Juvenile fish assemblages collected on unconsolidated sediments of the southeast United States continental shelf.
Fisheries management has been rapidly evolving for the southeast United States with the development of a formal stock assessment process (i.e., SEDAR (1)), and the identification of essential fish habitat (EFH; SAFMC, 1998). Single-species management plans have been used as the basis for fisheries management along the southeast United States for decades, and EFH is just beginning to be incorporated into management plans (e.g., Sargassum and Oculina bank habitat of particular concern: FR, 2000). Globally, as fish stocks continue to decline (Botsford et al., 1997) and harvest shifts to new species (Pauly et al., 1998), interest in ecosystem management and implementation of MPAs in many areas, including the southeast U.S. continental shelf, is growing (SAFMC, 2001). Understanding how juvenile fish use habitat is important for both single-species fishery management and ecosystem approaches to fishery management. A description of habitat needs at each life history stage for species that represent the "significant food web" are also a recognized part of fishery ecosystem plans (NOAA (2); CFEPTAP, 2004).
Adult population variability, in most species, is caused by variability in the survival of the early-life stages: egg, larval, and juvenile (Sissenwine, 1984; Rothschild, 1986). Survival of these early stages is influenced by both habitat quantity and quality (Gibson, 1994; Peterson, 2003). One approach to improving marine fisheries management is to incorporate habitat effects on early-life stage survival into stock assessments (Beck et al., 2001; Peterson, 2003). Determining how juvenile fish use habitat also benefits marine protected area (MPA) design and implementation. MPAs have been proposed to complement traditional fishery management practices by imposing site-specific rules to protect enclosed resources (Parrish, 1999; Dayton et al., 2000; Beck and Odaya, 2001). In some instances, MPAs provide benefits to outside areas through spillover effects (Roberts et al., 2001). MPAs may also provide a source of recruits to other nonprotected areas through planktonic transport (Cowen et al., 2000; Shanks et al., 2003). To be effective in protecting fishery resources, an MPA or a network of MPAs needs to encompass the habitats used by species throughout their life cycle (Browman and Konstantinos, 2004).
Habitat use by juvenile fish has been studied extensively along the southeast United States, particularly for commercial and recreational species and structured habitats. For example, there is information available regarding the habitat use of specific estuarine (e.g., Cynoscion nebulosus: Thayer et al., 1999; paralichthid flounders: Walsh et al., 1999) and reef-associated species (e.g., Mycteroperca microlepis: Ross and Moser, 1995; Lutjanus griseus: Chester and Thayer, 1990; Centropristis striata: Lehnert and Allen, 2002). The importance of structural habitat to juvenile fish is also demonstrated by the consistent use of seagrass (Thayer et al., 1999), oyster reef (Meyer and Townsend, 2000), pelagic Sargassum (Moser et al., 1998), mangrove (Thayer et al., 1987), marsh (Hettler, 1989), and rocky reefs (Lindeman et al., 2000). Unconsolidated sediments in estuarine systems and from the surf-zone out into shallow coastal areas (<10 m) are also important juvenile habitat (estuarine: Burke et al., 1991; Walsh et al., 1999; surf-zone: Wenner and Sedberry, 1989; Ross and Lancaster, 2002).
Despite this large body of research, little is know about the use of unconsolidated sediments on the inner-, mid-, and outer-shelves of the southeast U.S. continental shelf. Unconsolidated sediment is not identified as EFH of the southeast U.S. (SAFMC, 1998), although it is identified in several fishery management plans (red drum, snapper-grouper, rock shrimp, royal red shrimp, coastal migratory pelagies, golden crab, spiny lobsters, and calico scallops). The only offshore habitats that currently have specific protection through their own fishery management plans are coral, coral reefs, live hard bottom, and pelagic Sargassum (Barnette (3); FR, 2000). Research in other shelf ecosystems has identified unconsolidated sediments on the shelf as important juvenile habitat (Norcross et al., 1997; Steves et al., 2000; Sullivan et al., 2000; Johnson et al., 2001). Further, unconsolidated sediments on the southeast U.S. continental shelf cover a majority of the area (~60-80%; Parker et al., 1983), and likely serve as juvenile habitat for the more than 1200 fish species reported from the ecosystem (estimated from Kendall and Matarese, 1994). Thus, well-defined use of unconsolidated sediment habitat by juvenile fish is needed for sediment habitat to be incorporated into future fishery resource management on the southeast U.S. continental shelf.
Our purpose was to document juvenile fish habitat use and to examine the structure of juvenile fish assemblages in unconsolidated sediments off the Georgia coast region of the southeast U.S. continental shelf. Specific objectives were 1) to provide a list of species that use unconsolidated sediments on the shelf as juvenile habitat; 2) to determine which reef-associated species use unconsolidated sediments as juvenile habitat; and 3) to describe the relationships between the juvenile assemblages and environmental factors. The focus on reef fish was motivated largely by the emphasis to protect reef areas by using MPAs, as part of the management of the reef-associated snapper-grouper complex (SAFMC, 2001). If species of the reef-associated snapper-grouper complex use unconsolidated sediments during the juvenile stage, then protection of these habitats should be incorporated into the larger MPA effort.
Materials and methods
The continental shelf off the Georgia coast is the widest part (200 km) of the southeast shelf. The shelf in this region is gently sloping and comprises four depth zones (Menzel, 1993); inner-shelf (0-20 m); mid-shelf (20-40 m), outer-shelf (40-70 m), and shelf-edge (70-200 m). Each zone has different physical dynamics (Atkinson et al., 1985), climate (Blanton et al., 2003), and larval fish assemblages (Marancik et al., 2005). Demersal habitat consists of unconsolidated sediments, primarily medium to coarse quartz and carbonate sands (Nelson et al., 1999) interspersed with rocky reefs (Parker et al., 1983). Reefs of the southeast U.S. shelf range from no relief patchy live-bottom communities, to high-relief ledges. On the shelf off Georgia, rocky-reefs cover about 30% of the bottom (Parker et al., 1983). Rocky-reef habitats have a high diversity of invertebrate (Wenner et al., 1983) and vertebrate faunas (Chester et al., 1984; Parker and Mays, 1998; Lindeman et al., 2000). Located within the continental shelf off Georgia is the 56-[km.sup.2] Gray's Reef National Marine Sanctuary (Gray's Reef NMS, Fig. 1). The sanctuary depth ranges from 18 to 22 m and the benthic macrohabitat is mainly (~75%) unconsolidated sand sediments interspersed with patchy live-bottom and moderate relief ([less than or equal to] 2 m) hard-bottom ledges (Parker et al., 1994). The adult reef fish community of the sanctuary is typical of other inner-shelf (<30 m) reefs of the South and North Carolina shelves (Chester et al., 1984; Parker et al., 1994).
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Collection of juvenile fish and environmental data
Sampling of juvenile fish was conducted approximately quarterly from April 2000 through February 2002 (Table 1). Ten cross-shelf stations (stations 1-7), approximately 18.5 km apart, were sampled during most cruises (Fig. 1). Stations were missed on some cruises owing to weather and equipment failure (Table 1). The cross-shelf transect was 110 km long and stations were sampled on the inner-, mid-, and outer-shelf (10 to 50 m water depth). To avoid sampling within Gray's Reef NMS, four stations were placed immediately adjacent to the four sides of the sanctuary (stations 2.1-2.4). Additional stations were sampled along three transects inshore of Gray's Reef NMS and along four offshore transects during three cruises (Fig. 1 and Table 1). The benthic macrohabitat of the cross-shelf stations was determined by using a remotely operated vehicle (ROV, Phantom S2). The ROV was deployed off the starboard side of the ship. Approximately 30 m of the ROV tether was let out before the tether was attached to a 45-kg weight. The weight was lowered to 3 m above the bottom and the ship was allowed to drift. During April 2000, two 15-min drifts were made at eight of the ten cross-shelf stations. Because of inclement weather, no drifts were conducted at the inner- or outer-most stations. Video (HI-8 mm) was recorded of each drift.
Concurrent fish and hydrographic measurements were taken to examine the relationship between juvenile fish assemblages and the environment. At each station, temperature, salinity, density, and water depth were measured from the water's surface to one meter above the bottom with a Seabird CTD (SBE19, Seabird Electronics, Inc., Bellevue, WA). Juvenile fish were collected at each station by using a 2-m beam trawl with a 6-mm mesh body and a 3-mm mesh tail bag. Two kilogram weights were added to each skid of a standard 2-m beam trawl (Kuipers, 1975) to ensure that the trawl stayed on the bottom. Three 5-min bottom tows were made at each station. Samples were sorted on deck and fish and invertebrates were preserved in 95% ethanol.
Preparation of fish data
All beam trawl samples were sorted and fish were identified to the lowest possible taxonomic level by using previously published descriptions (e.g., Able and Fahay, 1998; Munroe, 1998). Identification to species was not possible for all fish. Taxa were separated into larval, juvenile, and adult age classes according to life-history characteristics from the literature and standard length distributions (SL, mm) from the beam trawl collections. Fish were classified as larvae if fin development was not complete (and defined as "larvae at settlement stage" when fin formation was complete and pigmentation incomplete; fish were classified as juveniles when pigmentation was complete, and were classified as adults if they exceeded the reported minimum SL for sexual maturity. Because the mesh of the beam trawl is large enough to extrude larvae and less efficient at catching large (>150 mm SL) fish (Kuipers, 1975), analyses in this study were conducted only on settlement and juvenile stages, which were combined and referred to as juveniles. Taxa were also classified as not reef-associated, strongly reef-associated or weakly reef-associated based on habitat-use information (Chester et al., 1984; Humann, 1994; Parker et al., 1994; Parker and Mays, 1998; Lindeman et al., 2000). Taxa found predominantly on rocky-reefs (e.g., Centropristis striata) were classified as strongly reef-associated. Those that use rocky-reefs and other habitats (e.g., Diplectrum formosum) were classified as weakly reef-associated.
Standard catch per unit of effort (CPUE, fish/5-min bottom tow) was calculated for each taxon. CPUE for each taxon at each station was the average of all replicate tows. Three juvenile stage data sets (i.e., cross-shelf, inshore, and offshore) were compiled by using data from the station groups (Table 1, Fig. 1): the cross-shelf data set consisted of data from stations one through seven (Fig. 1A); the inshore data set consisted of data from stations predominately inside the 20-m isobath (Fig. 1B), and the offshore data set consisted of date from stations >30 m in depth (Fig. 1C).
For statistical analyses, the three data sets were subdivided into two groups so that rare taxa would not greatly influence the classification of assemblages. The first group consisted only of abundant taxa, and the second group included abundant and rare taxa. Cross-shelf and offshore data sets were subdivided into taxa that made up at least 10% (abundant) and 1% (abundant and rare) of the collections at any one station. The inshore data set was subdivided at 5% and 1% levels. The data sets were further condensed by eliminating all taxa not identified to species level with the exception of Stenotomus sp. and Rypticus sp. which were probably single species. Several abundant taxa were excluded from the analysis because they were only identified to genus and have multiple species common in the area, and each species may differ in distribution: i.e., Etropus spp. (4 species), Prionotus spp. (14 species), Sphoeroides spp. (11 species), Microgobius spp. (3 species), and Bothus spp. (3 species). As a result, the numbers of taxa in the rare and abundant data sets used in analyses were as follows: cross-shelf 82 (rare) and 28 (abundant) (Table 2); inshore 28 and 13 (Table 3), and offshore 51 and 17 (Table 4).
Preparation of environmental data
Season and five environmental (or hydrographic) variables were chosen in an attempt to explain variation in the juvenile fish data. Cruises were assigned to one of four seasons (Table 1) based on wind (Atkinson et al., 1985) and temperature regimes (Marancik et al., 2005). Environmental variables were calculated as in Marancik et al. (2005). Briefly, CTD measurements of temperature ([degrees]C) and salinity were used to derive density ([[sigma].sub.t], Kg/[m.sup.3]). Bottom temperature, salinity, and density were used in the multivariate analyses with juvenile fish because benthic habitats were sampled and bottom values were highly correlated with the average water column and surface variables (Marancik et al., 2005). Vertical stratification was estimated by using Simpson's stratification parameter (Simpson and James, 1985), [PHI] (joules/[m.sup.3]), which is a measure of the resistance of water to mixing (higher numbers signify higher resistance to mixing).
Correspondence analysis (CA) and canonical correspondence analysis (CCA) were performed by using the statistical package CANOCO (ter Braak and Smilauer, 2002). Using the cross-shelf, inshore, and offshore data sets, we had seven objectives: 1) to describe the cross-shelf patterns in the juvenile fish assemblages; 2) to identify the species associated with the assemblages including the reef-associated species that contribute to these assemblages; 3) to describe the relationship among cross-shelf patterns in the assemblages and environmental variables; 4) to describe the seasonal patterns in the assemblages; 5) to determine the relation between seasonal assemblages and environmental variables; 6) to describe the along-shelf and cross-shelf patterns in the inshore data set; and 7) to describe the along-shelf and cross-shelf patterns in the offshore data set.
Correspondence analysis was used to define juvenile fish assemblages and to explore the factors that influence distribution of assemblages on the shelf off the coast of Georgia. CA arranges stations and species along gradients (Greenacre, 1984), creating a low-dimensional map (an ordination). Points that occur in close proximity can be considered to have similar species composition and abundance. Points that occur on the same dimension define gradients in the data. The eigenvalues, which are a relative measure of the amount of variance explained by each CA dimension (ter Braak and Smilauer, 2002), were used to determine the number of dimensions that best described the data. CA on untransformed CPUE data was used to define assemblages for the cross-shelf, inshore, and offshore data sets in relation to season.
Canonical correspondence analysis, which incorporates environmental variables by aligning species and station data along environmental gradients, was used to explore the relationship between juvenile assemblages and the environment. The species-environment correlation is a measure of the strength of the relation between the species data and the environmental data for each CCA dimension (ter Braak and Smilauer, 2002). The product of the species-environment correlation and the eigenvalue can be used to describe the variance in the data. CCA on untransformed CPUE data and standardized environmental data was used to explore the relation between the assemblages and environment for the cross-shelf, inshore, and offshore data sets in relation to season. Environmental data were standardized to a mean of zero and a standard deviation of one.
The environmental variables showed the typical seasonal and depth patterns across the shelf (Fig. 2). During the spring, bottom water temperature was near 20[degrees]C across the entire shelf (Fig. 2A). In the summer, bottom waters were warmest on the inner-shelf and cooler on the outer-shelf (Fig. 2A). Average fall bottom water temperature was intermediate between that of spring and summer and was warmest on the outer-shelf (Fig. 2A). The lowest bottom water temperatures were measured during the winter on the inner-shelf (Fig. 2A). Bottom salinity was lowest on the inner-shelf during all seasons (Fig. 2B). Bottom salinity was also low on the inner- and mid-shelves during the spring and rose to near 36 psu on the outer-shelf (Fig. 2B). During the summer, fall, and winter the mid- and outer-shelf bottom salinities remained near 36 psu (Fig. 2B). Bottom water density reflected the seasonal and cross-shelf patterns in temperature and salinity (Fig. 2C). Bottom water density was greatest during the winter when water temperatures were the lowest (Fig. 2C). In the spring, a cross-shelf pattern occurred and density was lowest inshore (Fig. 2C). During summer bottom water density was lowest inshore, where the water temperatures were low (Fig. 2C). There was no cross-shelf density pattern in the fall (Fig. 2C). Water column stratification was greatest during the summer and Simpson's stratification numbers were always higher on the outer-shelf (Fig. 2D). The low stratification numbers on the inner- and mid-shelves (Fig. 2D) indicated that there was a high probability of vertical mixing in all seasons.
[FIGURE 2 OMITTED]
Video analysis of the ROV tows indicated that the cross-shelf bottom on the continental shelf off the coast of Georgia consisted predominately of unconsolidated sand sediments. Hard-bottom (rock rubble) was seen in one video frame at station 2.3, on the southern edge of the Gray's Reef NMS. No ROV data were collected at the inner- or outermost stations; however, no hard-bottom has been reported from either station (SEAMAPSA, 2001). These data indicate that unconsolidated sediments were sampled.
Cross-shelf patterns in the juvenile fish assemblages
One hundred eighty one taxa were collected with the beam trawl, and of these, 121 were classified as juveniles (Appendix). Twelve strongly reef-associated species and 21 weakly reef-associated species were collected. The assemblages exhibited a cross-shelf gradient and the station groupings varied seasonally (Fig. 3). CA of both the 10% and 1% data sets resulted in the same overall patterns; however, rare species frequently were found between station groups in the ordination. During the spring, there were two cross-shelf station groups that overlapped at station 4 (Fig. 3A), an inner and mid-shelf group (stations 1-4), mainly inshore of the 30-m isobath, and an outer-shelf group (stations 4-7). Eigenvalues of the CA showed that the separation of the two groups was mainly along the first dimension (Table 5). During the summer, there was little cross-shelf pattern in the assemblages. The only exception was station 2.3, which was distinct from all other stations because live bottom was sampled at that station (Fig. 3B). When this station was removed from the analysis, there was no cross-shelf pattern in the summer data set (Fig. 3C). Three cross-shelf station groups were present in the fall (Fig. 3D): inner-shelf (station 1), mid-shelf (stations 2-5), and outer-shelf (stations 6-7). Separation of the groups was predominately along the first dimension (Table 5), which separated the inner- and mid-shelf station groups from the outer-shelf station group. During the winter, there was a cross-shelf gradient in the juvenile fish assemblages and the three overlapping groups were not as distinct as they were in spring or fall (Fig. 3, E and F). The species composition and abundance at station 7 from January 2001 was dissimilar from the rest of the winter samples (Fig. 3E) and generated a high eigenvalue for the second dimension (Table 5). The cross-shelf gradient along the first dimension had the highest eigenvalue (Table 5) in the winter; the first dimension showed three cross-shelf groups (Fig. 3F): an inner-shelf group (stations 1-2), a mid-shelf group (stations 2-5), and an outer-shelf group (stations 4-7).
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Species composition of juvenile fish assemblages
Five seasonal juvenile fish assemblages were associated with the cross-shelf station groups (Fig. 4, Table 2). The cross-shelf distribution of juveniles was related to adult distribution patterns and habitat use (Appendix). During the spring, the inner- and mid-shelf assemblage comprised species that are found in estuarine, coastal, and open-shelf habitats as adults (Fig. 4A, Appendix). Synodus foetens fell between the two station groups on the ordination, and was found in the both assemblages (Fig 4A). The outer-shelf assemblage was predominately coastal and open-shelf species (Fig. 4A, Appendix). Three reef-associated species were present in both assemblages (Table 2).
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Eighteen juvenile reef-associated species were collected during the summer (Table 2). Six species (Centropristis striata, Apogon pseudomaculatus, Haemulon aurolineatum, Stenotomus sp., Halichoeres bivittatus, and Parablennius marmoreus) were collected in June 2001 at station 2.3, when sampling was conducted over live-bottom. Sixteen of the 56 species from the summer sampling were collected solely during this season, and overall, the entire shelf was considered a single assemblage (Table 2).
Only estuarine and coastal species were observed in the inner-shelf assemblage during the fall (Fig. 4B, Table 2). The greatest number of species was observed in the mid-shelf assemblage (Fig. 4B, Table 2), which consisted of a mixture of estuarine, coastal, and open-shelf species (Fig. 4B, Appendix). Diplectrum formosum was collected from stations 2 to 7 and was in both the mid- and outer-shelf assemblages (Fig 4B). The outer-shelf assemblage consisted of only coastal and open-shelf species (Fig. 4B, Appendix). Seven reef-associated species were present in mid- to outer-shelf assemblages during the fall (Table 2).
There was a cross-shelf gradient in the winter juvenile fish assemblages that was influenced by the single station 7 (Fig. 3E), which had a high abundance of Monacanthus hispidus. Bothus ocellatus and B. lunatus were also collected only at this station (Table 2). The inner-shelf consisted of one dominant species (Fig. 4C), and the mid-shelf had the greatest number of species (Fig. 4C, Table 2). The outer-shelf assemblage consisted of estuarine, coastal, and open-shelf species (Fig. 4C). Six reef-associated species were found in the mid- and outer-shelf assemblages. The distributions of species in all three winter assemblages indicated cross-shelf mixing. An open-shelf species, Ogcocephalus nasutus, was present in the inner-shelf assemblage and Mugil cephalus, which uses estuaries as adults, was present in the outer-shelf assemblage (Table 2, Appendix). Finally, two slope species (Argentina striata and Antennarius radiosus) were present in the mid- and outer-shelf assemblages (Table 2, Appendix).
Cross-shelf patterns in juvenile fish assemblages and environmental variables
The juvenile fish assemblages and environmental variables all showed a cross-shelf gradient, which was correlated with depth during three of the four seasons (Table 6). The relationship between the other environmental variables and assemblages varied with season. In spring, the gradient in the inner- and mid-shelf and outer-shelf was mainly along the first dimension (Table 5) and was influenced by depth, bottom salinity, and bottom density (Fig. 5A). Inner- and mid-shelf stations were shallower and had less saline and dense bottom water than outer-shelf stations (Fig. 2). The spread along the second dimension in the outer-shelf group was less important (Table 5) and was influenced by the higher stratification of the outer stations (Fig. 2). A Monte Carlo permutation test of the environmental variables for spring indicated that depth, stratification, and bottom density were significantly related to the juvenile assemblages and the grouping of stations in the CCA (Table 6).
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The summer juvenile assemblage was not related to these environmental variables. The ordination of the station and species data changed with the inclusion of environmental data to the analyses, indicating a poor relationship between the juvenile data and the environment (Fig. 5B) The low eigenvalues also indicated that very little of the observed variation in the data was explained by the environment (Table 5). These results agree with the results from the CA, both of which indicate that the entire shelf is a single assemblage.
The fall cross-shelf patterns in the juvenile fish assemblages were related to depth and bottom salinity (Fig. 5C). The first dimension had the highest eigenvalue and species-environment correlation (Table 5) and was mainly influenced by depth; the shallower inner- and mid-shelf stations were separate from the outer-shelf stations. The second dimension was related to bottom salinity (Fig. 5C) and correlated with the separation of the inner-shelf station from the higher saline mid- and outer-shelf stations (Fig. 2). A Monte Carlo permutation test of the relationships between the assemblages and environmental data for the fall indicated that depth and bottom salinity were significantly related to the juvenile assemblages and cross-shelf station groups (Table 6).
The inclusion of environmental variables in the analysis of winter juvenile assemblage showed a weak relationship with the cross-shelf groups and juvenile assemblages, as indicated by the CCA correlation (Table 5). The addition of the environmental data also changed the ordination of the stations (Fig. 5D); yet there was still a cross-shelf gradient. Along the first dimension, depth, bottom temperature, and stratification were related to the juvenile assemblages and cross-shelf groups (Fig. 5D). The shallow inner- and mid-shelf groups were lower in bottom temperature and stratification, whereas bottom density was lowest on the inner- and outer-shelves and highest on the mid-shelf (Fig. 2). A Monte Carlo permutation test for the winter relationships indicated that depth and bottom density were significantly correlated with the fish assemblages and station groups (Table 6), although the bottom density did not appear to have any relation to the patterns described (Fig. 5D).
Seasonal patterns in juvenile fish assemblages
Many of the species (>68%) were present on the shelf in more than one season, which resulted in a large overlap of the seasonal assemblages (ordination not shown), including 12 of the 23 reef-associated species (Table 2). The assemblage data could be explained in three dimensions (as determined by CA of the 10% cross-shelf data set [Table 5]) and portrayed seasonal and cross-shelf patterns. Along the first dimension, there was separation between the winter inner-shelf assemblage and all other assemblages. The second and third dimensions portrayed a cross-shelf gradient in the spring, fall, and winter juvenile assemblage data. The summer assemblage overlapped all the cross-shelf groups from the other seasons except the winter inner-shelf assemblage. High abundances of Larimus fasciatus in the fall and Leiostomus xanthurus and Mugil cephalus in the winter (Table 2) caused these two seasons to be more dissimilar than were spring and summer, which were very similar. Many of the juveniles were found in the same cross-shelf assemblages during each season, whereas others shifted assemblages (Fig. 4).
Relation between seasonal juvenile assemblages and environmental variables
There appeared to be no relationship between the seasonal juvenile assemblages and environmental variables. The products of the CCA eigenvalues and species-environment correlations were extremely low (Table 5), and the CCA ordination of seasonal juvenile assemblages and environmental variables was different from the CA ordination. Thus, over the entire year, environmental variables did not help explain among-season variation in the juvenile assemblage data.
Along-shelf and cross-shelf patterns in the inshore juvenile fish data set
The inshore data set was made up of estuarine, coastal, and open-shelf species (Table 3, Appendix). There was a cross-shelf gradient in the spring and winter (Fig. 6). The innermost station group (8-m) separated from the other station groups along the first dimension (Fig. 7A) in spring. Most taxa from the 8-m assemblage (5 of 7) were not collected in high enough abundance to be included in the cross-shelf data set (Tables 2 and 3). In winter there was also a gradient from shallow to deeper stations (Fig. 6C). The assemblage nearest the origin in the winter (8-m assemblage) included estuarine species that were abundant at all the inshore stations (Table 3, Appendix). The coastal species, however, were more abundant at the deeper (12-m, 15-m, and 18-m) station groups (Table 3). There was no pattern in the along-shelf transects, from north to south, during either season (Fig. 6, B and D).
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Along-shelf and cross-shelf patterns in the offshore juvenile fish data set
The offshore juvenile fish data set included primarily (76%) coastal, open-shelf, and slope species (Table 4, Appendix) and patterns in the data set varied with season. During the fall, there were both cross-shelf (Fig. 7A) and along-shelf patterns (Fig. 7B). Along the first dimension, there was a cross-shelf gradient (Fig. 7A) from the shallow stations (30-45 m depth; Fig. 1C) to the 50-m station group. The juvenile assemblage at the 50-m station group had high abundances of reef-associated species (Table 4). The stations on the northern most transect (Fig. 1C) also separated from the others along the second dimension, and had higher abundances of reef-associated species. The cross-shelf pattern was present in the winter, with greater abundances of reef-associated species at the 50-m station group (Fig. 7C), but there was no along-shelf pattern (Fig. 7D).
One hundred and twenty-one taxa of juvenile fish were collected on unconsolidated sediments on the continental shelf off Georgia. The actual number of species was higher, but taxonomic problems limited species identification (e.g., identification of Etropus spp., Prionotus spp., Sphoeroides spp., and Microgobius spp.). With concurrent ichthyoplankton sampling of the cross-shelf stations (Fig. 1), we collected 161 taxa (Marancik et al., 2005); the larval community had more pelagic species, including several scombrids (e.g., Auxis rochei, Scomberornorus cavalla, and S. maculatus) and 17 myctophids. The large juvenile and adult fish communities of the shallow coastal zone (<10 m) and continental shelf (9-180 m) comprised about 150 species, including both pelagic and demersal species (Wenner et al. (4,5,6,7); Wenner and Sedberry, 1989). A maximum of 164 species were reported from rocky-reefs in the region (Chester et al., 1984; Parker et al. 1994; Baron et al., 2004). Fewer species inhabit estuaries than shelf habitats of the southeast (<90), particularly if different habitat types are considered (Ross and Epperly, 1985; Hettler, 1989; Nelson et al., 1991). Thus, unconsolidated sediments are as rich a habitat in terms of the number of species, as are pelagic, rocky reef, and estuarine habitats in the southeast U.S. continental shelf ecosystem.
Cross-shelf regions were defined on the Georgia shelf from spatial patterns in juvenile fish distributions. The number and extent of cross-shelf regions varied seasonally, but in general, three regions were identified: inner-shelf, mid-shelf, and outer-shelf regions. Juvenile assemblages were associated with the regions, yet some individual species were distributed across regions. Juveniles of year-round residents (e.g., Ophidion selenops, Diplectrum formosum, and Prionotus carolinus) were usually the most abundant species, although transient juveniles (e.g., Leiostomus xanthurus, Lagodon rhomboides, and Brevoortia tyrannus) were seasonally abundant. Cross-shelf gradients in species distribution have been found for other organisms and life stages of fish on the southeast U.S. shelf (macroinfauna: Atkinson et al., 1985; larval fish: Marancik et al., 2005; adult reef fish: Chester et al., 1984; adult demersal fish: Wenner et a1. (4,5,6,7)). Cross-shelf gradients also are common in demersal juvenile fish distributions in other continental shelf ecosystems (northwest U.S.: Norcross et al., 1997; Toole et al., 1997; Abookire and Norcross, 1998; Bailey et al., 2003; Johnson et al., 2003; northeast U.S.: Steves et al., 2000; Sullivan et al., 2000; southwest U.S.: Johnson et al., 2001).
The cause of cross-shelf gradients in juvenile fish distribution is difficult to determine. The primary environmental variable correlated with cross-shelf juvenile fish assemblages is often depth (Table 6; Norcross et al., 1997; Steves et al., 2000; Sullivan et al., 2000; Johnson et al., 2001; Johnson et al., 2003), although temperature, salinity, and sediment grain size also are correlated with depth (Norcross et al., 1997; Steves et al., 2000; Sullivan et al., 2000). On the Georgia shelf, salinity, density, and stratification correlated with the distribution of juvenile assemblages during the spring, fall, and winter (Table 6), and along with temperature (Figs. 2 and 6) likely influenced the distribution of juvenile fish, but the causative mechanisms remain unresolved. On the northeast U.S. shelf, cold bottom water left from winter resides on the mid-shelf during summer and fall (cold pool; Ketchum and Corwin, 1964). Steves et al. (2000) and Sullivan et al. (2000) hypothesized that cross-shelf patterns in settlement and juvenile fish distributions were caused by cross-shelf temperature gradients related to the presence of the cold pool on the mid-shelf. Similarly, juvenile flatfish species in Alaska exhibited cross-shelf gradients in habitat use that were influenced by temperature-depth interactions (Norcross et al., 1997). Hippoglossoides elassodon were most abundant in the colder, deeper locations, and Hippoglossus stenolepis were more abundant in the warmer, shallow locations (Norcross et al., 1997). On the Georgia shelf, juvenile assemblages were less distinct during summer, when environmental gradients were weakest, providing some support for the hypothesis that cross-shelf patterns in juvenile distribution were caused by environmental factors. Alternatively, in other studies it has been hypothesized that juvenile distribution results from selection of specific habitat characteristics within large-scale environmental gradients (Stoner and Abookire, 2002). For example, laboratory and field studies have found that some fish species select specific sediment characteristics or biogenic structures (Stoner and Abookire, 2002; Diaz et al., 2003; Stoner and Titgen, 2003), and spatial patterns in these habitat characteristics may cause spatial patterns in juvenile fish distribution. We did not stratify sampling by sediment characteristics or biogenic structures and thus we could draw no conclusion regarding the role of habitat characteristics in influencing juvenile fish distribution on the Georgia shelf.
No along-shelf spatial patterns were found in the juvenile fish community on the continental shelf off the Georgia coast; however, the along-shelf dimension sampled (~60 km) was relatively small compared to the along-shelf dimension of the southeast U.S. continental shelf ecosystem (~1000 km). Consistent patterns in along-shelf gradients in oceanographic features (Atkinson et al., 1985; Lee et al., 1991) and adult fish communities (Chester et al., 1984; Wenner and Sedberry, 1989) exist on the southeast U.S. shelf, but over larger along-shelf dimensions than sampled in the present study (200-400 km). Consistent patterns of juvenile use of along-shelf habitat over smaller dimensions (~100 km) have been reported for other shelf ecosystems (northwest U.S.: Norcross et al., 1997; Abookire and Norcross, 1998; northeast U.S.: Steves et al., 2000; Sullivan et al., 2000), but the relation to along-shelf environmental and habitat characteristics is unclear. Along-shelf patterns in juvenile fish distribution on unconsolidated sediments may occur on the southeast U.S. shelf, but at dimensions larger than 60-100 km.
Seasonal patterns in settlement and postsettlement movement both defined and blurred classification of juvenile fish assemblages on the Georgia shelf. Many of the resident shelf species were consistently collected in the same cross-shelf regions (i.e., inner and mid-shelf: Ophidion selenops, Prionotus carolinus, Dactyloscopus moorei, Stenotomus sp., and Serraniculus pumilio; outer-shelf: Symphurus minor, Serranus phoebe, Centropristis ocyurus, and Bothus lunatus), and the consistent collection of these species helped form a definition of juvenile assemblages. Other resident species shifted juvenile assemblages (e.g., Diplectrum formosum, Monacanthus hispidus, Bothus robinsi, Otophidium omostigmum, and Bothus ocellatus), possibly because of seasonal changes in settlement patterns or ontogenetic postsettlement movements, with the result that some classifications were blurred. Four scieanid species, present during the spring, summer, and fall as larvae (Marancik et al., 2005), were collected during the fall as juveniles and contributed to defining the fall inner-shelf (Larimus fasciatus and Menticirrhus americanus) and mid-shelf (Cynosion nothus and C. regalis) juvenile assemblages. These species may shift settlement or juvenile habitat (or both) between estuaries and the coastal ocean; this shift has been shown to occur off the coast of New Jersey (Able et al., 2003; Neuman and Able, 2003). Further, a number of species in the ecosystem spawn on the shelf yet use estuarine habitats as juvenile nurseries (Warlen and Burke, 1990; Able and Fahay, 1998). In our study, settlement stage L. xanthurus, Brevoortia tyrannus, and Lagodon rhomboides were collected on the shelf, and contributed to the definition of the inner- and mid-shelf assemblages. Some individuals of these estuarine-dependent species may not settle directly into estuarine habitats as has been demonstrated for Centropristis striata off the coast of New Jersey (Able and Fahay, 1998).
Only a few reef-associated species collected during the study used unconsolidated sediments consistently. Centropristis ocyurus, Diplectrum formosum, and Stenotomus sp. were the most common reef fishes collected on unconsolidated sediments, and made up >1% of the total catch (Appendix). Other less frequently occurring juveniles of important reef-associated species that were collected were Centropristis striata, Epinephelus niveatus, Pristigenys alta, Priacanthus arenatus, and Lutjanus analis.
Reef-associated species were collected across the entire shelf. Centropristis ocyurus and Stenotomus sp. were commonly collected on the outer-, inner-, and mid-shelves, respectively (Table 2, Appendix). Centropristis striata, which uses habitats in estuaries and coastal regions as juveniles (Able and Fahay, 1998), was collected on the inner- and mid-shelf in the spring and summer, during periods of high settlement (Able and Hales, 1997). The presence of many reef-associated species at the deeper (50 m) stations (Table 4) may indicate greater use of offshore unconsolidated sediments by reef-associated species or that sampling was done in an area closer to rocky-reefs. Several species of the South Atlantic Fishery Management Council snapper-grouper complex have been reported to use a variety of nonreef habitats as newly settled juveniles, including unconsolidated sediments on the shelf (Lindeman et al., 2000). Many coral reef fish also use several types of nearshore nonreef habitat as juveniles (de la Moriniere et al., 2002; Nagelkerken and van der Velde, 2002). These nonreef habitats are assumed to be important nursery habitats; however, strong evidence of movement from juvenile to adult habitats has been documented only for a few reef-associated fishes (Gillanders et al., 2003). The fact that reef-associated species also use unconsolidated sediments indicates there is an interdependence between reef habitats and unconsolidated sediments; yet the function of each habitat remains unquantified.
In addition to reef species, a number of commercially and recreationally important demersal species used unconsolidated sediments on the shelf off Georgia as juvenile habitat. Juvenile Cynoscion nothus, C. regalis and Menticirrhus americanus were collected on the inner- and mid-shelves in the fall, and settlement-size Leiostomus xanthurus were collected in the winter. However, small noncommercial demersal species were the most abundant juveniles collected during beam trawl sampling.
Much of the southeast U.S. continental shelf is impacted by trawl fisheries that can adversely impact unconsolidated sediments (Barnette (3)). Current management concerns focus primarily on bycatch reduction, impacts on stock assessments of commercially and recreationally important finfish, and destruction of coral, live hard-bottom, and SAV habitat (NOAA (8); Barnette (3)). The presence of reef-associated and sciaenid species in our samples indicate that the unconsolidated sediments of the shelf are potentially important habitats for early life stages, and that trawl fisheries on the shelf may impact the population dynamics of these species. Equally important may be the ecological effects on the small noncommercial demersal species that dominate the catch on unconsolidated sediments and that are abundant in the shrimp trawl bycatch (SAFMC, 1996).
Unconsolidated sediments serve as juvenile habitat for a number of species in the southeast U.S. shelf ecosystem. Some species use unconsolidated sediments throughout their life history, but for a number of species, unconsolidated sediments serve as only one of a mosaic of habitats through the life history (see Browman and Konstantinos, 2004). Additionally, there is growing recognition of the importance of unconsolidated sediments in the trophic ecology of the southeast U.S. shelf. Benthic primary production of the shelf has been shown to be 4-6 times greater than water-column production at specific locations (Nelson et al., 1999). Unconsolidated sediments are areas of reef fish feeding (Sedberry, 1985, 1990) and several important fish predators inhabit unconsolidated sediments (triglids, synodontids, Ross, 1976; Richards et al., 1979). Current ecosystem approaches to fisheries (see Sissenwine and Murawski, 2004) in the region largely ignore unconsolidated sediments (SAFMC, 1998, 2001), and although the importance of this habitat to juvenile fish production remains unquantified (sensu Beck et al., 2001), management efforts would be improved through a greater recognition of the potential importance of these habitats to fisheries production and the interconnectedness of multiple habitats in the southeast U.S. continental shelf ecosystem.
Appendix Juvenile taxa collected in beam trawl collections from the continental shelf off the coast of Georgia, USA. Seasonal catch per unit of effort (CPUE, fish/5 min) was calculated from cross-shelf stations (see Fig. 1 and Table 1). Mean (SD) of the total CPUE and standard length (SL, mm) was calculated from all stations. Adult distributions (AD) and whether species are reef-associated (RA) was determined from the literature. E = estuarine, C = coastal (0-20 m), O = open-shelf (20-70 m), Sl= slope (>70 m), W = weakly reef-associated, and S = strongly reef-associated. Cross-shelf stations Mean Family Species Spring Summer Fall Winter Elopidae Elops saurus 0.02 0.01 Muraenidae Gymnothorax saxicola Ophichthidae Ophichthus gomesii 0.01 Ophichthus ocellatus 0.05 0.03 0.02 Congridae Ariosoma balearicum 0.39 0.10 0.30 0.02 Clupeidae Brevoortia tyrannus 0.07 Etrumeus teres 0.02 0.01 Sardinella aurita 0.01 Engraulididae Anchoa hepsetus 0.09 0.19 1.14 Anchoa lamprotaena 0.07 Argentinidae Argentina striata 0.02 Synodontidae Synodus foetens 1.00 0.45 1.55 0.39 Synodus poeyi 0.26 Trachinocephalus myops 0.13 0.06 0.22 0.06 Gadidae Urophycis regia 0.28 0.68 Ophidiidae Ophidion grayi 0.02 Ophidion holbrooki 0.70 Ophidian marginatum 0.11 0.03 0.01 0.03 Ophidion selenops 3.63 0.35 4.92 1.49 Ophidion welshi 0.12 0.02 Otophidium omostigmum 0.60 0.09 0.69 0.38 Batrachoididae Porichtys plectrodon 0.03 Antennariidae Antennarius ocellatus Antennarius radiosus 0.02 Ogcocephalidae Halieutichthys aculeatus 0.02 0.04 Ogcocephalus nasutus 0.02 0.05 0.01 Ogcocephalus parvus 0.02 Exocetidae Hemiramphus balao 0.02 Hemiramphus brasilieusis 0.01 Hirundichthys affinis 0.05 0.02 Parexocoetus brachypterus 0.02 Syngnathidae Hippocampus erectus 0.12 0.04 0.01 0.04 Syngnathus scovelli 0.06 0.02 Syngnathus springeri 0.02 0.01 0.07 Scorpaenidae Scorpaena dispar 0.02 0.07 Scorpaena plumieri 0.07 0.13 0.08 0.02 Triglidae Prionotus spp. 0.73 0.17 15.31 0.52 Bellator brachychir 0.01 0.01 Bellator militaris 0.01 0.01 Prionotus carolinus 3.04 0.32 0.42 1.08 Prionotus evolans 0.03 Prionotus ophryas 0.01 Prionotus scitulus 0.08 Serranidae Centropristis ocyurus 0.73 0.04 0.08 Centropristis striata 0.07 0.04 Diplectrum formosum 0.96 2.50 2.39 0.16 Epinephelus niveatus Serraniculus pumilio 0.03 0.21 0.34 0.12 Serranus phoebe 0.31 0.04 0.02 0.04 Serranus subligarius Grammistidae Rypticus app. 0.01 Rypticus bistrispinus Priacanthidae Priacanthus arenatus 0.01 Pristigenys alta 0.02 0.05 Apogonidae Apogon sp. 0.01 0.03 Astrapogon spp./ Epigonus spp. 0.01 Apogon maculatus Apogon pseudomaculatus 0.04 Carangidae Carangidae 0.02 Decapterus spp. 0.14 Caranx bartholomaei 0.02 Caranx crysos 0.02 Chloroscombrus chrysurus 0.01 0.06 Decapterus macarellus 0.02 0.01 Decapterus punctatus 0.05 0.01 Trachurus lathami 0.02 Lutjanidae Lutjanus analis 0.01 Haemulidae Haemulon aurolineatum 0.05 0.05 Sparidae Stenotomus sp. 0.18 0.16 0.14 0.08 Lagodon rhomboides 0.06 Sciaenidae Cynoscion nothus 0.04 Cynoscion regalis 0.06 Larimus fasciatus 0.19 Leiostomus xanthurus 2.27 Menticirrhus americanus 0.07 Stellifer laceolatus Mullidae Upeneus parvus Mugilidae Mugil cephalus 0.18 Mugil curema 0.01 0.02 Labridae Halichoeres bivittatus 0.02 Xyrichtys novacula 0.01 Scaridae Scaridae 0.03 Uranoscopidae Kathetostoma albigutta 0.01 Dactylosco- Dactyloscopus pidae moorei 0.80 0.17 2.09 0.80 Blenniidae Chasmodes/ Parablennius marmoreus 0.04 Hypleurochilus geminatus 0.04 0.01 Parablennius marmoreus 0.02 Callionymidae Diplogrammus pauciradiatus 0.07 Gobiidae Microgobius spp. 0.06 0.82 1.42 0.01 Gobiosoma bosci 0.01 Gobiosoma ginsburgi 0.02 loglossus calliurus 0.01 Stromateidae Peprilus triacanthus 0.07 0.01 0.08 Bothidae Bothus ocellatus/ robinsi 0.07 0.08 0.07 Bothus spp. 0.86 0.41 4.50 0.33 Bothus lunatus 0.02 0.01 Bothus ocellatus 0.03 0.04 0.01 Bothus robinsi 1.21 0.23 0.52 0.34 Paralich- Citharichthys spp. 0.19 0.03 0.41 thyidae Etropus spp. 8.89 1.31 2.96 15.97 Ancylopsetta quadrocellata 0.22 Citharichthys gymnorhinus 0.03 Citharichthys macrops 0.20 0.04 0.02 0.13 Cyclopsetta fimbriata 0.03 0.04 0.05 Syacium papillosum 0.02 0.09 0.04 Scopthalmidae Scopthalmus aquosus 0.01 Soleidae Gymnachirus melas 0.04 0.03 Cynoglossidae Symphurus spp. 0.01 0.02 Symphurus diomedeanus 0.05 Symphurus minor 0.26 0.25 1.87 0.15 Symphurus parvus 0.05 0.02 Symphurus plagiusa 0.02 Symphurus urospilus 0.42 0.24 0.43 0.28 Balistidae Aluterus schoepfi 0.01 0.02 Cantherhines pullus Monacanthus ciliatus 0.02 Monacanthus hispidus 0.18 0.54 1.36 0.06 Monacanthus setifer 0.01 Ostrachdae Lactophyrs quadricornis 0.01 Tetraodontidae Sphoeroides spp. 0.03 0.13 0.01 Diodontidae Chilomycterus schoepfi 0.02 All stations CPUE Family Species Mean (SD) Elopidae Elops saurus 0.007 ([+ or -] 0.084) Muraenidae Gymnothorax Ophichthidae saxicola 0.005 ([+ or -] 0.069) Ophichthus gomesii 0.009 ([+ or -] 0.119) Congridae Ophichthus Clupeidae ocellatus 0.016 ([+ or -] 0.133) Ariosoma balearicum 0.135 ([+ or -] 0.431) Brevoortia tyrannus 0.014 ([+ or -] 0.116) Engraulididae Etrumeus teres 0.005 ([+ or -] 0.069) Sardinella aurita 0.005 ([+ or -] 0.069) Argentinidae Anchoa hepsetus 0.355 ([+ or -] 2.631) Synodontidae Anchoa lamprotaena 0.015 ([+ or -] 0.215) Argentina striata 0.005 ([+ or -] 0.069) Synodus foetens 0.643 ([+ or -] 1.570) Synodus poeyi 0.035 ([+ or -] 0.420) Gadidae Trachinocephalus Ophidiidae myops 0.091 ([+ or -] 0.354) Urophycis regia 0.302 ([+ or -] 0.867) Ophidion grayi 0.002 ([+ or -] 0.049) Ophidion holbrooki 0.121 ([+ or -] 1.226) Ophidian marginatum 0.050 ([+ or -] 0.270) Ophidion selenops 1.823 ([+ or -] 4.373) Ophidion welshi 0.019 ([+ or -] 0.194) Batrachoididae Otophidium omostigmum 0.392 ([+ or -] 1.192) Antennariidae Porichtys plectrodon 0.007 ([+ or -] 0.078) Antennarius ocellatus 0.002 ([+ or -] 0.048) Ogcocephalidae Antennarius radiosus 0.010 ([+ or -] 0.102) Halieutichthys aculeatus 0.014 ([+ or -] 0.118) Ogcocephalus nasutus 0.025 ([+ or -] 0.154) Ogcocephalus parvus 0.012 ([+ or -] 0.108) Exocetidae Hemiramphus balao 0.003 ([+ or -] 0.052) Hemiramphus brasilieusis 0.002 ([+ or -] 0.049) Hirundichthys affinis 0.017 ([+ or -] 0.146) Parexocoetus brachypterus 0.002 ([+ or -] 0.048) Syngnathidae Hippocampus erectus 0.055 ([+ or -] 0.236) Syngnathus scovelli 0.019 ([+ or -] 0.166) Syngnathus springeri 0.021 ([+ or -] 0.144) Scorpaenidae Scorpaena dispar 0.043 ([+ or -] 0.458) Scorpaena plumieri 0.078 ([+ or -] 0.335) Triglidae Prionotus spp. 2.700 ([+ or -] 9.684) Bellator brachychir 0.007 ([+ or -] 0.079) Bellator militaris 0.004 ([+ or -] 0.063) Prionotus carolinus 1.127 ([+ or -] 2.801) Prionotus evolans 0.004 ([+ or -] 0.081) Prionotus ophryas 0.002 ([+ or -] 0.049) Prionotus scitulus 0.033 ([+ or -] 0.180) Serranidae Centropristis ocyurus 0.313 ([+ or -] 1.592) Centropristis striata 0.017 ([+ or -] 0.161) Diplectrum formosum 1.360 ([+ or -] 3.378) Epinephelus niveatus 0.005 ([+ or -] 0.069) Serraniculus pumilio 0.155 ([+ or -] 0.734) Serranus phoebe 0.220 ([+ or -] 1.618) Serranus subligarius 0.007 ([+ or -] 0.146) Grammistidae Rypticus app. 0.046 ([+ or -] 0.590) Rypticus bistrispinus 0.054 ([+ or -] 0.596) Priacanthidae Priacanthus arenatus 0.002 ([+ or -] 0.049) Pristigenys alta 0.016 ([+ or -] 0.126) Apogonidae Apogon sp. 0.011 ([+ or -] 0.125) Astrapogon spp./ Epigonus spp. 0.002 ([+ or -] 0.049) Apogon maculatus 0.061 ([+ or -] 0.680) Apogon pseudomaculatus 0.028 ([+ or -] 0.213) Carangidae Carangidae 0.005 ([+ or -] 0.068) Decapterus spp. 0.031 ([+ or -] 0.278) Caranx bartholomaei 0.002 ([+ or -] 0.044) Caranx crysos 0.002 ([+ or -] 0.049) Chloroscombrus chrysurus 0.010 ([+ or -] 0.107) Decapterus macarellus 0.005 ([+ or -] 0.069) Decapterus punctatus 0.017 ([+ or -] 0.188) Trachurus lathami 0.002 ([+ or -] 0.046) Lutjanidae Lutjanus analis 0.002 ([+ or -] 0.049) Haemulidae Haemulon aurolineatum 0.016 ([+ or -] 0.185) Sparidae Stenotomus sp. 0.135 ([+ or -] 0.823) Lagodon rhomboides 0.012 ([+ or -] 0.128) Sciaenidae Cynoscion nothus 0.006 ([+ or -] 0.095) Cynoscion regalis 0.008 ([+ or -] 0.102) Larimus fasciatus 0.027 ([+ or -] 0.313) Leiostomus xanthurus 3.361 (22.193) Menticirrhus americanus 0.010 ([+ or -] 0.159) Stellifer laceolatus 0.005 ([+ or -] 0.097) Mullidae Upeneus parvus 0.002 ([+ or -] 0.049) Mugilidae Mugil cephalus 0.047 ([+ or -] 0.422) Mugil curema 0.027 ([+ or -] 0.214) Labridae Halichoeres bivittatus 0.010 ([+ or -] 0.152) Xyrichtys novacula 0.002 ([+ or -] 0.049) Scaridae Scaridae 0.009 ([+ or -] 0.093) Uranoscopidae Kathetostoma albigutta 0.002 ([+ or -] 0.049) Dactylosco- Dactyloscopus pidae moorei 0.689 ([+ or -] 2.073) Blenniidae Chasmodes/ Parablennius marmoreus 0.007 ([+ or -] 0.109) Hypleurochilus geminatus 0.021 ([+ or -] 0.160) Parablennius marmoreus 0.009 ([+ or -] 0.119) Callionymidae Diplogrammus pauciradiatus 0.025 ([+ or -] 0.170) Gobiidae Microgobius spp. 0.454 ([+ or -] 1.424) Gobiosoma bosci 0.014 ([+ or -] 0.150) Gobiosoma ginsburgi 0.005 ([+ or -] 0.068) loglossus calliurus 0.002 ([+ or -] 0.041) Stromateidae Peprilus triacanthus 0.042 ([+ or -] 0.250) Bothidae Bothus ocellatus/ robinsi 0.041 ([+ or -] 0.254) Bothus spp. 0.971 ([+ or -] 3.728) Bothus lunatus 0.005 ([+ or -] 0.069) Bothus ocellatus 0.046 ([+ or -] 0.341) Bothus robinsi 0.435 ([+ or -] 1.464) Paralich- Citharichthys spp. 0.132 ([+ or -] 0.671) thyidae Etropus spp. 10.563 ([+ or -] 20.936) Ancylopsetta quadrocellata 0.114 ([+ or -] 0.386) Citharichthys gymnorhinus 0.004 ([+ or -] 0.063) Citharichthys macrops 0.090 ([+ or -] 0.441) Cyclopsetta fimbriata 0.037 ([+ or -] 0.226) Syacium papillosum 0.040 ([+ or -] 0.269) Scopthalmidae Scopthalmus aquosus 0.002 ([+ or -] 0.049) Soleidae Gymnachirus melas 0.014 ([+ or -] 0.115) Cynoglossidae Symphurus spp. 0.005 ([+ or -] 0.067) Symphurus diomedeanus 0.007 ([+ or -] 0.109) Symphurus minor 0.552 ([+ or -] 1.878) Symphurus parvus 0.012 ([+ or -] 0.108) Symphurus plagiusa 0.029 ([+ or -] 0.270) Symphurus urospilus 0.257 ([+ or -] 0.717) Balistidae Aluterus schoepfi 0.005 ([+ or -] 0.066) Cantherhines pullus 0.012 ([+ or -] 0.128) Monacanthus ciliatus 0.005 ([+ or -] 0.069) Monacanthus hispidus 0.460 ([+ or -] 1.314) Monacanthus setifer 0.004 ([+ or -] 0.063) Ostrachdae Lactophyrs quadricornis 0.009 ([+ or -] 0.090) Tetraodontidae Sphoeroides spp. 0.126 ([+ or -] 0.600) Diodontidae Chilomycterus schoepfi 0.002 ([+ or -] 0.049) All stations SL (mm) Family Species Mean (SD) Elopidae Elops saurus 46.7 ([+ or -] 15.9) Muraenidae Gymnothorax Ophichthidae saxicola 69.5 ([+ or -] 0.7) Ophichthus gomesii 103.3 ([+ or -] 20.1) Congridae Ophichthus Clupeidae ocellatus 160.9 ([+ or -] 59.2) Ariosoma balearicum 126.5 ([+ or -] 44.2) Brevoortia tyrannus 24.5 ([+ or -] 1.8) Engraulididae Etrumeus teres 31.8 ([+ or -] 1.1) Sardinella aurita 36.0 ([+ or -] 2.8) Argentinidae Anchoa hepsetus 31.3 ([+ or -] 10.2) Synodontidae Anchoa lamprotaena 44.5 ([+ or -] 5.8) Argentina striata 52.0 ([+ or -] 1.4) Synodus foetens 65.8 ([+ or -] 40.1) Synodus poeyi 33.1 ([+ or -] 3.5) Gadidae Trachinocephalus Ophidiidae myops 92.3 ([+ or -] 47.6) Urophycis regia 69.7 ([+ or -] 21.3) Ophidion grayi 39.0 Ophidion holbrooki 98.8 ([+ or -] 47.3) Ophidian marginatum 94.8 ([+ or -] 43.0) Ophidion selenops 56.1 ([+ or -] 19.7) Ophidion welshi 107.9 ([+ or -] 27.1) Batrachoididae Otophidium omostigmum 60.0 ([+ or -] 21.8) Antennariidae Porichtys plectrodon 56.3 ([+ or -] 13.7) Antennarius ocellatus 47.0 Ogcocephalidae Antennarius radiosus 24.0 ([+ or -] 4.1) Halieutichthys aculeatus 14.4 ([+ or -] 1.5) Ogcocephalus nasutus 29.0 ([+ or -] 17.8) Ogcocephalus parvus 75.6 ([+ or -] 34.1) Exocetidae Hemiramphus balao 80.0 Hemiramphus brasilieusis 97.0 Hirundichthys affinis 35.4 ([+ or -] 13.8) Parexocoetus brachypterus 34.0 Syngnathidae Hippocampus erectus 60.8 ([+ or -] 19.9) Syngnathus scovelli 56.3 ([+ or -] 11.8) Syngnathus springeri 64.3 ([+ or -] 6.9) Scorpaenidae Scorpaena dispar 39.4 ([+ or -] 21.6) Scorpaena plumieri 43.5 ([+ or -] 31.0) Triglidae Prionotus spp. 11.6 ([+ or -] 3.3) Bellator brachychir 27.0 ([+ or -] 13.2) Bellator militaris 17.5 ([+ or -] 12.0) Prionotus carolinus 53.5 ([+ or -] 27.9) Prionotus evolans 90.0 ([+ or -] 62.2) Prionotus ophryas 16.0 Prionotus scitulus 133.3 ([+ or -] 19.4) Serranidae Centropristis ocyurus 31.0 ([+ or -] 12.0) Centropristis striata 33.1 ([+ or -] 14.8) Diplectrum formosum 28.2 ([+ or -] 23.8) Epinephelus niveatus 29.0 ([+ or -] 7.1) Serraniculus pumilio 22.5 ([+ or -] 7.5) Serranus phoebe 21.6 Serranus subligarius 30.7 ([+ or -] 9.3) Grammistidae Rypticus app. 41.8 ([+ or -] 12.9) Rypticus bistrispinus 42.5 ([+ or -] 5.2) Priacanthidae Priacanthus arenatus 15.0 Pristigenys alta 17.7 ([+ or -] 8.6) Apogonidae Apogon sp. 20.9 ([+ or -] 11.0 Astrapogon spp./ Epigonus spp. 9.2 Apogon maculatus 17.6 ([+ or -] 3.5) Apogon pseudomaculatus 18.6 ([+ or -] 14.1) Carangidae Carangidae 18.5 ([+ or -] 6.4) Decapterus spp. 24.8 ([+ or -] 5.7) Caranx bartholomaei 12.0 Caranx crysos 101.0 Chloroscombrus chrysurus 15.1 ([+ or -] 3.6) Decapterus macarellus 23.0 ([+ or -] 4.2) Decapterus punctatus 27.6 ([+ or -] 5.8) Trachurus lathami 16.0 Lutjanidae Lutjanus analis 18.0 Haemulidae Haemulon aurolineatum 45.3 ([+ or -] 26.8) Sparidae Stenotomus sp. 46.1 ([+ or -] 28.4) Lagodon rhomboides 27.1 ([+ or -] 27.9) Sciaenidae Cynoscion nothus 9.8 ([+ or -] 0.9) Cynoscion regalis 10.3 ([+ or -] 0.8) Larimus fasciatus 14.7 ([+ or -] 4.7) Leiostomus xanthurus 16.2 ([+ or -] 1.7) Menticirrhus americanus 13.3 ([+ or -] 9.1) Stellifer laceolatus 75.0 ([+ or -] 0.0) Mullidae Upeneus parvus 48.0 Mugilidae Mugil cephalus 21.7 ([+ or -] 2.3) Mugil curema 21.8 ([+ or -] 1.5) Labridae Halichoeres bivittatus 71.0 ([+ or -] 5.0) Xyrichtys novacula 41.5 Scaridae Scaridae 41.3 ([+ or -] 31.8) Uranoscopidae Kathetostoma albigutta 26.0 Dactylosco- Dactyloscopus pidae moorei 22.1 ([+ or -] 5.1) Blenniidae Chasmodes/ Parablennius marmoreus 19.0 ([+ or -] 2.6) Hypleurochilus geminatus 43.6 ([+ or -] 17.2) Parablennius marmoreus 20.3 ([+ or -] 4.3) Callionymidae Diplogrammus pauciradiatus 9.5 ([+ or -] 1.0) Gobiidae Microgobius spp. 16.7 ([+ or -] 1.9) Gobiosoma bosci 19.5 ([+ or -] 1.5) Gobiosoma ginsburgi 22.5 ([+ or -] 3.5) loglossus calliurus 14.7 Stromateidae Peprilus triacanthus 25.3 ([+ or -] 11.7) Bothidae Bothus ocellatus/ robinsi 15.9 ([+ or -] 2.6) Bothus spp. 18.4 ([+ or -] 3.0) Bothus lunatus 79.0 ([+ or -] 9.9) Bothus ocellatus 33.4 ([+ or -] 23.5) Bothus robinsi 37.3 ([+ or -] 35.7) Paralich- Citharichthys spp. 13.7 ([+ or -] 6.0) thyidae Etropus spp. 18.3 ([+ or -] 8.2) Ancylopsetta quadrocellata 38.1 ([+ or -] 17.7) Citharichthys gymnorhinus 18.5 ([+ or -] 7.8) Citharichthys macrops 76.9 ([+ or -] 44.8) Cyclopsetta fimbriata 28.9 ([+ or -] 14.5) Syacium papillosum 16.5 ([+ or -] 17.2) Scopthalmidae Scopthalmus aquosus 14.0 Soleidae Gymnachirus melas 17.1 ([+ or -] 7.5) Cynoglossidae Symphurus spp. 18.0 ([+ or -] 9.9) Symphurus diomedeanus 22.5 ([+ or -] 17.7) Symphurus minor 23.8 ([+ or -] 4.2) Symphurus parvus 15.9 ([+ or -] 1.7) Symphurus plagiusa 59.9 ([+ or -] 16.5) Symphurus urospilus 55.5 ([+ or -] 20.8) Balistidae Aluterus schoepfi 18.0 ([+ or -] 11.3) Cantherhines pullus 18.5 ([+ or -] 1.5) Monacanthus ciliatus 41.0 ([+ or -] 26.9) Monacanthus hispidus 34.4 ([+ or -] 22.6) Monacanthus setifer 91.0 ([+ or -] 0.0) Ostrachdae Lactophyrs quadricornis 67.8 ([+ or -] 83.6) Tetraodontidae Sphoeroides spp. 15.9 ([+ or -] 4.0) Diodontidae Chilomycterus schoepfi 17.0 Family Species AD RA Elopidae Elops saurus E, C Muraenidae Gymnothorax Ophichthidae saxicola C, O Ophichthus gomesii E, C, O Congridae Ophichthus Clupeidae ocellatus E, C, O Ariosoma balearicum E, C, O Brevoortia tyrannus E, C, O Engraulididae Etrumeus teres C, O Sardinella aurita C, O Argentinidae Anchoa hepsetus E, C, O Synodontidae Anchoa lamprotaena C Argentina striata Sl Synodus foetens E, C, O Synodus poeyi O Gadidae Trachinocephalus Ophidiidae myops O Urophycis regia C, O Ophidion grayi C, O Ophidion holbrooki C, O Ophidian marginatum C, O Ophidion selenops O Ophidion welshi C, O Batrachoididae Otophidium omostigmum O Antennariidae Porichtys plectrodon C, O Antennarius ocellatus O, Sl W Ogcocephalidae Antennarius radiosus O, Sl W Halieutichthys aculeatus C, O Ogcocephalus nasutus C, O Ogcocephalus parvus O Exocetidae Hemiramphus balao C, O Hemiramphus brasilieusis C, O Hirundichthys affinis C, O Parexocoetus brachypterus O Syngnathidae Hippocampus erectus E, C Syngnathus scovelli E, C Syngnathus springeri C, O Scorpaenidae Scorpaena dispar C, O W Scorpaena plumieri C, O W Triglidae Prionotus spp. C, O Bellator brachychir O Bellator militaris O Prionotus carolinus E, C, O Prionotus evolans E, C, O Prionotus ophryas C, O Prionotus scitulus C, O Serranidae Centropristis ocyurus O W Centropristis striata E, C, O S Diplectrum formosum C, O W Epinephelus niveatus Sl S Serraniculus pumilio C, O W Serranus phoebe C, O W Serranus subligarius C, O S Grammistidae Rypticus app. C, O S Rypticus bistrispinus C, O S Priacanthidae Priacanthus arenatus O S Pristigenys alta O S Apogonidae Apogon sp. O W Astrapogon spp./ Epigonus spp. Apogon maculatus O W Apogon pseudomaculatus O W Carangidae Carangidae Decapterus spp. O Caranx bartholomaei C, O Caranx crysos C, O W Chloroscombrus chrysurus C, O W Decapterus macarellus O Decapterus punctatus C, O Trachurus lathami C, O Lutjanidae Lutjanus analis C, O S Haemulidae Haemulon aurolineatum C, O W Sparidae Stenotomus sp. C, O W Lagodon rhomboides E, C, O W Sciaenidae Cynoscion nothus E, C Cynoscion regalis E, C Larimus fasciatus E, C Leiostomus xanthurus E, C, O Menticirrhus americanus E, C Stellifer laceolatus E, C Mullidae Upeneus parvus C, O Mugilidae Mugil cephalus E, C, O Mugil curema E, C, O Labridae Halichoeres bivittatus O S Xyrichtys novacula O Scaridae Scaridae Uranoscopidae Kathetostoma albigutta O Dactylosco- Dactyloscopus pidae moorei O Blenniidae Chasmodes/ Parablennius marmoreus E, C S Hypleurochilus geminatus E, C Parablennius marmoreus E, C S Callionymidae Diplogrammus pauciradiatus O Gobiidae Microgobius spp. Gobiosoma bosci E, C Gobiosoma ginsburgi E, C W loglossus calliurus C, O Stromateidae Peprilus triacanthus C, O Bothidae Bothus ocellatus/ robinsi Bothus spp. O Bothus lunatus E, C, O Bothus ocellatus C, O Bothus robinsi C, O Paralich- Citharichthys spp. thyidae Etropus spp. Ancylopsetta quadrocellata C, O Citharichthys gymnorhinus O Citharichthys macrops C, O Cyclopsetta fimbriata O Syacium papillosum C, O Scopthalmidae Scopthalmus aquosus E, C, O Soleidae Gymnachirus melas O Cynoglossidae Symphurus spp. Symphurus diomedeanus O Symphurus minor O Symphurus parvus O Symphurus plagiusa E, C, O Symphurus urospilus O Balistidae Aluterus schoepfi C, O W Cantherhines pullus S Monacanthus ciliatus Monacanthus hispidus C, O Monacanthus setifer O Ostrachdae Lactophyrs quadricornis O W Tetraodontidae Sphoeroides spp. Diodontidae Chilomycterus schoepfi E, C
We would like to thank all who helped with sample collections, sorting, and analyses: G. Bohne, R. Bohne, C. Bonn, J. Burke, M. Burton, B. Degan, M. Duncan, J. Govoni, M. Greene, E. Jugovich, S. Lem, J. Loefer, R. Mays, G. McFall, R. McNatt, A. Powell, R. Rogers, S. Shoffler, S. Varnam, and T. Zimanski. We would like to thank NOAA's Undersea Research Center at the University of North Carolina at Wilmington for use of the ROV and L. Horn for operating the ROV. We appreciate the hard work and dedication of the officers and crew of the NOAA Ship Ferrel, NOAA Ship Jane Yarn, NOAA Ship Oregon II, and RV Cape Fear. We would also like to thank A. Powell, M. Sullivan, J. Merriner, and an anonymous reviewer for their comments on previous drafts. Gray's Reef National Marine Sanctuary, the National Marine Sanctuary Office, and Center for Coastal Fisheries and Habitat Research provided funding for the project.
Manuscript submitted 26 October 2004 to the Scientific Editor's Office.
Manuscript approved for publication 25 August 2005 by the Scientific Editor.
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Harvey J. Walsh
Katrin E. Marancik
Jonathan A. Hare
NOAA, NOS, NCCOS
Center for Coastal Fisheries and Habitat Research
101 Pivers Island Road
Beaufort, North Carolina 28516
Present address (for H. J. Walsh): Biology Department MS #50
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts 02543
E-mail address (for H. J. Walsh): firstname.lastname@example.org
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Table 1 Number of beam trawl stations sampled off the coast of Georgia for juvenile fish. Station groups correspond to the station locations in Figure 1. Station group Year Month Dates Season Cross-shelf Inshore Offshore 2000 April 24-27 spring 9 June 19-22 summer 9 August 15-17 summer 9 October 03-07 fall 10 2001 Jan/Feb 30-01 wnter 10 March 21-23 winter 10 Apr/May 30-04 spring 10 11 June 04-09 summer 10 August 03-06 summer 10 September 07-09 fall 6 October 11-13 fall 10 2002 February 08-13 winter 10 10 10 Table 2 Taxa collected by beam trawl during two years of sampling (April 2000-February 2002) at the cross-shelf stations (see Fig. 1A) off the coast of Georgia, and used in correspondence analysis. Mean and standard deviation (SD) of catch per unit of effort (CPUE) were calculated for the entire data set. Taxa that constituted one or ten percent of any one station were used in the analyses, and an asterisk next to a taxon indicates that it was in the 10% data set. Seasonal juvenile assemblages from correspondence analysis are shown (I = inner-shelf; I/M = inner-/mid-shelf; M = mid-shelf; O-outer-shelf; and S = entire shelf: S). Taxa in bold indicate reef-associated species. CPUE Family Taxon Mean SD Elopidae Elops saurus 0.010 0.097 Ophichthidae Ophichthus gomesii 0.003 0.056 Ophichthus ocellatus 0.021 0.155 Congridae Ariosoma balearicum * 0.163 0.479 Clupeidae Brevoortia tyrannus 0.019 0.134 Etrumeus teres 0.006 0.080 Sardinella aurita 0.003 0.056 Engraulididae Anchoa hepsetus * 0.303 1.313 Anchoa lamprotaena 0.013 0.237 Argentinidae Argentina striata 0.006 0.080 Synodontidae Synodus foetens * 0.746 1.626 Synodus poeyi 0.048 0.487 Trachinocephalus myops 0.103 0.388 Gadidae Urophycis regia * 0.234 0.759 Ophidiidae Ophidion selenops * 2.185 4.844 Otophidium omostigmum * 0.364 1.190 Batrachoididae Porichtys plectrodon 0.006 0.072 Antennariidae Antennarius radiosus# 0.006 0.080 Ogcocephalidae Halieutichthys aculeatus 0.019 0.137 Ogcocephalus nasutus 0.024 0.150 Exocoetidae Hemiramphus brasilieusis 0.003 0.056 Hirundichthys affinis 0.022 0.169 Syngnathidae Hippocampus erectus 0.052 0.233 Syngnathus scovelli * 0.025 0.192 Syngnathus springeri 0.025 0.158 Scorpaenidae Scorpaena dispar# 0.019 0.161 Scorpaena plumieri *# 0.080 0.332 Triglidae Bellator brachychir 0.006 0.074 Bellator militaris 0.006 0.073 Prionotus carolinus * 1.047 2.970 Prionotus ophryas 0.003 0.056 Prionotus scitulus 0.022 0.146 Serranidae Centropristis ocyurus *# 0.167 1.344 Centropristis striata# 0.022 0.186 Diplectrum formosum *# 1.556 3.659 Serraniculus pumilio# 0.180 0.817 Serranus phoebe *# 0.085 0.466 Priacanthidae Priacanthus arenatus# 0.003 0.056 Apogonidae Pristigenys alta# 0.016 0.123 Apogon pseudomaculatus# 0.012 0.108 Carangidae Caranx bartholomaei 0.003 0.051 Chloroscombrus chrysurus# 0.014 0.124 Decapterus macarellus 0.006 0.080 Decapterus punctatus * 0.022 0.218 Trachurus lathami 0.003 0.054 Lutjanidae Lutjanus analis# 0.003 0.056 Haemulidae Haemulon aurolineatum * 0.022 0.214 Sparidae Stenotomus sp *# 0.119 0.811 Lagodon rhomboides# 0.016 0.149 Sciaenidae Cynosion nothus 0.009 0.110 Cynosion regalis 0.011 0.118 Larimus fasciatus *# 0.036 0.363 Leiostomus xanthurus * 0.621 3.752 Menticirrhus americanus 0.013 0.185 Mugilidae Mugil cephalus * 0.051 0.469 Mugil curema 0.010 0.099 Labridae Halichoeres biuattatus# 0.006 0.113 Xyrichtys novacula 0.003 0.056 Uranoscopidae Kathetostoma albigutta 0.003 0.056 Dactyloscopidae Dactyloscopus moorei * 0.837 2.329 Blenniidae Hypleurochilus geminatus 0.010 0.126 Parablennius marmoreus *# 0.006 0.080 Callionymidae Diplogrammus pauciradiatus * 0.025 0.174 Gobiidae Ioglossus calliurus 0.003 0.047 Stromateidae Peprilus triacanthus 0.038 0.218 Bothidae Bothus lunatus 0.006 0.080 Bothus ocellatus 0.021 0.155 Bothus robinsi * 0.497 1.643 Paralichthyidae Ancylcopsetta quadrocellata 0.063 0.300 Citharichthys macrops 0.096 0.475 Cyclopsetta fimbriata 0.031 0.184 Syacium papillosum * 0.042 0.282 Soleidae Gymnachirus melas * 0.019 0.134 Cynoglossidae Symphurus diomedeanus 0.010 0.126 Symphurus minor * 0.519 1.801 Symphurus parvus 0.016 0.125 Symphurus plagiusa 0.006 0.113 Symphurus urospilus * 0.324 0.806 Balistidae Aluterus schoepfi# 0.006 0.076 Monocanthus hispidus * 0.504 1.424 Monocanthus setifer 0.003 0.047 Ostrachdae Lactophyrs quadricornis# 0.005 0.068 Seasonal juvenile assemblage Family Taxon Spring Summer Elopidae Elops saurus S Ophichthidae Ophichthus gomesii S Ophichthus ocellatus I/M S Congridae Ariosoma balearicum * I/M S Clupeidae Brevoortia tyrannus Etrumeus teres Sardinella aurita S Engraulididae Anchoa hepsetus * I/M S Anchoa lamprotaena Argentinidae Argentina striata Synodontidae Synodus foetens * I/M, O S Synodus poeyi O Trachinocephalus myops O S Gadidae Urophycis regia * I/M Ophidiidae Ophidion selenops * I/M S Otophidium omostigmum * O S Batrachoididae Porichtys plectrodon Antennariidae Antennarius radiosus# Ogcocephalidae Halieutichthys aculeatus O S Ogcocephalus nasutus I/M S Exocoetidae Hemiramphus brasilieusis S Hirundichthys affinis S Syngnathidae Hippocampus erectus I/M S Syngnathus scovelli * S Syngnathus springeri I/M S Scorpaenidae Scorpaena dispar# S Scorpaena plumieri *# I/M S Triglidae Bellator brachychir S Bellator militaris O S Prionotus carolinus * I/M S Prionotus ophryas S Prionotus scitulus Serranidae Centropristis ocyurus *# O S Centropristis striata# I/M S Diplectrum formosum *# O S Serraniculus pumilio# I/M S Serranus phoebe *# O S Priacanthidae Priacanthus arenatus# S Apogonidae Pristigenys alta# S Apogon pseudomaculatus# S Carangidae Caranx bartholomaei O Chloroscombrus chrysurus# S Decapterus macarellus O Decapterus punctatus * S Trachurus lathami I/M Lutjanidae Lutjanus analis# S Haemulidae Haemulon aurolineatum * S Sparidae Stenotomus sp *# I/M S Lagodon rhomboides# Sciaenidae Cynosion nothus Cynosion regalis Larimus fasciatus *# Leiostomus xanthurus * Menticirrhus americanus Mugilidae Mugil cephalus * Mugil curema Labridae Halichoeres biuattatus# S Xyrichtys novacula S Uranoscopidae Kathetostoma albigutta Dactyloscopidae Dactyloscopus moorei * I/M S Blenniidae Hypleurochilus geminatus I/M S Parablennius marmoreus *# S Callionymidae Diplogrammus pauciradiatus * S Gobiidae Ioglossus calliurus O S Stromateidae Peprilus triacanthus I/M Bothidae Bothus lunatus O Bothus ocellatus S Bothus robinsi * O S Paralichthyidae Ancylcopsetta quadrocellata Citharichthys macrops I/M S Cyclopsetta fimbriata O S Syacium papillosum * I/M S Soleidae Gymnachirus melas * O S Cynoglossidae Symphurus diomedeanus O Symphurus minor * O S Symphurus parvus O S Symphurus plagiusa S Symphurus urospilus * I/M S Balistidae Aluterus schoepfi# S Monocanthus hispidus * I/M S Monocanthus setifer Ostrachdae Lactophyrs quadricornis# S Seasonal juvenile assemblage Family Taxon Fall Winter Elopidae Elops saurus M Ophichthidae Ophichthus gomesii Ophichthus ocellatus M M Congridae Ariosoma balearicum * M M Clupeidae Brevoortia tyrannus M Etrumeus teres M Sardinella aurita Engraulididae Anchoa hepsetus * M Anchoa lamprotaena M Argentinidae Argentina striata O Synodontidae Synodus foetens * M M Synodus poeyi Trachinocephalus myops M,O O Gadidae Urophycis regia * M Ophidiidae Ophidion selenops * M M Otophidium omostigmum * O M Batrachoididae Porichtys plectrodon M Antennariidae Antennarius radiosus# M, O Ogcocephalidae Halieutichthys aculeatus Ogcocephalus nasutus I Exocoetidae Hemiramphus brasilieusis Hirundichthys affinis M Syngnathidae Hippocampus erectus M I, M, O Syngnathus scovelli * I Syngnathus springeri M Scorpaenidae Scorpaena dispar# M Scorpaena plumieri *# M M Triglidae Bellator brachychir O Bellator militaris Prionotus carolinus * M M Prionotus ophryas Prionotus scitulus M Serranidae Centropristis ocyurus *# O Centropristis striata# Diplectrum formosum *# M, O M Serraniculus pumilio# M M Serranus phoebe *# O O Priacanthidae Priacanthus arenatus# Apogonidae Pristigenys alta# M Apogon pseudomaculatus# Carangidae Caranx bartholomaei Chloroscombrus chrysurus# M Decapterus macarellus M Decapterus punctatus * M Trachurus lathami Lutjanidae Lutjanus analis# Haemulidae Haemulon aurolineatum * O Sparidae Stenotomus sp *# M M Lagodon rhomboides# M Sciaenidae Cynosion nothus M Cynosion regalis M Larimus fasciatus *# I Leiostomus xanthurus * I Menticirrhus americanus I Mugilidae Mugil cephalus * O Mugil curema M Labridae Halichoeres biuattatus# Xyrichtys novacula Uranoscopidae Kathetostoma albigutta M Dactyloscopidae Dactyloscopus moorei * M M Blenniidae Hypleurochilus geminatus Parablennius marmoreus *# Callionymidae Diplogrammus pauciradiatus * Gobiidae Ioglossus calliurus Stromateidae Peprilus triacanthus M Bothidae Bothus lunatus O Bothus ocellatus M O Bothus robinsi * M O Paralichthyidae Ancylcopsetta quadrocellata M Citharichthys macrops M M Cyclopsetta fimbriata M Syacium papillosum * O Soleidae Gymnachirus melas * Cynoglossidae Symphurus diomedeanus Symphurus minor * O O Symphurus parvus Symphurus plagiusa Symphurus urospilus * M M Balistidae Aluterus schoepfi# M Monocanthus hispidus * M O Monocanthus setifer O Ostrachdae Lactophyrs quadricornis# Note: Taxa in bold indicate reef-associated species indicated with #. Table 3 Taxa collected by beam trawl during spring and winter sampling at stations inshore of Gray's Reef National Marine Sanctuary (see Fig. 1B), and used in correspondence analysis. Mean and standard deviation (SD) of catch per unit of effort (CPUE) were calculated for the entire data set. Taxa that constituted one or five percent of any one station were used in the analyses, and an asterisk next to a taxon indicates that it was in the 5% data set. Station depth groups for each season for juvenile assemblages, as determined from correspondence analysis, are shown. Taxa in bold indicate reef-associated species. CPUE Family Taxon Mean SD Congridae Ariosoma balearicum * 0.022 0.147 Clupeidae Sardinella aurita 0.011 0.105 Engraulididae Anchoa hepsetus * 0.613 5.135 Anchoa lamprotaena 0.022 0.147 Synodontidae Synodus foetens * 0.416 1.525 Gadidae Urophycis regia * 0.718 1.176 Ophidiidae Ophidion selenops * 0.794 1.867 Ogcocephalidae Ogcocephalus nasutus 0.011 0.105 Syngnathidae Hippocampus erectus 0.098 0.333 Scorpaenidae Scorpaena plumieri# 0.044 0.206 Triglidae Prionotus carolinus * 2.227 2.939 Prionotus scitulus 0.122 0.332 Serranidae Centropristis ocyurus# 0.022 0.147 Diplectrum formosum *# 0.099 0.366 Sparidae Stenotomus sp. *# 0.261 0.949 Sciaenidae Leiostomus xanthurus * 14.053 46.103 Stellifer laceolatus 0.022 0.210 Mullidae Upeneus parvus 0.011 0.105 Dactyloscopidae Dactyloscopus moorei * 0.545 1.108 Gobiidae Gobiosoma bosci 0.053 0.303 Stromateidae Peprilus triacanthus * 0.076 0.370 Bothidae Bothus ocellatus 0.010 0.095 Paralichthyidae Ancylcopsetta quadrocellata 0.344 0.604 Citharichthys macrops 0.088 0.353 Cynoglossidae Symphurus plagiusa * 0.112 0.538 Symphurus urospilus 0.109 0.403 Balistidae Monocanthus hispidus * 0.154 0.445 Ostraciidae Lactophyrs quadricornis# 0.011 0.105 Juvenile assemblage Family Taxon Spring Winter Congridae Ariosoma balearicum * 12-15 m Clupeidae Sardinella aurita 12-15 m Engraulididae Anchoa hepsetus * 8 m 8 m Anchoa lamprotaena 8 m 8 m Synodontidae Synodus foetens * 12-15 m 12-15 m Gadidae Urophycis regia * 12-15 m 12-15 m Ophidiidae Ophidion selenops * 12-15 m 12-15 m Ogcocephalidae Ogcocephalus nasutus 12-15 m Syngnathidae Hippocampus erectus 12-15 m 12-15 m Scorpaenidae Scorpaena plumieri# 12-15 m 12-15 m Triglidae Prionotus carolinus * 12-15 m 12-15 m Prionotus scitulus 12-15 m Serranidae Centropristis ocyurus# 12-15 m Diplectrum formosum *# 12-15 m 12-15 m Sparidae Stenotomus sp. *# 12-15 m 12-15 m Sciaenidae Leiostomus xanthurus * 8 m Stellifer laceolatus 8 m Mullidae Upeneus parvus 12-15 m Dactyloscopidae Dactyloscopus moorei * 12-15 m 12-15 m Gobiidae Gobiosoma bosci 12-15 m Stromateidae Peprilus triacanthus * 12-15 m Bothidae Bothus ocellatus 12-15 m Paralichthyidae Ancylcopsetta quadrocellata 8 m 12-15 m Citharichthys macrops 8 m 12-15 m Cynoglossidae Symphurus plagiusa * 8 m Symphurus urospilus 12-15 m 12-15 m Balistidae Monocanthus hispidus * 12-15 m 12-15 m Ostraciidae Lactophyrs quadricornis# 8 m Note: Taxa in bold indicate reef-associated species indicated with #. Table 4 Taxa collected by beam trawl during fall and winter sampling at stations offshore of Gray's Reef National Marine Sanctuary (see Fig. 1C), and used in correspondence analysis. Mean and standard deviation (SD) of catch per unit of effort (CPUE) were calculated for the entire data set. Taxa that constituted one or ten percent of any one station were used in the analyses, and an asterisk next to a taxon indicates that it was in the 10% data set. Station depth groups for each season for juvenile assemblages, as determined from correspondence analysis, are shown. Taxa in bold indicate reef-associated species. CPUE Family Taxon Mean SD Muraenidae Gymnothorax saxicola 0.024 0.155 Ophichthidae Ophichthus gomesii 0.036 0.246 Congridae Ariosoma balearicum 0.183 0.485 Synodontidae Synodus foetens * 0.410 0.980 Trachinocephalus myops 0.147 0.391 Ophidiidae Ophidion selenops * 0.813 2.289 Otophidium omostigmum * 0.957 1.401 Batrachoididae Porichtys plectrodon 0.012 0.105 Antennariidae Antennarius ocellatus# 0.012 0.109 Antennarius radiosus# 0.039 0.203 Ogcocephalidae Ogcocephalus nasutus 0.059 0.233 Ogcocephalus parvus 0.024 0.154 Syngnathidae Hippocampus erectus 0.024 0.154 Scorpaenidae Scorpaena dispar *# 0.152 0.989 Scorpaena plumieri# 0.137 0.510 Triglidae Bellator brachychir 0.012 0.109 Prionotus carolinus * 0.360 0.785 Prionotus scitulus 0.024 0.153 Serranidae Centropristis ocyurus *# 0.998 2.381 Diplectrum formosum *# 2.305 4.132 Epinephelus niveatus# 0.024 0.155 Serraniculus pumilio *# 0.206 0.579 Serranus phoebe *# 0.857 3.515 Serranus subligarius# 0.037 0.331 Grammistidae Rypticus sp *# 0.239 1.330 Rypticus bistrispinus *# 0.280 1.336 Priacanthidae Pristigenys alta# 0.049 0.217 Apogonidae Apogon maculatus *# 0.314 1.525 Apogon pseudomaculatus# 0.107 0.439 Haemulidae Haemulon aurolineatum# 0.035 0.233 Sparidae Stenotomus sp.# 0.049 0.267 Mugilidae Mugil cephalus 0.024 0.221 Mugil curema 0.037 0.192 Labridae Halichoeres bivittatus# 0.015 0.133 Dactyloscopidae Dactyloscopus moorei 0.049 0.266 Blenniidae Hypleurochilus geminatus 0.073 0.262 Parablennius marmoreus# 0.024 0.221 Callionymidae Diplogrammus pauciradiatus 0.048 0.212 Bothidae Bothus ocellatus * 0.143 0.701 Bothus robinsi * 0.665 1.145 Paralichthyidae Ancylcopsetta quadrocellata 0.060 0.284 Citharichthys macrops 0.024 0.152 Cyclopsetta fimbriata 0.095 0.394 Syacium papillosum 0.087 0.329 Cynoglossidae Symphurus minor * 2.047 3.593 Symphurus urospilus * 0.194 0.501 Balistidae Cantherhines pullus# 0.061 0.287 Monocanthus ciliatus 0.012 0.110 Monocanthus hispidus * 0.891 2.057 Monocanthus setifer 0.012 0.110 Ostraciidae Lactophyrs quadricornis# 0.012 0.108 Juvenile assemblage Family Taxon Spring Winter Muraenidae Gymnothorax saxicola 50 m Ophichthidae Ophichthus gomesii 30-45 m Congridae Ariosoma balearicum 30-45 m 50 m Synodontidae Synodus foetens * 30-45 m 30-45 m Trachinocephalus myops 30-45 m 30-45 m Ophidiidae Ophidion selenops * 30-45 m 30-45 m Otophidium omostigmum * 50 m 30-45 m Batrachoididae Porichtys plectrodon 50 m Antennariidae Antennarius ocellatus# 50 m Antennarius radiosus# 50 m Ogcocephalidae Ogcocephalus nasutus 30-45 m Ogcocephalus parvus 50 m Syngnathidae Hippocampus erectus 50 m 50 m Scorpaenidae Scorpaena dispar *# 50 m 50 m Scorpaena plumieri# 30-45 m 50 m Triglidae Bellator brachychir 30-45 m Prionotus carolinus * 30-45 m 30-45 m Prionotus scitulus 30-45 m Serranidae Centropristis ocyurus *# 50 m 50 m Diplectrum formosum *# 30-45 m 30-45 m Epinephelus niveatus# 50 m 30-45 m Serraniculus pumilio *# 50 m 30-45 m Serranus phoebe *# 50 m 50 m Serranus subligarius# 50 m Grammistidae Rypticus sp *# 50 m 50 m Rypticus bistrispinus *# 50 m Priacanthidae Pristigenys alta# 50 m Apogonidae Apogon maculatus *# 50 m Apogon pseudomaculatus# 30-45 m 50 m Haemulidae Haemulon aurolineatum# 30-45 m Sparidae Stenotomus sp.# 30-45 m Mugilidae Mugil cephalus 30-45 m Mugil curema 30-45 m Labridae Halichoeres bivittatus# 50 m Dactyloscopidae Dactyloscopus moorei 30-45 m Blenniidae Hypleurochilus geminatus 50 m 50 m Parablennius marmoreus# 30-45 m Callionymidae Diplogrammus pauciradiatus 50 m 30-45 m Bothidae Bothus ocellatus * 30-45 m 50 m Bothus robinsi * 30-45 m 30-45 m Paralichthyidae Ancylcopsetta quadrocellata 30-45 m Citharichthys macrops 30-45 m Cyclopsetta fimbriata 30-45 m Syacium papillosum 30-45 m Cynoglossidae Symphurus minor * 30-45 m 30-45 m Symphurus urospilus * 30-45 m 30-45 m Balistidae Cantherhines pullus# 50 m Monocanthus ciliatus 50 m Monocanthus hispidus * 30-45 m 30-45 m Monocanthus setifer 50 m Ostraciidae Lactophyrs quadricornis# 30-45 m Note: Taxa in bold indicate reef-associated species indicated with #. Table 5 Eigenvalues and species-environment correlations (r2) for each axis analyzed (correspondence analysis [CA] and canonical correspondence analysis [CCA]) by season and the entire year. A sharp drop in the eigenvalue marks the axes that explain most of the data. Eigenvalues alone explain the variance in the data for CA. The product of the species-environment correlation and the eigenvalue explains the variance in the data for CCA. CA axis Season 1 2 3 4 Spring Eigenvalue 0.574 0.326 0.273 0.251 [r.sup.2] Summer Eigenvalue 0.461 0.389 0.350 0.303 [r.sup.2] Fall Eigenvalue 0.604 0.376 0.275 0.224 [r.sup.2] Winter Eigenvalue 0.669 0.644 0.492 0.414 [r.sup.2] Year Eigenvalue 0.698 0.507 0.499 0.394 [r.sup.2] CCA axis Season 1 2 3 4 Spring Eigenvalue 0.538 0.292 0.172 0.052 [r.sup.2] 0.971 0.962 0.959 0.577 Summer Eigenvalue 0.248 0.160 0.123 0.049 [r.sup.2] 0.857 0.742 0.684 0.422 Fall Eigenvalue 0.447 0.301 0.121 0.090 [r.sup.2] 0.910 0.899 0.846 0.765 Winter Eigenvalue 0.531 0.306 0.181 0.118 [r.sup.2] 0.930 0.862 0.669 0.625 Year Eigenvalue 0.169 0.125 0.102 0.089 [r.sup.2] 0.606 0.628 0.615 0.522 Table 6 The P values from a Monte Carlo permutation test on the environmental variables for each season. Significant P values (P<0.05) are in bold. Season Variable Spring Summer Fall Winter Depth (m) 0.002 0.918 0.002 0.002 Stratification 0.002 0.002 0.622 0.178 Bottom temperature 0.410 0.138 0.094 0.070 Bottom salinity 1.000 0.160 0.020 0.316 Bottom density 0.034 0.848 0.102 0.020