats should be permitted anywhere in the mangrove system. No live- on boats should be allowed. 7. Cutting of shorel i ne mangroves or of a trail through the mangroves for boat mooring or any purpose other than the planned area management and use program should be prohibited. 8. Points for small boat docks, launching ramps or other access structures should be carefully selected and structures carefully planned, constructed, I icensed and managed. 9. No waste discharges or polluting substances of any kind should be permitted into the area. Sewage systems should provide for treatment recycling of the effluent unless suitable soil is available for septic tanks and leach fields which would not allow seepage of effluents to shore waters. 10. By zoning, licensing or other appropriate controls, buffer zones should be maintained adjacent to the mangrove area to minimize runoff, erosion, air or water pollution which may adversely affect the mangrove area. Buffer zones adjacent to water areas should be at least 150 feet wide to provide runoff interruption, soil infiltration and plant absorption of ground water. The width of the buffer zone should be wider where vege- tation is sparse or the slope is steep or the soil is not porous. In some cases reforestation may enhance the buffer zone. 11. Hunting of birds or the taking of eggs should be prohibited. 12. Restraint must be employed in constructing access roads. In keeping with recreational, educational and preservational objectives, access roads should be of minimum number and size, consistent with management goals. In no case should causeways be built across channels or ponds. 13. Development restraints should be promul- gated for the watershed which drains into the mangroves to control thevolumeand frequency of runoff. Canalization and other drainage modifications which would adversely affect the marine mangrove area should be pro- hibited. New drainage systems should utilize natural drainage ways wherever possible and should be designed so as not to increase stream discharge to the mangroves. Subsoil infiltration should be strictly controlled. Revegetation of cleared upland areas should begin as soon as possible. 14. Impervious surfaces (asphalt, concrete, etc.) should be kept at a minimum and provisions made to impound runoff from such surfaces and store it for use or percolate it into the soil. Suggestions For Managed Multiple Uses Of Man- grove Areas Within the context of the recommended protective status, the natural attributes of the two large mangrove areas should be developed to translate these attributes into useable social resources. Possible use of the areas include the following: 1. Recreation. * Nature trails, underwater trails, bird watching, hiking. * Fishing on a controlled basis by conser- vative methods. * Swimming. 2. Education. The potential for educatng students at all levels in areas of West Indian natural history is limitless. The mangrove lagoon on St. Thomas has already been used on a limited basis by the Environmental Studies Program of the Virgin Islands Department of Education. 3. Research. The mangrove areas provide the opportunity for research into (1) coastal geological processes, land formation and sediment production and (2) life histories and ecology of many forms of terrestrial and marine life, many of them important and valuable food species. 4. Commercial activity. For areas already irrevocably committed to marina/small boat/ dockage/service functions, a non-expansive management plan should be developed, imposing flexible constraints on current practices and non-flexible constraints on all proposed util ization. Management Guidelines for Reefs . 1 . Except where absol utel y necessary, reefs should not be subjected directly to filling, cutting, blasting or wastedischargeof any type. 2. Heated effluents should never be discharged in reef areas. 86 3. Except under careful control and licensing, corals and other reef organisms should not be collected com mercially. Recreational collecting should be discouraged. 4. Dredging operations adjacent to reefs should be designed to minimize impact on the reef. Monitoring is essential. 5. All shore and water related development should be evaluated for their relationship and possible effects upon adjacent reefs. Management Guidelines For Sandy Bottoms 1. Use options should be considered in light of the relatively tolerant quality of the habitat. 2. Where sand mining is proposed, adequate prior borings and sediment analyses should be conducted to describe the nature of the sediments and determine spoil handling requirements. 3. Where dredging is proposed, final depth contours should be as natural as possible, eliminating deep isolated holes. 4. Uses of sandy areas should be consistent with maintenance of adjacent reefs, beaches, grass beds, etc. Management Guidelines For Grass Beds 1. Dredging should be avoided in these areas wherever possible. If necessary, it is absolutely essential that the design slopes be natural and open the dredged area to free communi- cation with the rest of the bottom. Isolated deep holes are definitely to be avoided. To this end, it may be better to make shallower cuts over bigger areas to obtain a given volume of sand. While areas stripped of grass and algae take surprisingly long to re- cover, deep pits create and perpetuate a number of other problems which can per- manently alter the ecology of an entire bay. 2. Dredging, where permitted, should begin at the mouth of a bay and proceed inward with an upward slope. It is preferable to restrict dredging to bay mouths rather than the inner shallower bottom. Dredging close to the beach should be absolutely prohibited. At least several hundred feet of shoreward grass beds in front of a beach should be left untouched. 3. Boat anchorages in enclosed bays with grass beds can be destructive if vessel density over time becomes too high. Unless a bay has been committed specifically for anchorage, it may become necessary to specify permitted an- chorage areas and boat density. Fixed moor- ings, privately or publicly maintained and leased, are to be preferred. Management Guidelines For Cays 1. In conjunction with planning recommenda- tions from the Virgin Islands Department of Conservation and Cultural Affairs, certain cays should be set aside as inviolate wildlife sanctuaries. 2. Other publicly owned cays should be de- veloped for mUltiple use as recreation and nature areas, but any alternate or coincident use of a cay should be compatible with maintaining its value as a wildlife area. 3. Consideration should be given to establishing ranger or warden stations on strategically located cays, from which it would be easy to patrol and monitor the other islets. 4. Each cay should be evaluated individually to determine its use potentials. 87 Recommendations For Further Study * The general inshore current regimes of the islands need to be investigated and determined. Prevailing, as well as periodic, departures from the norm need to be quantified, especially in any areas programmed for a change in use patterns. A prime example is the industrial southwestern half of St. Croix where, despite at least two large scale environmental studies, current patterns are unknown except primarily from qualitative subjective descriptions from local residents. * Long Reef in Christiansted harbor should be restudied at intervals to follow up on two pre- vious studies which indicate damage from several sources. Also a unique opportunity exists to study reef recovery after termination of sewage discharge, wh ich is expected shortl y. * Techniques need to be developed for trac- ing sources of oil pollution. Procedures should be developed and implemented for enforcing Virgin Islands laws relating to oil and hazardous materials spills. * Offshore cays should be studied contin- uously for the purpose of developing management plans consistent with their frailty, ecologic and recreational value. They represent an irreplaceable local resource especially in view of the present population density loading on the larger islands. * Sand resources inventories should be con- ducted in offshore areas around all islands to locate deposits which can be mined economically with minimal environmental impact. * The effects to turbidity on local marine organisms and communities should be quantified as a means of assessing the possible impact of runoff, dredging, waste discharges, etc. Local water quality criteria for turbidity should reflect the findings of such a study. 88 * Periodic monitoring of heavy metals should be conducted in marine sediments sub- jected to municipal and industrial discharges. * Runoff from the land should be investi- gated during the rainy season to identify areas subjected to turbidity and siltation. Analysis of the watershed, rainfall and other information should be used to estimate discharges. * Quantitative studies should be mounted to describe the marine environment in strategic areas, i.e., all harbors, the south shore of St. Croix, the mangrove lagoons, and Fortuna and Persever- ance Bays on the southwestern end of St. Thomas. These should be· followed annually by quanti- tative surveys to assess change. * Detailed studies should be conducted on major salt ponds to quantify their functions and natural values and to provide rational basis for management and use allocations. * Establishment of "marine preserves" should be given . immediate priority, especially in the last remaining mangrove areas: Salt River and Great Pond, St. Croix and Jersey Bay, St. Thomas. * Existing and planned municipal and in- dustrial facilities on the south shore of St. Croix dictate a need for a comprehensive environmental assessment of the entire area. Such an assessment should stress the cumulative and secondary impacts of the total south shore development. * The feasibility of restorative action in bays damaged by past destructive dredging should be investigated. In certain cases, it is apparent that considerable environmental damage resulted, not simply because the bay was dredged, but because the operation was poorly designed and executed. * A permanent committee, similar to Flori- da's Coastal Coordinating Council, should be established to coordinate the Coastal Zone Manage- ment Plan. * Because of the small size and steep terrain of the islands, it is impractical to separate Coastal Zone Management from environmental manage- ment in general. Responsibility for enforcing all aspects of environmental controls should be consolidated in a single agency. * The government should secure title to critical offshore cays, declare certain ones as closed wildlife preserves and develop multiple use conser- vation plans for others. * The taking and sale of seabird eggs should be prohibited. * Laws relating to the clearing and develop- ment of guts should be strengthened and enforced. The "earth change" law should be rigorously enforced. These measures are needed to protect the unique and vanishing flora and fauna of the guts and to reduce destructive runoff to the area. Of) Summary Introduction With greater understanding of the complex under- standing of the complex interactions of natural coasfal systems, we can develop improved plans for maximum multi-use management of the Vir- gin Islands' limited coastal resources. Appropriate resource protection and wise use are imperative to maintain natural productivity and aesthetic values and to preserve options forfuture generations. The preceding compilation is intended as a first effort survey of the Virgin Islands' coastal resources describing our present knowledge of their inter- active processes, values and capacities and our needs for additional information. The report deals with the major biological and physical components of the marine resource base and their intrinsic limits to man-induced perturbations. The Inventory section describes important ocean- ographic, climateological, geomorphological, and marine ecology features of the islands' coastal zone. Beaches, rocky shores, salt ponds, mangroves, reefs, sandy bottoms, and grass beds are defined and described, as well as small cays and major biota. As far as possible, natural attributes, toler- ances and constraints are identified. The Analysis section reviews biophysical resource information, classifies coastal ecosystems and processes, identifies critical areas of high producti- vity, under stress or of a unique quality, and indicates some of the existing and potential impacts along the coastal zone. The Synthesis and Guidelines sections provide management recommendations for vital areas, areas of environmental concern, areas of normal concern, and for ecosystem quality control. Where possible, site specific constraints, degra- dation thresholds or limiting factors are also cited. The study concludes with a list of recommendations for further investigation and an annotated bib- liography. 90 Inventory Oceanography and Climatology - (1) Tides In the Virgin Islands, tidal ranges are not great, and tidal currents, except in some inshore local- ities, are not sign ifican1. There is one high and one low tide per day on the north coasts of St. John and St. Thomas, on the south coasts of St. John and 51. Thomas, and on all St. Croix coasts there is a second, reduced cycle of high and low tides. Fortunately, waves, swell and ocean currents usually do a good job of flushing most bays. These forces, however, are considerably reduced by the time they reach the heads of deep embay- ments. As a result, circulation may be very poor in the inner reaches of some of our larger em- bayments. These conditions are important for the planner because pollutants introduced to these calm areas will be very slowly dispersed. These quiet areas also are sites for relatively rapid deposi- tion. Sand transported naturally through these bays, as well as silt and debris from the land, tends to settle out, filling the bottom and eventu- ally extending the shoreline. (2) Currents Many factors interact to determine the direction of water flow in a bay. These include relative strengths of tides, winds, waves, swell, water density and pressure as well as the bay's bathy- metry, shoreline shape and size. Thus, patterns of water movements are changeable. This fact is im portant for the planner because it demonstrates the need for site specific studies of currents to determine prevailing conditions and variations. Generally, currents around the islands are driven by the North Equatorial or Canary Current which moves th rough the Caribbean from east to west and eventually joins the Gulf Stream off the south coast of North America. Local currents in individual bays vary considerably due to ex- posure, winds, tides, shoreline, and bottom geo- metry. (3) Waves and Swell Waves are the main source of energy that moves beach sediment and that affects shipping and shoreline structures during storms. The deepwater wave regime is driven by the northeast trade winds most of the year. Besides the normal easterly swell that affects windward coasts on the islands, there are two seasonal modes of wave approach that affect leeward coasts: a southeasterly chop and swell and a northern swell. Along coasts fronted by partly submerged reefs, waves playa significant role in circulating back reef water, thus dispersing pollution and diluting its effects. (4) Storm Waves And Tidal Flooding Tidal flooding, created by major hurricanes having an average frequency of once in 33 years, raise water levels in St. Thomas from five to twelve feet above normal. A six foot height floods lower parts of Charlotte Amalie for 800 feet landward from the shoreline. Besides flooding, damage to waterfront facilities and erosion of shores by storm waves can be heavy. Moreover, passing hurricanes may create a nimus tide of as much as 1.0 feet below mean low water that can temporarily affect grounding of vessels in shoal water and exposure of tidal flats. Large sea waves of extraordinary length called tsunamis are associated with submarine seismic disturbances. These waves seem to occur about once every 10 or 15 years in the Caribbean area. (5) Water Quality Water quality may be defined by any number of parameters depending on what information is required. Common quality indicators are temper- atures, salinity, dissolved oxygen, transparency and bacteria. Additional measurements often required are biochemical oxygen demand (B.O.D.), chemical oxygen demand (C.O.D.), nitrogen, phosphorous, silicon. Estimates of water color have limited value. The effects of these constituents on water quality are significant to the well-being of individual organisms, whole communities and entire eco- systems. All of these water components may assume pollution roles if changed from normal levels. Shoreline waters of the Virgin Islands have tem- peratures of 25.5 - 28 0 C between December - April and 27.0 - 29.00 C between June-October. Salinity (the amount of salt in the water) generally averages 35.5 - 36.2 parts per thousand and 34.0 -35.2 parts per thousand during the same periods. Almost all our waters contain dissolved oxygen near saturation. Turbidity in local waters is gen- erally low, and in most bays the sea bottom is visible. In areas where runoff from the land, sewage and boat traffic cause murkiness, the bot- tom is often not visible at ten feet depth. Local waters are low in nutrients which accounts for the low levels of planktonic productivity. However, localized productivity by reefs and sea grasses is very high. (0) Prevailing Winds and Hurricanes The Trade Winds approach the islands with great constancy in direction primarily from the east- northeast and east. Hurricanes or tropical cyclonic storms constitute a seasonal threat of potentially catastrophic proportions. Frequency, probability, seasonality and dimensional aspects are reviewed in the basic text. Adequate preventative natural disaster planning is an essential element of any coastal zone management plan, and greater emphasis is needed on this requirement. (7) Precipitation and Evaporation Rainfall is low, evaporation is high, producing very dry conditions over most of the islands ex- cepting some high mountain forests. Dryness and water loss are heightened by steep slopes which promote runoff, shallow rocky soil which holds little moisture, and strong sun and constant breezes which promote evaporation. Rainfall varies over the year, by island and by areas within a given island. On the average, St. Croix receives 40 inches per year, St. John 47 inches and St. Thomas 42 inches. Heaviest rain- fall occurs at Dorothea on St. Thomas and Analy on St. Croix. The wettest months are September - December; the driest, February - July. Rainfall is important to the coastal zone as it promotes runoff into the sea. Development in the watershed increases runoff. Bays suffering the effects of runoff (turbidity, siltation, eutrophi- cation, etc.) are St. Thomas and Christiansted harbors and Water Bay and Stumpy bays on St. Thomas. Evaporation affects the coastal zone by increasing salinity in salt ponds and shallow restricted parts of embayments. Biotic composition shifts in adaptation to high salinities, but when heavy rains catastrophically depress salinity to very low levels, many halophilic (salt tolerant) organisms die. Geophysical factors - (1) Bathymetry St. Thomas and St. John lie on the Puerto Rican Plateau, a submerged ancient island mass. This submarine shelf extends from the shoreline to the 100 fathom depth, where coral reefs, other bottom irregularities, winds, shoreline configuration and tides act to divert and diverge prevailing ocean currents. St. Croix lies on a shallow platform, separated from the Puerto Rican Plateau by the Virgin Islands basin with depths to 4,500 meters. North of the Virgins, the Puerto Rican Trench with depths to 9,170 meters is the deepest known area of the Atlantic. Other deep Caribbean basins around the Virgins are the Anegada and St. John passages and the St. Croix and J ungfern passages to the east and west, respectively, of St. Croix. (2) Seism ic Activity Since the Caribbean island arc marks a transition zone between continental and oceanic crustal masses, it is a nearly continuous belt of shallow focus earthquakes, none of which seriously affect the Virgin Islands. Marine Ecology - (1) Fisheries The striking similarity of various studies of fishing in the Virgin Islands going back over forty years empha<;izes how fisheries have been relatively static in a period of generally rapid change. As the economy and population have burgeoned, the demand for fish and the price per pound have climbed, but the number of fishermen has not changed significantly. The limited pelagic fish resources (billfish, tuna, wahoo, etc) of the northern Virgin Islands support a sport fishery along the edges of the shelf, but repeated exploratory fishing has made it clear that stocks are not sufficient to support an industrial fishery. The primary commercial resources are demersal fish (and invertebrates) associated with 92 coral reefs and tending to be concentrated around small irregularities at the bottom which provide refuge. A secondary finfish resource is inshore schooling fish, generally jacks, which are tra- ditionally taken with haul seines. Finfish stocks alone among the living marine re- sources offer long-term potential for increased yields, primarily by fishing stocks which are now only lightly exploited. Other species currently exploited include the sea turtle (often illegally), the conch, whelk, billfish (by sport fishermen), and the spiny lobster {currently reduced by over exploitation}. The low productivity of the fishery (both in total catch and catch per unit effort) is also a reflection of the naturally low primary productivity {little growth of phytoplankton, the base of oceanic food chains} of Virgin Islands waters. Most primary production inshore is benthic - the coral reefs, algae and grass beds - and most fish are caught in these areas. Much of the open shelf of the Virgin Islands is relatively flat but too deep {thUS the light is too dim} for sea grasses or vigorous coral reef growth. Thus, while there is room for improvement in fisheries, local conditions which limit production and harvesting do not allow development of a fishing industry akin to that of continental shelf areas. (2) Beaches As a buffer zone, beaches protect property from wave attack. They are also valuable for recreation for which they are in great demand. Beach sedi- ments are highly mobile and thus beaches are constantly changing their form and dimensions. Stability depends on a supply of sediment either from the land or from the sea which is the main source. Consequently, most beach sands are a mixture of different types of material that vary in size and composition, according to the source and rate of supply, as well as according to the wave and current processes acting on it. Backshore dunes act as a reservoir of sand and prevent massive flooding by storm tides. When sand is placed on a beach in an attempt to rebuild it artificially, natural processes continue unhampered, erosion is checked and sand is supplied to adjacent beaches. Grain size of artificially placed sand should approx- imate natural beach sand found on the site. Beach Rock Many sand beaches -of the Virgin Islands are broken by a ledge of rock that typically runs parallel to the beach or may be partially or com- pletely submerged offshore. Beach rock is formed in place, below the beach surface, by the natural cementing action of ground water as dissolved calcium carbonate precipitates. Biological acti- vity contributes to the cementation processes which take place quickly, probably within a few decades, perhaps even faster. Impact Of Man On Beaches Human interference with natural processes is one of the major causes of beach erosion in the Vir- gin Islands. (1) Mining large quantities of sand can cause rapid erosion by changing the wave refraction patterns. (2) Dredging nearshore sand deposits induces erosion and/or slumping. Tur- bidity generated by dredge spoil fines reduces nearshore grass cover which normally absorbs wave energy. (3) Sites once used for waste disposal on beaches to fill and to extend low land are now subject to erosion. Release of former wastes also presents a potential for pollution. (4) Engineering structures intended for shore protection, such as jetties and sea walls, often cause deleterious ef- fects when they interfere with natural coastal processes such as littoral drift. (5) Unregulated construction and improperly designed structures present a potential threat to life and property when they fail during storms. (6) Recreation can contribute to littering and pollution. A critical factor for upper backshore dune stability is vege- tative cover. Motorcycles, automobile traffic, trampling, etc. can trigger erosion. (3) Rocky Shores Whether steep and cliff-like or sloping and irregular with rock rubble at the water's edge, rocky shore areas are probably the most stable, least threatened component of the Virgin Islands coastline. They require little immediate concern,per se. (4) Mangroves Mangroves are flowering trees which can live in salt or brackish water. Several different trees are referred to by the common name "mangrove," but the most common are red mangrove, white mangrove and black mangrove. Rhizophoroo, kn?wn as "the plant that makes land," is the most typically recognized species. It grows at the water's edge, and new seedlings become established to seaward. The prop root system of the plants, besides providing support and hiding places for a wide variety of marine animals, traps sediments that accumulate from the plants or are washed down from the land. In so doing, the shoreline is slowly extended. Once the sediment becomes rather firmly established, the red mangroves die off naturally and are succeeded by other plants, initially black and then white mangroves. With their dense coverage and complex roots at the shoreline, they interrupt runoff from the land and help to trap fresh water, sediment and debris at the shoreline, thus protecting offshore marine areas from these pollutants. Each year red mangroves drop large quantities of leaves and seedlings, all of which do not survive to become new plants. The natural decomposition of these materials sustains a complex food web beginning with micro-organisms and scavengers and culminating in such higher trophic members as snappers, barracuda, lobsters, and birds. The nutrients and other food energy supplied by plant litter decomposition accounts for the large numbers and wide variety of plants and animals which are found in climax mangrove communities. (5) Salt Ponds Natural development of mangrove forests tends toward the· formation of closed ponds. Plants growing across a shallow bar or spit may merge with other mangroves. Channels may be maintained if a sufficiently strong current runs through period- ically, or a body of water may be sealed off. When the pond is cut off from open water, a mangrove or coral growth, for example, a salt pond is formed. An inventory of salt ponds in the Virgin Islands is included in the basic text. (6) Coral Reefs A reef is an area of extremely diverse marine life, Structurally, it is composed of the stoney skele- tons of hard corals which also are the dominant life forms. This living structure provides shelter and food for innumerable other organisms. Coral reefs are common characteristic features of the islands' coastal zone and are of fundamental environmental and economic value. Besides their intrinsic beauty, they are important as producers of sand for natural and man-made beach cover and for construction. As such, they represent one of the territory's very few naturally replaceable resources. Reefs also provide protection for harbors, shorelines and shore structures by abatement of waves and dissipation of their energy which other- wise would be expended on the shore with greater force. Also, reefs provide perhaps the largest portion of seafood presently harvested in the islands. Most species of fish consumed locally either live on the reefs or depend upon them in some measure for their food. Lobsters, too are taken primarily from reef areas. The high productivity of coral reefs of dredging in most cases is the clouding of the water by very find suspended particles. This turbidity cuts down the amount of light which reaches the corals and other reef organisms, threatening their survival. Another result of dredging is siltation of solid particles. Corals can be smothered because of their inability to cleanse themselves of heavy loads of sediment over time. (7) Sandy Bottoms And Grass Beds Large areas of sandy sea bottom are scattered throughout the platform. Sometimes they occur in shallow bays without apparent reason as most shallow bays are vegetated. The most extensive areas of essentially bare sand occur below 60 feet depth. Even here, the lack of extensive plant growth is not easily explained but may be due to low light intensity and/or the nature of the sedi- ment. Another possible explanation may be that the sand is shifting at a rate which prevents plant establishment. These areas are not, of course, barren. They usually support scattered algae and the flowering plant Ha/ophi/a. Sandy areas are not well understood, and the extent of their significance to regional ecosystems is unknown. 94 Grass beds are frequently referred to as marine pastures because they are areas of thick growth of sea grasses and algae resembling pastures on land and serving essentially the same functions. Most inshore bay bottoms are covered with such pastures as are some extensive areas outside of bays. Marine pastures produce a significant amount - perhaps most - of the oxygen generated in local inshore waters. On a bright day dissolved oxygen over a healthy grass bed will exceed the saturation value (i.e., the water becomes supersaturated), and small bubbles rise from the leaves to the sur- face. Grass beds help to stabilize the sand. Several species of small fish live in the pastures, but more important, a larger variety of others come here to feed on the plants and myriad creatures that live in the pastures. This is the habi- tat of the queen conch (Strombus gigas) and feed- ing grounds of the sea turtles. There is a very close knit relationship between the plants and animals in this habitat, both spati- ally and physiologically. The pasture is a low profile environment. The plants usually do not exceed eight inches in height, and all but a few of the associated animals live within this zone or in the sediment. Thus, except for visiting foragers and predators, the majority of community energy cycling goes on in close quarters. Wastes from the animals are utilized by the plants which produce oxygen and forage. Once destroyed, marine pastures usually require a long time to recover. Deep holes may never recover. Since the community is dominated by plants, a critical minimum amount of light is needed. Chronic, heavy turbidity is destructive. Quantitative tolerances have not been determined. (8) Offshore Cays The small offshore islands vary in size from bare protruding rocks to over 170 acres. Most are 5 - 50 acres. A few are inhabited by one or two families - and many are difficult to get onto even by boat. Simple rock protrusions like Booby Rock, Sail Rock and Cricket Rock serve mainly as roosting and nesting sites for sea birds. The larger islets have beaches, rocky shores, cliffs, and some vegetation, mainly zeric scrub. Most have at least one salt pond and are surrounded by some degree of reef development. Most of the more than 60 emergent rocks and cays are around St. Thomas. Analysis And Synthesis Of Biophysical Associations The composition of coastal ecosystems varies considerably, but certain combinations of habi- tats occur frequently in the island areas. The Virgin Islands are no exception, and the following typical systems have been chosen for illustration. (1) Rocky Shoreline Associations Dominant features: shoreline of hard resistant, highly fractured rock extending under the surface, resulting in active coral growth on the rocky base along shore. Characteristics: salt-tolerant plants on shore; turbulent, usually clean, clear well oxygenated water with tough hard and soft coral community and other living forms highly resistant to wave action. Bedrock usually lies beneath thin sand cover up to several meters offshore. Suitability: snorkeling, fishing, good dispersal for treated effluents, scenic value above and below the surface of the water. Restrictions: wave action precludes mooring, anchorage; light structures on shoreline rocks subject to wave, storm and corrosion damage. (2) Salt Pond - Bay Associations Dominant features: protected bay with sea grass bottom and beach shoreline sometimes with near- shore patch reefs, hypersaline and separated from sea by sand or pebble beach and berm combina- tions, often surrounded by mangrove. Characteristics: very low energy water motion in bay, pond acts as catchment and filter for flood water from land, usually supports wading birds and other wildlife in associated mangrove. Suitability: low energy bay usually good for watersports, boat anchorage. Ponds may be filled for development or opened for marinas. 0'::: Restrictions: structures on filled ponds need pilings, opening of ponds can release fine sediments and toxins to upset bay organisms and water quality. Filling or opening pond incurs water quality stresses on the adjacent bay. (3) Sand Beach - Grass Beds Associations Dominant features: sandy beach, with gently sloping bottom leading to sea grass and algal pasture on bottom of protected bay. Sometimes combined with salt pond habitat. Characteristics: beach sediments, grain size and profile change constantly in response to wave and currents. Sea grass acts as stabilizing factor in offshore movement of sand. Plants oxygenate water, assimilate community wastes, provide food and shelter for wide variety of animals. Suitability: good swimming and recreation areas, usually suitable for small boat anchorages and" moorings. Attractive areas for shoreline develop- ment. Frequently provide harvestable quantities of reef fish and conch. Restrictions: solid structures on the submerged beach act as barriers, interrupt sand transport, change beach shape and quality. Structures on pil- ings less so. Excessive development in the water- shed can result in deterioration of water quality, affecting recreational potential. Excessive and/or poorly designed dredging for sand can severely damage beach, coral communities and marine vista. (4) Mangrove - Lagoon - Reef Associations Dominant features: mangrove fringed shore or dense mUlti-species mangrove forest, mangrove mini-islands, landward salt ponds or tidal flats, quiet small lagoons between mangroves and pro- tective adjacent offshore reefs, usually shallow with narrow entrance channels. Characteristics: extremely high system produc- tivity and utilization of energy, rich in edible and other organisms, food chain based on mangrove leaf litter, quiet water with low flow promotes sedimentation. Area is important feeding and breed- ing ground for many birds, juvenile fishes and shellfish. Suitability: recreation, education, faunal preserves, fishing, marinas. Restrictions: low water flow makes areas unsuit- able for waste discharges. Filling land to shore- line will kill ecosystem base - the mangrove plants. Susceptible to turbidity and rapid sedimentation. While potentially good sites for marinas and sand dredging, they are generally intolerant of the impacts generated by these activities. Natural attributes of mangrove areas subject them to secondary environmental stresses they cannot tolerate. (5) Man-Made Shoreline And Structures Dominant features: developed shoreline with altered topography and drainage, high percentage of impermeable surface, unnatural shoreline (bulkhead, landfill, docks, moorings, etc.)' usually low-energy quiescent protected bay. Characteristics: high use levels, increased addition of pollutants and toxins to the bay, abnormally high turbidity and pollutants, impoverished floral and faunal communities, increased sedimentation, subject to rapid runoff, frequent hydrocarbon slicks, often develop colored phytoplankton blooms. Suitability: as previously modified natural systems, these areas could have priority consideration for sand dredging for channel maintenance or construc- tion sand (if properly executed) to protect ad- jacent resources. Within limitations of the ecosys- tem, these bays should be considered first as sites for further development, rather than opening up new areas. Restrictions: because of limited circulation and existing pollution loading, should not be con- sidered for direct waste discharge of any type. Future development needs to be gauged carefully to avoid exceeding ecosystem capability and acceptable pollution loading levels. Critical Areas - (1) Areas Of High Productivity Few quantitative measurements of productivity have been made in the Virgin Islands. The follow- ing areas are listed because the site-specific environ- ment there is known generally, from research on 96 similar sites, to be highly productive, or because it yields especially large amounts of seafood, although production may not be in situ. Thus, the list is conservative. Most reef banks are fished by traps and handlines. All grass beds sometimes contain harvestable quantities of conch. St. Thomas - Jersey Bay Mangrove Lagoon Southern Shelf Edge St. Croix- St. John - North Central and West Shelf Sandy Point Manning Bay Mangrove Area West Coast Shelf East End Reefs (Lang Ban k) South Shelf Edge Coral Bay and Environs (2) Areas Under Stress St. Thomas - St. Thomas Harbor, Crown Bay Lindbergh Bay St. Croix- St. John - Fortuna Bay Stumpy and Santa Maria Bays Water Bay Vessup Bay Jersey Bay Mangrove Lagoon Christiansted Harbor Altona Lagoon Canegarden Bay to Point Harvey Manning Bay Cruz Bay Great Cruz Bay Enighed Pond (3) Unique Areas St. Thomas - Jersey Bay Mangrove Lagoon Coki Point Peninsula St. Croix- Magens Bay Valley and Beach Botany Bay Estate Most Offshore Cays Lang Bank Salt River Westend Salt Pond Great Pond St. John - Lagoon Point, Coral Bay Newfound Bay Carval Rock and Congo Cay Regional Context Local planning should be geared to providing rational resource allocation consistent with main- taining regional environmental diversity. The development of marinas, as one example, should not be limited only by current economic demand or the availability of suitable sites, but ultimately by the regional need for allocating available sites for specialized uses, given the pattern of small boat visitation in the eastern Caribbean. The need for this type of evaluation for many coastal re- sources is mounting and is long overdue. Of the several extensive mangrove forest areas originally found in the islands, only two remain. The majority have been committed to the single purpose of land development and virtually obliterated. The re- maining two sites represent the Virgin Islands' only surviving opportunities to provide alternate allocations of these extremely important, highly threatened and presently unique resources. They represent valued remnants of the islands' natural heritage and, as such, should be maintained for future generations. I n a larger frame, we suggest that mangrove areas, for example, may be sig- nificant to the production of regional populations of lobsters and several species of commercially important fishes. In an even larger sense, man- groves, cays, and rain forests are known to be critical habitats for many species of migratory birds, some in danger of extinction. In addition, they harbor many of our locally rarer reptiles and birds. Summary Guidelines For Management Of Coastal Features In addition to general principles applicable to specific types of environments, management guidelines should be flexible enough to allow for site-specific evaluations of control and manage- ment needs. The following summary provides a preliminary basis for developing management plans for the ecological units described elsewhere in th is report. See the full section (page 131 et seq) for detailed recommendations. Q7 (1) Planning Guidelines For Beaches 1. Dredging in bays with beaches should not be allowed except under careful supervision and rigid controls. 2. Beach restoration with dredged sand should never be accomplished by simply pumping the sand onto the shore. 3. Structures on beaches should not be per- mitted except after careful study of poten- tial impact. 4. Sand should not be removed from beaches. 5. Shoreward earth change and drainage modi- fications near beaches must be carefully regulated. (2) Planning Guidelines For Rocky Shores 1. Structures on rocky shores should be secure- ly anchored to stable footings. 2. Soil and other land materials or waste pro- ducts should not be pushed over the shore into the sea. 3. If effluent discharges are contemplated, site studies are needed to determine where currents will carry pollutants and reduce impact. 4. On cliffs, a construction set-back require- ment may be advisable in some locations for safety and to avoid effects of erosion on near-shore resou rces. (3) Planning Guidelines For Salt Ponds Management and use allocations of salt ponds should be approached generally on an individual basis. It is probably not necessary that every salt pond in the islands be preserved as salt ponds vary in their relative importance to the surrounding watersheds and as wildlife habitats. 1. I n any case where a pond is to be opened to the sea, or an existing opening enlarged or otherwise modified, an adequate descrip- tion of pond bathymetry and sediments should be prepared and analyzed. 2. Sediments dredged from a pond should not be deposited directly in the sea or on the bay shoreline. 3. Mangrove stands should be maintained as a high priority component. 4. Openings to the sea should not be made until all internal work in the pond is com- pleted. 5. The relationship of the pond to the surround- ing watershed and its importance as a wild- life habitat should be determined in advance as it relates to the availability of similar habitats in the islands. (4) Planning Guidelines For Mangroves 1. The remaining large mangrove areas (espec- ially Salt River, St. Croix, and Jersey Bay, St. Thomas) should be placed in the territor- ial park system. Their development should be stringently restricted only for recreational, aesthetic and academic use. 2. Dredging and filling as a rule should be pro- hibited except on a small, carefully con- trolled scale and only after thorough study. 3. Collection of marine or terrestrial living organisms or physical materials should be prohibited or at least discouraged and regul- ated. 4. Limited sport fishing may be permitted, but it may be necessary to specify allowable areas, fishing gear and perhaps species, seasons and size limits. 5. Boat traffic within the area must be strictly controlled. 6. No anchorage for live aboard boats should be permitted. 7. Cutting of mangroves for any purpose other than the planned area management and use program should be prohibited. Annual mapping is recommended. 98 8. Access points for small boat docks, launching ramps or other access structures should be carefu Ily sel ected and structu res and opera- tions closely monitored. 9. No waste discharges or polluting substances of any kind should be permitted into the area. 10. By zoning, licensing or other appropriate controls, buffer zones should be maintained adjacent to the mangrove area to minimize human impact. 11. Hunting of birds or the taking of eggs should be prohibited. 12. Restraint must be employed in constructing access roads to maintain optimum natural tidal flushing and water circulation. 13. Development restraints should be promul- gated for the watershed which drains into the mangroves to control the volume and fre- quency of runoff. 14. Possible permissible uses include: * * * Recreation as nature trails, underwater trails, for bird watching, hiking, and fish i ng on a controlled basis by con- servative methods. Education and research developing po- tential for use by students at all levels in areas of natural history. Commercial activity for areas already irrevocably committed to marina/small boat/dockage/service functions. (5) Planning Guidelines For Reefs 1. Except where absolutely necessary, reefs should not be subjected directly to filling, cutting, blasting or waste discharge of any type. 2. Heated effluents should never be discharged in reef areas. 3. Except under careful control and licensing, corals and other reef organisms should not be collected commercially. Recreational col- lecting should be discouraged and eventually regulated as in the case of Florida. 4. Dredging operations adjacent to reefs should be designed to minimize impact on the reef. Monitoring is essential. 5. All shore and water related development should be evaluated for their relationship and possible effects upon adjacent reefs. (6) Planning Guidelines For Sandy Bottoms 1. Use options should be considered in light of the relatively tolerant quality of the habi- tat. 2. Where sand mining is proposed, adequate conducted to describe the nature of the sediments and determine spoil handling requirements. Final depth contours should be as natural as possible, eliminating deep isolated holes. (7) Planning Guidelines For Grass Beds 1. Dredging should be avoided in these areas wherever possible. If necessary, it may be better to make shallower cuts over bigger areas to obtain a given volume of sand. 2. Dredging, where permitted, should begin at the mouth of a bay and proceed inward with an upward slope. Dredging close to the beach should be absolutely prohibited. At least several hundred feet of shoreward grass beds in front of a beach should be left untouched. 3. Boat anchorages in enclosed bays with grass beds can be destructive if vessel density over time becomes too high. Fixed moorings, privately or publicly maintained and leased, are preferred. (8) Planning Guidelines For Cays 1. In conjunction with planning recommendations from the Virgin Islands Department of Conservation and Cultural Affairs, certain cays should be set aside as inviolate wild- I ife sanctuaries. 2. Other publicly owned cays should be developed for multiple use as recreation and nature areas, but any alternate or coincident use of a cay should be compatible with main- taining its value as a wildlife area and its scenic, aesthetic value as part of the marine landscape. 3. Consideration should be given to establishing ranger or warden stations on strategically located cays, from which it would be easy to patrol and monitor the other islets. Overview The Virgin Islands constitute a unique island system - a place of value, beauty, and inspiration, possessing a rich history, spectacular marine life, diverse coastlines and a salubrious climate. They also have a promising future as a habitat for resident faunal, floral, and human species, living in a balanced, natural harmony. There is, however, mounting evidence that the human component of our islands' population has, through oversight, uncontrolled expansion, and ill conceived actions, induced a broad spectrum of stresses that threaten the natural viability of the island system and could destry what Alexander Pope referred to as "the genius of the place." This process is especially apparent in the coastal zone of the Virgin Islands where competing human interests and dynamic components of natural ecosystems interface and interact. The present effort to develop a management plan for this critical zone of man-environment inter- relationship offers the promise of minimizing environmental conflict, improving resource allo- cation decisions; preserving our insular heritage and restoring the intricate balance with natural systems. The suggested guidelines outlined in the preceding pages are only a beginning. They will need continuous upgrading, updating and refine- ment, as independent and government sponsored research and more site-specific inventory data become available and as the competing interests and users of our coastal zone resources improve and expand upon their articulation of specific needs and objectives. Developing an ecologically sound, informed and balanced perspective on resource allocaion is one of the principal objec- tives of planning. Coastal zone planning is no exception. 100 Selected Bibliography These selected references, all of which are now available in the Virgin Islands, have been reviewed and are recommended as basic documentary sources for future Virgin Islands coastal zone planning. Each annotation concludes with an evaluation code based on the following system keyed to documents of in'trinsic utility to the planner. * * * * * * * * * * Essential Planning Reference Useful Planning Reference Marginal (Technical, Scientific) Background Reference Only Adams, J .B., et ai, 1975. Potential National Natural Landmarks, U.S. Virgin Islands. Prepared for the National Park Service by West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Provides a classification system, priority ratings and a descriptive statement of seven sites on St. Croix, three on St. John, and four sites on St. Thomas. Excellent coverage for St. Croix but marginal for St. Thomas and St. John. Useful; needs follow- up action. * * * * Anonymous, 1965. Conservation in the Eastern Caribbean: Proceedings of the First Eastern Caribbean Conservation Conference, St. john, U.S. Virgin Islands, October 7-4, 7965. Prepared by Caribbean Research Institute, College of the Virgin Islands, St. Thomas. Participants of widely varying interests and disciplines assessed island resources and planning. A resolution was passed establishing the Caribbean Conservation Association. In- cludes papers on government planning, resources management, economic factors, parks and reserves, and historic sites. Mar- ginal coverage of coastal and marine elements but useful for regional variations on role of island planner, problem identification. * 1()1 Armstrong, J., November 1974. Coastal Zone Management: The Process of Program De- velopment. Coastal Zone Management I n- stitute, Sandwich, Massachusetts. Developed as an unofficial technical guide for officials, discusses boundaries, uses, areas of concern, authority and organization, public partici- pation and estuarine sanctuaries. * Bandler, B.G., editor, November 1974. Our Troubled Environment - Can We Save It: Proceedings of Conference on the Virgin Islands Environ- ment, St. Thomas, U.S. Virgin Islands, May 70-77, 7974. Sponsored by the Caribbean Research Institute, college of the Virgin Islands, St. Thomas. Varied conference dis- cussions ranging from air and water to man- power training and economics to environ- mental research and land use. Emphasizes lack of local goals for research and develop- ment, lack of government leadership and need for improved planning and resources manage- ment strategies. * Beller, W.S., editor, October 1970. The U.S. Virgin Islands and the Sea. Report to the Governor. Released by Office of the lieu- tenant Governor, Government of the U.S. Virgin Islands, St. Thomas. Citizens' report makes clear that the Virgin islands' only major environmental resource, its marine assets, must be carefully used and actively protected. Recommendations aimed at for- mulating policy are made for environmental quality, living/nonliving resources, industry, recreation, Caribbean relations, education and government. * * Black, Crow and Eidsness, Inc., October 1973. Water Reclamation at St. Croix, U.s. Virgin Islands. Second Interim Progress Report, June 1972 to September 1973.Environmental Protection Agency Contract No. 1101GAK. Gainesville, Florida. Background data and information on geology, hydrology, soils and water quality in St. Croix groundwater recharge study area. Description of advanced wastewater treatment plant. * Bock, W.D., July 1969. Report on the Ecology of the Benthonic Foraminifera in St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix (Special Project No.2; Contribution No.3). Large size and low species diversity suggest high energy conditions in Cottongarden Point yacht club basin lagoon type environ- ment. 20 detailed plates. * Bowden, M.J., Allen, J., et ai, 1968. Water Balance of a Dry Island: The Hydroclimatology of St. Croix, Virgin Islands and Potential for Agriculture and Urban Growth. Clark Uni- versity, Worcester, Massachusetts (Geography Publications at Dartmouth College, No.6). Report of research to provide some data on rainfall, evapotranspiration and water deficit aimed particularly to aid St. Croix farmers. * * * Bowden, M.J., Fischman, N., et ai, 1970. Climate, Water Balance, and Climatic Change in the Northwest Virgin Islands. Caribbean Re- search Institute, College of the Virgin Islands, St. Thomas. Research data collection for St. Thomas, St. John and British Virgin Islands, following same pattern as earlier St. Croix research. Collects data and dis- cusses rainfall, rainfall variability, evapo- transpiration, water balance. Also discusses possible climatic change, seasonal and cyclic loss. * * * Bowden, M.J., et ai, 1974. Hurricanes in Paradise: Perception and Reality of the Hurricane Hazard in the Virgin Islands. Island Resources Foundation, St. Thomas. Historical review of incidence of, probability analysis of, and damage assessment on storms and flooding, followed by detailed investigations of local perceptions, reactions and adjustments. Sug- gestions given for increased preparedness. * * * * Bowman, J., 1974. Sediment Source Study of the Salt River Estuary, St. Croix. Open File Student Reports, West Indies Laboratory, Fairleigh Dickinson University, St. Croix. 102 Useful baseline data. Marginal value for management. * Brin, Darlan, 1973. Shoreline Environmental Problems and Recommended Policies for the U.S. Virgin Islands. Unpublished Paper for Course at University of California-Berkeley. Issues of the Virgin Islands coastal environ- ment discussed with relevancy to tourist industry, conservation and management co- ordination of planning and shoreline policy. Makes detailed recommendations for de- velopment of a coastal zone management program for the Virgin Islands. * * * Brody, R.W., 1972. Fish Poisoning in the Eastern Caribbean, Proceedings of the Twenty-fourth Annual Session, Gulf and Caribbean Fish- eries Institute. University of Miami, Rosen- stiel School of Marine and Atmospheric Sciences. Best short summary of local fish poisoning incidence. * * * Brody, R.W., 1973. A Study of Ciguatera Fish Poisoning in the Virgin Islands Area. Carib- bean Research Institute, College of the Vir- gin Islands, St. Thomas. Detailed report on NOAA, U.s. Office of Sea Grant Programs funded project on ciguatera in the Virgin Islands. Excellent illustrations of potentially toxic fish, data on epidemiology, toxicity factors, locational considerations and intox- ication levels. * * Brody, R.W., et ai, 1970. A Study of the Water, Sediments and Biota of Chocolate Hole, St. john, With Comparison to Cruz Bay, St. john. Report submitted to Virgin Islands Department of Health, Division of Environ- mental Health by Caribbean Research I nsti- tute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.3). Base line information. * * Brody, R.W., Towle, E.L., and Brownell, W., 1970. Marine Pollution in the Eastern Carib- bean. Review paper prepared for F AO Tech- nical Conference on Marine Pollution and Its Effects on Living Resources and Fishing, Rome, Italy. Historical value for placing Virgin Islands within a regional context vis a vis pressure on local environments. * Brown and Root, Inc., 1974. Environmental Impact Assessment Report for Construction of a Single Point Mooring Terminal and Submarine Pipeline System, South Coast, St. Croix, U.S. Virgin Islands. Prepared for Hess Oil Virgin Islands Corporation. Extensive technical data on marine and shoreline ecology of the south coast, oceanography and climatology and their relationships to probably oil spills. Deficient in ocean current information. * * Brownell, W. and Rainey, W.E., July 1970. Explor- atory Fishing for a Source of Non-Ciguatoxic Sport and Food Fish. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Virgin Islands Ecological Research Station Contribution No.2). An excellent, although specialized, report on the possiblity of expanding local exploitation of deep water fisheries resources. * * Brownell, W. and Rainey, W.E., August 1971. Research and Development of Deep Water Commercial and Sports Fisheries Around the Virgin Islands Plateau. Caribbean Re- search Institute, College of the Virgin Is- lands, St. Thomas (Virgin Islands Ecological Research Station Contribution No.3). Ex- cellent report on exploitation aspects of an u nderuti I ized local fisheries resou rce. Con- tains practical recommendations on gear and method modifications. * * Candelas, G., July 1971. Ecological Study of St. Thomas Harbor and Adjoining Channels (East and West Gregorie Channels). Prepared for the West Indian Company, St. Thomas. Cursory study, concluding that proposed reclamation project may have practically no effect on harbor ecosystems, if certain suggestions for careful dredging operations and sewage discharge are followed. Should be used with caution.* 1 fY~ Clark, J., 1974. Coastal Ecosystems: Ecological Considerations for Management of the Coastal Zone. The Conservation Foundation, Wash- ington, D.C., in cooperation with the National Oceanic and Atmospheric Administration, Office of Coastal Environment, U.s. Depart- ment of Commerce. Discusses coastal zone ecosystems and offers management principles and guidelines. Represents the best summary document available. Required reading and availability as a reference. * * * * Clark, J., 1974. Rookery Bay: Ecological Constraints on Coastal Development. The Conservation Foundation, Washington, D.C. While not a document dealing with the Virgin Islands per se, this study is very pertinent as it focusses on a mangrove area not unlike the St. Thomas mangrove lagoon and the Salt River area of St. Croix. Excellent guidelines and methodology. * * Clark, J., et aI, 1964-1965. The Botany Bay Survey Report, Botany Bay, St. Thomas, Virgin Islands: An Inventory of the Littoral Habitats and Living Resources of Greater Botany Bay. Sandy Hook Marine Laboratory, American Littoral Society, Highlands, New Jersey. Evaluates potential of site as nature study sanctuary. Investigational su rveys are reported, including habitat, underwater ecol- ogy and fishes observed. Only study of this site covering floral and faunal features in systematic detail. Very useful. * * * Clark, J. and Brownell, W., October 1973. Electric Power Plants In the Coastal Zone: Environ- mental Issues. American Littoral Society Special Publication No.7. Covers power plant design, vulnerability of biota, internal and external impacts, federal regulations, and recommends siting guidelines. * * * Clark, J. and Sarokwash, P.J., 1975. Rookery Bay Land Use Studies. Environmental Planning Strategies for the Development of a Mangrove Shoreline, Study No.9: Principles of Eco- system Management. The Conservation Foun- dation, Washington, D.C. Most recent update of mangrove management guidelines. Very adaptable to Virgin Islands circumstances. For optimum value, see also the entire series available from theConservation Foundation.** Collette, B.B. and Earle, S.A., editors, October 1972. Results of the Tektite Program: Ecology of Coral Reef Fishes. Natural History Museum, Los Angeles. Paper detailing scientific results of Tektite Project relating to various ecolog- ical aspects of coral reef fishes. Base line value. Few management factors covered. * * Cosner, O.J., 1972. Water In St. john, U.S. Virgin Islands, with a chapter on "Alternatives of Water Supply" by Dean B. Bogart. U.S. Department of the I nterior, Geological Survey, in cooperation with National Park Service and the Government of the Virgin Islands (Caribbean District open file report). Detailed investigation of ground water sources of water supply for St. John resulted in developments of small supply for Virgin Islands National Park. Rain water collection expected to continue as main domestic source. * * Coulbourn, W.D., et ai, October 1973. ERTS -7 Virgin Islands Experiment 589. Determine Boundaries of ERTS and Aircraft Data Within Which Useful Water Quality Infor- mation Can Be Obtained. Prepared for God- dard Space Flight Center by Grumman Ecosystems Corporation. Virtually useless, sophisticated high technology, research carried out in context external to the Virgin Islands. * Dtimmann, A.E., et ai, 1969. Study of the Fish- eries Potential of the Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Virgin Islands Ecological Research Station Contribution No.1). Funded by the former U.S. Bureau of Commercial Fisheries, this is an extremely valuable his- torical document embracing a spectrum of data never previously or subsequently assembled in one source. Regretfully out of print and not readily available. Needs updating at earliest possible opportunity. Includes catch, market, and importation data on food fish, in addition to a broad 104 view of the fishing industry of the Virgin Islands. Basic and essential. * * * Dasmann, R.F., Milton, J.P. and Freeman, P.H., 1973. Ecological Principles For Economic Development. The Conservation Foundation, Washington, D.C. General reference with excellent sections on tourism and humid tropics and a review of the interdependency of conservation, development and planning. See especially Chapter 2 on carrying capacity, diversity versus simplicity, community resi- lience, and survival thresholds. Basic planning reference. * * * Davis, J .H., Jr., September 1940. "The Ecology and Geologic Role of Mangroves in Florida," Papers from Tortugas Laboratory, vol. XXXII, pp. 307-409, Carnegie Institution of Wash- ington. Extensive, detailed study of ecological relationships, environmental associations and processes species of mangroves, particularly with reference to soils and geologic process- es. * * Deane, c., Thom, M. and Edmunds, H., 1973. Eastern Caribbean Coastal Investigations, 7970-73. 5 vols. British Development Division in the Caribbean, Trinidad. Detailed review of West Indian natural coastal processes, d redgi ng, sand extraction potential, coveri ng also associated environmental problems and management components. A valuable basic study of an endemic Caribbean island probl- lem - sand resources management. * * * Ditton, R.B., 1972. The Social and Economic Significance of Recreation Activity in the Marine Environment. Wisconsin Sea Grant Technical Report No. 11, Green Bay, Wis- consin. A model, although brief, review of recreational aspects of a coastal lone. No local equivalent study is available. * * * Donnelly, T., and Whetten, J., 1968. Field Guide to the Geology of the Virgin Islands. State University of New York, Binghamton, New York. Prepared for the Fifth Caribbean Geological Conference. Guide to geology of St. Thomas by Donnelly; field guide to geology of St. Croix by Whetten. Donnelly describes singularity of St. Thomas-St. John geology. Formations are detailed, followed by a long listing of localities of geologic interest. A similar format is presented by Whetten for St. Croix. * * * Ellis, R.H., Cheney, D.B., et ai, 1969. The De- velopment of a Procedure and Knowledge Requirements for Marine Resource Planning: The Classification of Marine Resources. Travelers Research Corporation, Hartford, Connecticut. Outlines a systematic, analyti- cal methodology for marine resource assess- ment and planning. Partially adaptable to the Virgin Islands. Deals with goal estab- lishment, problem/conflict classification and information synthesis procedures for the planner. * * Engineering Science, Inc., October 1968. Water Resources Study for the Virgin Islands of the United States [Water Reclamation Study j. Prepared for Government of the U.S. Vir- gin Islands. Reviews water supply problems and investigates feasible reclamation programs for individual islands. Describes direct reuse for irrigation, industrial and sanitary uses and indirect reuse via ground water recharge. * Environment Consultants, Inc., 1969. Report on Beach Enhancement, Marina Development and Land Use, Tamarind Reef Hotel Property, St. Croix, Virgin Islands. Christiansted, St. Croix. Site specific documentation and recom mendations. Graph ics, base line measure- ments and observations are useful. * Environment Consultants, Inc., 1970. Beach Erosion Survey, Forrest Waldo Property, La Grande Princess, St. Croix, Virgin Islands. Christiansted, St. Croix. Finds erosion at Waldo property due to sea wall constructed nearby. * Environment Consultants, Inc., 1970. Environ- mental Survey of Lemontree Bay Property, St. Croix, Virgin Islands. Christiansted, St. Croix. Identifies sources of water, air pol- lution, and suggests solutions where possible. Also makes. recommendations regarding sur- face drainage, ground water, soils, vegetation, beach and shore development. * Environment Consultants, Inc., 1971. Environ- mental Study of the Estate Whim Property, Long Point Bay, St. Croix, Virgin ISlands. Christiansted, St. Croix. Examines causes for shore erosion, beach instability, poor quality sand, reduced water quality and turbidity. Site specific; base line value only. * Erdman, 0.5., 1968. "Spawning Cycle, Sex Ratio and Weights of Blue Marline Off Puerto Rico and the Virgin Islands," Transactions of the American Fisheries Society 97 (2), pp. 131- 137. Esoteric value only. Covers breeding cycle May-September, peaks July-August. Females average 2.5 times heavier than males. Discusses development of ovaries and testes and size-frequency distribution of sexes. * Ewel, J.J. and Whitmore, J.L., December 1973. The Ecological Life Zones of Puerto Rico and the U.S. Virgin Islands. Institute of Tropical Forestry and U.S. Forest Service, Rio Piedras (Forest Service Research Paper UTF-18). Maps Puerto Rico and Virgin Islands ecosystems with gross details of soils, vegetation, climates, land use patterns, using Holdridge system of life zones (broad bio- climatic units). Appendices give data on bio-temperature and water balances. Mar- ginal value.* Fosberg, R.R., editor, 1963. Man's Place In the Island Ecosystem: A Symposium. Bishop Museum, Hawaii. Superb collection of both technical and general studies by top special- ists from diverse disciplines. A very valuable reference. Basic planning tool. * * * * Frankenhoff, C.A., et ai, May 1974. Environmental Planning and Development in the Caribbean. Results of an environmental planning work- shop sponsored by the Graduate School of Planning of the University of Puerto Rico. Contains sections written by Cruz Matos, John McEachern, Edward Towle, C. Franken- hoff and L. Guilini. Useful regional overview. Final chapter on oil pollution very relevant to Virgin Islands situation. * * * Freeman, P.H., 1974. Coastal Zone Pol/ution by Oil and Other Contaminants: Guidelines for Policy, Assessment and Monitoring In Trop- ical Regions. Smithsonian Institution, Wash- ington, D.C. The best overview on the manage- ment aspects of oil pollution in tropical island areas. Basic planning reference. * * * Garrison, L.E., Holmes, C.W. and Trumball' J. V.A., 1971. Geology of the Insular Shelf South of St. Thomas and St. John, U.S. Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Special Publication No.3). Preliminary re- port of reconnaissance study conducted jointly by U.S. Geological Survey and the Caribbean Research Institute. Purposes were (1) to provide reconnaissance map of dis- tribution of sediment types on shelf surface and (2) to map gross geological structure of the shelf. Results seen as useful for avoiding irreversible destruction of beaches, for pro- viding geologic history of area, for potential mining of marine sand deposits offshore. Maps detail shelf-edge information. * * Gerhard, L. and Bowman, J., 1975. Sedimentation in the Salt River Estuary, St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix, Special Publication No.8. Site specific use- ful document. * Gerhard, R.D. and Roels, O.A., 1970. "Deep Ocean Water As A Resource For Combined Mariculture, Power and Fresh Water Pro- duction," Marine Technology Society Journal, 4(5), pp. 69-78. Relates to Columbia Uni- versity, Lamont Geological Laboratory, Rust- op-Twist upwelling project on St. Croix. Background, historical value only. * Gill, A.M. and Tomlinson, P.B., 1971. "Studies on the Growth of Red Mangrove (Rhizophora mangle L.)," Biotropica, 3(2), pp. 109- 124. Technical value only. * 106 Greiner (J .E.) Company, Inc., January 1974. Summary: Feasibility Study, Improvements for Harry S. Truman Airport, St. Thomas, Virgin Islands. Prepared for the Virgin Islands Port Authority. Summary of feasibility study for improvements at Truman airport covering analysis of airport conditions and deficiencies, including poor land use of airport, short and long term program, costs and scheduling.* Greiner Engineering Sciences, Inc., August 1974. Harry S. Truman Airport Master Plan, St. Thomas, Virgin Islands: Environmental Impact Assessment Report. Prepared for the Virgin Islands statement of project to expand Truman airport, details expected impact on Lindbergh Bay marine ecosystems, on other areas by dredging, impacts on water quality, soils, air, noise, surface transportation, both temporary and long-term. See also revised 1975 version. * Greiner Engineering Sciences, Inc., August 1974. Harry S. Truman Airport Master Plan, St. Thomas, Virgin Islands: Summary of Environ- mental Impact Assessment. Prepared for Vir- gin Islands Port Authority. Abbreviated version of environmental impact statement (see also prior reference). Historical value only. * Griffin, G.M., 1974. Effects of Dredging On the Natural Turbidity Regime of the Northern Florida Keys. Harbor Branch Foundation, Publication No. 33. Lengthy technical docu- ment with a wealth of quantitative data on the effects of major dredging job. Base line data collected before dredging began and simultaneous data collected from unaffected area. * * Grigg, D.I., Crean, R.F., vanEepoel, R.P., 1972. Marine Environment of Brewers Bay, St. Thomas, Virgin Islands With a Summary of Recent Changes. Prepared for Virgin Islands Department of Health, Division of Environ- mental Health by Caribbean Research In- stitute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 15). Covers turbidity and sediment changes associated with dredging in the bay. Describes increase and decrease of turbidity during and after dredging as well as sediment character in the dredged hole. Useful summary data on Brewers Bay. See also subsequent studies on the environmental impact of St. Thomas airport expansion. * * Grigg, D.I., Raney W.E., Towle, E.L., 1975. Some Effects of Dredging on Water Quality and Coral Reef Ecology. Island Resources Foundation, S1. Thomas, Occasional Paper No. 22. Summarizes types of damage to reef areas caused by various types and methods of dredging. Outlines procedures for reducing impact. * * * Grigg, D.I., and vanEepoel, R.P., January 1971. Report on the Status of Water Quality in Cruz Bay and Chocolate Hole, St. John. Prepared for the Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.9). Follow up on prior study; see Brody reference on Cruz Bay. Useful base linedata.* * Grigg, D.I. and vanEepoel, R.P., June 1972. Water Quality and Benthic Biology Within the Thermal Plume From Harvey Alumina, Virgin Islands Plant. Caribbean Research Institute, College of the Virgin Islands, St. Thomas. Description of suspended solids, transparency, dissolved oxygen and sea bottom communities in area of thermal plume. * Grigg, D.I., vanEepoel, R.P., Brody, R.W., 1971. Water Quality and Environmental Status of Benner Bay - Mangrove Lagoon, St. Thomas. Caribbean Research I nstitute, College of the Virgin Islands, St. Thomas (Water Pol- lution Report No.1 0). One of many sectoral site specific studies, containing useful base line data. Marginal use to planners. * Grossman, I.G., 1962. "Chemical Qual.ity of Ground Water in St. Thomas, Virgin Islands," Geolo- gical Survey Professional Paper No. 450-B. U.S. Geological Survey, Washington, D.C. Describes chemical quality of ground water from 31 wells in shallow deposits (9-50 feet). Average dissolved solids was 1,650 ppm. Only 3 of 33 samples were less than 1,000 ppm. Wells in Charlotte Amalie had high chloride and nitrate concentrates. The most promising source of acceptable quality ground water was Turpentine Run. * Grumman Ecosystems Corporation, 1971. Virgin Islands Test Site Program: Technical Proposal, Volume I, amended. Bethpage, Long Island, New York. A funded proposal to determine methods of investigation to obtain coastal water quality information, ocean currents and pollution, and St. Thomas harbor status. Test site data to be used for other water research studies (see reference under Coul- bourn for report). Marginal value. * Hackley-Masters Science Seminar, March 1974. An Ecological Survey of Buck and Capella Islands, U.s. Virgin Islands. Tarrytown and Dobbs Ferry, New York (Series No.6). Hastily researched. Secondary school students made 10-day survey, detailing geology, topo- graphy, vegetation, insects, rats, birds, rep- tiles, shoreline flora and fauna. Should be used with caution. * Hackley-Masters Science Seminar, March 1975. An Ecological Survey of Saba and Turtledove Islands, U.S. Virgin Islands. Tarrytown and Dobbs Ferry, New York (Series No.7). Covers same subjects as previous reference pertaining to Buck and Capella islands. * Hart, W.J., 1966. A Systems Approach To Park Planning. International Union for Conserva- tion of Nature and Natural Resources (I UCN), Morges, Switzerland. Basic methodology use- ful. * Heald, E.J. and Odum, W.E., May 1970. "The Contribution of Mangrove Swamps to Florida Fisheries," Proceedings of the Twenty-Second Annual Gulf and Caribbean Fisheries Institute. University of Miami, Rosenstiel School of Marine and Atmospheric Sciences. A classic and often cited, energetics oriented summary. * * * Heald, E.J. and Tabb, D.e., 1973. Rookery Bay Land Use Studies. Environmental Planning Strategies for the Development of a Mangrove Shoreline, Study No.6: Applicability of the I nterceptor Waterway Concept to the Rookery Bay Area. The Conservation Foundation, Washington, D.e. Part of a larger series of studies of a major tropical mangrove area. See also references under Clark. A very useful set of documents, with guidelines and planning strategies directly relevant to the Virgin Islands. * Hernandez-Avila, M.L. and Roberts, H., August 1974. Form-Process Relationships on Island Coasts. Technical Report No. 166, Coastal Studies Institute, Louisiana State University. Variations in geometric properties and spatial arrangement of major coastal morphologic landforms (beaches, cliffs, rocky shores, and swamps) of the islands of Barbados, Dominica, Grenada, St. Lucia and St. Vincent were compared to coastal process sectors estab- lished by variations in mean wave power levels. * Herrick, T.R., 1966. Economic Study of the Submerged Lands of the Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas. Deals principally with sand reosurces and sand dredging. Historical value only. * Herrmann, R. and Schessel, D. (Hackley-Masters Science Seminar), March 1971. An Ecological Survey of Steven Cay, U.S. Virgin Islands. Tarrytown and Dobbs Ferry, New York. Qualitative, low-key description of the natural history of the cay based on two week stay by group of high school seniors and staff. Contains many generalities and some apparent errors. Limited source of information, but little else is available. Use with caution.* Herrnkind, W. and Olsen, D., April 1970-J une 1971. Ecological Study for the Development lOR of Lobster Management Techniques. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Sea Grant GH-86). Contains useful data but falls short of re- commending workable managementguidelines. Valuable only as historical document and research source. * Hite, J.e. and Stepp, J.M., editors, 1971. Coastal Zone Resource Management. Massachusetts Institute of Technology Press. Basic early text on coastal zone problems and program design. Some continuing value. * Hoffman, S., Robinson, A., Dolan, R., February 1974. Virgin Islands Beach Processes Investi- gation: St. john, Virgin Islands. U.s. Depart- ment of Interior, National Park Service, Washington, D.e. (U.s. National Park Service Occasional Paper No.1) Report examines relationships between surf zone processes and beach changes in reef-beach systems, emphasizing sediment exchange, with much documentation. Conclusion infers need to treat beaches as ephemeral. * * * Hogben, N. and Lumb, F.E., 1967. Ocean Wave Statistis. National Physical Laboratory, Ministry of Technology, Great Britain. Basic reference document. * Insular Environments, Inc., April 1972. Marine and Environmental Factors in Red Hook Bay, St. Thomas. Prepared for P.F. Lopez Associates, St. Thomas. Site specific consulting report. * * Insular Environments, Inc., September 1972. An Investigation of the Site Proposed for an Ocean Outfall at Cruz Bay, St. john, U.S. Virgin Islands. Prepared for the Government of the Virgin Islands, Department of Health, Division of Environmental Health. Site specific consulting report. * * Insular Environments, Inc., March 1973. Water Quality and Benthic Environment in the Area of the New Municipal Sewer Outfall at Red Point, St. Thomas, U.S. Virgin Islands. Prepared for the Government of the Virgin Islands, Department of Health, Division of Environmental Health. Site specific consulting report. * * Insular Environments, Inc., April 1973. The Potential Environmental Impact of the Construction of a Submarine Pipeline and Deepwater Tanker Mooring and Unloading Terminal in the Caribbean Sea Off Limetree Bay, St. Croix, U.S. Virgin Islands. Prepared for Hess Oil Virgin Islands Corporation. Site specific consulting report. * * I nsular Environments, Inc., May 1973. Preliminary Environmental Evaluation of Proposed De- velopment at Fish Bay, St. john. Prepared for Cocoloba Development Association, St. John. Site specific consulting report. * * Insular Environments, Inc., June 1973. Draft Environmental Impact Statement, Marine Sand Dredging, Christiansted Harbor, St. Croix, U.S. Virgin Islands. Prepared for Virgin Islands Port Authority. Site specific consulting report. * * Insular Environments, Inc., June 1973. Marine Environment of Canegarden Bay, St. Croix, U.S. Virgin Islands. Prepared for R. Weston, Inc., W. Chester, Pennsylvania. Site specific.* * Insular Environments, Inc., July 1973.Draft Environmental Impact Statement, Marine Sand Dredging, Red Hook- Vessup Bays, St. Thomas, U.S. Virgin Islands. Prepared for Virgin Islands Port Authority. Site spe- cific consulting report. * * Insular Environments, Inc., July 1973. Draft Environmental Impact Statement, Harbor and marine Terminal Expansion Port of Thomas, Virgin Islands. Prepared for Virgin Islands Port Authority. Site specific consulting report. * * Insul.u Environments, I ftC. September 1973. Description of tM Proposed Virgin Islands fieefinery Corporation Site, St. Croix, U.s. Virgin Islands: Terrestrial Biota and Pelagic Marine Macro-Fauna. Prepared for R. Weston, Inc., W. Chester, Pennsylvania. Site specific consulting report. * * Insular Environments, Inc. and Sigma Environ- mental Sciences, Inc., September 1975. St. Thomas Sewage Treatment Plant Sub- marine Discharge Site Evaluation. Prepared for Virgin Islands Government, Department of Conservation and Cultural Affairs, Division of Natural Resources Management. Describes benthic communities and water quality in area of sewage effluent diffuser in 65-70 feet of water after nearly two years of discharge. * Insular Environments, Inc. and Sigma Environ- mental Sciences, Inc., 1976. Environmental Assessment Report, Proposed Land Reclam- ation and Harbor Improvements, St. Thomas, Virgin Islands. Consulting report for the West Indian Company, Ltd. (proprietary). Useful data. * * Jacobsen, A.R., 1951. A Study of the Pollution of the Harbor Waters of the Virgin Islands. Government of the U.S. Virgin Islands, De- partment of Health. Early Survey resulting from Department of Health concern about poll ution from sewage, i nd ustri al waste and night soil disposition. Historical value only. * J adan, Doris, July 1971. A Guide to the Natural History of St. john. Virgin Islands Conser- vation Society and Promotion Graphics. Discusses natural resources on St. John, the Virgin Islands Department of Education's Environmental Studies Program (ESP) and details of study areas including Salt Pond Bay, Annaberg, Reef Bay. With bird list, vegetation list and many illustrations. Not scientific. * Joh.mn.es, •. E., 1970, 1972. "Coral Reefs and 'ollutioo," fPaper presented at FAa Technical Conference on Marine Pollution, ~ome, Italy, December 1970. Published in Wood, E.) .f.,Pollution of the Marine Environment, Amsterdam, 1972. Expertly summarizes effects of various kinds of pollution on coral reefs. Good review. * * * Kasperson, R. E., 1971 . Decentralized Water Reuse Systems in a Water Scarce Environ- ment: The Tourist Industry in St. Thomas, Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 13). Brief sur- vey of impact of tourism on water supply and sewage disposal in St. Thomas. Estimates costs of water and sewage treatment at major hotels. * Kesterman, F. and Towle, E.L., 1973. "Caribbean Weighs Impact of Stepped Up Oil Industry Activity," Journal of Maritime Law and Commerce, Vol. 4, No.3: also, Island Re- sources Foundation, St. Thomas, Occasional Paper No.8. Summarizes potential impact of expanded petroleum related activity (production, transhipment, storage, refining, and marketing) upon the Caribbean. Primarily of historical value.* Kumpf, H.E. and Randal, H.A., 1961. Charting the Marine Environments of St. john, U.S. Virgin Islands. Contribution No. 348 from the Marine Laboratory, University of Miami. In Bulletin of Marine Science of the Gulf and Caribbean, 11, no. 4, pp. 543-551. Landmark mapping effort to present coastal seabed featuresofSt. John.lncludeschart. *** LaRoe, E.T., 1974. Rookery Bay Land Use Studies. Environmental Planning Strategies for the Development of a Mangrove Shoreline, Study No.8: Environmental Considerations for Water Management. The Conservation Founda- tion, Washington, D.C. An important and usefui segment of a larger, multi-faceted investigation of a major mangrove ,system, with relevance to Virgin Islands' s)lOreline management. * * Little, E.L, Jr. and Wadsworth, F.H., 1964. Common Trees of Puerto Rico and the Virgin Islands. U.s. Department of Agriculture, Forest Service, Washington, 'D.C. Agricultural Hand- book No. 249. Describes and illustrates 250 11 n species of trees giVing ongln, distribution, scientific and common names, and uses. Sound, valuable, and well illustrated. * Lopez, P.F., 1973. Outdoor Recreation in the Virgin Islands, Executive Summary: A Guide to Assist in the Implementation of the Com- prehensive Island-wide Outdoor Recreation Plan, 1973 - 1988. Prepared for the Govern- ment of the u.s. Virgin Islands, Department of Conservation and Cultural Affairs. Con- tains useful graphic presentation of annual rainfall and monthly temperature records, plus a preliminary analysis of use patterns and preferences for marine recreation sites. * McEachern, J. and Towle, E.L., 1974. Ecological Guidelines for Island Development. Inter- national Union for Conservation and Nature and Natural Resources, Morges, Switzerland. Useful general planning recommendations. Designed as companion volume to Dasmann, Milton and Freeman study. * * * McEachern, J. and Towle, E.L., 1972. "Resource Management Programs for Oceanic Islands," Transactions of the Thirty-Seventh North American Wildlife and Natural Resources Conference. Island Resources Foundation, St. Thomas, Occasional Paper No.1. A review article which is pertinent to the Virgin Islands and a useful set of references. * McKinzie, W., et ai, June 1965. Soils and Their Interpretations For Various Uses, St. Croix, American Virgin Islands. U.s. Department of Agriculture, Soil Conservation Service, Spartanburg, South Carolina. Distribution, description and classification of St. Croix soils, their suitability and limitations for various purposes. * * McNulty, J.K., Robertson, W.B., and Horton, B.F., 1968. Departmental Study Team Report and Recommendations on Proposed New jet Airport, St. Thomas; U.S. Virgin Islands. U.S. Department of the Interior, Washington, D.C. Accepting as fact the pro- posed developmentof the St.Thomas mangrove lagoon for a new airport site, this study first discusses the value of the present coastal resources - terrestrial ecosystem, water bird and wildlife habitats, offshore islands and cays, salt ponds alteration, fish - and corals, currents and tides. The conclusions are drawn as to likely damage resulting from airport construction. Not a completely candid report. What is reported is accurate; what is not reported is important. * Mann, R., et aI, 1975. Aesthetic Resources of the Coastal Zone. Cambridge, Massachusetts. A planners handbook, prepared for the Office of Coastal Zone Management, NOAA, U.S.. Department of Commerce. Provides a conceptual framework, an evaluation methodology, a listing of permissible uses, and suggestions for public participation mechanisms.* Maguire, C. E., 1972. Solid Waste Planning Program for the U.S. Virgin Islands. Providence, Rhode Island. Consulting Report presented to the Government of the U.S. Virgin Islands. Has useful site analysis of specific locations and incorporates a master plan for solid waste management. Historical and contemporary value, but lacks sensitivity to special re- quirements and features of the coastal zone. * Mattson, P.H., editor, 1969. Transactions of the Fifth Caribbean Geological Conference; St. Thomas, July 7968. Queens College, Flushing, New York. Papers on geophysics, marine geology, regional geology, geomorphology, hydrology, igneous petrology, paleontology, and stratigraphy, including several directly relevant to the Virgin Islands.* Menasco-McGuinn Associates, August 1973. Virgin Islands Highway Functional Classification and Needs Study; Summary Report. Prepared for the Government of the Virgin Islands, Department of Public Works in cooperation with the U.S. Department of Transportation, Federal Highway Administration, Helena, Montana. Includes more than 30 maps de- veloped by the contract firm from aerial photographs and field investigations and 1 1 1 officially accepted by the Public Works Department. In addition to inventories and traffic counts, standards are established for design, pavement, present and anticipated use, routes, capital improvements, continuing data collection, and transportation planning. * Michel, J .F., 1970. A Study of the Hydrodynamic Effects of the Proposed Airport at Long Beach Point, St. Thomas, Virgin Islands. University of Miami, Ronsenstiel School of Marine and Atmospheric Sciences, Consulting Report to the Virgin Islands Port Authority. Useful for site specific data; otherwise of largely historical value. * Michel, J .F. and Tabb, D.C., 1968. A Study of the Biological and Coastal Engineering Aspects of the Proposed Jet Airstrip at Jersey Bay, St. Thomas, U.S. Virgin Islands. Part II: Coastal Engineering Considerations. University of Miami, Institute of Marine Sciences. Contains valuable base line data; otherwise useful only as an historical document on earlier development planning methodology with narrowly defined terms of reference. See also Tabb and Michel, 1968 for Part I. * Millas, J.D., 1968. Hurricanes of the Caribbean and Adjacent Regions, 7492 - 7800.Academy of the Arts and Sciences of the Americas, Miami, Florida. An historical summary based on an intensive search of sources. Useful for the researcher but of I ittle use to the plan nero * * Miller, J .W., VanDerwalker, J .G., and Waller, R.A., editors, August 1971. Tektite 2: Scien- tists-In-The-Sea. U.S. Department of the Interior, Washington, D.C. Aquanauts con- ducted marine research from ocean floor habitat at Lameshur Bay, St. John. Discusses habitat engineering and training; gives de- tailed results of specific marine biological research missions and ocean survey. Largely a technical report of limited use. * * Miller, W.R. and Whitney, S.c., 1975. "Data Management in Coastal Zone Planning," William and Mary Law Review, vol. 16, no. 4. School of Law, William and Mary College, Williamsburg, Virginia. Useful ex- position of national/local information manage- ment problems with recommendations. * Mollica, T., 1973. Comparison of Grass Bed Sediments from Salt River and Tague Bay. West I ndies Laboratory , Fairleigh Dickinson University, St. Croix. Open File Student Reports. One of numerous site specific studies with intrinsic historical value as a source of local base line data.* Multer, H.G. and Gerhard, L.C., editors, 1974. Guidebook to the Geology of Some Marine and Terrestrial Environments, St. Croix, U.S. Virgin Islands. West I nd ies Laboratory, Fairleigh Dickinson University, St. Croix. Special Publication No.5. An excellent, basic, academic document for serious investigators. An invaluable reference for any planner as it contains base line information, graphics and process descriptions obtainable from no other source. * * * Murray, D., 1969. Birds of the Virgin Islands. Dukane Press, Hollywood, Florida. Ten watercolor plates by the author, marginal sketches. Brief popularized descriptions of common avian residents and migrants. Several taxonomic inaccuracies and sketchy infor- mation. Use with caution. * Neurauter, T., 1974. Past Depositional Environ- ments of Lower Salt River. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Student Reports. Site specific useful data.* Nichols, M., et ai, 1972. EnVironment, Water and Sediments of Chrfstiansted Harbor, St. Croix. Prepared for the Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 16). Excellent detailed investigation of harbor environment, including descriptions, aerial photo studies, hydro- graphy (tides and currents), water quality, reef ecology, fisheries, bottom vegetation and sediment, sedimentation, utilization of 1 1 ') harbor. * * Oakes, A.J. and Butcher, J .0., April 1962. Poison- ous and Injurious Plants of the U.S. Vir- gin Islands. U.S. Department of Agricultural Research Service, Washington, D.C. (Mis- cellaneous Publication No. 882). Covers selected vegetation with details for species outlining toxicity and symptoms in humans. * Ogden, J .c., editor, 1972. An Ecological Study of Tague Bay Reef, St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Special Publication in Marine Biology, No.1. Student project to assemble data to serve as base line for detecting future change in this coral reef. Includes individual studies of benthic algae, grazers fishes and other fauna. Well edited and useful. See also later publication by Multer and Gerhard.* Ogden, J .c., Yntema, J .A., and Clavijo, I., July 1975. An Annotated List of the Fishes of St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Special Publication No.3. Intended for use in conjunction with standard guides. Also includes description of St. Croix en- vironments, ciguatera, and game and spear- fishing records. * Olsen, D., et ai, 1972. The Ecology of Fishes in Two Mangrove Lagoons in the U.S. Virgin Islands. Marine Resources Development Foun- dation, San German, Puerto Rico and Virgin Islands Department of Conservation and Cultural Affairs. Reports trapping study of fishes in Manning Bay, St. Croix and Jersey Bay, St. Thomas. See also the following reference. * * Olsen, D., 1975. Analysis of Catch Data for the Virgin Islands Commercial Fisheries. Virgin Islands Department of Conservation and Cultural Affairs, Bureau of Fish and Wild- life. Annual Report for Project No. 2-239-R-1. Excellent specialized work by a trained statistical biologist. Sound methodology. Best used in conjunction with variously cited reports by Olsen, Dammann, Brownell, Rainey. * * Owen, W. and Konrad, M., April 1972. Thermal Survey: Harvey Alumina Discharge, St. Croix, Virgin Islands. Prepared forCaribbean Research Institute, College of the Virgin Islands, St. Thomas by Vast, Inc., Frederiksted, St. Croix. Study of thermal plume of bauxite refining plant formerly owned by Harvey Alumina Corporation (now Martin Marietta), southwest of former Krause Lagoon area, St. Croix. Only study of its kind in Virgin Islands waters. Useful for base line data and methodology.* Percious, D.J., vanEepoel, R.P. and Grigg, D.L, 1972. Reconnaissance Survey of St. Thomas Harbor and Crown Bay, St. Thomas, Virgin Islands. Caribbean Research I nstitute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 18). Useful survey with synoptic, site specific data. Principally his- torical val ue. * * Phillips, R.C., October 1960. Observations On the Ecology and Distribution of the Florida Sea Grasses. Florida State Board of Conserva- tion, Marine Laboratory, St. Petersburg. Distribution, environmental requirements, li- mits and biology of 5 species of marine spermatophytes. Pertinent to Virgin Islands envi ronm ents. * Pressick, M.L. and Towle, E.L., 1974. Marine Parks: Research and Education Programs as Feedback for Management. Paper presented at the Second International Conference on Underwater Parks and Reserves, Asilomar, California, April 23-26, 1974. Also, Island Resources Foundation, St. Thomas, Occasional Paper No.6. Outlines value of advance planning for non-resident research activity for management of special marine park areas. Relevant to the Virgin Islands National and Territorial park systems. * Rainey, W.E. and Pritchard, P.C.H., 1972. "Dis- tribution and Management of Caribbean Sea Turtles." Transactions of the Technical Session on Marine and Coastal Resources at the Thirty-seventh North American Wildlife and Natural Resources Conference, sponsored by the Wildlife Management Institute, Mexico City, Mexico, March 12-15, 1972. Also, Island Resources Foundation, St. Thomas, Occasional Papers No.3. Summarizes the regional resource management problems of the species, Chelonia mydas. ** * Randall, J .E., 1964. "Contributions to the Biology of the Queen Conch Strombus gigas," Bulletin of Marine Science, Institute of Marine Science, University of Miami, 14, pp. 246-295. One of a very limited number of studies of this species found in the Virgin Islands. * * Randall, J .E., 1968 .. "Conservation In the Sea: A Survey of Marine Parks," Oryx, vol. 10, no. 4. Includes information on St. John and St. Croix (Virgin Islands National Park areas). * Ray, G.c., 1975. A Preliminary Classification of Coastal and Marine Environments. Inter- national Union for Conservation of Nature and Natural Resources (IUCN), Morges, Switzerland, Occasional Paper No. 14. Brief, useful review of problem of ecosystem definition, contrast between terrestrial and marine areas, with a system for classification by zoogeographic regions, by coastal biotic provinces, and by habitats.* * Ray, G.c., 1976. Critical Marine Habitats, De- finition, Description, eriteria and Guidelines for Identification and Management (draft version). International Union for Conservation of Nature and Natural Resources (I UCN), Morges, Switzerland. Expanded version of 1975 paper. See especially "Summary Guide- lines for Protection" and "Ecological Ap- proach to Planning." Ray is currently heading an I UCN task force on a global inventory of critical marine habitats, hence the emphasis on a workable classification system. * * * Redding, M.J., November 1973. Aesthetics In Environmental Planning. U.S. Environmental Protection Agency, 600/5-73-009. Basic, well organized, thoughtful and systematic study suggesting alternative methodologies and implementation strategies for adding aesthetic concepts to public and private sector planning. Appendix contains useful examples of en- vironmental planning done by various federal agencies that incorporate attention to aes- thetic impacts.* Reynolds, J. R., August 1970. Preliminary Study of Sewage Disposal Practices in Areas Not Served by the Public Sewage System of Charlotte Amalie, St. Thomas, Virgin Isfands. Prepared for Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research I nstitute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.6) Historical value only. Needs updating. Present practices apparent- ly are more effective and less subject to personnel failures, due to training programs for sewage plant operators. See also Shatrosky reference. * Robas, A.K., December 1970. South Florida's Mangrove-Bordered Estuaries: Their Role in Sport and Commercial Fish Production. University of Miami Sea Grant Information Bulletin No.4. Useful background study for understanding role of Virgin Islands mangrove areas as nursery for local fish species. * * Robinson, A.H., August 1973. Natural Versus Visitor-Related Damage to Shallow Water Corals: Recommendations for Visitor Manage- ment and the Design of Underwater Nature . Trails in the Virgin Islands. National Park Service, St. John, Virgin Islands. Technical report summary of damage based on outside literature and National Park Service staff observation. Fuller visitor impact data is expected in future; in the interim, some generalizations are made concerning visitor management. Describes in detail reef corals of present and natural damage. Finds visitor damage minimal but feels future management needed.* * Robinson, T.M., et aI, 1973. Water Records of the Virgin Islands, 7962-7969. U.S. Geological 114 Survey. Covers surface-water, quality of water and ground water records of Virgin Islands (stream flow, chemical and physical character- istics of water and ground water levels). * Robinson, T.M., 1971. Earthquake-Accelerated Decline of Water Level in an Observation Well in St. Thomas, Virgin Islands. U.S. Geological Survey, Professional Paper 750-B, in Geological Survey Research, pp. B252-B253. Describes increased rate of water level decline in a well near Turpentine Run following a 4.7 Richter shock centered about 30 miles north of St. Thomas at 60 kilometer depth. * Robinson, T.M., 1972. Ground Water in Central St. Croix, U.S. Virgin Islands. U.S. Department of the Interior, Geological Survey, in coop- eration with the Government of the Virgin Islands (Caribbean District open file report). Data from 237 wells including complete chemical analyses of water quality. Available water in aquifer would require desalting by electrodialysis for poor quality water or distillation.* * Robinson, T., et aI, 1970. Magens Bay Master Plan. Consulting report prepared by Design Collaborative, St. Thomas, for the Magens Bay Beach Commission, St. Thomas. Includes excellent summary of biological and hydrolo- gical features of the associated watershed, salt pond, mangrove, beach and bay area. Has useful base line information for future planning and management. Site specific. * * Rundel, P.W., 1974. An Annotated Bibliography of West Indian Plant Ecology. Published for the Island Resources Foundation, St. Thomas by the Virgin Islands Department of Conservation and Cultural Affairs, Division of Libraries and Museums. Result of Founda- tion sponsored research. Primarily useful as a research reference guide. * Shatrosky, E.L., vanEepoel, R.P. and Grigg, D.L, October 1972. Operating Characteristics of Package Sewage Plants on St. Thomas, Virgin Islands, January-June 7972. Prepared for Virgin Islands Department of Health, Division of Environmental Health by the Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 20). Continues analyses of 19 plants. Consummation of three prior reports. Princi- pally of historical value.* Smith, F.G.W., 1971. Atlantic Reef Corals. Uni- versity of Miami Press. Technical reference for coral identification. * * * Smith, J .W., 1974. Growth Studies on Gorgonian Octocorals {abstract only).Proceedings of the Florida Keys Coral Reef Workshop. State of Florida, Department of Natural Resources, Coastal Coordinating Council. Average growth rate for seven species of gorgonians, measured over thirteen months was 4.1 centimeters/year. Range for individuals was 2.4 to 5.5 centimeters/year. Studies at Key West. Ranges similar to those in Jamaica and Dry T ortugas. * Sorensen, J. and Demers, M., 1973. Coastal Zone Bibliography: Citations to Documents on Planning, Resources Management and Impact Assessment. Sea Grant Publication No.8, University of California, La Jolla, California. Standard b ibl iograph ical reference. * * Stephens, W.M., 1963. Mangroves: Trees That Make Land. Smithsonian Institution, Washing- ton, D.C. Reprint from Smithsonian Report for 1962, pp. 491-496. Brief popular account of natural processes and value of mangroves. * Stott, S., 1974. Economics of Conch (Strombus gigas) on St. Thomas, Virgin Islands. Unpub- lished survey by Island Resources Foundation, St. Thomas. Of limited value to planner.* Stursa, M.L., December 1974. Florida Keys Coral Reef Workshop, Proceedings. Sponsored by Florida Coastal Coordinating Council, State of Florida, Department of Natural Resources. Practical, management oriented report with some discussion of stress, tolerance and mortal ity, and research needs. * * * Sverdrup, H.U., Johnson, M.W. and Fleming, R.H., 1942. The Oceans. Prentice Hall, Inc., Englewood. Standard reference work. * Swingle, W.E., Dammann, A.E., and Yntema, J .A., 1969. Survey of the Commercial Fishery of the Virgin Islands of the United States. Proceedings of the Twenty-second Annual Session, Gulf and Caribbean Fisheries I n- stitute, 26, pp. 110-121. University of Miami, Rosenstiel School of Marine and Atmospheric Sciences. Summary of information available in Dammann (1969) on Virgin Islands com- mercial fisheries. * :!f * Tabb, D.C., 1967.Report of Investigation: The Biological and Ecological Effects of Dredging for Sand in the Water and Brewers Bay Areas of St. Thomas, Virgin Islands. University of Miami, Institute of Marine Sciences. Con- sulting Report prepared for Office of the Governor, Government of the U.s. Virgin Islands. Very general appraisal based on brief site observations (apparently of shorelines only). Recommends allowing dredging of Brewers Bay. List of some organisms observed in rocky shoreline habitat.* Tabb, D.C. and Michel, J .F., 1968. A Study of the Biological and Coastal Engineering Aspects of the Proposed Jet Airstrip at Jersey Bay, St. Thomas, U.S. Virgin Islands. Part I: Biological Considerations. University of Miami, I nstitute of Marine Sciences. Contains valuable base line data; otherwise useful only as an historical document. See also Michel and Tabb, 1968 for Part 11.* Thompson, J. R., 1973; Ecological Effects of Offshore Dredging and Beach Nourishment: A Review. Miscellaneous Paper No. 1-73, U.s. Army Corps of Engineers, Washington, D.C. Fine annotated bibliographic review article written for both the specialist and the layman/planner. Extensive summary of ecological processes intruded upon by dredging. * * * * Towle, E.L., 1973. Environmental Management of Island Based Ocean Engineering Projects. Paper presented at the Third Technical Session of the First Caribbean Oceaneering Conference in San Juan, Puerto Rico,sponsored by Inter-American University. Also, Island Resources Foundation, St. Thomas, Occasional Paper No.5. Critical analysis of St. John based Tektite undersea habitat project with special reference to local application problems and relevance to local research needs. * * * Towle, E.L., 1973. The Role of the Travel-Tourism Industry In International Marine Recreation Development. Presented at Ninth Annual Marine Technology Society Conference, Wash- ington, D.C. Also, Island Resources Foun- dation, St. Thomas Occasional Paper No. 19. Background for recreation planning, stressing need for educational dimension.* Towle, E.L. and Hanif, M., 1973. National Parks in the Caribbean Area. Paper presented to the Conference on Science and Man in the Americas, Mexico City. Also, Island Resources Foundation, St. Thomas, Occasional Paper No.2 * Towle, E.L., Marx, R., and Tyson, G.F., 1976 (revised edition). Shipwrecks of the Virgin Islands (7523-7900). Island Resources Foun- dation Monograph, St. Thomas. Most compre- hensive listing available. Includes U.s. and British Virgin Islands. * * U.s. Government, Department of Agriculture, Virgin Islands Soil and Water Conservation District, 1971. Environmental Protection Handbook: A Guide to Assist in the Imple- mentation of the Environmental Protection A ct of the United States Virgin Islands. Kingshill, St. Croix. Standards and specifi- cations for soil erosion control, slope control practices, water conservation, for persons applying for Virgin Islands "Earth Change" perm its. I ncl udes seven page glossary. See latest edition. * * U.S. Government, Department of the Army, Corps of Engineers, 1975. Flood Plain Infor- mation, Tidal Areas St. Thomas, St. Croix and St. john, U.S. Virgin Islands. Office of the Governor of the U.S. Virgin Islands, 116 Virgin Islands Planning Office. Provides (1) historical data on hurricanes and related flooding and (2) future flooding predictions for major storms of 100 year frequency plus worst possible flood plates are fold out maps of coastline showing areas of expected flooding. * * * U.s. Government, Department of the Interior, Bureau of Outdoor Recreation, 1970. Islands of America. Excellent inventory of the island resources of the United States with a plan for an island heritage trust. * * * U.s. Government, Department of the Interior, Federal Water Pollution Control Administra- tion, 1967. Biological Aspects of Marine Water Quality, St. Thomas, St. Croix and St. john, U.S. Virgin Islands. Historical value only.* u.s. Government, Naval Oceanographic Office, 1963. Oceanographic Atlas of the North Atlantic Ocean, Section IV, Sea and Swell. Standard reference. * U.s. Government, Naval Oceanographic Office, 1963. Sailing Directions for the West Indies, vol. II, H.O. Publication 22. Standard refer- ence with detailed descriptions of physical features of Virgin Islands coastlines. * University of Texas (Austin)' Division of Natural Resources and the Environment, 1973. The Management of Bayond Estuarine Systems in the Texas Coastal Zone. Prepared for Office of the Governor, State of Texas. Describes coastal ecosystem units of Texas. Gives their attributes, beneficial and detri- mental uses and inherent factors influencing uses. Many of these ecosystems are locally comparable. Useful document for planning insights. * * * vanEepoel, R.P., November 1969. Report on Effects of Dredging in Water Bay, St. Thomas. Prepared for Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.2). A controversial study with some continuing instructive value on how not to dredge close inshore and why.** vanEepoel, R.P. and Grigg, D.!., January 1970. Survey of the Ecology and Water Quality of Lindberg Bay, St. Thomas. Prepared for the Virgin Islands Department of Health, Division of Environmental Health by Carib- bean Research I nstitute, College of the Virgin Islands, St. Thomas {Water Pollution Report No.4} Base line value {see other parallel studies of dredged and stressed sites in Cruz, Water, Benner, Vessup and Brewers Bays and Christiansted harbor}. * * vanEepoel, R.P., et aI, 1971. Notes On Some Oceanographic Marine Factors In the u.s. Virgin Islands. Prepared fo r Vi rgi nisi ands Water and Power Authority by Caribbean Research I nstitute, College of the Virgin Islands, St. Thomas. I nstitute Special Publi- cation No.2. Despite the title, this is a report on the definition of a suitable medium depth route for a submarine electric (40 megawatt) cable linking St. Croix and St. Thomas. Contains useful oceanographic data summaries and bathymetric graphics on the submarine features between the two islands separated by a relatively deep trench except to the east- ward where a route appeared feasible. * * * vanEepoel, R.P., et aI, June 1971. Water Quality and Sediments of Lindbergh Bay, St. Thomas. Prepared for Virgin Islands Department of Health, Division of Environmental Health by the Caribbean Research Institute, College of the Virgin Islands, St. Thomas {Water Pollution Report No. 11}. Historical and technical value with observations on the still depauperate dredge hole and marginal re- colonization. * Veri, A. R., et aI, 1973. Rookery Bay Land Use Studies. Environmental Planning Strategies for the Development of a Mangrove Shoreline, Study No.2: The Resource Buffer Plan, A Conceptual Land Use Study. The Conserva- tion Foundation, Washington, D.C. Very useful segment of a larger set of studies. Excellent methodology. * * * 1 1 '7 Virgin Islands Government, Department of Con- servation and Cultural Affairs, Division of Natural Resources Management, 1975. Virgin Islands Water Quality Monitoring, 7970- 75. Excellent Departmental report sum- marizing statistical data and problems of island growth and pollution, pollution monitor- ing and abatement programs, and improve- ments in water quality. All Virgin Islands waters now meet Virgin Islands water quality standards. * * Virgin Islands Government, Department of Con- servation and Cultural Affairs, Division of Planning, 1974. Virgin Islands Comprehensive Outdoor Recreation Plan, Executive Summary. Contains useful tabular data on the recreational value, size, and accessibility of offshore cays, island wide recreational demand factors, and maps of facilities and sites.* Virgin Islands Government, Department of Health, Division of Environmental Health, 1971. A Report on the Environment Surrounding the Hess-Harvey Alumina Plants on St. Croix. In-house Report. Air, water and marine bio- logical observations. Description of indus- trial plants' processes. Mostly qualitative descriptions of environmental impacts assoc- iated with plants' construction and operation.* Virgin Islands Government, Planning Board, September 1967. Conservation of Beaches: A Study of Problems, Needed Policies, Resources and Actions Required of Private Enterprise, Citizens, and the Government of the United States Virgin Islands, revised draft. St. Thomas, Virgin Islands and Cam- bridge, Massachusetts; report prepared by Reginald Isaacs. Study of beach problems, government policies and proposed manage- ment planning from 1967 vantage point. * Weaver, J.D., ed itor, 1960. Transactions of Caribbean Geological Conference, Mayaguez, Puerto Rico, january 4-9, 7959. Published by the University of Puerto Rico, Mayaguez, Puerto Rico. Technical report on scholarly papers and abstracts, some bearing upon the Virgin Islands. Background use only.* Weil, S. and Otsoka, c., 1974. Salt River Mangroves- A Preliminary Study. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Student Reports. Useful background information on a unique area.* Westermann, J .H., 1952. Conservation in the Caribbean. Foundation for Scientific Re- search in Surinam and the Netherlands Antilles, Utrecht, Netherlands, Publication No.7. Reviews conservation problems and programs in Caribbean islands. Discusses regional problems in agriculture, soil, water and wildlife conservation; Reviews contem- porary views on the population problem. * Weston, R.F., Inc., 1975. Environmental Assess- ment Study for a Two Hundred Thousand BPCD Refinery, St. Croix, U.S. Virgin Islands. West Chester, Pennsylvania. Prepared for the Virgin Islands Refinery Corporation. Detailed study of area background setting (socio-economic, land use, natural areas, landmarks, climate, oceanography, ecology), expected impacts and means to alleviate impacts, particularly oil spill prevention alternatives. * White, G.F., and Haas, J.E., 1974. Assessment of Research on Natural Hazards. Massachusetts Institute of Technology Publication, Cam- bridge, IMassachusetts. Scholarly review of methodology especially relevant to the Virgin Islands for hurricane, flooding and earthquake disaster planning. Most up to date study available covering national re- sponses, acceptable levels of risk and adjust- ment choices in public decision making and planning for hazard prone areas. * * * Wilcher, R., 1974. A characterization of Sedi- mentary Facies Relationships of Salt River, St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Student Reports. Useful background data on a critical unique area. * Wust, G., 1964. Stratification and Circulation in the Antillean-Caribbean Basins. Part 1 : Spreading and Mixing of the Water Types, 118 with an Oceanographic Atlas. Columbia University Press, London. Technical treatment of Caribbean oceanography. * Yokel, B.J., 1975. Rookery Bay Land Use Studies. Environmental Planning Strategies for the Development of a Mangrove Shoreline, Study No.5: Estuarine Biology. The Conservation Foundation, Washington, D.C. Excellent presentation on the biological processes operative in a mangrove lagoonal system similar to those in the Virgin Islands. * * * Zube, E.H., January 1968. The Islands: Selected Resources of the United States Virgin Islands and Their Relationship to Recreation, Tourism and Open Space. University of Massachusetts, Department of Landscape Architecture. Pre- pared for the U.S. Department of the Interior. Provides basic resource inventory data for governmental agencies. A general, short- term production emphasizing open space systems. * * * * SUPPLEMENTAL BIBLIOGRAPHY Bristol, Childs, Crowder and Associates, Inc., February 1975. Proposed Master Plan and Feasibility of Development of the Cruz Bay- Enighed Pond Areas, St. john, United States Virgin Islands. Published for the Virgin Is~ands Port Authority. Coral Gables, Florida. Report has given prime consideration to St. John's natural resources and considers environmental impacts of its recommendations. Incorporates separation of cargo docking from passenger-tourist-pleasure boat docki ng. * Dong, M., et ai, 1973. The Role of Man Induced Stresses in the Natural Evolution of Long Reef and Christians ted Harbor, St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix, Virgin Islands. Useful base I ine reference. * Environment Consultants, Inc., 1969. Beach Erosion Survey: Forrest Waldo Property, LaGrande Princess, St. Croix, Virgin Islands. Christiansted, St. Croix. Site specific con- sulting report. * Environment Consultants, Inc., November 1969. Environmental Study of the Green Cay Development Property, St. Croix, U.S. Vir- gin Islands. Christiansted, S1. Croix. Site specific conSUlting firm recommendations with useful base line data on beach-rock formation, wave and swell condition, drainage and littoral transport of sand. * * Grigg, D.1. and vanEepoel, R.P., 1970. The Status of the Marine Environment at Water Bay, St. Thomas. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.7). Useful base line information concerning a controversial dredging project and its impact on coastal processes at Water Bay. * Grigg, D.L, vanEepoel, R.P., and Brody, R.W., 1970. Water Quality and Marine Environment of Vessup Bay, St. Thomas. Caribbean Re- search Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.8). The only study of this site. Useful base line data. * Hackley-Master Science Seminar, March 1973. An Ecological Survey of Great St. james, u.s. Virgin Islands. Tarrytown and Dobbs Ferry, New York. A marginal quality survey by secondary school students. Should be used with extreme caution.* Kimmelman, B., et ai, 1974. Studies In Environ- ment: Outdoor Recreation and the Environ- ment, Volume 5. Socio-economic Environ- mental Studies Series, Office of Research and Development, U.S. Environmental Pro- tection Agency, Wash ington, D.C. The section on coastal areas pr(wides a useful evaluation methodology. * * McGuire, J .W., 1925. Geographic Dictionary of the Virgin Islands of the United States. U.S. Coast and Geodetic Survey, U.S. Depart- ment of Commerce, Washington, D.C. An invaluable reference. * National Academy of Sciences, 1970. Waste Management Concepts for the Coastal Zone: Requirements for Research and Investigation. Washington, D.C. A comprehensive eval- uation of the scientific and engineering aspects of coastal wastes management with special emphasis on physical processes, chemical and biological factors, and recom- mended studies. Required reading. * * * Onuf, c., 1973. Annotated Bibliography on the Biological and Ecological Effects of Oil Pollution in Tropical Waters. Office of I nter- national Programs, Smithsonian Instituti.on, Washington, D.C. A very useful reference of a technical nature (see also Freeman, 1974). * * Randall, H., 1964. A Study of the Growth and Other Aspects of the Biology of the West Indian Topshell, "Cittarium pica". Bulletin of Marine Science, vol. 14. pp. 424-443. I nstitute of Marine Science, University of Miami. Classic study of limited value to the planner.* Rivera, L.H., et ai, 1966. Soils and Their Inter- pretation for Various Uses, St. Thomas, St. john, Virgin Islands. U.S. Department of Agriculture, Soil Conservation Service, Kings- hill, St. Croix. Distribution and classification of St. Thomas and St. John soils and their suitability and limitations for various pur- poses. Useful for soil runoff and erosion control. * * Rivera, L.H., et ai, 1970. Soil Survey of the Vir- gin Islands of the United States. U.S. Depart- ment of Agriculture, Soil Conservation Service, Kingshill, S1. Croix. A summary report, useful for runoff assessment and as a basic study. * * Unger, I., 1966. Artificial Reefs - A Review. Special Publication No.4, American Littoral Society, Highlands, New Jersey. A standard reference on artificial reefs including a section on the Randall installed reef at Lameshur Bay, St. John. A very useful summary. ** U RS Madigan-Praeger, Inc., 1974. Report on Plans for Seaport Development and Reloca- tion for the Virgin Islands. Port Authority. New York. Specialized study of S1. Croix port facilities with references to container- ized logistics, upgrading, berth utilization, cruise ship traffic and a master plan for Christiansted and Frederiksted. Very use- ful statistical data.* vanEepoel, R.P. and Grigg, D.I., 1970. Effects of Dredging at Great Cruz Bay, St. john. Prepared for the Virgin Islands Department of Health, Division of Environmental Health by the Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No.5). Historical and tech- nical value. See other studies of Cruz Bay under Brody, et al,1969 and Grigg and vanEepoll, 1971.* * 120 Wilpur Smith Associates, 1976. Virgin Islands Mass Transit Study. Columbia, South Carolina. Detailed survey and transit development plan, including assessments of inter-island marine transportation and coastal nodal points. Ex- cellent data.* * Zube, E.H., ed. 1976. Studies In Landscape Per- ception. Publication No. R-76-1 of the Insti- tute for Man and the Environment, Univer- sity of Massachusetts, Amherst, Massachusetts. Useful for methodology. See especially the section on cross-cultural aspects of landscape perception.* * ·' ° 0 • \ ."" ,f' .1 I l , , ~ , ..... t:;I! . 'Olfic.e,O,f:tthe G'overnor '_, I. "'~;£-- . ,... i • " -i" . j '.' , . ~1>.'.! .: . ," • " 'vi¥gi;~;;),(Siaiid$ Planning Office Coastal Zone': Management Program