Habitat heterogeneity: importance of salt marsh pools and high marsh surfaces to fish production in two Gulf of Maine salt marshes

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1 Vol. 368: , 2008 doi: /meps07560 MARINE ECOLOGY PROGRESS SERIES Mr Ecol Prog Ser Pulished Septemer 25 Hitt heterogeneity: importnce of slt mrsh pools nd high mrsh surfces to fish production in two Gulf of Mine slt mrshes Richrd A. McKenzie 1, 2, *, Michele Dionne 1 1 Wells Ntionl Esturine Reserch Reserve, 342 Ludholm Frm Rd., Wells, Mine 04090, USA 2 USDA Forest Service Institute of Pcific Islnds Forestry, 60 Nowelo St., Hilo, Hwi i 96720, USA ABSTRACT: Both permnent high mrsh pools nd the intertidl surfces of Sprtin ptens high mrshes in southern Mine, USA, proved to e importnt hitt for resident mummichog Fundulus heteroclitus production. Mnipultions of fish movement onto high mrsh surfces reveled similr growth rtes nd production mong fish tht were (1) restricted to pools, (2) hd ccess to known res of mrsh surfce, or (3) hd free ccess to the entire mrsh. Smller scle mnipultions with mrked fish reveled tht mles with ccess to the mrsh surfce ccumulted significntly more iomss, often exhiited higher growth rtes, nd hd 1.6 greter production rte thn mles restricted to pools. Femle production ws only slightly higher for fish tht could ccess the mrsh compred to fish restricted to pools. While oth pools nd mrsh surfce ppered to support fish production, hitt prtitioning lso existed etween sexes of mummichogs; mles my rely more on the mrsh surfce for food while femles rely more on pools. Growth nd production of mummichogs in pools on the high mrsh surfce ws lower thn vlues reported from more southern, low mrsh dominted systems. This ws ttriuted to differences in (1) iotic fctors of slt mrsh pools (this study) nd tidl creeks nd chnnels (other studies), (2) climte, nd (3) tidl inundtion nd ccess time to the mrsh surfce. Fish production on the surfce of Gulf of Mine high mrsh ecosystems ws equivlent to production in djcent tidl creeks nd chnnels. Thus, the high mrsh surfce proved to e n importnt hitt for supporting fish production in this region. KEY WORDS: Secondry production High slt mrsh Gulf of Mine Fundulus heteroclitus Resle or repuliction not permitted without written consent of the pulisher INTRODUCTION Studies exmining the hitt vlue (e.g. food source, refuge) of slt mrshes long the northwestern Atlntic cost hve primrily focused on systems south of Cpe Cod, Msschusetts, USA (e.g. Weiserg & Lotrich 1982, Hlpin 1997, Currin et l. 2003). Fr less is known out costl mrshes in the stte of Mine, which differ in geomorphology, climte, hydrology, nd ecology from more southerly systems. Slt mrshes in Mine re often exposed to hrsh New Englnd winters when ice disturnce (e.g. rfting) cn ffect sediment deposition (Argow & Fitzgerld 2006), plnt recoloniztion (Ewnchuk 2003) or inter-specific plnt competition (Bertness & Ewnchuk 2002). Tidl rnges re lso much greter (i.e. 3 to 10 m), delineting New Englnd mrshes into distinct high nd low elevtionl zones, the former eing more sptilly undnt (Jcosen et l. 1987). These rod expnses of high mrsh re dominted y Sprtin ptens mrsh grss tht is only inundted y flood tide levels tht rise ove the cut nks of mrsh chnnels. Men monthly se level cn vry y tens of centimeters (Morris et l. 2002) nd in the Wehnnet River estury, cn led to vrition in frequency of high mrsh flooding from 2% (this study) to 40% of flood tides (Murphy 1991). In contrst, low mrsh zones (dominted y S. lterniflor) tht re inundted on every flood tide (the domi *Emil: rmckenzie@fs.fed.us Inter-Reserch

2 218 Mr Ecol Prog Ser 368: , 2008 nnt vegettion zone in southern mrshes) comprise much smller proportion of totl vegetted mrsh in New Englnd (e.g. 7% of the Wehnnet mrsh). Thus, ccess to the surfce of high mrshes in New Englnd is reduced for resident nd trnsient nekton compred to low mrsh zones, which orgnisms cn ccess on dily sis nd for longer periods of time due to prolonged sumergence. A dominnt lndscpe feture of Mine s tidl mrshes is the extensive presence of slt mrsh pools (e.g. 13% of the slt mrsh surfce, Dionne 2006). These pools re shllow (i.e. 10 to 30 cm), soft-ottomed depressions in the high mrsh of vrile depth, size, nd surfce re tht retin wter during low tides. These hitts re somewht nlogous to su-tidl mrsh creeks, providing n qutic environment for nekton nd enthos (i.e. fishes, crustcens, other invertertes) during low tide conditions (Murphy 1991, Deegn et l. 2000) s well s food for nekton or wding irds (Knei 1986, Erwin 1996). A fish frequently found in these pools in undnce is the mummichog Fundulus heteroclitus, resident species common in Atlntic slt mrshes (Weiserg & Lotrich 1982). These fish re known to ccess the mrsh surfce during dytime high tides (Weiserg et l. 1981), where they ctively feed on detritus, vrious enthic mcroinvertertes (Knei & Stiven 1978, Knei 1986), ditoms, nd other enthic microlge (Jmes-Pirri et l. 2001, Currin et l. 2003). While they lso forge in su-tidl res (e.g. tidl creeks), higher growth rtes nd gut content indices hve een oserved in mummichogs with ccess to the mrsh surfce (Weiserg & Lotrich 1982, Jvonillo et l. 1997, Fell et l. 1998). Thus, mummichogs provide n importnt link or trophic rely etween mrsh production nd nershore fisheries production s they re n importnt food source for mny juvenile nd dult species of fish (Knei 2000). For exmple, in New Jersey slt mrsh, mummichogs represented 9 to 23% of the dry weight in the diet of commercilly importnt striped ss Morone sxtlis (representing 51% of totl fish dry weight) (Tupper & Ale 2000, Nemerson 2001) nd 8 to 43% of the dry weight in the diet of young-of-the-yer (YOY) Atlntic croker Micropogonis undultus (Nemerson 2001). Given their undnce in Gulf of Mine slt mrsh esturies, mummichogs likely provide trophic rely in Mine slt mrshes s well. However, in these high mrsh ecosystems where ccess to the mrsh surfce is significntly reduced reltive to low mrshes, it is not known how slt mrsh pools cn supplement growth rtes or production of fish nd therefore contriute to overll slt mrsh nekton production. During the summers of 2002 nd 2003, growth rtes nd secondry production were used to descrie energy trnsfer on the surfces of slt mrshes long the cost of Mine. Mummichog ccess to the mrsh surfce during high tides ws mnipulted to test the hypotheses tht (1) fish restricted to pools hve positive growth rtes nd thus secondry production, nd (2) tht growth rtes nd secondry production re higher for fish with free ccess to the mrsh surfce compred to fish restricted to pools. MATERIALS AND METHODS Site description. The Wehnnet River estury is mrsh-dominted system locted within the Wells Ntionl Esturine Reserch Reserve, 32 km north of the Mine/New Hmpshire order, USA (Fig. 1). This shllow estury is tidl inlet tht nerly drins t low tide, hs smll tidl prism, nd men tidl rnge of 2 to 3 m. Freshwter is delivered primrily vi the Wehnnet River, which drins 36.5 km 2 wtershed. The mrsh-esturine system comprises 4.91 km 2 of ck rrier mrsh of which 3.26 km 2 is Sprtin ptens high mrsh plin fringed with S. lterniflor low mrsh, nd 1.43 km 2 of intertidl snd nd mud. The Moody mrsh is mrsh-dominted system locted 26 km north of the Mine/New Hmpshire order. Fig. 1. Loction of control (c), poolplus-mrsh (x), pool-only (o), nd procedurl control (p) tretments in the Moody nd Wehnnet mrshes. The loction of minienclosures (m) is lso identified in the Wehnnet mrsh

3 McKenzie & Dionne: Vlue of hitt heterogeneity to fish production 219 Similr to the Wehnnet mrsh, this system is locted directly ehind ck rrier ech, nerly drins t low tide, hs smll tidl prism, nd men tidl rnge of 2 to 3 m. Freshwter is delivered primrily vi the Ogunquit River, which drins 62.2 km 2 wtershed. The mrsh-esturine system comprises 0.28 km 2 of ck rrier mrsh of which 0.16 km 2 is Sprtin ptens high mrsh plin nd fringing S. lterniflor low mrsh, nd 0.12 km 2 of intertidl snd nd mud. Physico-chemicl prmeters. Surfce res of mrsh pools nd distnces etween the centers of pools nd the min chnnels were determined from stellite imges using ArcView. At low tide, verge perimeter depths were mesured every meter long the outer perimeters of the pools using meter stick. Dissolved oxygen concentrtions, tempertures, nd slinities were mesured 2 to 4 cm elow the wter surfce of pools using YSI dtproe 85 once month from June through August only during the 2003 seson. Dissolved oxygen concentrtions, tempertures, nd slinities were lso mesured every 30 min over the durtion of the study (i.e. 3 mo ech yer) from the min chnnel of the Wehnnet Mrsh using YSI 6600 dtsonde. These vlues were used s proxy for physico-chemicl prmeters in tidl creeks nd chnnels djcent to slt mrsh pools. Connectivity etween pools nd high mrsh surfce. Connectivity etween mrsh pools nd the high mrsh surfce nd thus the periods of time fish could ccess the mrsh surfce ws determined from mrsh elevtions nd wter depth mesurements. Connectivity ws estimted for the durtion of the study period (June through August) of oth yers nd only in the Wehnnet mrsh. Mrsh elevtions reltive to men se level (MSL) were mesured t ech smple pool in the Wehnnet Mrsh using Trimle 4800 GPS, visul surveying equipment, nd known Ntionl Geodetic Survey enchmrk (PID OC0449). Wter depth ws continully mesured reltive to MSL every 30 min in the min chnnel of the Wehnnet mrsh using YSI 6600 dtsonde. For ech pool, percent connectivity ws determined y dividing the sum of the numer of depth redings the mrsh elevtion surrounding tht pool y the totl numer of depth redings. Averge vlues were then determined for ech tretment. Inverterte densities. Benthic invertertes were smpled from Wehnnet nd Moody mrsh pools in June, August, nd Septemer 2002 nd Triplicte sediment smples were collected from the ottom of ech pool using mini-eckmn gr. Smples were preserved in 70% ethnol, stined with Rose Bengl, nd sieved through 500 mm mesh sieve. Invertertes were sorted nd identified to the lowest prcticl txonomic ctegories. Totl inverterte densities were determined ech month y verging the totl numer of invertertes from ech replicte nd dividing y the re smpled (0.01 m 2 ). Mnipultion of fish movement. Enclosures were constructed round slt mrsh pools to mnipulte fish movement onto the mrsh surfce during the growing sesons (June to Septemer) 2002 nd Pools were hphzrdly chosen long tidl creek in the Wehnnet (n = 12) nd Moody mrshes (n = 9) (Fig. 1). Mrsh pools were t similr distnces (4 to 6 m) from tidl creeks. Three tretments were then rndomly estlished in triplicte in ech mrsh system: (1) pool-only (fish were restricted to pools during high tide), (2) pool-plus-mrsh (fish could ccess mrsh re surrounding pool equl to 3 the pool s surfce re), nd (3) control (enclosure sent, fish could freely ccess mrsh from pool, nd vice vers). Procedurl controls were lso constructed in triplicte on the Wehnnet mrsh where enclosures were present ut rised 20 cm off the mrsh surfce llowing fish ccess to the mrsh surfce, llowing testing for rtefctul effects of enclosures. Tretments enclosing nturl popultions of fish (i.e. non-mnipulted) were estlished during the first week of June. enclosures were constructed from rigid 1 m high, 3 mm mesh Vexr ttched to PVC support poles. The lower edges of the Vexr were ttched to sides of pool wlls using 20 cm long lndscping stples, closing off pools so tht fish could not leve during high tide. Pool-plus-mrsh tretments were constructed y urying the ottom 10 cm of Vexr in the mrsh surfce nd then ttching to PVC support poles. Procedurl controls in the Wehnnet mrsh were constructed in mnner similr to pool-only tretments, except tht the ottom of the mesh ws rised 20 cm from the surfce of the mrsh. Mesh from ll tretments ws periodiclly clened with rush to remove ny deris tht hd ccumulted during high tides. To prevent predtion y irds, 1 cm mesh ird netting ws plced over ech pool. Fish were smpled once month from June through August during the first yer using 3 to 4 un-ited minnow trps plced in ech pool for 30 to 45 min for mrk-recpture density estimtes. Becuse minnow trps indequtely smpled smll YOY fish, which mke up mjor portion of production (Teo & Ale 2003), nd ecuse poor recpture rtes hindered density estimtes, modified lift nets were used from June through August during the second yer to smple fish in pools. Lift nets were constructed of 3 mm mesh, knotless nylon netting tht smpled n re of 2.8 m 2. Nets were rndomly lid t the ottom of the pools for 30 to 45 min, fter which they were quickly lifted out of the wter. Fish, shrimp, nd crs were then identified, counted, mesured to the nerest mm, nd weighed to

4 220 Mr Ecol Prog Ser 368: , 2008 the nerest 0.01 g. Density estimtes were clculted in 2003 y dividing the totl numer of fish y the re of the lift net (2.8 m 2 ). During the summer of 2003, mini-enclosures with controlled fish densities were creted in the Wehnnet mrsh to llow us to trck production of individully mrked fish. Mini-enclosures were locted t equl intervls long the inside edge of single mrsh pool tht ws locted within the sme mrsh re s the lrge scle enclosures (Fig. 1). Four pool-only enclosures were constructed out of PVC pipe frme nd 3 mm mesh Vexr, nd enclosed 0.25 m 2 re of the pool ottom. Four pool-plus-mrsh enclosures were similrly constructed, enclosing 0.25 m 2 re of the pool ottom nd 0.75 m 2 re of djcent mrsh. Fish densities were determined from dt from the previous yer nd consisted of 4 mummichogs (2 mles, 2 femles) plced into ech enclosure. Mles nd femles were of similr length nd weight (mles: 47.5 ± 1.17 mm, 1.29 ± 0.10 mg respectively; femles: 50.9 ± 1.2 mm, 1.90 ± 0.15 mg respectively). Initil weights nd lengths were otined for ll fish, which were then individully identified with sucutneous injection of Liquitex crylic rtist color ltex pint. Ltex injections hve een successfully used in the pst to mrk smll fish (Sweeney et l. 1998) nd lortory experiment demonstrted tht this technique did not significntly increse fish mortlity (Eerhrdt 2004). Once week for 6 wk, ll fish were removed, remesured, nd re-weighed. Growth nd production rtes. For ech pool smple, mummichogs were grouped into 10 mm size clsses (e.g. 20 to 29 mm) nd verge iomss ws then determined for ech clss. Monthly growth rtes were then clculted for ech size clss using the exponentil model (Chpmn 1978): G inst = (ln wt 2 ln wt 1 ) / t 2 t 1 (1) where G inst is instntneous growth rte, wt 2 is the verge wet weight for size clss n mesured t time 2 (t 2 ), nd wt 1 is the verge wet weight for size clss n 1 mesured t time 1 (t 1 ). Secondry production ws clculted using the cumultive growth method (Chpmn 1978): P = G inst B (2) where totl production P is equl to the summtion of the products of G inst, nd B the men stock iomss: B = (N n 1 wt n 1 + N n wt n ) / 2 (3) where N n 1 nd wt n 1 re the estimtes of popultion size nd verge wet weights (respectively) of size clss n 1, nd N n nd wt n re the popultion size nd verge wet weights (respectively) of size clss n. Production ws clculted seprtely for smll YOY mummichogs (<40 mm) nd for dult nd lrge YOY mummichogs (>40 mm). Totl production ws equl to the sum of these 2 groups. Despite the fct tht production ws only mesured over 3 mo intervls during oth yers, it ws ssumed to e n ccurte, yet conservtive estimte of nnul fish production in these mrsh ecosystems (ised towrds lower vlues). Feeding ctivity of mummichogs is significntly reduced during winter months (Fell et l. 1998), which is likely due to decresed wter tempertures. In order to compre results from this study with results from other slt mrsh systems, growth nd production rtes were reclculted using dry iomss of mummichogs. Dry iomss ws clculted using length-weight regression (Bgenl & Tesch 1978): DW = ( ) (TL) 3.22 (4) where TL ws the totl length (mm) of the mummichog nd DW ws dry weight (g). Constnts were determined from regressions of dry weight nd totl length from 60 mummichogs collected from the Wehnnet mrsh. Sttistics. Physicl prmeters (i.e. surfce concentrtions of dissolved oxygen, temperture, slinities), percent connectivity, totl inverterte densities, fish densities, growth rtes, nd secondry production were first compred etween control nd procedurl control sites in the Wehnnet using 1-wy nlysis of vrince (ANOVA) to test for tretment rtefcts. If no significnt differences were found (e.g. p 0.25; Underwood 1997), it ws ssumed tht there were no rtefctul effects on fish production from the enclosures, nd control nd procedurl control sites were pooled for comprisons etween the Wehnnet nd Moody sites. Physicl prmeters, totl inverterte densities, nd fish densities were compred etween sites (Wehnnet versus Moody) nd mong tretments (control, pool-plus-mrsh, pool-only) using 3-wy fctoril ANOVA tht ccounted for the repeted mesures (over time) on ech pool. Fixed effects of the model included tretment, site, nd dte, in ddition to ll 2-wy nd 3-wy interction terms. Becuse different techniques were used to smple fish in 2002 nd 2003, growth rtes could not e compred etween yers. For ech yer, 3-wy fctoril ANOVA ws used to compre growth rtes, with tretment, site, nd ech 10 mm size clss s fixed effects. For ech yer, only size clsses with replicte vlues from ll 3 tretments from oth the Wehnnet nd Moody mrshes could e compred. Two-wy ANOVAs were performed to exmine differences in secondry production, percent contriutions to totl productivity y smll YOY s well s

5 McKenzie & Dionne: Vlue of hitt heterogeneity to fish production 221 dult nd lrge YOY fish, nd percent connectivity in the Wehnnet mrsh. For secondry production nd % contriution to production, min effects included site nd pool tretment s fixed fctors whose interction term ws estimted. Min effects for hydrologic connectivity (mesured only in the Wehnnet mrsh) included yer nd tretment s fixed fctors, s well s their interction. Person s product moment correltion nlysis ws used to determine reltionships mong production, fish densities, nd physicochemicl prmeters. Sttisticl significnces were Bonferronidjusted to n α vlue of Growth rtes nd chnges in iomss for oth mle nd femle mummichogs from mini-enclosures were compred etween tretments (pool-plus-mrsh versus pool-only) using 1-wy ANOVAs tht ccounted for repeted mesures on ech fish. Production rtes from mini-enclosures were compred etween tretments nd sexes using 2-wy ANOVA. Totl inverterte densities, fish densities, nd production dt did not meet ssumptions of normlity nd equl vrince nd were therefore log (x + 1) trnsformed prior to nlysis. All dt presented in tles, figures, nd text re the lest squre mens; ll normlized dt were ck trnsformed nd Bskerville corrected. Growth rtes from lrge scle enclosures nd totl inverterte densities re reported s verges ecuse lest squre mens could not e clculted from tretments where only single growth rte ws ville or where inverterte densities were missing. The covrince structures for ll repeted mesures except for mini- enclosure comprisons were utoregressive of order one (i.e. mesurements on the sme pool in June were potentilly more correlted with July thn August). The covrince structure used for mini-enclosure repeted mesures ws compound symmetry s it provided etter fit to the dt. Post- Tukey-Krmer method nd ll sttisticl nlyses were performed in PROC MIXED from SAS 9.1 (2002. SAS Institute, Cry, North Crolin) t n α level of RESULTS Physicl prmeters Wehnnet Control Pool Pool-plus-mrsh Men lthough percent connectivity etween these 2 hitt types ws significntly greter in 2003 (5.1 ± 0.7%) thn in 2002 (2.3 ± 0.07%) (p < 0.05, F = 7.62, df = 1, 16) (Tle 1). Percent connectivity could not e determined for the mrsh pool where mini-enclosures were estlished, ut ws expected to e similr to the lrge scle tretments due to its proximity to these pools (Fig. 1). Mummichogs were exposed to similr environmentl conditions mong the different tretments in the Wehnnet nd Moody mrsh pools, ut not etween the 2 sites. While pool res nd depths were similr etween tretments nd sites (Tle 1), verge dissolved oxygen concentrtions, wter tempertures, nd slinities mesured in June, July, nd August 2003 were similr only mong the different tretments t ech site (Fig. 2). Averge dissolved oxygen concentrtions, wter tempertures, nd slinities were ll significntly higher in the Wehnnet Mrsh pools thn in the Moody Mrsh pools (p < 0.001, F = 27.36, df = 1, 44; p < 0.001, F = 97.07, df = 1, 13; p < 0.001, F = 41.85, df = 1, 41, respectively) (Fig. 2). Prmeters were not significntly different etween control nd procedurl control tretments nd were thus pooled. In the Wehnnet mrsh, dissolved oxygen levels were similr etween mrsh pools nd the min chnnel (Fig. 2). However, wter tempertures of mrsh pools were nerly 10 C wrmer thn the min chnnel. Slinities were generlly higher in mrsh pools thn in the min chnnel, especilly in July nd August. Tle 1. Men depth, re, nd % connectivity (lest squre mens ± SE) from the 3 tretments in the Wehnnet nd Moody mrshes. Vlues for the Wehnnet control tretments were pooled etween control nd procedurl control s there were no significnt differences etween them. Percent connectivity ws deter- mined y dividing the time tht the mrsh ws flooded y the entire study period. Two-wy ANOVAs reveled no significnt differences in depth nd re mong tretments or etween sites. Different superscripted non-old letters in column indicte significnt difference in men % connectivity mong tretments (Tukey Krmer pirwise comprison, p < 0.05), while different superscripted old letters cross rows indicte differences in men percent connectivity etween yers hoc nlyses were conducted using the sed on 2-wy ANOVA (p < 0.05) Mummichog popultions in mrsh pools were le to ccess the mrsh surfce during oth yers of the study, Men depth (m) 0.28 ± ± ± ± 0.01 Men re (m 2 ) 22.7 ± ± ± ± 3.4 Men % connectivity to high mrsh ± ± ± ± ± ± ± ± 0.01 Moody Control 0.30 ± ±6.3 n n Pool 0.30 ± ± 6.3 n n Pool-plus-mrsh Men 0.28 ± ± ± ± 3.6 n n n n

6 222 Mr Ecol Prog Ser 368: , 2008 Dissolved oxygen (mg l 1 ) Temperture ( C) Slinity (ppt) c /1/03 7/1/03 8/1/03 9/1/ Wehnnet control Wehnnet pool-plus-mrsh Wehnnet pool-only Wehnnet min chnnel Moody control Moody pool-plus-mrsh Moody pool-only Fig. 2. Monthly ptterns of () dissolved oxygen, () temperture, nd (c) slinity from the min chnnel of Wehnnet Hror (j) nd ner the surfces of slt mrsh pools in the Wehnnet (d) nd Moody (m) mrshes. Vlues from the control tretments in the Wehnnet mrsh re pooled vlues from control nd procedurl control tretments. Dtes re month/dy/yer. Vlues re mens ± SE, n = 3 for pool-plusmrsh nd pool-only tretments, n = 6 for control tretments Lrge scle enclosures Inverterte food sources in mrsh pools were undnt during the 2002 nd 2003 smpling sesons. Although sttisticl comprisons of totl inverterte densities could not e mde in 2002 due to n incomplete dt set, densities were generlly similr etween tretments nd months (Fig. 3). In 2003, inverterte densities were highly vrile with no significnt differences mong tretments, etween mrshes, or mong months smpled (Fig. 3). Invertertes lrgely comprised oligochetes, polychetes, ostrcods, nd forminiferns. Chnges in smpling ger etween yers resulted in the collection of smller size clsses of fish in Mummichogs smpled in 2002 from the Wehnnet nd Moody mrshes hd verge lengths of 46.7 ± 1.5 nd 48.3 ± 1.0 mm nd verge wet weights of 1.4 ± 0.1 Men inverterte density (ind. m 2 ) Control Pool-plus-mrsh Jun 02 Aug 02 Sep 02 Jun 03 Aug 03 Sep 03 Control Pool-plus-mrsh Jun 02 Aug 02 Sep 02 Jun 03 Aug 03 Sep 03 Fig. 3. Men monthly inverterte densities (+SE) from the 3 tretments in () Wehnnet nd () Moody mrshes, Vlues for the control tretments in the Wehnnet mrsh re pooled from control nd procedurl control tretments. Incomplete dt sets re presented for 2002 to show tht when comprisons were possile, inverterte densities were similr etween tretments. Missing rs: missing smples nd 1.5 ± 0.1 g, respectively, over the 3 mo smpling period. In 2003, fish lengths nd weights verged 33.5 ± 2.2 mm nd 0.40 ± 0.05 g, respectively, from the Wehnnet mrsh nd 39.9 ± 1.6 mm nd 0.72 ± 0.07 g, respectively, from the Moody mrsh. Mummichog densities were similr mong ll tretments in ech month, ut sttisticl comprisons could only e mde for 2003 dt due to poor recpture rtes in Densities were similr etween Wehnnet nd Moody mrsh pools during June nd July, ut were significntly greter in the Wehnnet mrsh thn in the Moody mrsh in August (p < 0.05, F = 6.00, df = 1, 44). Densities significntly incresed with time in oth the Wehnnet nd Moody mrsh pools (p < 0.001, F = 46.33, df = 2, 32) (Tle 2). Men YOY densities were significntly higher in Wehnnet mrsh pools (44.7 m 2, 95% CL: 30.0, 66.4) thn Moody mrsh pools (20.5 m 2, 95% CL: 13.1, 32.0) (p < 0.05, F = 7.15, df = 1, 15), while dult densities were similr in Wehnnet (8.1 m 2, 95% CL: 4.2, 14.7) nd Moody mrsh pools (9.7 m 2, 95% CL: 4.8, 18.5).

7 McKenzie & Dionne: Vlue of hitt heterogeneity to fish production 223 Tle 2. Men fish densities (ind. m 2 ) from 3 tretments in the Wehnnet nd Moody mrshes. Vlues re cktrnsformed lest squre mens (lower, upper 95% confidence intervl) with vlues from the control tretment in the Wehnnet mrsh pooled from control nd procedurl control tretments. Different nonold superscripted letters cross row indicte significnt difference in men fish density with time, while old superscripted letters in column indicte significnt difference in men fish density etween the Wehnnet nd Moody mrshes. Both re sed on Tukey-Krmer pirwise comprisons in 2-wy ANOVA (p < 0.05) June July August Wehnnet Control 1.6 (0.5, 3.6) 9.7 (5.1, 17.8) 36.9 (20.6, 65.5) Pool-mrsh 3.1 (0.8, 8.0) 14.5 (6.0, 33.2) 38.8 (17.0, 87.0) 1.7 (0.2, 4.9) 14.5 (6.0, 33.3) 49.2 (21.7, 110.1) Men 2.1 (1.0, 3.7) 12.7 (8.0, 19.8) 41.3 (26.8, 63.3) c Moody Control 3.4 (1.0, 8.8) 11.1 (4.5, 25.8) 25.3 (10.9, 57.3) Pool-mrsh 2.4 (0.5, 6.6) 10.4 (4.2, 24.2) 15.7 (6.5, 35.8) 5.5 (1.9, 13.4) 13.8 (5.7, 31.8) 16.9 (7.1, 38.6) Men 3.6 (1.9, 6.3) 11.7 (7.0, 19.1) 18.9 (11.6,30.4) Mummichog growth rtes were similr mong ll tretments in 2002 nd 2003 (Tle 3). In 2002, growth rtes were similr mong the different size clsses compred (45, 55, 65 mm), ut were significntly higher from pools in the Wehnnet (0.032 ± g wet wt d 1 ) thn the Moody mrsh pools (0.022 ± 0.003) (p < 0.05, F = 4.9, df = 1, 65) (Tle 3). In 2003, growth rtes in the smller size clsses (25 nd 35 mm) were significntly higher (0.028 ± nd ± g wet wt d 1, respectively) thn the lrger size clsses (45 nd 65 mm) (0.018 ± nd ± g wet wt d 1, respectively) (p < 0.01, F = df = 3, 45), ut growth rtes were similr etween Tle 3. Averge instntneous growth rtes (g wet wt d 1 ± SE) for ech fish size clss from ll mrsh tretments smpled in 2003 nd Vlues without SE represent growth rte from single sttion. When replicte vlues were ville for ll 3 tretments, comprisons of G inst were mde y mrsh, tretment, nd ech size clss using 3-wy ANOVAs. No significnt min effects were found for mrsh or tretment Size clss Wehnnet mrsh Moody mrsh (mm) Control Pool-plus-mrsh Control Pool-plus-mrsh 8 July ± ± ± ± ± ± ± ± Aug ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± July ± ± ± ± ± ± ± ± ± ± ± ± July ± ± ± ± ± ± ± ± ± ± ± ± Aug ± ± ± ± ± ± ± ± ± ± ± ± ± ±

8 224 Mr Ecol Prog Ser 368: , 2008 sites. Comprison of ll growth rtes clculted for 2002 nd 2003 (mrshes comined) mong tretments reveled tht growth rtes were often highest from pool-only nd pool-plus-mrsh tretments (Figs. 4 & 5). Fish less thn 40 mm totl length hd the highest growth rtes. Totl fish production, dult nd lrge YOY production, nd smll YOY production were not significntly different mong tretments or etween sites, lthough production tended to e highest in pool-plus-mrsh nd pool-only tretments (Fig. 6). YOY production contriuted significntly more to totl production in the Wehnnet mrsh (72.5 ± 0.07%) thn in the Moody mrsh (46.1 ± 0.07%) (p < 0.05, F = 6.96, df = 1, 15); dult production contriuted more to totl production in the Moody mrsh (53.9 ± 0.07%) thn in the Wehnnet Mrsh (27.5 ± 0.07%) (p < 0.05, F = 6.96, df = 1, 15). Person s correltion reveled tht totl fish production ws significntly correlted to YOY fish densities (r = 0.70, p < 0.001). YOY fish densities were positively correlted to wter temperture (r = 0.59, p = 0.004) nd distnce from the min chnnel (r = 0.58, Instntneous growth rte (g wet wt d 1 ) Control Pool-plus-mrsh 0.04 Control 0.02 Pool-plus-mrsh Mid-length of size clss (mm) Instntneous growth rte (g wet wt d 1 ) Control Pool-plus-mrsh 0.01 Control Pool-plus-mrsh Mid-length of size clss (mm) Fig. 5. Averge growth rtes (±SE) () 9 July nd () 25 August 2003 from control, pool-plus-mrsh, nd pool-only tretments pooled for the Wehnnet nd Moody mrsh. Vlues from the control tretments in the Wehnnet mrsh re pooled from control nd procedurl control tretments. Figures include individul dt points tht were not included in sttisticl comprisons p = 0.006), ut were negtively correlted to wter depth (r = 0.58, p = 0.006). Bonferroni djustments of α vlues reveled tht the ltter 3 results were not significnt. Mini-enclosures 0.10 With the exception of 1 of the pool-only tretments, 0.08 mrked fish were successfully recptured from the 0.06 mini-enclosures on ech of the 5 smpling points. Dt from this enclosure were not included in the nlyses Control Biomss of femle nd mle mummichogs significntly 0.02 Pool-plus-mrsh incresed (p < 0.001, F = 44.77, df = 4, 32 nd p < 0.001, F = 98.64, df = 4, 20, respectively) in oth the pool-only nd c the pool-plus-mrsh mini-enclosures (Fig. 7). Chnge 0.10 in femle iomss over time ws not significntly differ 0.08 ent etween tretments lthough wet weights were of 0.06 ten greter from pool-plus-mrsh thn pool-only mini- Fig. 4. Averge growth rtes (±SE) () 9 July, () 25 July nd (c) 25 August 2002 from control, pool-plus-mrsh, nd pool- only tretments pooled for the Wehnnet nd Moody mrshes. Vlues from the control tretments in the Wehn net mrsh re pooled from control nd procedurl control tretments. Figures include individul dt points tht were not included in sttisticl comprisons enclosures. However, the rte of chnge in mle mummichog iomss over time ws significntly higher for the pool-plus-mrsh thn pool-only mini-enclosures (p < 0.05, F = 4.03, df = 4, 20) (Fig. 7). There were no pprent differences in femle growth rtes etween pool-plus-mrsh nd the pool-only tretments (Fig. 8), lthough growth rtes were much lower during the first week. Mle growth rtes were generlly higher in the pool-plus-mrsh tretments. However, these differences were not significnt (Fig. 8). Secondry production of oth femle nd mle mummichogs ws higher in pool-plus-mrsh thn

9 McKenzie & Dionne: Vlue of hitt heterogeneity to fish production Totl production ns Adult production ns Smll YOY production ns Secondry production (g m 2 d 1 ) Control Pool-mrsh Totl production ns Adult production ns Smll YOY production ns Wet weight (g) Pool-nd-mrsh 1.0 6/16/03 6/30/03 7/14/03 7/28/03 8/11/03 8/25/ Pool-nd-mrsh Control Pool-mrsh 6/16/03 6/30/03 7/14/03 7/28/03 8/11/03 8/25/03 Fig. 6. Men secondry production estimtes from () Wehnnet nd () Moody mrshes, Vlues re cktrns Fig. 7. Men (±SE). Chnges in iomss (g) of individully 2003 formed lest squre mens (+ upper 95% confidence inter mrked () femle nd () mle mummichogs from minimrsh pooled from control nd procedurl control tretments. re month/dy/yer vl), with vlues from the control tretment in the Wehnnet enclosure pool-plus-mrsh nd pool-only tretments. Dtes Totl production is the sum of dult nd smll YOY (<40 mm) production. Adult production includes dult nd lrge YOY (>40 mm) production. There were no significnt differences in production etween sites or mong the three tretments for totl, dult, or juvenile production (2-wy ANOVA). ns: no signficnt difference pool-only enclosures (0.06 g m 2 d 1, 95% CL: 0.04, 0.08, nd 0.04 g m 2 d 1, 95% CL: 0.01, 0.07, respectively, for femles; 0.08 g m 2 d 1, 95% CL: 0.05, 0.10, nd 0.05 g m 2 d 1, 95% CL: 0.03, 0.09, respectively, for mles) (Fig. 9). While these ptterns of production were more pronounced for mles, there were no significnt differences etween tretment or sex nd no significnt interction etween these 2 fctors. in hydrologicl conditions. Moody mrsh pools were closer to hevily developed uplnd res thn Wehnnet mrsh pools nd likely received incresed inputs of surfce nd groundwter. Runoff my hve lso lowered dissolved oxygen concentrtions in the Moody mrsh even though wter tempertures were lower thn t Wehnet mrsh. These freshwter runoff inputs re impounded on the surfce of Moody mrsh y djcent dringe ditches recently plugged to flood the mrsh for fish nd wildlife mngement. Fish size nd densities DISCUSSION Physicl prmeters mong mrsh pools Vriility in physico-chemicl prmeters resulted in similr within mrsh men vlues mong different tretments (Fig. 1). Differences in tempertures nd slinities etween sites were likely due to differences Internnul differences in fish size nd iomss were due to inefficient smpling of smller size clsses y minnow trps. Minnow trps lso hd low recpture rtes of mrked fish; densities nd production could only e estimted from 2003 lift net dt. Fish densities were similr mong ll tretments in Wehnnet nd Moody mrshes; densities incresed over time in ll tretments due to recruitment of YOY

10 226 Mr Ecol Prog Ser 368: , 2008 Instntneous growth rte (g d 1 ) tht numers of fish immigrting were similr to those Pool-nd-mrsh emigrting. Site fidelity hs een reported for popul tions of mummichogs in other est cost USA slt mrshes. Only 7% of tgged mummichogs were recptured outside mrsh pond into which they hd een relesed (Hunter et l. 2007). In other studies, mrked mummichogs were recptured 0 to 5 m from their relese sites (Ale et l. 2006) or returned to the site of their originl cpture fter eing trnsported to other res of the mrsh (Lotrich 1975, Eerhrdt 2004). Site fidelity is lso evident from distinct isotope signtures of mummichogs from different res within mrsh systems (Currin et l. 2003, McMhon et l. 2005). 7/3/03 7/15/03 7/30/03 8/18/03 Pool-nd-mrsh Growth nd production rtes /3/03 7/15/03 7/30/03 8/18/ Fig. 8. Men (±SE) instntneous growth rtes (g d 1 ) of individully mrked () femle nd () mle mummichogs from mini-enclosure pool-plus-mrsh nd pool-only tretments. Dtes re month/dy/yer Individul production (g m 2 d 1 ) Pool-plus-mrsh Femle Mle Fig. 9. Men secondry production (g m 2 d 1 ) of individully mrked femle nd mle mummichogs from mini-enclosure pool-plus-mrsh nd pool-only tretments. Vlues re men cktrnsformed lest squre mens + upper 95% confidence intervl mummichogs. Similr densities mong the different tretments reveled tht, even though control tretments were open to the mrsh-esturine system, little emigrtion or immigrtion of fish occurred from djcent pools or tidl creeks. An lterntive explntion is Vriility in physico-chemicl prmeters mong individul mrsh pools provided fish with heterogeneous environments. This my hve een responsile for the lck of significnt differences mong growth rtes nd secondry production mong lrge scle tretments. Similr growth nd production rtes etween lrge-scle enclosures nd open control pools my hve lso een due to the importnt su-tidl hitt provided y mrsh pools to resident fish in Mine mrshes, where ccess to the mrsh surfce is limited to the higher tides. Fish in Wehnnet mrsh pools were only le to ccess the high mrsh surfce 2.3 to 5.0% of tidl innundtions during our study period. Connectivity ws not mesured in Moody mrsh pools, ut similr rtes of ccess were ssumed to occur sed upon oservtions of tidl flooding on the mrsh surfce s well s the presence of deris on Vexr mesh round pools. Thus, fish were lrgely restricted to mrsh pools in ll tretments during our study period. Similr growth nd production rtes were likely due to undnt food sources within mrsh pools, such s concentrted numers of shrimp, juvenile mummichogs or enthic mcroinvertertes (Fig. 4). All hve een identified s importnt food sources for mummichogs (Fell et l. 1998, Currin et l. 2003, McMhon et l. 2005). The grss shrimp Plemonetes pugio ws the most undnt orgnism smpled from Wehnnet nd Moody mrsh pools, with densities often 4 to 7 fold higher thn those of Fundulus heteroclitus (uthors unpul. dt). Grss shrimp were commonly found in the guts of mummichogs (uthors pers. os.) nd re known to e n importnt component in dult mummichog diets (Knei & Stiven 1982, Weiserg & Lotrich 1986, Knei & Scheele 2000, Dvis et l. 2003). Another importnt food source tht supports mummichog production is enthic microlgl growth on mrsh sediments (Crech et l. 1997, Currin et l. 2003), which is more undnt in well lit mrsh

11 McKenzie & Dionne: Vlue of hitt heterogeneity to fish production 227 pools thn on shded, vegetted surfces (Currin et l. 2003). Comprison of results etween mini-enclosures within the sme pool my present more ccurte results s fish in pool-only nd pool-plus-mrsh mini-enclosures were exposed to similr environmentl conditions. Although fish were lrgely restricted to mrsh pools (see ove), mle nd femle mummichogs with ccess to the mrsh surfce hd 1.6 nd 1.5 higher rtes of secondry production, respectively. Mles with ccess to the mrsh surfce lso ccumulted iomss t significntly higher rte nd exhiited higher growth rtes thn mle fish restricted to pools. Femle mummichogs hd similr rtes of iomss ccumultion nd growth in oth cge tretments. Thus, results from the mini-enclosures suggest tht the Sprtin ptens mrsh surfce lso provides importnt hitt for resident fish in Mine, lthough hitt vlue my vry etween mles nd femles. This my prtilly explin the etween-pool vrition in growth nd production rtes in lrge-scle enclosures tht were not seprted y sex. Comprison of stle isotope composition of muscle tissue from mummichogs smpled from pool djcent to the study site showed tht mle mummichogs hd significntly lighter δ 13 C nd hevier δ 15 N signtures thn femles (uthors unpul. dt). Differences in concentrtions of hevy metls in tissues from mle nd femle mummichogs hve lso een reported from polluted mrshes (Ferrro et l. 2001). These results ll suggest tht mles nd femles my e feeding in different res of the mrsh. The lrger ody size of femles compred to mles in this species my llow femles to monopolize pool resources, leving mles to seek resources on the mrsh surfce during tidl flooding. Ptterns in secondry production in lrge-scle enclosures were lrgely driven y ptterns in YOY fish, s reported elsewhere (Knei & Wgner 1994, Knei 2000). For exmple, smll fish represented >70% of totl mummichog production in New Jersey slt mrsh (Hgn et l. 2007). Comprison of Wehnnet nd Moody mrsh pools reveled tht YOY contriuted significntly more to totl production nd fish densities in the Wehnnet mrsh. Fctors responsile for these ptterns hve not een isolted, ut correltions etween YOY densities, depth, wter temperture, nd distnce from the min chnnel suggest tht environmentl conditions my hve een more suitle for YOY mummichogs in Wehnnet mrsh pools s these systems were wrmer nd shllower thn Moody mrsh pools. Becuse environmentl conditions in Moody mrsh pools pper to e influenced y humn ctivities, ecologicl prmeters of YOY mummichogs (e.g. densities, production) my provide excellent indictors for how slt mrsh systems respond to humn ctivities. Slt mrsh pools s hitt Access to the vegetted mrsh surfce is eneficil to resident fish diets nd growth rtes. Growth rtes nd iomss were reduced in mummichogs restricted to tidl creeks in Delwre mrsh (Weiserg & Lotrich 1982) nd to Msschusetts mrsh pools (Jvonillo et l. 1997). Similr ptterns hve een reported for the killifish Fundulus prvipinnis in Cliforni slt mrshes. Killifish with ccess to the vegetted mrsh surfce consumed 6 s much food s fish restricted to tidl creeks (West & Zedler 2000), result supported y ioenergetics model predicting incresed growth rtes for F. prvipinnis with ccess to mrsh vegettion (Mdon et l. 2001). Our results suggest tht, unlike studies conducted in Sprtin lterniflor dominted low mrsh systems, oth mrsh pools nd surfces of S. ptens high mrshes re importnt feeding res for resident fish nd dd to overll fish production in southern Mine mrshes. While our findings support our hypothesis tht fish restricted to pools would hve positive growth nd production rtes, there ws only limited support for our hypothesis tht the high mrsh surfce lso contriutes to these prmeters. Further studies llowing fish ccess to lrger res of high mrsh, s well s studies exmining linkges etween pools nd high mrsh res, re needed to etter quntify the reltive contriutions of pool nd mrsh surfce resources to totl esturine productivity. Comprison of results from this study to others is complicted y differences in loction nd smpling methods. The upper rnge of lrge YOY nd dult growth rtes reclculted from dry weights for our study (1.15 g dw mo 1 ) ws higher thn reclculted estimtes from Msschusetts (0.39 g dw mo 1 ) (Vliel et l. 1977) nd Delwre (0.18 g dw mo 1 ) (Meredith & Lotrich 1979) (Tle 4). However, the 2 ltter vlues my e underestimtes (Teo & Ale 2003). Vliel et l. (1977) used minnow trps tht collected dult fish >60 mm nd excluded smller size clsses tht my hve higher growth rtes (e.g. Figs. 3 & 4). In Delwre, verge densities of different size clsses my hve een underestimted (Meredith & Lotrich 1979), which would lso underestimte verge weights nd growth rtes. The upper rnge of growth rtes for lrge YOY nd dults from New Jersey slt mrsh (Teo & Ale 2003) were nerly 2 higher thn our estimte. This my e due to the different rnge of size clsses used in New Jersey for lrge YOY nd dults (>30 mm) compred to our study (>40 mm). However, the highest reclculted growth rte for the 30 to 39 mm size clss in our study ws 1.05 g dw mo 1, which is 2 lower thn vlues reported from New Jersey. Thus, mummichog growth nd production from southern Mine mrsh surfces pper to e lower thn in New Jersey (Tle 4).

12 228 Mr Ecol Prog Ser 368: , 2008 Tle 4. Comprison of instntneous growth rtes (G inst dry wt mo 1 ) for smll nd lrge YOY nd dults, nd totl, smll nd lrge YOY nd dult fish production (g dry wt m 2 yr 1 ) from this study nd from studies conducted in New Jersey, Msschusetts, nd Delwre, USA. Instntneous growth rtes from the Wehnnet nd Moody mrshes were reclculted using dry weights Loction G inst Production Smll YOY Lrge YOY, Totl Smll YOY Lrge YOY, Adults Adults my (or my not) e lower in slt mrsh pools, this hitt provides n importnt energy source to mny of the resident nd trnsient nekton species tht feed in these ecosystems nd likely contriute significntly to overll esturine productivity in the Gulf of Mine. Wehnnet Conservtion nd mngement mrsh (this study) implictions Moody mrsh (this study) Mrsh pools in the Wehnnet nd New Jersey Moody mrshes provide vlule con- (Teo & Ale tinully immersed hitt tht supports 2003) resident fish popultions. Even though Msschusetts ccess to the high mrsh surfce during (Vliel et l. the growing seson ws limited y low 1977) frequency of tidl inundtion, the high Delwre mrsh surfce is still n importnt com (Meredith & Lotrich 1979) ponent of resident fish production. In yers when pools re more frequently Production estimte is the corrected vlue reported in Teo & Ale (2003) Monthly growth rtes re reclculted from growth mesured over 4 to flooded (Murphy 1991), greter con 26 d, ssuming there re 30 d mo 1 Lower production rtes could e due to our conservtive estimtes eing mde over 3 mo field seson; however, this does not fully ccount for lower growth rtes. Lower wter tempertures in Mine mrshes, s well s longer nd colder winters, nd thus shorter growing sesons, could reduce growth rtes nd production of resident fish. Lower rtes could lso e due to the fct tht mummichogs in mrsh pools from this study hd reduced forging time on the high mrsh surfce compred to the other studies, where similr size clsses smpled from tidl creeks nd chnnels (Vliel et l. 1977, Meredith & Lotrich 1979, Teo & Ale 2003) hd dily ccess to Sprtin lterniflor low mrsh res to forge. Alterntively, slt mrsh pools my provide su-optiml hitt for fish production compred to tidl creeks or chnnels. In Rhode Islnd slt mrsh, mummichog growth rtes were lower from slt mrsh pools thn in creeks or chnnels (Hlpin 2000), which ws ttriuted to differences in iotic fctors etween the 2 types of hitt nd thus qulity of hitt provided. Direct comprison of fish production in pools nd creeks in Mine mrshes re needed to determine their reltive contriutions to secondry mrsh production. However, there is nerly twice s much hitt in Mine slt mrsh pools compred to tidl creeks nd chnnel (Dionne 2006), which suggests tht totl fish production within mrsh pools my e equl to or greter thn production within creeks nd chnnels. Thus, while production nd growth rtes triution y the high mrsh to pool fish production is to e expected. High mrsh res lso provide importnt spwning res for mummichog popultions. Shllow wter depths in the interior portions of the high mrsh protect developing fry from predtion y lrger fish. These fry cn then colonize mrsh pools, s evidenced y the incresed numers reported here in the month of August. The vlue of the vegetted mrsh surfce s feeding re lso ppers to vry etween sexes, with ccess to the mrsh surfce enefiting mles more thn femles. Thus, while it is tempting to think tht n increse in the numer of pools on the mrsh surfce will increse fish production, it is importnt to rememer tht vegetted Sprtin ptens high mrsh res lso ply vitl role in the life cycle of resident mrsh fish nd thus fish production. This is especilly true s the cretion of mrsh pools on the mrsh surfce through excvtion or plugging of mosquito ditches hs recently ecome populr mrsh restortion technique in New Englnd nd elsewhere (Admowicz & Romn 2005, Koniski et l. 2006). It is not entirely cler how pools creted in this wy compre to nturl pools. It is lso uncler how shifts from roust high mrsh to stunted low mrsh vegettion (Admowicz & Romn 2002) or even mud flts (uthors pers. os.) tht occur s result of rised wter tles from ditch plugging might influence fish production. Future mrsh mngement efforts need to mintin lnce etween vegetted res nd mrsh pools to sustin resident fish popultions nd the other fun tht rely on them for food sources.

13 McKenzie & Dionne: Vlue of hitt heterogeneity to fish production 229 Acknowledgements. This study ws funded y the Mine Stte Se Grnt College Progrm t the University of Mine (NOAA grnt numer NA16RG1034, project numer R-02 06) nd y the G. Ford Wells Ntionl Esturine Reserch Reserve Postdoctorl Fellowship. The United Sttes Deprtment of Agriculture Forest Service s Institute of Pcific Islnds Forestry in Honolulu, Hwii supported R.A.M. while working on this mnuscript. Reserch ws conducted in portions of the Rchel Crson Ntionl Wildlife Refuge y permission of the United Sttes Fish nd Wildlife Service. We thnk E. Brzer Jr., C. Ellis, M. Hs, J. Miller, L. Weintru, nd E. Wilson for their invlule ssistnce in the field nd the l. We lso thnk J. Bldwin for his ssistnce with the sttisticl models used in this study. LITERATURE CITED Ale KW, Hgn SM, Brown SA (2006) Hitt use, movement, nd growth of young-of-the-yer Fundulus spp. in southern New Jersey slt mrshes: comprisons sed on tg/recpture. 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