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F p P IP I1 P IW I v P r p p p™) EFFECTS OF FRESHWATER RUNOFF ON NEARSHORE TROPICAL MARINE FISHERIES by Canoy, M.J. Beets, J Martin, F.D Weichert, B Agreement No. 14-34-001-1150 Project No. A-017-VI Technical Report No. 16 September 1983 The work upon which this report is based was supported in part by funds provided by The United States Department of the Interioi as authorized under the Water Research and Development act of 1978. Caribbean Research Institute College of rrie Virgin islands St. Thomas, U.S.V.T. 00802 CO/63 if r p IN 1; IP p DISCLAIMER Contents of this publication do not necessarily reflect the views and policies of the U.S. Department of the Interior^ nor does mention of trade names or commercial products constitute their endorsement or recommendation for use by the U.S. Government. %% wf ipl ?pl ^) fSl jl*J Rp) Iwl IV. V, VI XI TABLE OF CONTENTS List of Figures List of Tables Abstract Introduction Methods Results Conclusions and Recommendations References Appendix A Appendix B Appendix C Eggs Key Larvae Key Energy Symbols I I Page i v v vi 2 6 8 41 42 44 49 52 /f* * /pi [tpl S^ p*l fpl fR r 1. Fi gure 1: If. Fi gure 2: III. Fi gure 3: IV. Fi gure 4: V. Fi gure 5: VI Figure 6A: VI I. Figure 6B: VIII. Appendix A IX. Append!x B X. Appendix C LIST OF FIGURES Geographic Setting of the V irg in Islands Location of Bays and Significant Features Bathymetry and 1chthyopIankton Samp Ie Rainfall Annual Distribution Rainfall Relative to Salinity and Average Breeding Condition General Model of Systems Details of the Bay Systems Eggs Key Larvae Key Energy SymboIs i v 10 12 27 28 44 49 52 IP lljpl SIF r IP [pi r If! r 1 Table 1. II Table 2. 111 Table 3. IV Table 4. V. Table 5. VI. Table 6. VI 1. Table 7. VI 1 1. Table 8. IX. Table 9. X. Table 10. LIST OF TABLES Daily Rainfall Records Surface Temperatures Surface Sal in ities Total numbers of Phytoplankton Zooplankton Numbers Sample parameters for Ichythoplankton Tows Egg and Larval Densities Egg Abundance by Station Larval Abundance by Station Sorensen Si mi larity Index Between Stations and Dates for Larvae and Eggs 13 14 I6 I7 18 19 21 29 39 f L w\ t^i pi P> ABSTRACT The island of St. John Is a small tropical Island 19 Square miles extent and with a population of about 3,000 persons. About two-thirds C2/3) of the island is National Park, now designated as a Biosphere Reserve. At one time 95$ of the island was cleared and planted in sugar cane, indigo, hemp, and bayberry. Most of the Island Is now In secondary to tertiary successional tropical forests. The two watersheds and bays studies were Lesser Lame- shur and Greater Lameshur Bay, both undeveloped areas. The geomorphic profiles for both watersheds are similar; a small flat alluvial plain with fossil beach berms and mangroves at the shore. Easterly winds dominate this area, and the resultant swells enter the bay at a broad angle. During heavy weather they may be refracted enough to break on the cobble beach. The marine fisheries of the V.I. exist In a low nutrient ambient area nearly devoid of the seasonal cues, which in temperate fisheries key the reproductive efforts of the fish so that their larvae appear at the time optimum for their survival and growth. In the V.l. appearance of nu trients and the timing of reproduction appear related; but instead of being keyed by seasonal changes, they may be re lated to the rain and freshwater input, to day length, tides, VI iipi o d f!F! p p IP) p It! P ra to the occurance, survival, and maintenance of the young of various fishery species. VI I ' —-il f 1 r-T| r~^i r*=i r~^i r_^i <—i rr^r% '—i «-^f r—1 r-^ r-=| r—k ATLANTIC OCEAN AHeOAOA^U •-&*. ST. THOMAS " ST. JOHN', 1/ OOROA 6 7°00" CARIBBEAN SEA 66° 30 0 10 tO BO 40 klluMttu • • i I 1 66°00' ___J 10 BO _l U- 40 milt* 69°30' —J es°oo' rigure 1.--Geographic setting of the Virgin Islands of the United States ST. CROIX /8°00- 64°30 ___J P?J p> p> p*i p pi sSI 1PI NTRODUCTION Rainfall In the Caribbean Is highly variable, both in time and location, but differences are not so pronounced specially that comparisons between two watersheds on the same Island can not be made. Rainfall for the sampling year, May 1982 through June 1983, was below norma I in total accumulation at both study sites. References to rainfall on St. John Indicate that this Is not unexpected. Bowden (1969) In particular says that the Lameshur watershed when "... Compared to three eastern stations of St. John ....... has a higher rainfall and a greater reliability." Most of the rainfall accumulation on St. John and the other islands tend to be in short showers of less than 1 Inch. Evapo- transportation is practically always higher than rainfall in this region (Sediment Reduction Plan), and the effects of the light rains are lost to the Island almost immediately. Rainfalls of greater than an inch are needed to recharge the aquifer. If the rain comes after a dry period, however, the effects may still be lost due to runoff. The water will start to soak into the surface soil somewhat, but the dampening of the clayey Cramer-Isaac soils will make them less permable CSoil Survey, 1970), and most of the water from such a down pour situation will run off. The question of the effect of this runoff on local fisheries is examined in this study. The surface soils or the watersheds for both bays are com posed primarily of Cramer grave Iy clay loam with slopes of il^ sPI p) (PI 12 to 60 percent. The U.S. Department of Agriculture Soil Survey (.1970) characterized drainage as good, runoff as medium to rapid, and permablllty as moderate. The Cramer series soils here are generally shallow C25 - 50 cm) over partly weathered basic volcanic rock. The southern slope is cobbly alluvial land, and stony with resultant rapid permeability and low water holding capacity. Drainage area for the watershed is 536 acres (2.17 km^) (Sediment Reduction Program, 1979). A natural berm which rises between the flats and a cobble beach generally serves to retain the runoff. There is one permanently inhabited dwelling in the watershed, the N.P.S. ranger residence (F igure 2). A septic field is used for waste disposal. There are also two pit/chemical toilets for use of park visi tors. A beach occupies the Northern shore of the bay. In Lesser Lameshur the Juacas sand beach to the east is sepera- ted from the cobble beach by a rock outcropping which ex tends into the bay about 30 meters, with several rocks emer gent. The outfall occurs on the western end of the cobble beach. Use of the beach by visitors is not high, as access must be over the single dirt road or by foot. The bay bottom in Greater Lameshur near the cobble beach Is rocky with scattered corals. The slope is gradual and 20 to 30 meters offshore in a depth of 2 meters the bottom change to sand. Maximum depth near the mouth of the bay is 15 meters Most of the central part of both bays is covered with a grass tiw) Ifm\ If"!I |ip| I bed composed mainly of ThaI ass ia. The remainder of the eastern and western shore are steeper and rocky with good coral and gorgonlan development. WATER RESOURCE EDITION ST. JOHN U.S. VIRGIN ISLANDS Camilla H< Point Figure 2: Location of the Lameshur Bays and significant Geographic Features L, •L^ HL^^j ita^j I............. ffpl E $pi IpI METHODS There Is an existing rainguage and data system. A weather station and tide guage was established at the shore lab at Greater Lameshur Bay. In periods of high flow, if the beach berm is broached, a fluorescent dye is to be intro duced and the dilution factor computed from samples of bay water to estimate the true Inflow, A record of nutrients was kept for 3 years, and oxygen and gross phytopIankton Ccells per milliliter) were recorded In this study. ReproductI ye condition was determined on adults of the common fishery species by dissection and measurement of the gonads as well as microscopic sections of the gonadal tissue. These measurements were correlated with rainfall and with the appearance of both larval fish and phytopIankton in the bay. The fish were taken by trap, net, and hand. Zooplankton and phytopIankton were estimated by taking three standard tows with plankton nets weekly as well as by grab samples within the turtle grass and coral communities. IchthyopI an kton was analyses from 20 samples taken in Greater Lameshur Bay, Lesser Lameshur Bay, and off Yawz? Point CF igure 3). Table 6 summarizes sample dates for loca tion, type of sample, time of day sampled and volume filtered The net used in sampling was a o.5 m ring net with a three point bridle and 153u mesh. Volume filtered was measured using a General Oceanics flowmeter In the mouth of the net. IpI Europo Boy Little Lomeshur Bay Great Lameshur Bay 100 200 300 meters O 500 10O0 teet Depth in feet Coral reef Figure 3: Bathyopaetry Ichthoplankton and Sample Stations pn W\ tSI pi pi SSI ^i BSJ ^B1 Horizontal tows were made at about 2m depth. Oblique tows were made using 2 meter stages at 6, 4, 2 m and just below the surface except for Little Lameshur which was too shallow. In Little Lameshur the stages were 4 and 2m and surface. The net was towed at each stage for 2 minutes. Times for horizontal tows varied and are reflected by the volume f i Itered. Analysis and correlation of the data was done to show the relationship between runoff time and volumes with the gonadal condition of adults and with the appearance of food and larval forms in the bay. Report Inq was on a semi-annual basis and the reports have been designed to serve as a reference and guide for planners, developers, and local resource managers as well as providing data to the national OWRT offices. RESULTS Data resulting from the study are summarized in Tables 1_7. The daily, monthly and yearly rainfall are shown in Table 1 for Lesser and Greater Lameshur respectively. The rainfall patterns in the southeast quarter of the Island are very consistant over years of time (Purcell and Canoy, 1983) and generally are found to have a mean of 43.98 inches (111.7 cm). Rainfall was highest at both stations in April, May and October, and lowest in February, March and June. 1 • 1 vO 1 H P cr p I-1 •1 P b P »i fl> 0 O *i a a> a H- 3 p 3 n> w cr d w p p CD >1 W cr (D a w o rv o g O > •—1 -H ~< «-1« > On 1 CO V—1 • ro o en en to •s ro o to w »-* • CO *«J en ro t-* • vo CO Sj eo k-4 i ro ro sj en .n» ro o •,co or en «J •—) «, ro to CO 1 r—1 1 1 WWNrONMNNrONNNMMMMi-iwi-iMMu MOlDOOSIOiUl4iWNMOVOCnNja>UiJswi\3MO(OCnsjrMn.N(.oi\j o o o o o • o • ooo- o • o o • o • o o • O • • o • o • o • CO J-* O^vl CO CO en *-j o O) o o co »si en ro ro i-j en o c«> en en en • • • o o • o o • o o • ooo* • • o o • • • • O O • • • o OOO O O O v-jroo mmo ^ ^itn.ts to Co en en .c ro en oo j> *-• rxi co vo <« tn co O O • O • O • O • O' ' • • • • • o o o o • • o«« en ro o oooeooo o ^ i-* en o o o o -r» a oo en ^j vj^NNNen en o vJ nj w w si vo co qq o • . . OO' • • • • • • OO' • • oooooo enroo o ro >-» ro en en co roo <J m co »o »-* ro o *-» •vJMU) co en «-• o >-• »-» en eo eo ro u> i^ en »-* vo ro o • oo» • o o- • O O O O • OOO' • - • o • >-* MO v-J O O -fc» *-* O O *-* t-J O OO'-'V-' O en O >-i i\) m w si js. a> m ro en ro r\? >n ro en cr OOO1 O O • • • O' • • O' ' ' ' • • OOOO' • • • ' • o m to ro o ooo »~»ooj^oo iomo »-• o o en o o •£» co en sj m went-jm w si en u> i - en j~-> ho ' ' • • O O • OO' OOOOO' • O' OO' o- oooo- oo env-JMO o o v-*oo oro o o o »—' ro en i—• .e» ro i-j no o co o o o o o o o • o • • • o • • • • • • • • o • of:? ' • o ro oom oooo»-j»-j>-,ro o o o no en en en co en co -In rsj co en io co co o^ OOO' OOOOO' OOOOOOOO! oooooo- • o o o o O v-J O. O nj *-J o CO ,-J o en |o * O • • • O' • • • • OOOO' OO' • • OO' • • • »-ioo Jsoooo o ooo .r»oo»-i*-j.- J> ^-» si oo si oo oj n en ,t> »—» ro sj si ro o si «.o n-« >—i O'OOO OOOOON3 o -, ^4 en ro co en co en ro m co o R S i CO o o • .• • o O O O • • OO- OOO OOO O »-J M o 3? cz 1^ CM en rn •a o o —< o a m o •?> J • P3 13 CO cv v«« • oooooo- • •^ ^ f^> eTi c/i ro en o ^ vo !r1 S § CI- CD CO to CD CO CO r—U 100 90 • BO ^ 70 I « SO 40 O 30 20 10 |S1 Ui Jan.I Feb. I Mar. Figure 4 SB • S3 Apr- • HayI ju^'lliUIll limp I 1..1.. I . rr^ i11 IL July • Aug. I Sept. « Oct. » *Jil No*. • Dec. MONTH Rainfall data used in th e estimation 10 ps| 31 SsFl Temperature of the surface water in degree centigrade at the bay sites (0.5 m water depth) is presented in Table 2 and the salinity given in part per thousand (ppt) is shown in Table 3. The temperatures in Lameshur Bays ranged from 30,8°C in October inshore to 26.2°C at Little Lameshur and 26.4°C at Greater Lameshure In February. Sali n it ies for the two bays ranged from 34.0 ppt (October; GLB Station 1) to 36.2 ppt (December; GLB Station 2) and 34.0 to 38 ppt (February; LLB Station 1). The stations at the mouth of the bays tended to be cooler and more saline. Preliminary perco lation studies show hyposaline, cooler, water to be percola ting through the sand bottom at several sites during the months of November - February. Phytop Iankton:trlooms were found to follow rains by four to six days. The duration of the blooms was from six to 20 days depending on the volume of runoff and circulation of a given bay. The average density of cells during these blooms was about 30,000 per liter, but highs of over a million per liter were recorded at times. During normal periods dino- flagellates about equaled all other species with diatoms a close second. During blooms dinofI age I Iates increased by 100X, diatoms by about 10X and all other by 2-3X. Zooplankton populations increased in one to three weeks after phytopI ankton bloomed. No direct correlation could be found as to either the timing or the magnitude of the increase 1 1 D I 3 Rssj i | r~~D r—3 i 73 r—g 1 3 (—3 Fssg r—g 1—3 1 3 r~j r—3 F^f) 1-33 r^T) r inches 1.50 - 1.00 0.50- 0 mm 33 22 11 ••Ml .»•••• , .,. . L_l_i__LLL__ jj *' jj •» fl> /-i u u /« 10 ?o jo -j i) ;-j 9 i'j 2d. i u /j i »• Bl^'a." I MiM .- j m:'l,-.(f j M4ICII I J.'..I j M4T* | Jml | 1UU S?7oo Breeding \ Cond. Figure 5 Rainfall, Salinity, and Average Level of Breeding Condition for Fish from the Lameshur Bays 12 0 1982 KpJ L 1983 iSfl Table 2 10 May 18 May 31 May 28 June 31 July 25 August 7 Sept. 30 Sept. 10 Oct. 18 Oct. 28 Oct. 8 Dec. 20 Jan. 20 Feb. 18 March 10 April Greater Lesser 30.0 29.8 29.2 28.0 28.0 28.5 28.4 27.9 28.5 28.2 28.5 28.0 30.1 29.5 29.1 29.0 30.0 29.5 29.1 29.0 30.2 29.8 29.2 29.5 30.0 29.5 29.5 29.5 30.5 29.8 29.5 29.8 30.5 30.2 30.0 29.5 30.8 30.1 29.9 29.5 30.0 29.9 29.9 29.5 27.4 27.5 27.0 27.0 27.9 27.5 27.0 27.0 26.5 26.4 26.2 26.2 27.9 27.8 27.5 27.0 27.5 26.5 _ _ Surface Temperatures in Greater and Lesser Lameshur Bays 13 (pi r IP1 p£l pst 1982 1983 10 May 18 May 31 May 28 June 31 July 25 August 7 Sept. 30 Sept. 10 Oct. 18 Oct. 28 Oct. 8 Dec. 20 Jan. 20 Feb. 18 March 10 April Greater Les ser 36.0 36.0 36.0 37.0 35.0 36.0 36.0 36.5 35.0 35.5 35.5 36.0 35.0 35.5 36.0 36.5 35.5 35.0 35.0 36.0 35.0 35.5 35.0 35.0 35.0 35.0 34.5 - 34.0 35.0 35.0 35.0 34.5 34.5 34.0 35.5 34.0 34.5 34.0 34.0 34.5 35.5 34.5 35.0 35.9 36.2 34.5 35.5 34.5 35.5 36.0 35.5 36.0 36.0 38.0 37.0 36.0 35.0 35.0 35.0 34.5 35.0 — — Table 3 Surface Salinities in Greater and Lesser Lameshur Bays 14 |PR| |P1 [ipi ip»i r They may be partly dependent on the specific populations present and th.e composition and volume of the runoff. Du ring the zooplankton blooms the numbers rose from 10-15 th.ous.and per cubic meter to as hjgh as 600 thousand per m"5 15 1982 TpTI (53 551 1983 r Table4 <r p| RSI DATE 10 May 18 May 31 May 28 June 31 July 25 Aug. 7 Sept 30 Sept 10 Oct. 18 Oct. 28 Oct. 8 Dec. 20 Jan. 20 Feb. 18 Mar. 10 Apr. Lesser STA. 1 STA. 11,608 94 8,457 92 1,092 514 458 79 105 278 187 117 169 75 243 129 201 258 209 60 238 108 250 203 172 176 66 46 85 70 27 50 Greater STA 1 STA. 41 61 400 68 632 210 206 59 144 53 117 83 102 123 154 58 60 34 18 17 219 65 118 161 179 287 128 60 47 48 Total numbers of Phytoplankton from stations in Greater and Lesser Lameshur Bays (organisms per Liter). 16 1982 p?i 1983 SI Table 5 Lesser Great er DATE TOW 1 TOW 2 TOW 1 TOW 2 10 May 35 8111 13576 14508 18 May 122 14875 11863 5677 31 May 131 13870 9720 8437 28 June 67 36411 23605 34948 31 July 503 17768 36155 18242 25 Aug. 385 166199 14868 6005 7 Sept. 659 210575 115615 80822 30 Sept. 5187 198449 636529 323626 10 Oct. 1171 71593 145572 33617 18 Oct. 1192 102184 304875 67493 28 Oct. 73959 91968 44200 66498 8 Dec. 140348 43177 125351 35495 20 Jan. 46585 21283 35043 15208 20 Feb. 78868 189499 66124 33163 18 Mar. 2186 2232 9262 11753 10 April 110926 139246 — — Zooplankton numbers in organisms per Liter 17 00 -~u Table 6 Sample parameters IchythyopIanton tows Great Lameshur Bay Date Type of tow Time of day YoIume Date Type of tow Time of day VoIume Cm3) 12 Jan HorIzontaI Night 1202 26 Feb Ob IIque J 126 264 Little Lameshur Bay Date Type of Time of tow day Volume (m^) Yawzi Point 24 Feb Obi ique 0615 252 14 Jan HorIzonta Day 563 21 Apr Ob Iique 1945 491 27 Feb Obi Ique 1305 214 26 Jan HorIzontaI 0513-0523 322 20 May Ob IIque 0917 377* 22 Apr 0b IIque 0651 510 26 J an Hor izonta Night 515 24 July 0b Iique 0717 375* 13 July 0b Iique 0710 399 1 23 Feb HorIzontaI 1112-1114 56 24 July 0b Iique 0649 344 Date 18 Feb 26 Feb 20 May 24 May 24 July Type of tow Hor1zontaI 0b 1Ique 0b 1Ique 0b Iique Oblique Time of day 0710 1 140 0815 0638 0619 Volume 179 248 406 278* 280 23 Feb 0b IIque 1805 140 *) Flowmeter readings suspect, volumes estimated based on 3 most recent samples from same area. S~I Tafelae 'f Egg and larval density by station and date. —s\ ___________________________________________________________________________________ Date Egg Density A. Great Lameshur Bay 12 Jan 644 14 Jan 14,150 26 Jan 1,038 23 Feb 1,718 26 Feb 48 21 April 54 20 May 29 24 July 81 Larval Density 390 94 247 740 147 82 35 75 B. Little Lameshur Bay 24 Feb 701 29 27 Feb 10 179 22 April 20 22 13 July 24 246 24 July 10 145 C. Yawzi Point 18 Feb 6 42 26 Feb 1,946 8 20 May 95 292 24 May 864 585 24 July 513 1,056 19 —1 ' w\ w\ I"1 If— ro—• ~1 f—I pi FISH AND FISH LARVAE Table 8 presents egg densities for these samples reported as numbers of eggs per -1000 m^. The eggs are reported as morphological types, except where Identification is absolutely certain. However, it should be noted that types A,B and AB almost certainly are anchovy eggs while types F,I,V, and X are almost certainly herring eggs. In order to confirm these relationships, eggs with advanced embryos must be located so that they can be compared with described larvae. Types A,B and M are the most frequently encountered types occuring in three to five of the seven samples. Table 9 gives similar information for the larvae. Type designations were made using the Gaelic alphabet to avoid con fusion between egg type designations and larvae type designa tions. The following observations should be noted: BA early yolk-sac larvae correspond very well with late embryos of type Z eggs and probably represent a percoid species. BF larvae correspond with type X embryos. Carangidae 1 is probably a scad larva, but the specimen cond 11 loru-was. too poor to confirm this. Gobiidae 2 seems to be a Coryphopterus species The.greatest biomass of adult fish in Lameshur Bay is com posed of anchovies and dwarf herrings, however their eggs do not always make up the majority of the IchtyopIankton (see Table 8). Table 7 shows that, when they are abundant, they are extremely abundant, reaching densities over 12,000/1000 m^. 20 r pi c r (iP (ipi P r IPi * 2 r Z 2 23 L AA 2 p AB n L AD 1 P p AG 37 [! AH 8 AI 5 j1 AJ 8 520 AK 12 H AL 8 Table 8 Egg abundance by sampling station. Abundances reported as number per 1000 m3 A. Great Lameshur Bay Type 12 Jan 14 Jan 26 Jan 23 Feb 26 Feb 21 Apr 20 May 24 Jul A 20 78 143 6 B 495 9309 19 21 D 96 257 23 E 16 17 43 F 9 G 19 11 H I K 2 3 L 43 1193 M 36 81 18 N 50 22 0 6 * 6 S 37 T A U 9 V 2 3561 W 1112 13 66 AE 1 AF 1 ra AM 1 AO 21 0 (IP r [pi n o 0 u ifpi D 0 r n Continued Table g. Type 12 Jan 14 Jan 26 Jan 23 Feb 26 Feb 21 Apr 20 May 24 Jul AS AT AV AW AX AY BA BI BJ BK BL BN Clupeidae 1 1 Clupeidae 2 2 Synodontidae 1 1 Synodontidae 3 Synodontidae 4 Scarus Sp. 2 B. Little Lameshur Bay rype A D J L 186 M 107 P V Z 8 AG AK 4 AN 8 AO 4 AP 4 AQ 67 AR 4 AS 111 11 4 2 12 14 2 24 36 24 Feb 27 Feb 22 Apr 13 Jul 24 Jul 75 22 14 8 6 6 2 Table 8 Continued B. Little Lameshur Bay Type 24 Feb 27 Feb 22 Apr 13 Jul 24 Jul |p AT 52 ^ AU 4 2 4 AZ 5 BA 10 BB 2 p r I1 r o p r r pi P |ip p BE 3 Synodontidae 1 67 2 C. Yawzi Point Type 18 Feb 26 Feb 20 May 24 May 24 Jul A 28 10 B 6 121 4 C 56 D 7 E 15 4 G 14 I 7 J 12 86 L 47 M 1653 P 5 7 Q 4 R 56 S 8 U 2 AL 25 AQ 11 AV 4 p BA 54 BB 4 BC BD BE 2 104 BF BG 23 11 126 r pitI p p Ifl.'^ Table 8 Continued C. Yawzi Point Type 18 Feb 26 Feb 20 May 24 May 24 Jul BH 4 58 212 BL 29 BN 90 BP 2 BQ 2 22 BR 2 14 BS 68 BT 18 BU 79 BV 245 Clupeidae 2 2 Synodontidae 1 4 Synodontidae 2 22 4 Synodontidae 5 5 14 Scarus sp. 20 Soleidae 1 4 24 IB pfl |B) SI ®PI Jp^l $>P) Another point which this limited amount of data Indicates is that there are large differences in ?chthyopIankton com munities among the locations and between sampling dates. Attached as appendices are keys to the eggs and yolksac larvae. These should provide information concerning criteria for identification of the types. Table 8 summarizes the distribution and abundance of fish eggs among these samples. The egg types appearing most fre quently were types A,B, L, and synodontidae 1, all of which were found on 7 of the 14 sampling dates. Type M was found on 6 of the dates while types D,E,J and P were found on 5 of the dates. The biggest densities of individual egg types were 9309/1000m for type B on 14 January, 3561/IOOOm3 for type V on 14 January, l653/1000m3 for type M on 26 February, M93/1000m3 for type L on 23 February and M2/1000m3 and 1112/1000m3 on 14 January. A key to the egg types is being developed. The following eggs have been tentatively placed in families: A,B,AB and AG in Engraulidae; F,L,V and BO in Clupeidae; Z in CaI 1ionymidae; K in Bothidae; and BT in Carangidae. Other egg types have been placed in family groupings as indicated by names (e.g. Synodon tidae 1, Scarus sp.), and the placement is considered to be more sure than those listed above. Table 9 summarizes the distribution and abundance of fish larvae among samples. The larval types which occured most fre quently were Gobiidae 7 which occured on 10 of the 14 sampling dates, Syngnathinae which appeared on the 9 of the dates and 25 ff?Fl i~| w\ Clupeidae which appeared on 7 of the dates. The highest densities of individual larval types were 8I8/I000m3 for Clupeidae, 339/IOOOm3 for gobiidae 19, and 278/IOOOm3 for EngrauI Idae 3. Keys to the identification of larval types may be found in Appendicies A and B. The clupeid larvae which are all reported as one type may represent two or more species, but more than 90^ of them match descriptions given by Powles (1977) for Jenk ins ?a 1amprotaen ia. Unfortunately most of the other clupeids are not adequately described to rule out confus ion. Microdesmidae I is probably genus Cerda1e, but it is not certain as there are no good descriptions for this group of larvae. Diodontidae I matches Leis' (1978) description of Diodon antennatus which would be entirely possible, however none of the other western Atlantic diodontids are described so that there are no data concerning variance within the family. Monacanthidae 1 is either in genus StephanoIep is or Monacanthus, but this distinction awaits further analysis. The scorpaenids represent an interesting taxonomic problem. The pectoral fins are much smaller in proportion to body size than is seen in most other scorpaenids (e.g. Miller, Watson and Leis, 1979; Moser, Ahlstrom and Sandknop, 1977; Taning, 1961) except some northern Atlantic Sebastes (Russel 1976). The urostyle is also much larger and more pronounced than seen in 26 IHUMANJSOl|RCE§ | PREDATOR SOURCE "**. RESPIRATION Figure 6A: General Model of Systems 27 i--,-... fL i 1.............. t 1.7 x 10 KcAL/MVDAY Figure 6B; Details of the Bay Systems L kcal/m2/day\3L i___ sfr---— kcal/mvdayj — coral-based SYSTEM •l- • ffml S!i| w S*l iP?l w liffl Table 9 Larval abundance by sampling station. Abundances reported as number per 1000 m3. A. Great Lameshur Bay ^Pe 12 Jan 1A Jan 26 Jan 23 Feb 26 Feb 21 Apr 20 May 2A Jul & 6 & 6 C 12 b 3 e 6 F 3 3 22 K 31 17 7 1 Z 34 m 7 O 4 P 8 r 2 8 P • 1 15 C A U 4 A A. A A£ 8 AC 11 O.Z 8 JNP 2 4 AV» 4 /M 2 4 A.r 2 AP 2 AC 4 AU 2 pn 3 em "gP 2 f3C 2 2 29 !|Pi > Table 9 Continued ps) A. Great Lameshur Bay L Type 12 J 1^1 PH 3 CAi 2 !P( CP 2 CC 3 c6 2 iSl :' ce i cp i C5 i ch 2 •) C1 l • Cl 2 flfl cm i L CP m cr I cu p bA - 6& pi be bb be PB bs bh 6i psi bl bm en ^fHP| er eu r pB L re HP) pb - pe. §F) PP L p5 SI ph . pm 1A Jan 26 Jan 23 Feb 26 Feb 21 Apr 20 May 2A Jul A A 6 A A 2 17 17 7n fjpl pfpl jip^l Table 9 Continued A. Great Lameshur Bay Type 12 Jan 1A Jan 26 Jan 23 Feb 26 Feb 21 Apr 20 May 2A Jul pn 17 PP 17 FP 17 Clupeidae 1 9 Anchoviella perfasciata 1 3 Engraulidae 3 278 Engraulidae A A Petrotyx sanguineus 1 Hippocampus sp. 22 Syngnathinae 1A Scorpaenidae 1 3 Scorpaenidae 2 Scorpaenidae 3 Triglidae 2 Serraninae 1 Carangidae 1 Labridae 1 2 Clinidae 1 1 Clinidae 2 1 Blenniidae 1 7 Blenniidae 2 Gobiidae 1 1 39 Gobiidae 2 Gobiidae 7 36 11 Gobiidae 8 1 Gobiidae 12 Gobiidae 16 Gobiidae 18 Gobiidae 19' Gobionellus sp. Gempylidae 1 2 Scombridae 1 Cubiceps sp. 2 Callionymidae 1 A8 2 71 36 10 A8 8 2 71 28 7 36 11 2 17 71 339 3! Table 9 Continued » A. Great Lameshur Bay Type 12 Jan 1A Jan 26 Jan 23 Feb 26 Feb 21 Apr 20 May Bothidae 1 4 Sphoeroides sp. 17 2 IS pn B. Little Lameshur Bay Type o r- u pin P>° &p pi" en Co cp &e bo c>»- eg ep er4- Clupeidae 1 Engraulidae A Syngnathinae Scorpaenidae 2 Scorpaenidae A Scorpaenidae 6 Labridae 2 Gobiidae A Gobiidae 5 Gobiidae 6 Gobiidae 7 Gobiidae 8 Gobiidae 9 2A Feb 27 Feb 1A 9 5 37 1A 5 5 5 5 19 1A 19 1A 22 Apr 13 Jul 2A Jul A3 138 2 50 32 6 3 3 87 12 13 2A Juxy P Table 9 Continued B. Little Lameshur Bay Type 2A Feb 27 Feb Gobiidae 10 Gobiidae 11 Gobiidae 1A Elacatinus sp. (IP r 22 Apr 6 2 C. Yawzi Point Type c h P P z: A6 Ar A7 Al Am An AO AP Bh &m I5P- or *L 6u eA e* ec ee ep e"5 18 Feb 26 Feb 20 May SB 13 Jul 2A Jul 2A May A A A A A 11 A3 A 2A Jul 1A 7 A3 7 7 11 7 7 A A A 7 33 »Table 9 Continued C. Yawzi Point 5^ Type - eh pi el - el W) ero en eo pn p»b PP H3 Pn PP fjW pp SS PC . pu w> 3A *. 3P 3C 3*> S« pi SP 33 PI Sh !- •57 f8 52. - 3W i 3n * SO ESI 3P 3P- 3^ [(3 •5C 3U |P) hA he F» he I hP P»| hS 18 Feb 26 Feb 20 May 2A May 2A Jul A 7 A A A A A A A 2 2 5 5 7 2 2 25 22 2 5 2 10 25 A 5 5 1A 5 7 5 2 2 2 A 2 5 5 2 A A 7 32 34 r^1™! r r Jf*I BjpEI (PI fj?Fw| Ifpl Table 9 Continued C. Yawzi Point Type hh hi hi hw hn ho hp hr hr> hr. hu 1A 7J5 1C 1b 1P 15 ih 71 Clupeidae 1 Engraulidae 5 Serrivomeridae 1 Synodontidae 1 Synodontidae 2 Syngnathinae Scorpaenidae A Scorpaenidae 5 Serraninae 1 Serraninae 2 Serraninae 3 Labridae 2 Clinidae 2 Blenniidae 3 Gobiidae 3 Gobiidae 6 Gobiidae 7 18 Feb 26 Feb 20 May 2A May 2A Jul A A 11 7 7 A 18 A A A A A A 7 A A A A 7 79 15 AA 2 35 A A 11 A 22 18 58 818 A A 11 A 7 0 1 Table ^ Continued C. Yawzi Point r Type 18 Feb 26 Feb 20 May 2A May 2A Jul Gobiidae 8 10 Gobiidae 9 2 Ip^l Gobiidae 11 2 Gobiidae 16 2 7 11 r Gobiidae 17 27 7 18 Gobiidae 19 11 r Gobiidae 20 17 Gobiidae 21 2 ppl Gobiidae 22 20 Gobiidae 23 A r Gobiidae 2A A Microdesmidae 1 A u Syacium papillosum 2 Monacanthidae 1 7 Ostracioritidae 1 A I' Sphoeroicles 1 2 Diodontidae 1 A D ra ffp) r (pi r o ipi o 36 w^ Wl 5M literature description, however the presence of a pit in the parietal region and the development of head spines typical of scorpaenids confirms the Identifications. Scorpaenidae 3 flexion larvae have pigment present in the pectoral axil which may prefigure the dense axillary pigment of several species in the genus Scorpaena but most obvious is Scorpaena pI urn ier i. The serrivomerid eel IeptocephaI us taken at Yawzi Point was a bit of a surprise, as the family Serrivomridae is typical of open ocean, and adults normally live at fairly great depth. Very few leptocephali of these eels have been recorded from the western Atlantic; and, after futher exami nations, this speciment will be archived in either the U.S. National Museum or the Los Angeles County Natural- History Museum. Similarity index values were calculated for both egg types and larval types between stations for the whole set of samples for 24 July when all 3 stations are represented and between dates for Great Lameshur Bay. The index is that of Sorensen (1948) which Is S = 2 x no. species in common * (no. species at sta- tionj + no. species at station2). These values are presented in Table 10. It becomes obvious from these index values that there Is a high degree of variability and in all probability only a minor portion of the total number of species available have been samp Ied. Despite the fact that 10 samples from Great Lameshur Bay and only 5 samples from Yawzi were processed, Yawzi Point had 37 (H^i * PI nearly the same total number of types of eggs and more species of larvae represented. Yawzi Point and Little Lameshur Bay have the same number of samples processed, yet Yawzi Point has nearly twice as many egg types represented and more than three times as many types of larvae. Table 7 shows total egg and larval densities for each sampling date by stations. It would appear from these data that during January and February the major spawning and nur sery area was Great Lameshur Bay, while in May and July Yawzi Point served as the major spawning and nursery area. This may indicate either a movement offshore by spawning fish later in the year or, as seems more likely, a shift in species spawning. This pattern of utilization needs futher investigation as it has implications for environmental impact elsewhere in the Car ibbean. psi 5&I IP) Table 10 Stfrenson similarity index value between stations and between dates for larvae and eggs. The parenthetical value is the largest value possible with the particular distribution of species numbers. Great A. Egg types Lameshur Little Lameshur .36A (.597) Yawzi Point .A8A (.863) Great B. Larval types Lameshur Little Lameshur .208 (.500) Yawzi Point .2A6 (.947) C. Great Lameshur by dates: 12 Jan 1A Jan Little Lameshur .375 (.719) Little Lameshur .218 (.A62) Egg types 26 Jan 23 Feb 26 Feb 21 April 20 May w$\ 1A Jan .235 (.882) SSI 26 Jan .133 (.844) .293 (.732) - 23 Feb .222 (.592) .3A8 (.696) .353 (.470) sp$ 26 Feb 0 (.286) .111 (.333) .207 (.207) .364 (.545) psi 21 April .138 (.690) .160 (.800) .278 (.556) .333 (.889) .154 (.462) St 20 May .095 (.286) 0 (.333) .069 (.207) 0 (.545) 0 (1.000) 0 (.462) ipt 2A July 0 (.286) 0 (.333) .138 (.207) .182 (.545) 0 (1.000) 0 (.462) 0 (1.000) •PI 39 si r F» m w\ 1^*7 Table %Q (continued) D. Great Lameshur by dates: Larval types 12 Jan 14 Jan 26 Jan 23 Feb 26 Feb 21 April 20 May 14 Jan .049 (.643) 26 Jan .077 .054 (.982) (.650) 23 Feb .089 .067 .098 (.634) (1.000) .650) 26 Feb .170 .188 .046 .056 (.783) (.839) (.800) (.839) 21 April .174 .129 .143 .228 .108 (.783) (.839) (.800) (.839) (1.000) 20 May .158 .174 .118 .148 .276 .214 (.526) (.870) (.540) (.870) (.714) (.714) 24 July .053 0 .059 .074 .069 .143 .100 (.526) (.870) (.540) (.870) (.714) (.714 (1.000 40 w\ y$\ CONCLUSIONS AND RECOMMENDATIONS 1. The volume and concentration of freshwater and nutrients input to the nearshore waters depends on the development history of the watershed and its geomorpho logy. 2. Most fish species breed indiscriminately with respect to location or environmental cues such as freshwater, tide presence of food, etc. 3. The survival and growth of the larval fish depends, among other things, on there being food of appropriate size and type readily available from the time they hatch. 4>v Therefore the survival of the young fish, but not repro ductive attempts, depends on # 1 above. This provides a P secondary level link of runoff quantity and quality. 5. It Is possible to produce an ecosystem model to describe this system which with refinement could be used as a tool in planning and management. m 6. It is recommended that V.I. Planners pay close attention to any development which will alter runoff characteristics 7. It is also recommended that a long term (at least 2 years) study be initiated to determine critical parameters and to develop fully an ecosystem model for planning. 41 iijwi pd fp?l PS! St SSt REFERENCES Bowden, Martyr J., Nancy Fishman, Patricia Cook, James Wood and Edward Masta, 1969. Climate, Water Balance and Climatic Change in the North West Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas, U,$. V.I. Canoy, M.J. "Accumulation of Heavy Metals in Tropical Fishery." 1972. Paper presented at the American Society of Ichthyology and Herpetology. Boston 1972. Canoy, M.J. and Martin F.D. " An Integrative Function of Opportunistic Feeding in Two Tropical Bays". 1974. Paper presented to the American Society of Ichthyologists and HerpetoIogists . Ottawa. Canoy, M.J. 1980 "Ecosystem Modeling for Marine Resources Management". Caribbean Research Institute Report, 1978 (from AID Seminar in Guyana). Cosner, Oliver J. and Dean B. Bogart, 1972. Water in St. John US Department of the Interior, Geological Survey, Open File Report. Hargraves, Paul E., Robert W. Brody and Paul Burkholder, 1970. A study of the Phytoplankton of the Lesser Antilles Region. By II. Mar. Sci. 20 (2) 00. 331-349. Hulbert, Edward M., 1970. Competition for Nutrient by Marine Phytoplankton in Oceanic, Costal and Estuarine Regions. Ecology 51 (3) pp. 475-484- Leis, J.M. 1978. Systematics and Zoogeography of the Porcupine Fishes (Dodon, D iodonti dae. Tetradonti formes ) with comments on egg and larval development, N0AA Fish. Bull. 76 (3): 535-563. Miller, J.M. Watson and J.M. Leis. 1979- An Atlas of Common Nearshore Marine Fish Larvae of the Hawaiian Islands. S,ea Grant Misc. Rept. UN IHISEAGRANT-MR-80-02, 179 pp. Moser, H.G. E.H. Ahlstrom and E.M. Sandknop. 1.979. Guide to the Identification of Scorffr ionfish Larvae (Fam iIy Scorpaenidae) In the Eastern Pacific with Comparative notes on species of Sebaster and He IIcoIenus from other oceans. NOAA Tech. Rept. NMFS Circular 402, 71 pp. 42 jspl !PJ gwl Powles, H. 1977. Description of larval Jenkinsln lampro- taen ia (Clupeidae, Dussamieriinae) and their distri bution off Barbados, West Indies. Bull. Mar. Scl. 27; 788-801. Purcell, Thomas W., 1980. The Effects of Rainfall Runoff on Two Undeveloped Tropical Bays on St. John, U.S. Virgin Islands Water Resources Research Center, Caribbean Research Institute, College of the Virgin Islands, Technical Report No. 5. Russell, F.S. 1976. The Eggs and Planktonic Stages of British Marine Fishes. London: Academic Press, K524 pp. Stone, Robert, 1942. Meteorology of the Virgin Islands. Sclentifi Survey of Puerto Rico and the Virgin Islands. New York Academy of Sciences, 19 (t) pp. 1-138. Svedrup, H.U. Martin W. Johnson and Richard H. Fleming, 1942. The Oceans. Prentice Hall, Inc., Engiewood Cliffs, N.J. Monthly Normal Temperature, Precipitation and Heating and Cooling Days, 1941-1970, August 1973, U.S. Department of Commerce, NOAA, CIimatography of the United States No. 81. A Sediment Reduction Program, 1979. Department of Conservation and Cultural Affairs, U.S. Virgin Islands by CH2M Hill, Ga insvI IIe, Florida. Soil Survey; Virgin Islands of the United States, 1970. U.S. Department of Agriculture, Soil Conservation Service. Taning, A.V. 1961. Larval and post-larval stages of Sepastes species and He!icclenus dactylopterus. In: Trout, G.C. (ed) ICES/ICNAF redfish symposium. Can. Perm. Intern. Explor. Mer. , Rapp Proc.-Verb. 150: 234-240. 43 IP ffpl I Appendix A A Key to Fish Eggs of Lameshur Bay f. Dr. F.D. Martin r ip?i i ||Pl PI P 44 r ' sii Key to the Fish Eggs of Lameshur Bay 1A Spherical or subspherical 2 1B Ellipsoidal, spindle-shaped or irregularly shaped 29 2A When viewed with transmitted light yolk cloudy,translucent, granular or opaque 3 2B When viewed with transmitted light yolk colorless, transparent 19 3A Oil droplet(s) (or yolk inclusions resembling oil droplets) 4 3B No oil droplets 16 4A Oil droplet (or yolk inclusion) single 5 4B 1 to many oil droplets 13 5A No visible perivitelline space 6 5B Perivitelline space present 8 6A Diameter greater than 0.7 mm 7 6B Diameter about 0.6 mm, yolk granular or cellular. . .Type B (probably Engraulidae) 7A Diameter about 0.8 mm, yolk granular Type A (probably Engraulidae) 7B Diameter 1.2-1.5 nam Type C 8A Perivitelline space very narrow, less than 5% of diameter . 9 8B Perivitelline space about 10% or more of diameter 12 9A More than 1.0 mm diameter 10 9B 1.0 mm or less diameter 11 45 r K? 10A Diameter 1.2-1.5 mm Type G 10B Diameter 1.7-1.9 mm Type Q 11A Diameter 0.8-0.9 mm Type D 11B Diameter 0.5-0.6 mm Type E 12A Embryo elongate slender; diameter about 1.2 mm. . . .Type F (probably Clupeidae) 12B Embryo robust, broad finfold; diameter about 1.2 mm .Type K (probably Bothidae) 13A Oil droplets 10 or less 14 13B Many oil droplets; no visible perivitelline space; diameter about 0.6 mm Type S 14A Diameter less than 2.0mm 15 14B Diameter about 2.2 mm; broad perivitelline space; yolk granular in appearance Type H 15A Diameter 0.8-1.0 mm; perivitelline space *\0$ or l*ss; 2-10 oil droplets Type J 15B Diameter 1.0-1.2 mm; perivitelline space *\0% or more; 1-4 oil droplets Type R 16A Perivitelline space visible 17 16B No perivitelline space visible 18 17A Diameter about 1.8 mm; embryo slender Type I (probably Clupeidae or an anguilliform) 17B Diameter 0.5-0.7 mm; yolk granular in appearance. . .Type 0 18A Diameter 0.6-0.8 mm Type P 46 jpsi P>1 "0\ pR p&l pH) 18B Diameter 1.0-1.1 mm Type Y 19A One oil droplet 20 19B No oil droplet or several minute ones or one or two plus several minute ones V 25 20A Perivitelline space visible 21 20B No visible perivitteline space; 0.8 mm diameter . . .Type N 21A Perivitelline space 5-10$ diameter 22 21B Pervitelline space 5% or less of diameter; 0.8 mm diameter Type L 22A Diameter less than 1.0 mm 23 22B Diameter 1.0 mm or greater 24 23A Diameter 0.8-0.9 mm Type M 23B Diameter 0.5-0.7 mm Type W 24A Diameter 1.3-1.4 mm; chorion surface with a fine granular appearance, prismatic in transmitted light Type T 24B Diameter 1.0-1.2 mm; chorion smooth, transparent. . .Type U 25A Diameter less than 1.0 mm 26 P 25B Diameter about 1.3 mm; surface of chorion with a fine pattern of hexagonal figures Synodontidae 26A Chorion smooth and transparent 27 26B Chorion made up of many small flat plates; prismatic in transmitted light; diameter 0.6-0.8 mm Type AA 47 pi Jp^ p£) pi 27A Fine reticulation of granular lines on surface of yolk . . 28 27B No such reticulation; diameter 0.6-0.8 mm Type Z 28A No oil droplets or 5-10 very minute ones; 0.5-0.7 mm diameter Type V (may be Clupeidae, Jenkinsla sp.) 28B 1-2 very small oil droplets plus 5-10 extremely minute ones; 0.5-0.7 mm diameter Type X (may be aberant Type V eggs) 29A Ellipsoidal; 1.0 x 0.8 mm; no oil droplet; yolk granular; chorion translucent, granular looking Type AB (probably Engraulidae) 29B Spindle shaped, 2.3 x 0.4 mm; 1-2 oil droplets; yolk homogenous; chorion transparent to prismatic. . . Scaridae, Scarus sp. 48 lifp] * f L P I' IS I1 jffpl fwlF I' (pi Appendix B A Key to the Larval Fishes of Lameshur Bay 49 Jp^l fpj ptfR SI flpj Key to the Yolk-Sac Larvae of Lameshur Bay 1A Anus not yet formed 2 1B Anus formed 9 2A Oil droplet(s) present in yolk. . . 3 2B No oil droplets in yolk 6 3A 1-4 oil droplets 4 3B Several minute oil droplets; about 25 myomeres; surface of yolk sac appears granular . . .pP (resembles embryos seen in Type X eggs) 4A Oil droplet(s) centrodorsally located 5 4B One oil droplet posteriorly located. . . .pp 5A 1 oil droplet; yolk homogenous. . .pb 5B 1-4 oil droplets; yolk with a large inclusion of different optical density, in transmitted light inclusion more trans parent, in reflected light more opaque than rest of yolk. . 6A Yolk homogenous 7 6B Yolk granular in appearance; 16 post yolk-sac myomeres. . .J&C 7A No pigment anyplace, TL less than 1.0mm 8 7B No pigment anyplace, TL 1.1-1.3 mm; 10-13 post yolk-sac myomeres. . .pT 8A 0.9-1.0 mm TL . . .p& (resembles embryos seen in Type Z eggs) 8B 0.8 mm TL . . .pe 50 9A Gut simple; one melanophore under stomach; 1 melanophore on nape with scattered melanophores on top of head; 2 melano phores on dorsal margin of caudal peduncle . . .U 9B Gut looped; no pigment anywhere Bothidae 1 51 APPENDIX C ENERGY SYMBOLS 52 $^n j^i I3S1 (SI (iBJ IPI |({»lt| ^1 APPENDIX t SYMBOLS USED IN MODEL DEVELOPMENT The symbols used in diagrams of models are those of the enery circuit language developed by H. T. Odum. Each symbol has both a verbal meaning and an exact mathematical equivalent which can be found in Odum (1971a, 1972a). Forcing Function. An external source of energy with or without materials whose driving forces are independent of model behavior. Program can be constant, sinosoidal, etc. and is controlled from outside the model. Flow Limited Forcing Function. Jui external source of energy with or without materials whose input can be a limiting factor due to inter actions within the model. kJ (: J = kU r o r J =J - kJ X; 0 =KOp^xMX) 53 \ • ^ r Production and Regeneration'Module . A group module representing an inter active production process and stor age. Normally used to depict green plant photosynthesis. On a region al scale the module represents the production and consumption of entire ecosystems (P/R). Details of rela tionships in a particular model are shown within the group symbol. Pathway. Shows a flow of energy with or without materials which is proportional to a quantity in stor age or external sources at each end (J = k(Q1 -Q2)). The heat sink re presents energy losses due to fric- tional forces and backforce along the pathway. Adding Junction. Shows the inter section of two pathways capable of adding. Arrow indicates direction of flow and absence of any backforce. Money Pathway. Dashed line indicates a flow of money with arrow indicating direction. 5 4 o fpl ISI Forcing Function. An external source of energy with or without materials whose input is determined by some variable within the model (X). Inflow can only be limited by the variable with which the forcing function interacts. Storage Module. Represents a stor age of energy of materials within a system where a quantity is stored as the balance of inflows and outflows (j£ = J - kQ) and where outflow in--.: eludes depreciation. Self-Maintaining Consumer Model. A group module which represents a con sumer unit including a combination of a storage module and at least one multiplier where-energy stored in one or more places in the .module is fed back to do work on processing input energy to that unit; response is autocatalytic if the above features are included. The group symbol is of ten used to organize model components. When used in this way, it does not im ply additional pathways beyond those actually shown. 55 " • • N. N, >*J SENSOR -^J, Force from a Flow Symbol. Flow rate of one pathway (J ) delivers a force X that is proportional to the sensed flow and derives its energy from it. Price Transactor. Symbol indicates an economic transaction with price (P) the ratio of money flow to energy flow (J2/J,). Price may be constant or may vary in a variety of ways. Heat sink indicates the energy cost of maintaining transactions. - Multiplicative Workgate. rSymbol in dicates intersection of^two pathways coupled to produce an outflow propor tional to the product of the forces driving both flows. General re sponse is a limiting factor type (J = kN1N2). Drag Action Workgate. -Synbol indi cates an intersection where an in crease in one flow has a retarding effect on the output flow (J = kN,(l - kN2)). Sensor symbol indi cates there is no appreciable loss from H? in this interaction. 56