Orlando José Ferrer Montaño 1, * 1 Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, MS 39762, USA.

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1 Turkish Journl of Fisheries nd Aqutic Sciences 9: (29) DOI: /trjfs Assessing the Hbitt Structure for Common Snook (Centropomus undecimlis Bloch, 1792) nd Trpon (Meglops tlnticus Vlenciennes, 1847) in Snt Teres Lgoons, Puerto Rico Orlndo José Ferrer Montño 1, * 1 Deprtment of Wildlife nd Fisheries, Mississippi Stte University, Mississippi Stte, MS 39762, USA. * Corresponding Author: Tel.: ; Fx: ; E-mil: orferrer@luz.edu.ve Abstrct Received 16 June 28 Accepted 13 My 29 This pper ssessed whether the hbitt structure of the Snt Teres lgoons, Humco Nturl Reserve (HNR), Puerto Rico ws ble to support long-term fisheries of trpon (Meglops tlnticus) nd common snook (Centropomus undecimlis). Reltions between fish nd invertebrte communities nd the physicochemicl nd hbitt structure of the lgoon system were identified. Snt Teres 2 (ST2) ws physicochemiclly nd structurlly different thn Snt Teres 1 (ST1). Reduced turbidity nd incresed hbitt complexity creted by submersed vegettion in ST2 were reflected in the composition of the fisheries resources. Trpon predominted in ST2 nd common snook predominted in ST1. Ctch-perunit-effort (CPUE) of tilpi (Mozmbique tilpi Oreochromis mossmbicus nd redbrest tilpi Tilpi rendlli) ws the highest in ST2, nd CPUE of grss shrimp (Plemonetes sp.) ws the highest in ST1. Tilpi represented 96% of the trpon diet, wheres grss shrimp represented 23% of the snook diet. Links between fish hbitt use nd hbitt structure indicted tht the Snt Teres lgoons hve the hbitt structure necessry to support trpon nd snook long-term fisheries. Keywords: Cribben Se, costl lgoon, fisheries, hbitt. Introduction Fish bundnce, species diversity nd use (e.g., spwning, nursery, durtion of residency) hve been used to determine whether prticulr wetlnd hbitts provide dequte functionl vlue for fish (Levin et l., 1996). Fish rpidly colonize new sites, often leding to the perception tht such sites provide fully functionl vlue (Cllwy et l., 21). However, ccumulting evidence suggests tht species occurrence or bundnce my not ccurtely indicte hbitt vlue (Minello nd Web, 1997). The sptil distribution of food nd hbitt differences my be importnt in determining fish hbitt use (Lim nd Dill, 199). Costl lgoons re importnt hbitts for fish reproduction, feeding nd shelter (Kuo et l., 21). The lgoon system t Humco Nturl Reserve (HNR), Puerto Rico represents n importnt source of fish for the surrounding municiplities. It hs developed with no nthropogenic ttempts; e.g., engineering the topogrphy or hydrology, mending the soil, nd/or mnipulting vegettion or fun to ccelerte or modify ecologicl processes (Vilell nd Gry, 1997; Zedler, 21). However, the connection to the se nd the interconnectivity of the lgoons re dependent on remnnt rtificil chnnel tht likely llows the entire lgoon system to mintin its ecologicl integrity. These fcts confer the lgoon system unique ecologicl sttus; it is not n rtificil system, becuse it ws not conceived s such nd becuse it s historicl development followed with little direct humn intervention, but it cnnot be considered s nturl system either, becuse n rtificil chnnel supports its ecologicl functionlity. Becuse of historicl evidence indicting costl lgoon existed in the re [United Sttes Deprtment of Commerce (USDC) nd Deprtment of Nturl nd Environmentl Resources of Puerto Rico (DNER), 1986], the lgoon system is defined here s seminturl environment. Thus, the interest ws to determine whether the HNR lgoon system hd hbitt structure equivlent to tht of nturl system to support common snook (Centropomus undecimlis Bloch, 1792; from now on just snook) nd trpon (Meglops tlnticus Vlenciennes, 1847) long-term fisheries. Mterils nd Methods Study Site The HNR lgoon system, locted in estern Puerto Rico (18 1' N, 65 46' W) (Figure 1), ws creted in 1979 when Hurricne Dvid nd Tropicl Storm Frederick overtopped nd breched extensive levees nd ditches tht diverted Anton Ruiz River to mintin sugr cne industry tht ws estblished in the 192s when extensive wetlnd res were deforested nd drined (USDC-DNER, 1986). Two mjor chnnels (Mndri nd Fronter) were dredged, nd pumping sttion ws constructed t their confluence to drin the entire re. Agreements between the sugr cne industry owners nd the Centrl Fisheries Reserch Institute (CFRI) Trbzon, Turkey nd Jpn Interntionl Coopertion Agency (JICA)

2 174 O.J. Ferrer Montño / Turk. J. Fish. Aqut. Sci. 9: (29) Figure 1. Mp of Humco Nturl Reserve, Puerto Rico showing mjor hydrogrphic fetures. Puerto Rico Government, nd legl ctions filed by locl environmentl orgniztions led to the designtion of the re s nturl reserve in 1986 (DNER, 1995). Six lgoons compose the system: Mndri 1, 67 h; Mndri 2, 74 h; Mndri 3, 52 h (Mndri System; MS); Snt Teres 1 (ST1), 27 h; Snt Teres 2 (ST2), 24 h (Snt Teres System; STS); nd Plms, 5 h. The entire lgoon system only connects to the se through the MS during periods of substntil precipittion; this semi-closed nture likely influences fish nd invertebrte bundnce nd species composition, nd determine hbitt structure of the lgoon system (Jckson et l., 21). This study ws limited to the STS becuse most of the fisheries developed in the HNR lgoon system concentrte on it (Jckson et l., 21). The immersed wetlnd of the STS is minly chrcterized by erect, rooted, herbceous hydrophytes, typiclly cordgrss (Sprtin sp.) nd cttil (Typh dominguensis Pers.); ST2 lso contins submersed vegettion (njs, Njs sp. nd chr, Chr sp.) tht potentilly provides microhbitt structure importnt to fish. The STS is shllow (~1 m), nd wter levels mostly vry in response to precipittion. Determintion of Prey Avilbility For ssessing invertebrtes nd erly life stges of fish, microhbitts were smpled using light trps nd pop nets. Sixty-seven light trps (Floyd et l., 1984) were set for one night/month from pproximtely 3-h before sunset to 1-h fter sunrise from My 2 through April 21. A 12-h Cylume chemicl stick illuminted ech trp. Ninety-four pop nets (Lrson et l., 1986; Killgore et l., 1989) were set for 1 minutes ech from June 2 through My 21. Smples were retrieved by crefully inserting.5-mm mesh net mounted in n luminium frme below the pop net nd then lifting it slowly to the surfce with trpped prey items. Fish nd invertebrtes collected were preserved in 5% formlin, counted nd identified in the lbortory. Snook nd Trpon Stock Assessment For ssessing snook nd trpon, 84 gill nets nd 42 trp nets were used during Mrch, June, July, October 2 nd Jnury-April 21. Gill nets were 3 m long by 2 m deep nd consisted of four 7.5 m

3 O.J. Ferrer Montño / Turk. J. Fish. Aqut. Sci. 9: (29) 175 pnels of 1.3, 2.5, 3.8 nd 5.1 cm br-mesh monofilment nylon netting. 2 to 15 gill nets per month in ech lgoon were set erly to mid-morning. Trp nets were 1.3 cm br-mesh nylon with two 1.8 m by.9 m frmes, four.8-m dimeter hoops nd 14 m by.8 m led. One to nine trp nets were set per month in ech lgoon; ll trp nets were set in midmorning nd retrieved soon fter sunrise the following morning. Fish collected were mesured to the nerest millimeter (totl length), weighed to the nerest grm, nd returned to the wter. 14 snook nd 12 trpon were retined to determine stomch contents. Although this smple cn be considered s too low, the mount of fish retined ws limited to minimize the smple-relted fish mortlity tht might influence future ctches in these smll lgoons s well s generte negtive public rection to the study. Guts were removed nd preserved in 5% formlin; nd in the lbortory whole guts nd gut contents were individully weighed (wet weight) nd contents exmined with dissecting microscope. Gut contents were sorted by prey item nd ech individul item weighed to the nerest.1 g. All items were identified to the lowest possible txon. Fish identifictions were bsed on Erdmn et l. (1986). Primry reference for identifiction of invertebrtes ws Pennk (1989). Physicochemicl Vribles Depth (m), Secchi trnsprency (m), wter temperture ( C), dissolved oxygen (mg/l), dissolved oxygen percent sturtion (%), specific conductnce (μs/cm), slinity (ppt), totl dissolved solids (g/l), turbidity (NTU) nd ph were determined t ech smpling site. Depth ws mesured with stdi rod nd the remining vribles with Dtsonde 4A Hydrolb Multi-Prmeter Wter Qulity Instrument with Surveyor 4 disply (Hch Corportion, Lovelnd, Colordo). All redings were tken t the time of light trps nd pop net setting t mid-wter depth. Records of lgoon system wter levels were tken from depth guge t the cnl in front of HNR hedqurters. Dily precipittion dt from 1988 to 21 were obtined from records t HNR hedqurters. These vlues were used to clculte monthly verge precipittion for 12 yers preceding the study, s well s for the study period. Dt Anlyses Fish nd invertebrte ctch-per-unit-effort (CPUE) were independently determined for smpling ger nd specific hbitt type. A pired-smples Student s t-test (PROC MEANS; SAS, 23) ws used for testing differences of fish nd invertebrte CPUEs between lgoons. A one-wy nlysis of vrince (ANOVA, PROC GLM; SAS, 23) ws used to test for differences in fish nd invertebrte CPUEs mong microhbitts within lgoons. Dt of ll smpling dtes were pooled for these nlyses. Levels of sttisticl significnce for ll nlyses were set t P<.5. All ANOVA ssumptions were tested following directions by Milliken nd Johnson (1992) nd Underwood (1997). Results Physicochemicl Vribles Over 54% (93 out of 17 cm) of ll precipittion during the study occurred between My nd September 2 (Figure 2). The wettest months were My, August nd September 2, when totl precipittion ws 53% higher thn the 12 yr verge (24.3 vs cm). The driest month ws Mrch 2, when totl precipittion ws 66% lower thn the 12-yr verge (2.8 vs. 6.9 cm). Overll, 2 ws dry yer with 26 cm (16%) precipittion deficit reltive to Wter level ws the lowest during April-July 2 nd the highest during September- October 2 (Figure 2). The substntil increse in the wter level observed in August 2 ws the result of Hurricne Debby, which produced 11 cm of 7 5 S l i n i t y (ppt) P r e c i p i t t i o n / W t e r L e v e l (cm) S T 1 S T 2 P r e c i p i t t i o n W t e r L e v e l M r A p r M y J u n J u l A u g S e p O c t N o v D e c J n F e b M r A p r M y Figure 2. Men monthly lgoon wter level (cm), monthly precipittion vlues (cm) nd men monthly slinity (ppt) for Snt Teres 1 (ST1) nd Snt Teres 2 (ST2), Humco Nturl Reserve, Puerto Rico, Mrch 2-My 21.

4 176 O.J. Ferrer Montño / Turk. J. Fish. Aqut. Sci. 9: (29) precipittion. Reltive to ST1, ST2 hd greter depth nd Secchi disk depth, nd lower slinity, totl dissolved solids, turbidity, ph, nd specific conductnce. In generl, verge slinity in the lgoons incresed nd decresed following ptterns of precipittion in the reserve (Figure 2). Totl Abundnce of Fish nd Invertebrtes A totl of 11 fmilies nd 14 species of fish were collected with ll smpling ger: 2,637 in ST1 (71.3%), nd 1,59 (28.7%) in ST2. The the highest bundnces of trpon nd tilpi (Mozmbique tilpi Oreochromis mossmbicus nd redbrest tilpi Tilpi rendlli) were from ST2, wheres the the highest bundnce of snook ws from ST1. A totl of 18,642 grss shrimp (Plemonetes sp.) ws collected (15,311 in ST1; 3,331 in ST2). Reltive Abundnce of Prey Items Snt Teres 2 yielded the gretest men CPUE of tilpi collected with pop nets nd ST1 yielded the gretest men CPUE of tilpi collected with light trps. However, difference between lgoons ws significnt (t = 3.68, df = 11, P<.5) for pop nets but not for light trps (t =.16, df = 11, P>.5). Snt Teres 2 yielded significntly greter men CPUE of tilpi collected with gill nets (t = 7.9, df = 7, P<.5) nd trp nets (t = 3.11, df = 7, P<.5) thn ST1. Snt Teres 1 yielded the gretest men CPUE of grss shrimp collected with pop nets nd light trps however, difference between lgoons ws significnt for light trps (t = 3.6, df = 11, P<.5), but not for pop nets (t =.67, df = 11, P>.5). Overll, reltive bundnce of tilpi ws greter in submersed vegettion (i.e., njs, chr) thn in the other plnt communities in ST2, wheres in ST1 no difference between plnt communities ws observed (Figure 3). On the other hnd, reltive bundnces of grss shrimp were homogeneous mong plnt communities in ST2, wheres in ST1 CPUE of grss shrimp ws greter in cordgrss for pop nets nd no differences were detected between plnt communities for light trps (Figure 4). 8 C t c h - p e r - u n i t - e f f o r t (fish / ger - set) b b S T 1 S T 2 S T 1 S T 2 b C t t i l C o r d g r s s N j s C h r P o p N e t L i g h t T r p Figure 3. Men ctch-per-unit-effort ± SE (fish/ger-set) of Mozmbique tilpi (Oreochromis mossmbicus) nd redbrest tilpi (Tilpi rendlli) collected with pop nets or light trps mong microhbitts t Humco Nturl Reserve, Puerto Rico, My 2-My 21. Microhbitts: Cttil= Typh dominguensis Pers., Cordgrss= Sprtin sp., Njs= Njs sp., Chr= Chr sp. Mens with the sme letter re not significntly different mong microhbitts. C t c h - p e r - u n i t - e f f o r t (individul / ger - set) b S T 1 S T 2 S T 1 S T 2 P o p N e t L i g h t T r p C t t i l C o r d g r s s N j s C h r Figure 4. Men ctch-per-unit-effort ± SE (individul/ger-set) of grss shrimp (Plemonetes sp.) collected with pop nets or light trps mong microhbitts t Humco Nturl Reserve, Puerto Rico, My 2-My 21. Microhbitts: Cttil= Typh dominguensis Pers., Cordgrss= Sprtin sp., Njs= Njs sp., Chr= Chr sp. Mens with the sme letter re not significntly different mong microhbitts.

5 O.J. Ferrer Montño / Turk. J. Fish. Aqut. Sci. 9: (29) 177 Food Hbits Totl length rnges of fish used for stomch content nlyses were 192 to 562 mm for snook, nd 38 to 552 mm for trpon. Eleven (79%; 8 from ST1, 3 from ST2) stomchs of snook nd six of trpon (5%; 2 from ST1, 4 from ST2) contined prey items. Stomch contents of snook were dominted by vegetl mtter, followed by grss shrimp, tilpi, crbs, nd snils, wheres trpon stomchs were dominted by tilpi nd grss shrimp. Snook nd Trpon Assessment Men CPUEs for snook nd trpon collected with trp nets nd gill nets re shown in Tble 1. Men CPUE of snook collected with gill nets ws not significntly different between lgoons (t = 1.5, df = 7, P>.5). Only three snook (one in ST1, two in ST2) were collected with trp nets. Therefore, no sttisticl nlyses were done. Men CPUE of trpon collected with gill nets ws significntly greter in ST2 thn in ST1 (t = 2.37, df = 7, P<.5). Snt Teres 2 yielded greter men CPUE thn ST1 of trpon collected with trp nets, lthough difference between lgoons ws not significnt (t =.83, df = 7, P>.5). Discussion Fish nd invertebrtes re primry ttributes reflecting hbitt vlue for wetlnds (Minello nd Zimmermn, 1992; Willims nd Desmond, 21); benthic invertebrtes provide food-web support for consumers such s birds nd fish (Qummen, 1984), nd fish function s vehicles for nutrient cycling nd energy trnsfer cross hbitts t number of trophic levels in the esturine food web (Kwk nd Zedler, 1997). In return, wetlnds provide these nimls with res for refuge, reproduction, feeding, nd other essentil functions (Willims nd Desmond, 21). This study suggests tht current environmentl conditions of the lgoons provide importnt hbitts tht could support fisheries of trpon nd snook. These findings re not just bsed on the prdigm tht fish presence reflects hbitt vlue, but confirmtion tht the STS provides spwning hbitt nd refuge to fish nd invertebrtes tht serve s food to trpon nd snook. Juveniles nd sub-dult fish dominted the ctches of both snook nd trpon, indicting the lgoons ct s erly life stge hbitts. Although femle snook mture t mm fork length (FL) nd mles t mm FL (Peters et l., 1998), nd some of them in the lgoon exceeded this length, snook require slinities >27 ppt for spwning (Peters et l., 1998), indicting these fish were not reproductively ctive. Trpon do not mture until 88 mm FL (Crbtree et l., 1997), fr exceeding the mximum size cptured in this study. Thus, it ws concluded tht trpon nd snook did not use the lgoon system s spwning ground, nd tht erly life stges nd juveniles of these species likely enter the lgoons from the se in pursuit of food nd refuge. It ws evident from this study tht the ctul importnce of the lgoon system for trpon nd snook hs to do with the connection to the ocen being opened. The time of yer nd durtion of open connection to the se my control bundnce nd species composition within intermittently open esturies (Griffiths, 21), suggesting tht the longer system is open to the se, the greter the chnce of mrine fish entering. In Puerto Rico spwning of trpon nd snook occurs during Mrch-October, nd recruitment during My-November (Crbtree et l., 1992). However, the lgoon system rrely remins connected to the se for more thn two weeks nd mostly during the pek hurricne seson (September) (Jckson et l., 21). Consequently, despite snook nd trpon spwn in the vicinity (Crbtree et l., 1992), recruitment of these species to the lgoon system would be limited. However, the limited connection of the lgoons with the se cretes conditions fvouring trpon nd snook estblishment in the lgoons. Low slinity in ST2 fvours submersed vegettion, which plys n Tble 1. Men ctch-per-unit-effort ± SE (fish/ger-set) of common snook (Centropomus undecimlis Bloch) nd trpon (Meglops tlnticus Vlenciennes) collected from Snt Teres 1 nd Snt Teres 2 with gill nets nd trp nets, Humco Nturl Reserve, Puerto Rico, Mrch 2-April 21. NS= no smple Snook Trpon Month Gill Net Trp Net Gill Net Trp Net Snt Snt Snt Snt Snt Snt Snt Snt Teres 1 Teres 2 Teres 1 Teres 2 Teres 1 Teres 2 Teres 1 Teres 2 Mrch NS. NS. NS 5.5 ±.5 NS. June.9 ± ± ± 2..3 ±.3. July 2.3 ± ± ± ± October.3 ±.3 NS.. 1. ± 1. NS.. Jnury.5 ± ± ± ± 3. Februry..3 ±.2.3 ±.1.5 ±.3.5 ± ±.9..2 ±.2 Mrch..3 ± ±.4.. April ±.7.. Averge.5 ±.2.2 ±.1.4 ±.1.1 ±.1.9 ± ±.5.4 ±.4.3 ±.2

6 178 O.J. Ferrer Montño / Turk. J. Fish. Aqut. Sci. 9: (29) importnt role in structuring the physicochemicl nd biologicl chrcteristics of this lgoon. Submersed mcrophytes in ST2 dmpen wve ction so tht finegrined mud, chrcteristic of the whole lgoon system bottom, ccumultes in shllow wter mong the vegettion, rendering it clerer wter system (Jckson et l., 21). Clerer wter systems with submersed vegettion represent better hbitt for lrge fish predtors (e.g., trpon nd snook) tht rely hevily on vision for prey encounters (Helfmn et l., 1997). The ptterns of distribution mong the microhbitts show lrge similrities in ctches of grss shrimp within the lgoons. In ST2, grss shrimp distributed evenly mong the microhbitts, indicting n extensive use of ll vilble hbitts in this lgoon. Conversely, in the bsence of submersed vegettion in ST1, grss shrimp select cordgrss s the preferred microhbitt. Why grss shrimp were significntly more bundnt in ST1 thn in ST2 despite tht ST2 hd more hbitt complexity is not cler. It cn be explined by fish predtion rte. Although overll fish bundnce ws higher in ST1 thn in ST2, most of this bundnce ws numericlly represented by crested goby, smll demersl species (1 cm mximum TL; Mrtin nd Ptus, 1984) tht is not reported s n importnt predtor nd thus it is not expected to significntly predte on grss shrimp or fish within the lgoons. Smll tilpi, on the other hnd, were significntly more bundnt in ST2 thn in ST1. Although dult tilpi re herbivorous or detritivorous (Erdmn, 1967; Puly, 1976), erly life stges nd juveniles re crnivorous (Froese nd Puly, 2). Thus, tilpi potentilly predte on smll plemonids nd could hve ccounted for the difference in grss shrimp bundnce between the lgoons. It ws evident from the stomch content nlyses tht tilpi were n importnt food source for snook nd trpon. Tilpi were found more in trpon stomchs thn in snook; 96% of the trpon diet ws composed of tilpi nd 4% grss shrimp. Tilpi were ubiquitous in the lgoon system nd spwned successfully in ll the lgoons severl times yer (Jckson et l., 21). Thus, trpon, which were more bundnt in this lgoon, seem to tke dvntge of the most bundnt food resource in ST2. In conclusion, collection of fish nd invertebrtes with severl smpling gers nd strtegies nd exmintion of the hbitt structure of the STS indicted tht it is ble to support long-term fisheries of snook nd trpon. Acknowledgments We thnk Mnuel Córbet nd the HNR personnel for their support during the implementtion of this project. Thnks re lso due to Rmón del Morl nd Miguel Ortiz for helping me with much of the fieldwork, nd to Professor Cedr Grcí (University of Puerto Rico t Humco) for fish identifiction. Erlier versions of the mnuscript were significntly improved by incorporting review comments from Anit Kelly. Federl Aid Project F provided finncil ssistnce. References Cllwy, J.C., Sullivn, G., Desmond, J.S., Willims, G.D. nd Zedler, J.B. 21. Assessment nd monitoring. In: J.B. Zedler (Ed.), Hndbook for restoring tidl wetlnds. CRC Press, Boc Rton, FL, USA: Crbtree, R.E., Cyr, E.C., Bishop, R.E., Flkenstein, L.M. nd Den, J.M Age nd growth of trpon, Meglops tlnticus, lrve in the estern Gulf of Mexico, with notes on reltive bundnce nd probble spwning res. Environmentl Biology of Fishes, 35: Crbtree, R.E., Cyr, E.C., Chcón-Cheverri, D., McLrney, W.O. nd Den, J.M Reproduction of trpon, Meglops tlnticus, from Florid nd Cost Ricn wters nd notes on their ge nd growth. Bulletin of Mrine Science, 61: Deprtment of Nturl nd Environmentl Resources of Puerto Rico Opertion of the Humco Wildlife Refuge, Grnt Agreement FW-1. Estdo Libre Asocido de Puerto Rico. Sn Jun, Puerto Rico, 27 pp. Erdmn, D.S Inlnd gme fishes of Puerto Rico. 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