Gulf and Caribbean Research Volume 20 Issue 1 January 2008 Coral Reefs of Miskitus Cays, Nicaragua Ana C. Fonseca Universidad de Costa Rica, afonseca(5)cariari.ucr.ac.cr DOI: 10.18785/gcr.2001.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Fonseca, A. C. 2008. Coral Reefs ofMiskitus Cays, Nicaragua. Gulf and Caribbean Research 20 (l): 1-10. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/2 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contactJoshua.Cromwell@usm.edu. Gulf and Caribbean Research Vol 20, 1-10, 2008 Manuscript received, February 3, 2006; accepted, October 2, 2007 CORAL REEFS OF MISKITUS CAYS, NICARAGUA Ana C. Fonseca Centro de Investigation en Ciencias del Mar y Limnologia (CIMAR), Universidad de Costa Rica , San Jose, Costa Rica, 2060-1000, e-mai l: afonse ca @cariari .ucr.ac.cr ABSTRACTS The Miskitus Cays, on the Caribbean coast of Nicaragua, consist of eighty mangrove and two sand and gravel cays, surrounded by seagrass beds, octocoral gardens, patch reefs, reef crests, extended algae platforms, short reef walls, and two marginal reefs around the sand cays. Seventy sites were inspected and eighteen sites were selected for rapid assessments in order to determine the status of the coral reefs. Linear transects and the intercept point methods were used to determine the relative benthic cover, and the density, size and health of coral colonies was estimated follow- ing the AGRRA protocol. Water was highly turbid due to the shallowness of the reefs and high wave energy. Northwest reefs, closer to the Coco river mouth, were affected by terrestrial sediments and were overgrown by algae whereas storm damage was evident in the eastern reef crest fronts. In total, 39 stony coral species were found and 12 new species were reported for Cayos Miskitus. Mean live coral cover was high (43.4%), but it was still lower than the algae cover (54.2%). Mean coral diameter (59.7 cm) and height (4.2 cm) were high but total mortality (27.9%), bleaching (4%) and diseases (3%) were low. Reefs of Nicaragua are in the best condition of the Caribbean region of Central America but good management of the fisheries, the marine reserve, and the Coco river basin are urgent to maintain reef quality. Introduction The Caribbean shoreline of Nicaragua is about 463 km long with a broad continental shelf where coral reefs grow, especially in the north section (Murray et al. 1982, Hallock et al. 1988). The coast is divided into the Autonomous North Atlantic Region (RAAN) and the Autonomous South At- lantic Region (RAAS); the RAAN is mainly inhabited by the Miskitus indigenous people (USAID 1996). Coral reefs of the Caribbean coast of Latin America are described in Cortes (2003). The Miskitus Cays Biological Reserve, created in 1991, is located 50 km from the coast, northeast from Puerto Cabezas inside the RAAN. It has a radius of 40 km around Major Miskitu Cay (14°23’N- 82°46’W) totaling 50,000 ha, and a coastal and marine belt 20 km wide between Wounta and Gracias a Dios Cape. The total area of the reserve is 765,867 ha (Jameson 1996). The marine ecosystem consists of eighty mangrove and two sand and gravel cays, surrounded by a mosaic of shallow inter- connected marine habitats (Aevizon 1993, Jameson 1996). The communities in the north littoral of Nicaragua, mainly Sandy Bay and Puerto Cabezas, use the area of this marine reserve for artisan fishing. Fishing for shrimp and finfish is done close to the coast, whereas lobster, shark and turtle fishing is concentrated around the cays (Harrington and Gallucci 1996, USAID 1996, Maradiaga 1998). The first scientific study in Miskitus Cays was on algae and seagrass (Phillips et al. 1982), followed by Ogden and Gladfelter (1983) and Marshall (1984). Between 1993 and 1995 the “Ministerio del Ambiente y los Recursos Naturales de Nicaragua (MARENA)”, the Caribbean Conservation Corporation (CCC) and the United States Agency for In- ternational Development (USAID) developed a preliminary management plan for the reserve where a general description of coral reefs, seagrasses and lagoons was provided. Aevizon (1993) provided qualitative descriptions of these coral reefs and their fishing resources and Jameson (1996) reported 27 coral species from this system. There are no quantitative studies in this section of the Caribbean coast of Nicaragua, although the coral reefs of Corn Island in the RAAS have been widely studied (reviewed in Ryan and Zapata 2003). The main objective of this study was to quantitatively as- sess the coral reef status in Miskitus Cays in comparison with other reefs in the Caribbean coast of Central America, providing baseline data that can be used for future research and monitoring. Materials and Methods A rapid reef assessment was conducted in August 2001 in- side the 50,000 ha around the Major Miskitu Cay (14°23’N- 82°46’W; Figure 1) in order to diagnose the status of its coral reefs in terms of reef substrate cover, coral colony den- sity, and health. In total, seventy sites recorded with GPS were inspected by snorkeling for 15 min to determine habi- tat type and coral species richness. These sites were assessed and distributed as follows: four to the north, seventeen to the northeast, two to the east, six to the southeast, three to the south, three to the southeast, ten to the west, and twenty five to the northwest. Of these, eighteen sites were selected for SCUBA diving and evaluation with linear transects. These were distributed as follows: one to the north, five to the northeast, one to the east, one to the southeast, three to the south, two to the southwest, two to the west, and three to the northwest. We report the site names used by the local fishermen. Coral reefs are very shallow in this area, so three 10 m long 1 Fonseca linear transects parallel to the depth contour and separated by 5 m each were evaluated in each site at a depth between 1 and 5 m. In sites with distinguishable reef crests (crashing waves), transects were done at the base of the crest. Gener- ally, there were no reef platforms associated with these reef crests. Reef crest complexity was estimated in Creole Bar, Toro Cay and Witties by following the contour of the hot- tom with a chain (Rogers et al. 1994). In sites consisting of reef patches or reef spurs, transects were done over these formations. Along the 10 m transects, the point intercept method was used to record the rela- tive substrate cover every 25 cm (Nadon and Stirling 2006). Corals were identi- fied after Humann (1993), and the AGRRA protocol (Lang 2003) was used to de- scribe adult coral colonies longer than 25 cm, including their diameter (cm), height (cm), old and recent mortal- ity, and presence of diseases. Analysis of Variance (ALKO- VA) followed by Bonferroni pairwise comparisons were used to compare the rela- tive substrate cover (%) and coral colonies density (# colonies/ 10 m) among sites after log 10 transformation of the data to aid in meeting the normality and homogeneity of variance assumptions. Results Description of the reef habitats The Miskitus Cays reef system is shallow (< 5 m) and con- sists of a series of mangrove cays (10 %), two sand and coral- line gravel cays surrounded by a mosaic of extensive seagrass beds (73%) and algae, several octocoral gardens, patch reefs, and reef crests (17%) oriented from north to south. The reef system extends up to 20 km from the cays, and water visibil- ity was low (5 to 10 m). Seagrasses were dominated by Thalassia testudinum and/ or Syringodium filiforme in sandy substrate, and they were found mainly around the mangrove cays and to both sides of the reef crests. Octocoral gardens, in sand patches or rocky bottoms, were dominated by Pseudopterogorgia cimeri- cana, Plexaura flexuosa, Gorgonia ventalina, and some disperse colonies of live coral like Diploria strigosa, Siderastrea siderea, and Porites astreoides. Reef crests had a mean complexity index of 1.84 at a depth between 1 to 5 m. Reef crests were formed mainly by A cropora palmata , most of which were dead, and M illepora complanata. Other dominant species were M ontastraea faveo- lata, S. siderea, D. strigosa, P. asteroides, Agaricia agaricites, and A garacia tenuifolia. The windward base of the reef was up to 5 m deep and several reef bases were dominated by gardens of A cropora cer - vicornis, A cropora prolifera and big colonies (up to 2 m wide and high) of M. faveolata. In some sectors, the reef crests were adjacent to wide shallow platforms of flat carbonate rock covered by fleshy non-coralline algae, especially Die- tyota spp., Padina spp., Galaxaura comans, Sargassum natans, Asparagopsis taxiformis, Turbinaria turbinata and Stypopodium zonale, with a few disperse coral colonies of P. astreoides, D. strigosa, and S. siderea. In other sectors, the reef fronts con- sisted of sand with seagrass beds or octocoral gardens also with low coral cover. In some reefs there were also deep walls (50 m) covered by a great diversity of reef organisms, small coral colonies and big octocorals and antipatharians, and in a few cases spurs and grooves were found at the base of these walls. Some of these crests presented an edge relatively close to the crest, with a small wall down to 16 m maximum, with complex caverns and great diversity, adjacent to sand and in some cases the seagrass Halophila baillonis. In the leeward side of the reef crests the substrate was usually covered by dead coral gravel, algae, octocorals and disperse colonies of LEGEND Reefs Mangroves Seagrasses Sand Keys /V Reserve limit Transect sites A inspection sites UTM-NAD27 Zone 16 Figure 7. Map of Miskitus Cays , Nicaragua. Transect sites have quantitative information whereas inspection sites have qualitative information (Modified from Valerio 2001). + = latitude and longitude grid points. 2 Coral reefs of Miskitus Cays, Nicaragua TABLE 7 . Damage by site and coral species (see Figure 1). Sites not listed had no damage. Codes: Black Spot Disease (BSD), White Band Disease (WBD), White Plague (WP), Black Band Disease (BBD) and White Spots (WS). Tumors = neo- plasm; Damselfish chimneys = produced by damselfish bites. Sampling site Coral species (Damage) Bojotle Kira Siderastrea siderea (BSD) Montastraea faveolata (BSD) Acropora cervicornis (WBD) Ahuya Luphia Siderastrea siderea (WP, BSD) Acropora cervicornis (WBD) Martinez reef Siderastrea siderea (BSD) Dump Siderastrea siderea (BSD) Macandra Diploria strigosa (Tumours) Acropora palmata (Damselfish chimneys) Hamkira Acropora palmata (Damselfish chimneys) Acropora cervicornis (WBD) Montastraea faveolata (BBD) Wiplyn Siderastrea siderea (BBD) Acropora prolifera (WBD) Gigi Diploria strigosa (WP) Montastraea franksi (BSD) Montastraea faveolata (BSD) Siderastrea siderea (WP, WS) Colpophyllia. natans (BBD) Dusmusta Diploria strigosa (BBD, Tumours, WP) Diploria clivosa (BBD) Acropora palmata (WBD) Montastraea faveolata (BBD) Lamarcka reef Acropora palmata (WBD) Nasa reef Acropora cervicornis (WBD) Siderastrea siderea (BSD) Diploria strigosa (BBD) Witties Acropora cervicornis (WBD) Siderastrea siderea (BSD) Creole Bar Montastraea faveolata (WP, BBD) Siderastrea siderea (BBD) Colpophyllia natans (BSD) Montastraea annularis (BSD) Toro Cay Acropora cervicornis (WBD) Acropora palmata (Damselfish chimneys) Franklin reef Diploria strigosa (BBD) Ned Thomas Acropora prolifera (WBD) Siderastrea siderea (BSD) Acropora palmata (Damselfish chimneys) Yanka Laya Acropora palmata (Tumours) the corals Siderastrea spp., Diploria spp., and Porites spp. Circular patch reefs, ranging from 20 to 100 m in diam- eter, were dispersed around the islands and were < 10 m deep. These reefs were also surrounded by sand patches and seagrass beds. There are a great number of patch reefs in the area around the cays, especially to the north near Ahuya Luphia and Bojotle Kira, to the northeast near Morrison Dennis cays (MARAS), and near Sammy, Strap Kira and Hamkira cays. Finally, there were two marginal reefs around the two sand cays in the northeast Hamkira and Hamkira sirpe. In these reefs, it was also possible to find healthy gar- dens of A. palmata, A. prolifera, and A. cervicornis. In the west (Toro Cay, Glena Bar) and northwest (Sammy, reef patches around Hamkira) areas, significant suspended sediment was present which reduced water visibility. In this sector and some parts of Nasa and Gigi in the southwest, several reef patches were covered by a thick mat of the green algae, Chaetomorpha gracilis, and most coral colonies were dead. In Toro Cay and Glena Bar to the west, there was also a high cover of the cyanobacteria, Schizotrix spp. Based on qualitative observations, diseased coral colo- nies were found in 24% of the inspected sites (Table 1). This is especially true at Wiplyn, Dusmusta and Gigi (the west), at Nasa reef (southwest), at Ned Thomas (south), at Cre- ole Bar (north), and at Ahuya and Bojotle Kira (northeast). The most frequent disease in Miskitus cays was Black Band Disease (BBD) in colonies of M. faveolata, S. siderea, Colpo- phyllia natans, and Diploria spp. Furthermore, there was a great incidence of Black Spot Disease (BSD) in colonies of S. siderea, White Band Disease (WBD) in colonies of A cropora spp. and White Plague (WP) in colonies of S. siderea, D. stri- gosa, and M. faveolata. Composition, richness, density and status of coral colonies Thirty nine scleractinian coral species were found at Miskitus Cay (Table 2), similar to what has been found in other reefs from the southern Caribbean coast of Central America (Table 3). The richest sites were those in which the reef crest was associated with a vertical complex and/ or deep wall (Table 4). These deep wall systems were Creole Bar, North West Miskitu reef, and Macandra and Witties in the south. Nassa reef in the southeast also exhibited high coral species richness but had a short wall down to 10 m deep. Finally, the patch reefs of Ahuya Luphia were also rich due to their 3 to 8 m high depth. The poorest sites in coral species richness were the patch reefs located in carbonate rock platforms covered with fleshy macro-algae such as Mar- tinez reef, Owen shoal and Flag Reef. The poorest reef crest sites were Yanka laya, Ryan and Sammy in the northwest, Mas Widi in the west, Trikam rock in the southeast and Maxide and Dump in the northeast. Coral colony density was significantly different among sites (F 1736 = 2.17, p = 0.025). Sites with densities between 1 and 10 colonies per 10 m were patch reefs such as, Bojotle Kira and Ahuya Luphia in the north, and Ryan, one of the most deteriorated reef crests in the northwest and Maxide to the northeast. Density was > 16 colonies in Macandra and Creole bar to the north, Franklin reef and Ned Thomas in the south, Nasa reef and Toro cay in the southwest, and Hamkira and Yanka Laya in the northwest (Table 5). The dominant (> 35%) coral species in most of the reef crests were A. palmata and M. faveolata with exception of the 3 Fonseca TABLE 2 . List of marine invertebrates observed in Miskitus Cays, Nicaragua coral reefs in August 200 1 . SPONGES (Phylum Porifera, Class Demospongiae) Callyspongia plicifera Ircinia strobilina Diplastrella megastellata Agelas confiera Cliona sp. MILLEPORINES (Phylum Cnidaria, Class Hydrozoa, Order Milleporina) Millepora alcicornis Millepora complanata ANEMONES (Phylum Cnidaria, Class Anthozoa, Order Actinaria) Stichodactyla helianthus Condylactis gigantea Bartholomea annulata ZOANTHIDS (Phylum Cnidaria, Class Anthozoa, Order Zoanthidea) Palythoa caribaeorum Zoanthus pulchelus SC LE RACTI N IANS (Phylum Cnidaria, Class Anthozoa, Order Scleractinia) Acropora cervicornis Acropora palmata Acropora prolifera Porites porites Porites astreoides Oculina diffusa Madracis mirabilis Madracis decactis Stephanocoenia michelinii Montastraea annularis Montastraea faveolata Montastraea franksi Montastraea cavernosa Dichocoenia stokesii Favia fragum Siderastrea siderea Siderastrea radians Solenastrea bournoni Solenastrea hyades Diploria strigosa Diploria clivosa Colpophyllia natans Meandrina meandrites Manicina areolata Leptoseris cucullata Agaricia grahamae Agaricia agaricites Agaricia tenuifolia Mycetophyllia danaana Mycetophyllia lamarckiana Mycetophyllia aliciae Mycetophyllia ferox Isophyllastrea rigida Scolymia cubensis Scolymia lacera Mussa angulosa Eusmilia fastigiata CTENOPHORES (Phylum Ctenophora, Class Tentaculata) Leucothea multicorn is Ocyropsis crystallina SEA CUCUMBERS (Phylum Echinodermata Class Holothuroidea) Isostichopus badionotus Holothuria mexicana SEA URCHIN (Phylum Echinodermata Class Echinoidea) Echinometra viridis Echinometra lucunter Diadema antillarum Meoma ventricosa SEA STARS (Phylum Echinodermata, Class Asteroidea) Oreaster reticulatus Linckia guildingii Asterina folium TUNICATES (Phylum Chordata, Class Ascidiacea) Clavelina puertosecensis sites where the majority of A. palmata colonies were dead such as Witties, where P. astreoides (45%) dominated. Wiplyn was dominated by D. strigosa (40%) and A. prolifera (40%), Toro Cay was dominated by A. tenuifolia (48%), the fringing reef of Hamkira was dominated by A. cervicornis (42%), and Ryan crest and Bojotle Kira reef patches were dominated by S. siderea (30% and 50%, respectively). Only in the spurs of Creole Bar and the deep reef patches of Aliuya Luphia was M. annularis abundant (33% and 20%, respectively). M ontas- traea faveolata was especially abundant in Nasa reef (76%), D. strigosa in London reef (100%), and A. palmata in Yanka Laya (79%). The fire coral, Millepora complanata, was also common in these reefs and it contributed to the construe- tion of the reef crests. In general, the mean diameter and height of coral colo- nies was high in Yanka Laya, Toro Cay, Nasa reef and Lama- rcka. The lowest mean diameter was found in London reef. The mean height was also higher in Maxide and Lamarcka (Table 6). The largest colonies of A. palmata (> 80 cm) were found in Miskitu reef, Maxide, Ned Thomas, Lamarcka, Hamkira and Yanka Laya, whereas relatively small colonies (diameter <50 cm) were noted in Ryan. The colonies of D. strigosa were larger (> 50 cm) on average in Franklin reef, Macandra and Bolotle Kira, whereas those of M. faveolata > 1 m diameter were found in Macandra and Ryan. Siderastea siderea was larger (50 cm) in Wiplyn and Ryan (Table 7) than other ar- eas. Overall, the mean diameter and height of coral colonies for all the reef system of Miskitus Cays was high (59.7 cm and 46.2 cm, respectively). Recent mortality was 3.2%, old mortal- ity was 25.7% and total mortality 28.9%. The ratio between live and dead coral was high (3.9, Table 6). Recent mortality of coral colonies was highest in Witties (24%), while old mortality was highest in Nasa reef (54%), followed by Ned Thomas (49%) and Bojotle Kira (49%) (Table 6). Total mortal- TABLE 3. Comparison of stony coral species richness in the Central American Caribbean coast. Country Site Reference # Coral species Panama Bocas del Toro Guzman 1998 32 Costa Rica Cahuita Cortes 1996-1997 41 Manzanillo Cortes 1996-1997 32 Nicaragua Miskitu Cays This study 39 Corn Island Ryan and Zapata 2003 25 Honduras Cayos Cochinos Guzman 1998 56 Roatan Siirila 1992, Villeda et al. 1 997 47 Guatemala Punta Manabique Fonseca 2003 29 Belize Carrie Bow Cay Cairns 1982 44 4 Coral reefs of Miskitus Cays, Nicaragua ity was highest in Nasa reef (54%) followed by Bojotle Kira (50%). The ratio between live and dead colonies was highest in Hamkira and lowest in Nasa reef. Bleaching was high- est in Ahuya Luphia (20%) and Creole Bar (19%). Mean bleaching for Miskitus Cays was 4% (Table 6) and in only 6 of 18 sites (33%) was there evidence of bleaching, and it was always partial. I found disease in only 28% of the sites (5 of 18 sites) and in 26% of the coral species (10 of 39 spe- cies). The highest incidence of disease was found in Wiplyn (40%) and mean disease incidence overall was 3% (Table 6). There was not evident damage by anchors, but damage by storms was great, since colonies of A. palmata were frag- mented and dead, especially in all the reef fronts and mainly in the ones to the east of Miskitus Cays. Relative substrate cover analysis There was a significant difference among sites and low variability within each site on coral live cover (F.7,36 = 2-399, p = 0.01) and algae (F 1?36 = 2.238, p = 0.02). The sites with higher live coral cover (> 50%) than the algae cover were the reef crests of Dump in the north, Franklin reef and Ned Thomas in the south, Lamarcka and Nasa reef in the south- west, and Hamkira and Yanka Laya in the northwest. The other sites had higher algae cover than live coral cover. The TABLE 4. Number of coral species ranked by site from August 200 1 collections. Site Physical Attribute # coral species Creole Bar-Blue Channel Reef Crest/Deep Wall 31 Macandra Short Wall 29 Witties Reef Crest/Short Wall 29 Ahuya Luphia Patch Reef 28 NW reef Deep Wall 27 Nassa Reef Crest/Short Wall 25 Ned Thomas Reef Crest 20 Franklin reef Reef Crest/Deep Wall 17 Hamkira Fringing Reef 17 Gigi Reef Crest 16 Toro cay Reef Crest/Short Wall 16 Hamkira sirpe Fringing Reef 16 London reef Reef Crest 15 Wiplyn Reef Crest 15 Bojotle Kira Patch Reef 14 Lamarcka Reef Crest 14 Dusmusta Reef Crest 14 Miskitu reef - Farrel reef Reef Crest 13 Glena Bar Reef Crest 13 Maxide Reef Crest 11 Dump Reef Crest 11 Sammy Reef Crest 1 1 Ryan Reef Crest 1 1 Yanka Laya Reef Crest 8 Mass Widi Reef Crest 7 Martinez reef Patch reef 7 Flag reef Patch reef 7 Owen shoal Patch reef 5 Trikam rock Reef crest 3 TABLE 5. Density (mean ± standard deviation) of coral colonies (n=3) by site along transects from August 200 1 collections. Site Density (Colonies/ 10m transect) Maxide* 4.0 ± 1.0 Bojotle Kira* 4.7 ±2.5 Ryan 10.0 ±7.8 London reef 11.7 ±6.4 Ahuya Luphia* 13.7 ±5.5 Dump 13.7 ±7.0 Miskitu reef 14.0 ±5.6 Wiplyn 14.7 ±9.0 Lamarcka 15.0 ± 1.7 Witties 15.7 ± 1.5 Toro cay 16.7 ±7.1 Creole Bar 17.7 ± 1.2 Ned Thomas 18.3 ±5.0 Macandra 18.3 ±5.7 Nasa reef 18.7 ±2.3 Hamkira 20.0 ± 1 1.4 Franklin reef 20.7 ±6.0 Yanka Laya 21.3 ±4.0 * Counted only colonies with a diameter > 25 cm. patch reefs of Bojotle Kira were the sites with less live coral cover and higher algae cover, followed by the reef patches of Ahuya Luphia, and the reef crest of Ryan. However, only the patches of Bojotle Kira had significantly lower coral cover than all other sites after Bonferroni pairwise comparisons (p < 0.05). Moreover, in Ahuya Luphia, the bottom consist- ed mainly of sandy material within the colonies, whereas in Ryan it consisted mainly of mud. Mean live coral cover for Miskitus Cays was high (43.4%), but lower than the algae cover (54.2%). In all sites, the percentage of non-coralline algae was higher than the percentage of coralline algae. In Miskitu reef (or Farrel reef) in the east, London reef in the southeast, Witties in the south and Wiplyn in the west a higher dead coral cover with algae than live coral cover was found (Table 8). Discussion Miskitus Cays show a great diversity of interconnected marine habitats and resources which give shelter to reef spe- cies of great commercial value like turtles, dolphins, sharks, reef fishes, lobsters and queen conchs which are the base of the economy of the local fishing communities (Ryan et al. 1998). Most of the Miskitus Cay coral reef system is < 30 m deep, with high wave energy and low visibility that creates an environment dominated by seagrasses, octocoral gardens, coral reef patches, and reef crests built mainly by A cropora spp. and M illepora spp. Both coral species are known as the main reef crest builders in the Caribbean (Kramer and Kramer 2000). This high species richness and great cover of A. palmata, A. prolifera and A. cervicornis in some reefs of Miskitus Cays suggests a quality habitat complex unknown 5 Fonseca TABLE 6. General characterization of coral colonies in August 2001 by site, sd = standard deviation. Site Diameter, cm (x±sdl Diameter, cm (x ± sd) Recent mortality (%) ± sd Old mortality (%) ± sd Total mortality (%) ± sd Ratio Live:Dead % Bleached % Disease Macandra 59.4 ± 37.8 49.4 ±31.4 0.0 24.6 ± 29.2 24.6 ± 29.2 3.1 0.0 0.0 Maxide 93.3 ± 87.0 65.6 ±59.6 0.0 26.1 ±36.5 26.1 ±36.5 2.8 0.0 0.0 Dump 62.5 ± 39.6 52.9 ± 30.6 0.0 34.3 ± 24.7 34.3 ± 24.7 7.3 0.0 0.0 Bojotle 54.4 ± 30.2 35.6 ± 19.7 1.0 ± 1.8 49.4 ±33.3 50.4 ±35.1 1.0 12.5 0.0 Ahuya 40.0 ± 23.2 23.4 ± 34.6 8.0 ± 17.9 8.0 ± 12.5 16.0 ±30.4 5.3 20.0 0.0 Creole 49.8 ± 25.4 43.1 ±23.4 12.6 ±24.9 16.6 ±25.5 29.2 ±50.4 2.4 19.0 0.0 Miskitu 63.3 ±44.5 35.0 ±28.3 0.0 13.3 ±30.3 13.3 ±30.3 6.5 0.0 0.0 London 30.0 ± 0.0 50.0 ± 0.0 0.0 25.0 ±0.0 25.0 ±0.0 3.0 0.0 0.0 Witties 45.0 ± 24.4 33.4 24.1 20.5 ± 30.6 44.6 ±32.1 3.7 9.1 4.5 Franklin 55.9 ± 26.8 42.5 ± 27.3 0.0 31.8 ±27.5 31.8 ±27.5 2.1 0.0 0.0 Ned Thomas 60.8 ± 36.8 51.7 ± 31.4 0.1 ±0.4 49.5 ±31.1 49.6 ±31.5 1.0 3.8 0.0 Lamarcka 67.7 ± 36.7 57.5 ± 37.4 4.5 ± 16.6 20.8 ±23.9 25.3 ±40.5 2.9 0.0 4.6 Nasa 67.8 ± 30.5 51.6 ± 29.1 0.0 54.2 ± 37.8 54.2 ± 37.8 0.8 0.0 0.0 Wiplyn 54.0 ± 27.9 38.0 ± 13.0 4.0 ± 6.5 7.0 ± 11.0 11.0± 17.5 8.1 0.0 40.0 Toro 75.2 ±50.6 52.6 ±25.3 2.4 ±5.8 23.9 ±26.9 26.3 ±32.8 2.8 14.3 4.8 Hamkira 46.0 ± 24.3 36.7 ± 18.3 0.0 8.3 ± 19.4 8.3 ± 19.4 11.1 0.0 0.0 Yanka Laya 84.2 ± 36.3 69.5 ± 34.4 0.0 20.8 ±23.6 20.8 ±23.6 3.8 0.0 0.0 Ryan 66.0 ± 35.3 42.0 ±25.8 0.0 29.2 ±33.5 29.2 ± 33.5 2.4 0.0 0.0 x, all Cayos Miskitus 59.7 46.2 3.2 25.7 28.9 3.9 4.0 3.0 in much of the Caribbean and is very important in terms of conservation. These very fragile species have been inten- sively destroyed in other reefs of the Caribbean by hurri- canes, anchoring and diving (Precht et al. was found in A cropora as expected. White Band Disease is thought to be a major factor in the decline of elkhorn and staghorn corals in the wider Caribbean (Aronson and Pre- 2002). Miskitus Cays has high coral richness (39 species) similar to other sites in the Caribbean (reviewed in Fonseca 2003, Ryan and Zapata 2003). The reef crest complexity index (1.84) found at depths < 5 m is also high, suggesting high reef complexity. Recent and total mortality in Miskitus Cays was lower (3.2 and 27.6%, respectively) than in other shallow reefs from the Mesoamerican Reef System (18 and 49%, respectively); however, mean bleaching and disease incidences were similar (Kramer and Kramer 2000). Sev- eral diseases known to be widespread throughout the wider Caribbean (Green and Bruckner 2000) were also found in Miskitus Cays, and the BBD showed the highest frequency (Kramer and Kramer 2000). Dark Spot Disease was most com- mon on massive Siderastrea and Montas - traea (Bruckner 2001), and the WBD TABLE 7 . Mean diameter (cm) of dominant coral colonies in August 200 1 by site. Site Siderastrea siderea Montastraea annularis Montastraea faveolata Diploria strigosa Acropora palmata Macandra 38.3 ~ 116.7 50.0 58.3 Maxide - - - 27.5 88.0 Dump 30.0 - 51.4 30.0 75.4 Bojotle 38.8 - 76.7 50.0 - Ahuya 25.0 40.0 52.5 - - Creole 37.5 45.0 73.6 - - Miskitu 25.0 - - - 103.3 London - - - 30.0 - Witties - - - 35.0 75.0 Franklin 48.3 - - 56.0 78.1 Ned Thomas 40.0 - 70.0 - 84.1 Lamarcka 13.6 - 45.0 25.0 83.8 Nasa 30.0 - 74.5 25.0 80.0 Wiplyn 60.0 - - 40.0 - Toro - - 55.0 - 62.5 Hamkira 40.0 - 55.0 26.7 98.8 Yanka Laya - - 60.0 - 92.3 Ryan 55.0 - 110.0 - 50.0 6 Coral reefs of Miskitus Cays, Nicaragua cht 2001), causing major changes in the composition and structure of reefs (Green and Bruckner 2000). The highest incidence of disease was found in Wiplyn, and may be related to its proximity to MARAS, the largest human settlement in the area where people are discharging waste water and solids directly into the sea. The incidence and prevalence of diseases may also increase when corals are stressed by sedimentation, hurricanes, nutrients, toxic chemicals and warmer-than-normal temperatures (Richard' son 1998), as is evidenced by the imports from Hurricane Mitch in 1998 (Kramer and Kramer 2000), and other ear- lier events (Jameson 1996). Jameson (1996) did not find corals with active diseases, although he observed low levels of bleaching and anchor damage. In this study, no anchor damage was found because the highest reef development occurs in the crests and boats do not anchor directly over them. However, even though large coral colonies within reef crests are dispersed it would be better if mooring buoys were installed in diving and fishing sites to protect the coral colo- nies. Finally, in 1995 and 1998, late summer temperature in- creased from 29.5 to 31.TC throughout the Caribbean, and this coincided with several bleaching reports (Guzman and Guevara 1998, McField 1999). Apparently, slrallow reefs ex- perienced catastrophic losses due to the initial bleaching but now show minimal signs of remnant bleaching (Kramer and Kramer 2000). The coral reef in the Miskitus Cays appear to have recovered because observed mortality was low. Most of the Miskitus reef system is in good health, espe- cially in the south and southwest sections. The sites in best condition within the Miskitus Cays Biological Reserve are Nasa reef in the southwest, the protected side of the fringing reef around Hamkira and Yanka Laya in the northwest, and to a lesser extent Lamarcka in the southwest, Franklin reef and Ned Tliomas in the south, and Creole Bar-Blue Channel in the North. Blue Channel is a potential site for reef fishes’ reproductive aggregations. The most deteriorated sites, with non-coralline algae overgrowth and diseases, are those in the west-northwest, especially Ryan, North West reef, Toro Cay, Gigi and Glena Bar and some reef patches around Hamkira and Sammy. This appears to be due to sediments, and asso- ciated nutrients and pesticides coming from the deforested mangroves of MARAS and the runoff of Coco River. The mean live coral cover for Miskitus Cays is relatively high (43%) compared to other continental Caribbean coral reefs (Table 9), with 7 sites having higher live coral (>50%) than algae cover. However, most sites had lower coral cover than algae cover. The percentage of non-coralline algae was higher than the percentage of coralline algae (Table 9) as is typical of the Caribbean region due to a combination of hurricanes, bleaching, diseases, eutrophication, and low herbivory rates as a consequence of over fishing and Dia- dema mass mortality (Goreau et al. 1998, Hayes and Goreau 1998, Kramer and Kramer 2000). The most diverse and structurally complex coral reefs reported for the Central American coast were Belize, Honduras and Panama (Cortes 1997). However, Miskitus Cays has a great development of TABLE 8 . Relative coverage of benthic substrate (n = 3; = no data) by site in August 2001 . Site % Live coral % Dead coral with algae % Non- coralline algae % Coralline algae % Total algae Sediment Others Difference between % live coral and % algae Macandra 46.3 ± 13.6 17.9 ±3.7 21.9 ± 17.1 1 1 .4 ± 1 .4 51.2 ± 13.6 0.8 ± 1.4 1.6 ± 1.4 -4.9 Maxide 32.5 ± 19.9 25.2 ± 30.1 36.6 ± 47.5 4.9 ±8.4 66.7 ± 20.7 0.8 ± 1.4 - -34.2 Dump 64.2 ±5.1 27.6 ± 15.7 4.1 ±7.0 0.8 ± 1.4 32.5 ± 7.4 - 3.2 ± 3.7 31.7 Bojotle Kira 13.0 ± 11.0 - 84.6 ±7.8 - 84.6 ±7.8 - 2.4 ±4.2 -71.6 Ahuya Luphia 22.8 ±5.1 2.4 ±0.0 43.9 ± 10.6 19.5 ±6.4 65.8 ± 8.8 6.5 ±9.2 4.9 ±4.9 -43 Creole Bar 42.3 ±2.8 4.9 ±4.2 43.1 ±9.8 7.3 ±2.4 55.3 ±3.7 - 2.4 ± 2.4 -13 Miskitu reef 33.3 ± 1.4 66.7 ± 1 .4 - - 66.7 ± 1.4 - - -33.4 London reef 44.7 ± 27.0 55.3 ±27.0 - - 55.3 ±27.0 - - -10.6 Witties 33.3 ±7.4 66.7 ± 7.4 - - 66.7 ± 7.4 - - -33.4 Franklin reef 49.6 ± 29.5 41.5 ± 28.8 4.1 ±7.0 1 .6 ± 2.8 47.2 ±28.3 1 .6 ± 2.8 1.6 ±2.8 2.4 Ned Thomas 62.6 ± 16.2 30.1 ± 11.0 4.9 ±4.9 1 .6 ± 2.8 36.6 ± 16.0 - 0.8 ± 1.4 26 Lamarcka 56.9 ± 17.1 35.0 ±23.0 4.9 ± 8.4 1 .6 ± 2.8 41.5 ± 17.6 - 1.6 ±2.8 15.4 Nasa reef 59.4 ± 12.0 39.8 ± 13.4 - 0.8 ± 1.4 40.6 ± 12.0 - - 18.8 Wiplyn 31.7 ± 10.6 68.3 ± 10.6 - - 68.3 ± 10.6 - - -36.6 Toro cay 43.9 ± 11.2 24.4 ± 8.4 16.3 ±5.1 14.6 ±8.8 55.3 ±11.5 0.8 ± 1.4 - -11.4 Hamkira 56.9 ±22.7 6.5 ±6.1 30.1 ± 16.6 1.6 ± 1.4 38.2 ± 18.0 0.8 ± 1.4 4.1 ± 3.7 18.7 Yanka Laya 58.5 ±23.3 32.5 ± 34.3 8.9 ± 15.5 - 41.5 ±23.3 - - 17 Ryan 29.3 ± 22.4 9.8 ± 9.8 52.8 ± 32.4 - 62.6 ± 24.4 7.3 ± 12.7 0.8 ± 1.4 -33.3 Total x for Miskitus Cays (n=54) 43.4 ± 14.8 30.8 ± 26.0 19.8 ± 27.0 3.7 ± 6.4 54.2 ±14.1 2.6 ± 2.9 2.3 ± 1.4 - 10.8 7 Fonseca TABLE 9, Comparison of mean live coral and algae coverages between Miskitus Cays and other coral reefs of the Central American Caribbean coast. Country Reef name Reef type % Live coral % Algae Year Reference Panama Bocas del Toro Insular 27 21 1999 CARICOMP 1999 Costa Rica Cahuita Continental 13 60 1999 CARICOMP 1999 Nicaragua Great Corn Island Insular 36 37 1998 CARICOMP 1999 Nicaragua Cayos Miskitus Insular 43 54 2001 This study Honduras Roatan Insular 34 38 1997 Fonseca and Radawsky 1997 Guatemala Punta Manabique Continental 9 65 2000 Fonseca 2003 Belize Carrie Bow Cay Insular 16 65 1997 CARICOMP 1 999 Belize Calabash Cay Insular 10 58 1997 CARICOMP 1999 Mexico Puerto Morelos Continental 1 93 1999 CARICOMP 1999 reef crests, and Miskitus Cays and Corn Island should be considered high quality reefs suited for a high conservation status in the Caribbean because of their high live coral cover and diversity, and low mortality. Coral reef degradation in the American region is caused mainly by increased influx of terrigenous sediments (Rog- ers 1986, Ginsburg 1994) primarily due to deforestation, uncontrolled coastal development, and inappropriate agri- cultural practices (Cortes and Risk 1985). While suspended sediment loads appear to be the greatest human threat to Nicaragua's reefs (Ryan et al. 1998), unregulated fishing activities have also caused damage. Despite these multiple threats, Nicaragua still lacks a concrete management strategy for its coastal and marine resources due mainly to a general lack of political awareness about the key role that coral reefs play in supporting fisheries and biodiversity, institutional and human capacity gaps and inadequate legislation for reef conservation (Ryan and Zapata 2003). Integrated manage- ment of Nicaraguan river basins and coastal-marine reserves is urgent and this can be promoted by extending land-con- servation approaches to marine ecosystem biodiversity. Acknowledgments This study was administered by URACCAN-IREMADES, financed by PROARCA Costas/WWF Central America, and executed thanks to J. Mendoza-Lewis, L. Paredes, P. Mercado, O. Breedy, L. Salomon, E. Cabezas (Creole), J. Enriquez (Pipito), P. Enriquez (Calvo), A. Lucer, S. Saballo, Dina, S. Enriquez, G. Recta, F. Cepeda and N. Windevoxhell. We also thank P. Smith and M.S. Peterson for the meticulous revi- sion of the English language. Literature Cited Alevizon, W. 1993. A preliminary survey of the coral reefs and reef fisheries of the Miskitu Cays, Nicaragua. Technical Re- port, Caribbean Conservation Corporation, Miami, Florida, USA, 16 p. Aronson, R.B. andW.F. Precht. 2001. Evolutionary palaeoecol- ogy of Caribbean coral reefs. In: Allmon, W.D. and D.J. Bot- tjer, eds. Evolutionary Paleoecology: The Ecological Context of Macroevolutionary Change. Columbia University Press, New York, NY, USA, p. 171-233. Bruckner, A.W. 2001. 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ECO-AMBIENTE, 200 p. 10 Gulf and Caribbean Research Volume 20 Issue 1 January 2008 Habitat Condition and Associated Macrofauna Reflect Differences Between Protected and Exposed Seagrass Landscapes Chet E Rakocinski University of Southern Mississippi Cynthia A. Moncreiff Anchor Environmental, LLC Mark S. Peterson University of Southern Mississippi , mark.peterson(a)usm.edu Katherine E. VanderKooy University of Southern Mississippi Todd A. Randall U.S. Army Corps of Engineers, New England District DOI: 10.18785/gcr.2001.03 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Rakocinski, C. F., C. A. Moncreiff, M. S. Peterson, K. E. VanderKooy and T. A. Randall. 2008. Habitat Condition and Associated Macrofauna Reflect Differences Between Protected and Exposed Seagrass Landscapes. Gulf and Caribbean Research 20 (l): 11-19. Retrieved from http://aquila.usm.edu/gcr /vol20/issl/3 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(3)usm.edu. Gulf and Caribbean Research Vol 20, 1 1-19, 2008 Manuscript received February 14, 2007; accepted June 4, 2007 HABITAT CONDITION AND ASSOCIATED MACROFAUNA REFLECT DIFFERENCES BETWEEN PROTECTED AND EXPOSED SEAGRASS LANDSCAPES Chet F. Rakocinski 1 , Cynthia A. Moncreiff 2 , Mark S. Peterson, Katherine E. VanderKooy, and Todd A. Randall 3 Department of Coastal Sciences, The University of Southern Mississippi, Gulf Coast Research Laboratory, 703 East Beach Drive, Ocean Springs, MS 3 9564, USA Corresponding author, email: chet.rakocinski@usm.edu 2 present address: Anchor Environmental, LLC., 1011 DeSoto Street, Ocean Springs, MS 39564, USA 3 present address: US Army Corps of Engineers, New England District, Environmental Resources Section, 696 Virginia Road, Concord, MA 01742, USA ABSTRACT; Seagrass landscape configurations associated with different physical settings can affect habitat-structure and plant-animal relationships. We compared shoal grass (Holodule wrightii) habitat and macrofaunal variables between two fragmented seagrass landscapes at barrier-island locations subject to different disturbance regimes. Five seagrass habitat variables including above ground biomass (AGB), shoot number, per shoot biomass, epiphyte biomass and below ground biomass (BGB), differed significantly between the island landscapes. Per shoot biomass and epiphyte biomass also varied significantly over the seagrass growing season; and epiphyte biomass showed a strong landscape-time interaction. Abundances of microgastropods normalized to AGB differed significantly between landscapes. An inverse relationship between the abundance of microgastropods and epiphyte loading suggests a possible functional link. However, additional temporal mismatch between epiphyte loading and microgastropod abun- dance indicates that controls on epiphyte loading were complex. Seagrass habitat was more fragmented within the Cat Island (Cl) landscape. Wind direction and strength imply that the Cl landscape experienced more physical distur- bance than the Horn Island (HI) landscape. This study highlights some potential links involving landscape configura- tion, habitat structure, and macrofaunal associations which can be further addressed using hypothesis-driven research. Introduction Seagrass ecosystems exist as hierarchically organized habi- tats in various states of fragmentation, mediated by land- scape-scale forces (Pittman et al. 2004). Hierarchical spatial patterns arise from the interaction of broad-scale external effects on habitat configuration and local internal effects on habitat structure (Bostrom et al. 2006). For example, physical disturbance induces variability in the spatial con- figuration of patches of varying sizes and interpatch distanc- es within the seagrass landscape (Fonseca and Bell 1998). Furthermore, processes occurring at broad spatial scales may constrain those occurring at local spatial scales (Allen and Starr 1988). Consequently, landscape-scale features, such as areal cover, patch size, and interpatch distance, may covary with habitat-structure (Bostrom et al. 2006), as expressed by shoot density, above ground biomass (AGB), below ground biomass (BGB), epiphyte loading (Moore and Fair- weather 2006) or associated macrofauna (Hovel et al. 2002). Although macrofaunal associations change with the spa- tial arrangement of seagrass habitat (Turner et al. 1999, Frost et. al 1999), responses by individual taxa can vary relative to landscape configuration (e.g., patch size and distance) (Bell et al. 2001). The apparent inconsistency reflects the fact that macrofaunal taxa relate individualistically to different en- vironmental scales (Bostrom et al. 2006), thus accounting for different response thresholds to habitat fragmentation. Seagrass ecosystems also form complex trophic networks de- fined by internal feedbacks on habitat function, including those exerted by macrofauna (Connolly and H indell 2006). For example, some bivalves enhance seagrass condition by locally increasing both light accessibility and sediment nu- trients (Peterson and Heck 2001). Such links also may be decoupled by broad-scale physical disturbance or habitat fragmentation. Again, critical thresholds in functional links with decreasing habitat connectivity depend on the spe- cies’ biology and the physical setting (With and Crist 1995, Fonseca and Bell 1998, Monkonnen and Reunanen 1999). The first step towards understanding habitat function rel- ative to landscape-scale factors is to identify potential habitat- scaling relationships. So we compared shoal grass (Holodule wrightii) habitat and macrofaunal metrics during the seagrass growth phase between two barrier- island landscapes exposed to different levels of disturbance. Habitat metrics included: above ground biomass (AGB); epiphyte biomass; shoot num- ber; per shoot biomass; and below ground biomass (BGB); macrofaunal metrics included abundances of microgas- tropods, peracarid grazers, capitellid polychaetes, Neanthes polychaetes, and macrofaunal diversity. Our working hy- pothesis was that seagrass landscape, habitat and faunal met- rics should differ concertedly between more disturbed Cat Island (Cl) and less disturbed Horn Island (HI) landscapes. 11 Rakocinski et al. Study Area Two seagrass landscapes separated by 45 km extended along the north-central HI shoreline and around the west- ern tip of Cl (Figure 1). Horn Island is part of the Gulf Is- lands National Seashore under the jurisdiction of the US National Park Service. Waters surrounding Cl were man- aged only by state and federal dredge and fill regulations prior to and during the time frame of this study (Cl was acquired by US NPS in 2003). The HI landscape: (1) is apparently less exposed to physical disturbance than Cl; and (2) has been protected from trawling within 1.6 km of shore since May 1995 by the U.S. National Park Service. Materials and Methods Disturbance and habitat fragmentation Physical disturbance within the Cl and HI landscapes over four months prior to and during the study period from 15 May until 9 August 1998 was estimated from hourly measurements of wind direction, wind speed, and wave height taken at NOAA Data Buoy 42007 located off the north point of the Chandeleur Islands (30°05’24” N; 88°46’12” W), 19 km south of HI and 40 km south- east of CL Monthly mean (± 1 se) wind directions were calculated using circular statistics (Oriana Ver 1.0; Kovach 1994). Salinity was compared between the eastern and western portions of Mississippi Sound using data obtained from the MS Department of Marine Resources for rough- ly 40 stations during the May - June (80 vs. 90 observa- tions) and July - August (171 vs. 29 observations) periods. Seagrass fragmentation was quantified from 4m resolu- tion digital aerial photographs of seagrass cover taken in March 1998. ArcGIS 8.2 was used to digitize seagrass patch- es occurring within 13 hectares both off the west tip of Cl and along the northwest central side of HI. The digitized areas coincided with the landscape areas used for this study (Figure 1). Four, one hectare quadrats were randomly placed within each of the two island landscapes with the restric- tions that they could not overlap with each other or fall out- side of the seagrass-depth contour within designated areas. Field sampling Three sites separated by ~ 0.3 km were located within each of the two island landscapes (Figure 1). Three monthly sampling events during the seagrass growth phase ensued on 3 June, 22 June, and 5 August, 1998. At each site, three cores of seagrass and associated macrofauna (i.e., subsam- ples) were randomly taken within a ~ 0.01 km 2 area us- ing a 16.0 cm diameter plexiglass corer to extract 0.02 m 2 Figure 7. Map of the study region showing the two barrier-island landscapes and the six sites. Circular graphs depict monthly wind direction vectors, along with mean (± 95% Cl) wind velocities measured at NOAA Data Buoy 24007 during the study. 12 Habitat And Macrofaunal Differences Between Seagrass Landscapes TABLE 7 . Variation in wind and wave strength over the study period between 15 May and 9 August 1 998 measured at NOAA Data Buoy 42007 (30°05'24" N; 88°46'12" W). Values represent monthly means (± 1 se) obtained by aggregating hourly data for each day and daily values for each month. Monthly means (± 1 se) of wind directions were calculated using circular statistics, Oriana Ver 1.0 (Kovach 1 994). Significant wave height (meters) was calculated as the mean of the highest one third of all of the wave heights during the 20 minute sampling period. Month Wind speed (m sec 1 ) Wind direction (°) Significant wave height (m) Mean wave period (sec) May 15-31 4.56 ±0.281 196.2 ±3.11 0.35 ± 0.057 3.00 ± 0.036 June 1 - 30 5.24 ±0.325 186.0 ±2.21 0.48 ± 0.033 3.84 ±0.103 July 1 -31 4.41 ± 0.249 229.3 ± 2.36 0.27 ± 0.025 2.98 ± 0.237 August 1 - 9 4.79 ± 0.503 82.6 ±4.31 0.57 ± 0.079 3.71 ±0.193 sediment plugs to a depth of 15 cm. A total of 54 cores were taken (i.e., 2 landscape areas x 3 sites x 3 cores x 3 periods). A 0.5 mm mesh polypropylene sieve was used to remove fines, while still retaining all plant material and as- sociated macrofauna. Water column salinity (psu), turbidity (NTU), water temperature (°C), water depth (m), substrate type, and photosynthetically active radiation (PAR) (pmol photons m' 2 sec' 1 ) were recorded for each sampling event. Laboratory processing Plant material was carefully separated by gentle rins- ing in tapwater and frozen for later processing. Associ- ated coarse sediment and macrofauna were rewashed in a 0.5 mm mesh sieve and preserved in 10% formalin. Ten randomly selected shoots were used to quantify the epi- phyte load by scraping shoots and leaves with a dull razor blade. Shoot and epiphyte fractions were dried at 105 °C for 24 h or until a constant weight was obtained, and then weighed to the nearest 0.001 g using an O’Haus microbal- ance. In addition, remaining AGB and separated BGB fractions were dried and weighed (mg) as described above. Preserved macrofaunal organisms were sorted, identified to the lowest practical taxonomic level, and enumerated. Data analysis Metrics for comparing seagrass fragmentation included number of patches, total patch area, patch area percent cover, mean patch size, and standard deviation in patch size. Patch metrics were compared between HI and Cl us- ing Students independent-sample t-tests (p < 0.05). Two- tailed t-tests were based on assumptions of equal or un- equal variance, depending on the outcome of Levene’s tests of homogeneity of variance in SPSS 13.0 (SPSS 2004). Habitat and macrofaunal variables examined included the number of short shoots (shoot number), above-ground biomass without epiphytes (AGB), epiphyte biomass (= arcsine square-root (epiphyte biomass/(epiphyte biomass + AGB))), below ground biomass (BGB), per shoot biomass, microgastropod abundance (normalized to AGB), pera- carid grazer abundance (normalized to AGB), capitellid abundance, Neanthes abundance, and macrofaunal diver- sity (Shanon-Wiener H’; base 2). Macrofaunal abundances were log transformed (i..e, log 10 (N+l)) prior to analysis. To accommodate spatial and repeated time effects, the Linear Mixed Models (LMM) procedure was employed in SPSS 13 (SPSS 2004). LMM is very flexible in that it can model covariance and heterogeneous variability in the context of concurrent fixed and random effects (Verbeke and Molenberghs 2000). The Unstructured Covariance Model was fit as it provides the least restricted covariance structure and is equivalent to the multivariate form of Repeated Measures AN OVA. Site was treated as a subject variable and time as a repeated effect. Landscape and time were considered fixed main effects, and the landscape- time interaction term was also included. Tests of fixed effects utilized Type III sums of squares. Cases for LMM comprised means of the three cores per site-time event. For selected seagrass and macrofaunal variables, means (± 1 se) were plotted for each of the three sites from each island landscape across the three sampling dates. An inverse hyperbolic curve of the form Y = a X' b between the abundance of microgastropods (i.e., Bittio - lum varium and Astyris lunata ) and epiphyte mass (as the proportion of total AGB) was fit for the 54 cores. Results Disturbance and habitat fragmentation Wind direction and strength measured at NOAA Data Buoy 42007 implied that the Cl landscape was more ex- posed to physical disturbance than the HI landscape just prior to and during the study period. Winds typically origi- nated from the south-southwest for the three month period between 15 May and 9 August (Figure 1; Table 1). However, Cl sites were relatively protected near the end of the study period in early August, when winds primarily originated from the east. Wave action in concert with wind strength was relatively high in June, when the mean wave height was 0.48 ± 0.033 m (mean ± 1 se) while the mean wind velocity was 5.24 ± 0.325 m sec' 1 . Although HI sites are lo- 13 Rakocinski et al. cated farther than Cl sites from several major freshwater discharge sources, including the Bonnet Carre Spillway, and the Jourdan and Pearl Rivers (90 km vs. 46 km, 67 km vs. 25 km, and 80 km vs. 35 km, respectively), salinity was similar between the two island landscapes during the study period. Salinity averaged 14.8 ± 4.5 (3c ± 1 sd) vs. 17.0 ± 4.3 between western and eastern portions of Mississippi Sound during May - June 1998; and 22.7 ± 4.5 psu vs. 22.5 ± 4.4 psu during July - August 1998. Other conditions includ- ing water temperature, depth, turbidity, sediment composi- tion (i.e., sand) and light were also similar between areas. Seagrass habitat was notably more fragmented within the Cl landscape than in the HI landscape (Table 2). The num- ber of patches, total patch area, and mean patch size, were significantly different between island landscapes (t-tests; all p < 0.002). The mean number of 20.75 patches per hectare at Cl was more than three-fold higher than at HI; whereas, the mean total patch area of 4520.89 m 2 per hectare (i.e., 45.21% seagrass cover) at HI was nearly four-fold higher than at Cl (i.e., 12.35% seagrass cover). The grand mean patch size of 645.84 m 2 at HI was ten-fold larger than at CL Seagrass habitat variables All five seagrass habitat variables including AGB, shoot number, per shoot biomass, epiphyte biomass, and BGB dif- fered significantly between island landscapes (Table 3). Per shoot biomass and epiphyte biomass, also varied significant- ly in time. The landscape-time interaction was significant for epiphyte biomass, and marginally significant for BGB. AGB was usually higher within the HI landscape, espe- cially in August (Figure 2A). Over the study period, mean AGB ranged from 0.59 to 0.96 g dw per 0.02 m 2 at HI; whereas it ranged from 0.45 to 0.62 g dw per 0.02 m 2 at CL Conversely, shoot number was slightly higher at Cl (Figure 3A). However, per shoot biomass was clearly higher at HI than at Cl, and also increased during the study pe- riod (Figure 3B). Between June and August, per shoot bio- mass increased from 0.0061 to 0.0113 g dw at HI, whereas it increased from 0.0040 to 0.0067 g dw at CI. Epiphyte biomass was markedly higher at the CI landscape (Figure 4A); however, this metric also declined markedly in time at CI, while remaining nearly the same at HI. Monthly epi- phyte biomass ranged from 3.7 to 9.4 percent of total AGB at HI; whereas it ranged much higher, from 11.3 to 41.3 percent of total AGB at CI. BGB values were also consis- tently higher at HI over the three sample periods (Figure 2B); although BGB increased over time at CI (Table 3). Mean BGB ranged from 3.0 to 3.9 g dw per 0.02 m 2 at HI; whereas BGB ranged from 0.9 to 1.6 g dw per 0.02 m 2 at CI. Macrofaunal variables Macrofaunal species richness (S) was similar between the two barrier island landscapes: 86 taxa were collect- ed from both of the landscapes, each of which yielded 32 unique taxa. Thus, a total of 118 taxa were enumer- ated over the study period. Diversity (i.e., macrofaunal H’; base 2) was the only macrofaunal metric for which the landscape-time interaction was even marginally sig- nificant. Otherwise, Diversity was similar between land- scapes and sample periods; mean diversity ranged from TABLE 2 . Seagrass landscape metrics reflecting differences in habitat fragmentation from digital aerial images of the Cat Is- land and Horn Island landscapes taken in March 1 998. Values represent means (± 1 sd) of metrics for four randomly selected 1 -hectare (ha) quadrats within each designated 13.2-ha bounding plot area. CAT ISLAND Plot Total Plot Area (m 2 ) Number of Patches Total Patch Area (m 2 ) % Seagrass Cover x Patch Size (m 2 ) Patch Size sd (m 2 ) 1 10000 17 1316.14 13.16 77.42 103.67 2 10000 23 617.59 6.18 26.85 78.91 3 10000 21 2439.89 24.40 1 16.19 1 15.24 4 10000 22 567.42 5.67 25.80 24.66 Aggregate 40000 83 4941.04 12.35 59.53 84.59 HORN ISLAND Plot Total Plot Area (m 2 ) Number of Patches Total Patch Area (m 2 ) % Seagrass Cover x Patch Size (m 2 ) Patch Size sd (m 2 ) 1 10000 5 4558.46 45.58 759.74 1559.66 2 10000 7 5439.96 54.40 777.14 912.15 3 10000 8 3300.78 33.01 412.60 876.66 4 10000 7 4784.37 47.84 683.48 905.43 Aggregate 40000 27 18083.55 45.21 645.84 1020.1 1 14 Habitat And Macrofaunal Differences Between Seagrass Landscapes TABLE 3. Linear Mixed Models (LMM) results for nine seagross habitat and macrofaunal variables. Landscape and time are considered fixed effects. Time is also considered to be a repeated factor and sites are regarded as subjects. Unstructured (= com- pletely general covariance matrix) LMM model used , as explained in the text; No. model parameters = 12. ACB = Above Ground Biomass; BGB = Below Ground Biomass; GRZ PERACARIDS = Grazing Peracarids. Faunal abundances tested on log 10 (N+ 1 ) scale. Epiphyte biomass tested as arcsine square-root proportion of total AGB. Bold = significant , Bold underline = marginally significant. Dependent Variable -2RLL LNDSCP F P TIME F P LND x TIME F P AGB -14.546 8.666 0.042 0.973 0.453 2.027 0.247 SHOOT NUMBER 102.216 12.597 0.024 0.345 0.727 0.430 0.677 PER SHOOT BIOMASS -72.863 1 18.749 <0.001 15.783 0.013 2.577 0.191 EPIPHYTE BIOMASS -39.295 123.619 <0.001 47.888 0.002 31.608 0.004 BGB 25.592 17.508 0.014 0.257 0.786 4.464 0.096 MICROGASTROPODS -14.664 155.083 <0.001 27.161 0.005 0.413 0.687 GRZ PERACARIDS 3.574 0.602 0.481 2.053 0.243 1.140 0.406 CAPITELLIDS -1.550 6.557 0.063 2.971 0.162 3.658 0.125 NEANTHES -8.639 0.421 0.552 1.961 0.255 1.992 0.251 DIVERSITY 7.336 0.906 0.395 1.640 0.302 5.488 0.071 2.32 to 2.82 per 0.06 m 2 (i.e., for 3 cores combined). The overall macrofaunal density was notably four-fold higher at HI (mean (± 1 se) = 247. 1 (± 35. 7) per 0.02 m 2 ) than at Cl (mean (± 1 se) = 61.0 (± 5.0) per 0.02 m 2 ). Typical seagrass- associated macrofauna included the amphipods, A mpelisca holmesi and C ymadusa compta ; the isopods, Edotea triloba and Erichsonella attenuata ; the gastropods, Astyris lunata and Di- astoma varium , the caridean shrimp, Hippolyte zostericola , La- treutes parvulus , and Palaemonetes pugio; the brachyuran crab, C allinectes sapidus; and anomuran crabs, Pagurus spp. The macrofauna primarily comprised microgastropods (52.0% HI vs. 10.4% Cl), peracarid crustaceans (18.1% HI vs. 9.6% Cl), and infaunal polychaetes (13.6% HI vs. 23.4% Cl). Microgastropod abundances differed significantly be- tween landscapes; abundances were higher by an order of magnitude at HI (Figure 4B). They also varied significantly in time. Microgastropods comprised 84% Bittiolum varium and 16% A styris lunata. Changes in log abundances were parallel across the sample period between landscapes, first decreasing, and then increasing to the highest levels. Mean microgastropod abundances ranged from 33.0 to 296.4 per g dw AGB at HI; and from 5.3 to 22.7 per g dw AGB at CL A significant inverse hyperbolic relationship was appar- ent between the abundance of microgastropods and the epiphyte load (Figure 5). Although low epiphyte values cor- responded with a fairly wide range in microgastropod abun- dance, high epiphyte values (i.e., > 20 percent of total AGB) never occurred in association with high snail abundances. When scaled to AGB, abundances of peracarid grazers did not differ significantly between island landscapes; mean abundances ranged from 8.4 to 35.7 per g dw AGB. Ma- jor peracarid grazers included the ampithoid amphipods (A mpithoe and C ymadusa) and the isopod, Erichsonella. In- faunal polychaetes mostly consisted of the nereid, Neanthes (65% of total) and capitellids (18% of total; mainly C apitella and M ediomastus). Mean abundances of Neanthes ranged widely from 4.3 to 34.9 per 0.02 nr. Mean abundances of A B Figure 2, A. Variation in mean (± 1 se) AGB during the study period. B. Variation in mean (± 1 se) BGB during the study period. 15 Rakocinski et al. A B Figure 3. A. Variation in the mean (± 1 se) number of shoots during the study period. B. Variation in mean per shoot biomass (± 1 se) (per 10 shoots) during the study period. A B Figure 4. A. Variation in the mean (± 1 se) epiphyte biomass as a proportion of total ABG during the study period. B. Variation in the mean (± 1 se) abundance of microgastropod snails scaled to AGB. capitellids ranged from 1.7 to 11.3 per 0.02 m 2 at HI; whereas at Cl they ranged noticeably lower, from 0.8 to 1.4 per 0.02 m 2 ; and the difference in capitellid abundances between is- land landscapes was marginally significant (Table 3). Discussion Fonseca and Bell (1998) established that physical setting is the main determinant of seagrass landscape configura- tions, ranging from continuous to widely-dispersed patch- es with increasing disturbance. Other former studies also document patchy landscapes in high energy environments (Bostrom et al. 2006). The Cl landscape was more exposed to physical disturbance in the form of winds and wave ac- tion than HI. Although both seagrass landscapes were frag- mented, the seagrass landscape was correspondingly more fragmented at Cl (i.e., 12% cover at Cl vs. 45% cover at HI). Fonseca and Bell (1998) proposed the critical thresh- old of ~ 50% coverage, below which the loss of structural habitat integrity accelerates with increasing fragmentation. Low seagrass coverage at Cl corresponded with relatively low per shoot biomass, high epiphyte loading, and low BGB. A feasible link between effects of external and internal pro- cesses on habitat function might involve epiphyte loading. High epiphyte loading is known to suppress photosynthetic efficiency by preempting light, water column nutrients, car- bon, and oxygen (Sand-Jensen 1977, Sand-Jensen et al. 1985). Epiphyte loading may also exacerbate physical disturbance by increasing hydrodynamic impacts (Jernakoff et al. 1996). A recent paradigm shift in seagrass ecology recognizes the relative importance of top-down rather than bottom- up controls on epiphyte loading (Jernakoff et al. 1996); and calls for full consideration of the role of plant-animal interactions in studies of eutrophication effects in seagrass ecosystems (Hughes et al. 2004). However, attempts to link landscape-scale metrics and faunal responses in seagrass eco- systems have been equivocal (Bell et al. 2001). Macrofauna potentially exert internal feedbacks on habitat function in a variety of ways (Connolly and Hindell 2006), and these feedbacks might also be susceptible to disruption from physical disturbance and resulting habitat fragmentation. Any important plant-animal relationship requires two conditions. First, the animal should exhibit either direct or indirect functional links to plant habitat via actions af- fecting plant condition. Examples include predation on grazers, epiphyte grazing, or nutrient retention or delivery. Second, the strength of the functional link should vary with specific density of the animal (sensu Murphey and Fonseca 1995), or with abundance normalized to some habitat met- 16 Habitat And Macrofaunal Differences Between Seagrass Landscapes ric (e.g., AGB). The latter condition also implies potential sensitivity to landscape-scale changes in seagrass habitat. Accordingly, we examined abundances of microgastropods and peracarid grazers in relation to ABG. In this study, the clearest indication of a functional plant-animal link was an inverse relationship between the abundance of microgas- tropods and epiphyte loading. The dominant microgastro- pod, Bittiolum varium, is an important grazing component in seagrass ecosystems (van Montfrans et al. 1982, Edgar 1990, Neckles et al. 1993). Thus, microgastropods poten- tially enhance seagrass condition by removing epiphytes and redirecting nutrients to the sediments. Recently, Fong et al. (2000) showed that gastropod grazers, Clithon spp., directly improved the condition of Z ostera japonica by removing epi- phytic algae. But gastropod densities were positively corre- lated with seasonally high epiphytic loading in their system. Extremes in spatial configurations of seagrass habitat must bracket habitat fragmentation thresholds for individual taxa, above which dispersal and recolonization becomes ineffec- tive (Monkkonen and Reunanen 1999, Bostrom et al. 2006). For example, some threshold level of habitat fragmentation might impair the seagrass-epiphyte-microgastropod relation- ship by disrupting dispersal (Bell et al. 2001) or by increas- ing the chance of local extinction (Fahrig 2002). Recruit- ment of Bittiolum varium involves the production of seasonal cohorts via a planktonic larval stage that persists for about three weeks in the water column (Qurban 2000). Planktonic dispersal of larval gastropods implicates landscape fragmen- tation within the context of source-sink dynamics; it would behoove larvae to settle before they are swept away from suit- able habitat. Spatial isolation of seagrass beds from sources of planktonic larvae might occur. Extinction rates of macro- faunal populations might also be increased within fragment- ed seagrass habitat due to edge-effects (i.e. perimeter: area) that foster increased predation or emigration within smaller beds (Bologna and Heck 1999, Hovel and Fipcius 2001). Additional temporal mismatch between epiphyte biomass and microgastropod abundance suggests that controls on ep- iphyte loading were complex. This incongruence could have arisen from changes in the rate of seagrass senescence across the summer period (Nelson 1997, Fong et al. 2000). Higher rates of senescence and resultant lower epiphyte loading may occur as rates of seagrass production increase seasonally with water temperature (Peterson and Heck 2001). Another possible cause of seasonal decline in epiphyte loading at Cl could involve exacerbated loss of seagrass shoots with high epiphyte loads due to consequent hydrological disturbance (Jernakoff et al. 1996). Seasonal differences in nutrient availability could also limit the development of epiphytes. Temporal mismatch between epiphyte biomass and mi- crogastropod abundance could also reflect algal succession- al patterns, possibly involving interactions with microgastro- pods. Microgastropod grazers consume mostly diatoms (van Montfrans et al. 1982); however, there were clearly large quantities of filamentous epiphytic algae at the Cl site (pers. obsv.). An alternate algal successional pattern might be fos- tered by lower grazing pressure on the biofilms of surfaces of seagrass shoots. As has been shown for various peracar- ids (Duffy et al. 2001), selective grazing by microgastropods could favor slower growing early successional epiphytes, perhaps by conditioning seagrass surfaces. Alteration of the algal canopy by grazing might also facilitate colonization by early successional epiphytes (Sommer 1999). For whatever reasons, other studies show that the epiphyte community of disturbed seagrass habitat shifts towards filamentous al- gae and away from diatoms (Pinckney and Micheli 1998). Although the importance of the seagrass canopy to sec- ondary production is known, the role of the seagrass root- rhizome mat is not well understood. In this study, capitel- lids appeared to be more abundant at the HI landscape, where BGB was also consistently higher. This suggests a facultative association for this infaunal deposit feeder in seagrass habitats. Indeed, it is thought that below-ground seagrass production may also foster infaunal secondary production (Orth et al. 1984, Williams and Heck 2001). Despite limitations, this study highlights some potential links involving landscape configuration, habitat structure, and macrofaunal associations which can be further ad- dressed using hypothesis-driven research. Of course, the gen- erality of this study is limited by the lack of interspersion of seagrass landscape types. Furthermore, potential complexity of relationships involving multiple spatiotemporal scales ob- 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Epiphyte Biomass as Proportion Total AGB Figure 5 . Inverse hyperbolic relationship between the abundance of microgastropod snails normalized to AGB versus epiphyte biomass expressed as the proportion of total AGB. 17 Rakocinski et al. scures progress toward a coherent seagrass landscape-habitat function paradigm. Such a paradigm is especially important for successful seagrass restoration, which is predicated on knowing the right abiotic and biotic conditions for the re-establishment of the entire plant and faunal community (Fonseca et al. 1998, Pranovi et al. 2000). Such formidable challenges can only be met with experimental studies of spe- cific mechanisms and effects that are relevant on the land- scape scale. Acknowledgments We thank J.D. Caldwell, J.M. Cote, R.K. McCall, B.R. Blackburn, and S.J. VanderKooy for their assistance in the field and laboratory. Special thanks go to M. Foster, formerly of the USM Gulf Coast Geospatial Center, for quantifying seagrass patchiness for this study. 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Hay eds. Marine Community Ecology, Sinauer Associates, Inc., Sunderland NJ, USA, p.317-337. With, K.A. and T.O. Crist. 1995. Critical thresholds in species’ responses to landscape structure. Ecology 76:2446-2459. 19 Gulf and Caribbean Research Volume 20 Issue 1 January 2008 Seagrass Distribution in the Pensacola Bay System, Northwest Florida Michael A. Lewis U.S. Environmental Protection Agency Richard Devereux U.S. Environmental Protection Agency Pete Bourgeois National Wetlands Research Center DOI: 10.18785/gcr.2001.04 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Lewis, M. A., R. Devereux and R Bourgeois. 2008. Seagrass Distribution in the Pensacola Bay System, Northwest Florida. Gulf and Caribbean Research 20 (l): 21-28. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/4 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(cDusm.edu. Gulf and Caribbean Research Vol 20, 21-28, 2008 Manuscript received March 19, 2007; accepted June 8, 2007 SEAGRASS DISTRIBUTION IN THE PENSACOLA BAY SYSTEM, NORTHWEST FLORIDA Michael A. Lewis 1 *, Richard Devereux 1 , and Pete Bourgeois 2 'US. Environmental Protection Agency, National Health & Environmental Effects Research Laboratory, Gulf Ecology Division, Gulf Breeze, Florida 32561 USA, * e-mail : Lewis.Michael@epa.gov 2 U.S. Geological Survey, National Wetlands Research Center, Gulf Breeze Project Office, Gulf Breeze, Florida 32561 USA ABSTRACT; Aerial surveys of seagrass coverage in the Pensacola Bay system (PBS) have been conducted during 1960, 1980, 1992 and 2003. This report summarizes the results for the 2003 survey and compares the results to those previously reported for other surveys. The estimated coverage of seagrass for the PBS during 2003 was 1 ,654 ha. Continuous and patchy coverages ranged from 0 to 684 ha and 1 1 to 543 ha, respectively, for five PBS subsys- tems. In 2003, the majority of seagrass coverage occurred in Santa Rosa Sound (76%). Declines in total coverage occurred for East Bay (93%) and Escambia Bay (75%) whereas increases were observed for Pensacola Bay (32%) and Santa Rosa Sound (8%). The approximate 9% decline (about 160 ha or 395 a) in total coverage since 1992 represents an estimated 7 to 8 million dollar loss in ecological services. The changes in coverage are likely due to naturally occurring and anthropogenic factors but it is not possible to differentiate the relative contributions of these fac- tors alone and in combination on seagrass distribution. The ability of seagrasses to exist long-term in Florida's fourth largest estuarine system is uncertain due to the adverse effects of rapid urbanization in the watershed. Active resource management which includes more frequent in-situ monitoring and aerial assessment and the availability of relevant water and sediment quality criteria protective of submerged aquatic vegetation are needed to prevent future declines. Introduction Seagrasses have at least 13 ecological roles (Dawes et al. 2004) and they support a diverse biotic community that may contain as many as 113 species of epiphytes, 148 macroalgal species, 80 macrofaunal species, and 75 fish species (Humm 1964, Virnstein et al.1983, Zieman and Zieman 1989, DeT- roch et al. 1996). Seagrass meadows including those domi- nated by Thalassia testudinum Konig (turtle grass), the most abundant species in the Pensacola Bay System (PBS), sup- ported twice the macrofauna than did unvegetated sedi- ments (Santos and Simon 1974, Virnstein et al. 1983). The economic importance of one seagrass acre has been estimat- ed to be between $9,000 and $28,000 (Texas) and $20,500 (Florida) due to commercial, recreational and storm protec- tion functions (Handley et al. 2007) and $19,000 based on nutrient cycling (Costanza et al. 1997). About 1.2 million of 59 million hectares (ha) of seagrasses have been destroyed worldwide during the last decade and, similar to corals, seagrasses are considered to be in a crisis stage. Declines have occurred at 40 locations (Short and Wylie-Echeverria 1996, Hemminga and Duarte 2000) including the Gulf of Mexico (GOM), where seagrass coverage has been reduced 20 to 100% during the past 50 yrs (Dawes et al. 2004, USGS and GOMP 2004). For example, about 85% of the seagrasses along Florida’s coasts have been destroyed by 1992 (USEPA 1992). Florida’s Gulf Coast contains about 680,000 ha of seagrasses of which about 2% (17,474 ha) is adjacent to the Florida panhandle region (Madley et al. 2003). The trends in coverage and condition of the seagrasses in northwest Florida are considered to be poorly understood (Dawes et al. 2004). However, seagrass research for the PBS, the focus of this report, has been conducted intermittently during the past 40 yrs (Table 1) and includes four major aerial surveys conducted since the 1960s. The objectives of this report are to summarize the results of the 2003 aerial survey and to compare the results primarily to those for the previous sur- vey conducted during 1992. Materials and Methods Study Area The PBS is located in northwest Florida and its watershed consists of about 18,000 km 2 of forests, agricultural lands, and urban and industrial areas (Figure 1). It is the fourth largest estuary in Florida and extends 32 km inland and comprises about 886 km of coastline and 435 km of inland waterways. Mean water residence time is about 25 d (Solis and Powell 1999). The PBS is comprised of five subsystems: Big Fagoon, East Bay, Escambia Bay, Pensacola Bay, and San- ta Rosa Sound (Figure 1, Table 2). Santa Rosa Sound and Big Fagoon are marine lagoons that are parallel to the GOM and retain high salinities due to limited freshwater input. Both areas contain sections that are classified as Outstand- ing Florida Waters (FDEP 2001). Aerial Surveys Although aerial surveys of the PBS are available since the 1940s, only those conducted during 1960, 1980, 1992 and 2003 were specific for determining seagrass coverage. Re- sults of the 1960, 1980, and 1992 surveys have been report- 21 Lewis et al. ed previously (FDEP 2001, Schwenning et al. 2007) and the results for the October 2003 survey form the basis of this report. The experimental techniques for these surveys have differed, and these differences need to be considered in the context of the conclusions for the across-year comparisons reported here. Methodologies for the 1992 and 2003 sur- veys were similar but not identical. The seagrass data were derived from interpretation of 1:24,000 natural color scale photographs (1992 survey) and 1:12,000 scale color infrared photographs (2003 survey). Personnel from NASA (Stennis, MS) and Aerial Cartographies of America (Orlando, FL) performed the 1992 and 2003 flights, respectively. Black and white photographs (1:24,000 scale) and natural color photographs (1:24,000 scale) were used for the 1960 and 1980 surveys, respectively. Personnel from U.S. Geologi- cal Survey’s National Wetlands Research Center (NWRC, Lafayette, LA) conducted the mapping procedure which included photo-interpretation of the aerial photographs, cartographic transfer, and digitization for all surveys. The classification scheme for all surveys was derived by USGS/ NWRC based on the coastal land cover classification system of the National Oceanic and Atmospheric Administration’s Coastwatch Change Analysis Project (NOAA 2003). The amount of groundtruthing or field verification of the aerial surveys has been variable, and for the 2003 survey it con- sisted of single visits to the five PBS subsystems to confirm seagrass presence. No in-situ measurements of plant condi- tion or species identification were performed. Results and Discussion Seagrass Coverage An estimated 1,654 seagr ass-vegetated ha (4,085 acres) were present in the PBS based on the October 2003 aerial survey (Table 3). Of this total, most coverage occurred in Santa Rosa Sound (76%). Seagrass coverage as a percent of total surface area was 18% (Santa Rosa Sound), 5% (Big Lagoon), 1% (Pensacola Bay) and < 1% (Escambia Bay, East Bay). Continuous and patchy coverages ranged from 0 to 684 ha and 11 to 543 ha, respectively in the PBS (Table 3). About 52% of the 2003 total coverage was continuous, and almost all continuous coverage (99%) occurred in Santa Rosa Sound and Big Lagoon. The 2003 total seagrass coverage (1,654 ha) represents an almost 9% reduction relative to the estimated total for the 1992 survey (1,814 ha). Reductions in total coverage relative to 1992 occurred for East Bay (93%), and Escambia Bay (75%) while increases were observed for Pensacola Bay (32%) and Santa Rosa Sound (8%) (Figure 2). Total cover- ages in Big Lagoon for 1992 and 2003 were almost identi- cal. Continuous coverage decreased in Escambia Bay (69%), Santa Rosa Sound (14%), Pensacola Bay (100%), and East Bay (100%), which contrasted an almost 64% increase in coverage for Big Lagoon. Patchy coverage decreased in Big TABLE 7 . Listing of seagrass and habitat condition research conducted for the Pensacola Bay System, Florida. Subsystem References Big Lagoon Hopkins 1973 Heck et al. 1996 Lores et al. 2000 FDEP 2001 East Bay Van Breedveld 1966 McNulty etal. 1972 Rogers and Blisterfield 1975 Escambia Bay Moore 1963 USDOI 1970 Livingston et al. 1 971 McNulty etal. 1972 Hopkins 1973 Rogers 1974 Rogers and Blisterfield 1975 Woodward and Clyde 1997 Lewis et al. 2000 Lores et al. 2000 Lores and Sprecht 2001 Murrell et al. 2002 Murrell and Lores 2004 Pensacola Bay Moore 1963 McNulty et al. 1 972 Rogers and Blisterfield 1975 Rodriguez and Hunner 1994 Murrell et al. 2002 Santa Rosa Sound Moore 1963 Van Breedveld 1966 McNulty etal. 1972 Hopkins 1973 Rogers and Blisterfield 1975 Winter 1978 Macauley et al. 1988 Heck et al. 1 996 Lores et al. 2000 FDEP 2001 Lewis et al. 2001 , 2002 Pensacola Bay USEPA 1975 System (general) Williams 1981 Lewis 1986 Ridenauer and Shambaugh 1986 Jones et al. 1 992 Collard 1991 Thorpe et al. 1 997 DeBusk et al. 2002 Dawes et al. 2004 McRae et al. 2004 USEPA 2004 USEPA 2005 Schwenning et al. 2007 22 87°0’0”W Seagrasses in Pensacola Bay Florida o o CO 23 Figure I. 1 The Pensacola Bay System in northwest Florida and its watershed (insert). Shaded areas represent 87°0'0"W continuous (green) and patchy (red) seagrass coverage estimated from a 2003 aerial survey Lewis et al. TABLE 2. Geomorphological characteristics and water body classifications for Pensacola Bay subsystems. Some data adapted from USEPA (1975). N/A - not available. Subsystem Surface Area (km 2 ) Volume (TO 6 m 3 ) Mean Depth (m) Water Body Classification 1 Florida Impaired Water 2 Assessed Parameters Big Lagoon 46.8 N/A N/A 2 (OFW) N - East Bay 25.9 259.3 2.4 2 Y Fecal coliforms, Nutrients Escambia Bay 57 225.7 2.4 3 M Y Nutrients Pensacola Bay 133.6 793.8 5.9 3M Y Bacteria Santa Rosa Sound 68.2 N/A N/A 2 (OFW) Y Fecal coliforms 1 2 = shellfish propagation or harvesting , 3M = Recreation , propagation and maintenance of well-balanced populations of fish and wildlife (FDEP 1996). OFW = Portion designated as Outstanding Florida Water (OFW) (FDEP 2004). 2 Contains segments for TMDL development (FDEP 2006). Lagoon (51%), East Bay (93%), and Escambia Bay (76%) and increased in Pensacola Bay (50%) and Santa Rosa Sound (58%). Historical Perspective The numerous seagrass investigations conducted in the PBS have been temporally and spatially inconsistent and research methodologies have varied. Seagrass mapping has been the focus of most studies, and only limited informa- tion is available describing physiological and morphological parameters of plant condition such as above- and below- ground biomass, shoot density, blade height and epiphyte/ biomass ratio, which have been reported for grasses in Big Lagoon, Santa Rosa Sound and Escambia River delta region (Heck et al. 1996, Lores et al. 2000, FDEP 2001). Historically, the largest seagrass declines within the PBS occurred between 1960 and 1980 and subsequent declines have been less severe (Table 3, Figure 2). Seagrass meadows in Santa Rosa Sound and Big Lagoon, with few exceptions, have dominated the PBS since 1960 (coverage range as a percent of total = 75 to 90%). Their combined dominance increased 12% since 1992 to 87% of total coverage in 2003. The consistent coverages in these areas are due, at least in part, to relatively less urbanization of the shorelines (sec- tions are included in a state park and a national seashore) and to limited freshwater input which stabilizes salinity and reduces the entry of watershed contaminants. In a detailed study conducted in these areas (Heck et al. 1996), seagrasses declined during 1993 - 1995 in both areas due to a combi- nation of propeller scarring, reduced water clarity, changes in salinity and burial due to hurricanes. Lores et al. (2000) reported seagrass coverage was also decreasing in Big Lagoon during 1997 and 1998. Seagrass research has been conducted less frequently in East, Escambia and Pensacola Bays, where seagrasses have been relatively uncommon since the 1960s (range of com- bined total coverages = 9 to 25%; Table 3). Seagrass cov- erage in East Bay was almost non-detectable and the least of any subsystem in 2003. Submerged aquatic vegetation in Escambia Bay is primarily limited to tidal freshwater grasses, Vallisneria americana Michx (tape grass) in the upper reaches and the more salinity tolerant Ruppia maritima L. (wigeon grass) in more seaward areas. Vallisneria americana is not a true seagrass, although its ecological value is similar to that of seagrasses. This species is included in this analysis, since prior assessments did not differentiate between species. Total coverage in Escambia Bay fluctuates greatly, with a TABLE 3. Continuous (C) and patchy (P) seagrass coverage (hectares) in Pensacola Bay subsystems. Data for 1 960, 1 980 and 1 992 aerial surveys from Schwenning et al. (2007). Subsystem I960 AERIAL SURVEY 1980 1992 2003 Big Lagoon C 107 193 99 162 P 164 43 118 58 East Bay c 45 12 5 0 p 431 87 160 1 1 Escambia Bay c 4 4 36 11 p 101 20 143 34 Pensacola Bay c 44 10 13 0 p 328 46 101 151 Santa Rosa c 1,247 850 796 684 Sound p 1,387 629 343 543 TOTAL 3,858 1,894 1,814 1,654 Seagrasses in Pensacola Bay Florida historical maximum occuring in 1992 followed by a 75% decline in 2003. Lores et al. (2000) reported increased cover- age of V americana near the Escambia River delta for 1997 and 1998 relative to 1992, but coverage decreased during 2000 due to drought and high salinity (Lores and Sprecht 2001). Although continuous seagrass coverage in Pensacola Bay was not detectable in 2003, patchy coverage increased from 101 ha to 151 ha since 1992. Causes of Seagrass Declines The factors responsible for declines in seagrass coverage for the PBS, other than direct effects due to mechanical and physical factors, have been more often speculative than con- firmed. Supportive documentation is limited, and current understanding of the causative factors responsible for the seagrass changes alone and in combination remains elusive, which has limited effective restoration efforts and resource management. Declines have been attributed to controllable factors such as point and nonpoint source contaminants, prop scarring, dock shading, armoured shorelines, and dredging, as well as to the non-controllable effects of epi- sodic weather events which have been increasing in recent years. A few investigators have reported the effects of nutri- ents (Heck et al. 1996, Lores et al. 2001) and low salinity (Lores and Specht 2001) and the potential for chemical phy- totoxicity (Lewis et al. 2007) on seagrasses within the PBS. The PBS is a contaminant-impacted estuary based on the results of many reports included in Table 1. Turbidity due to erosion and accelerated eutrophication have reduced light penetration in all subsystems. In addition, regulatory effects-based guidelines and criteria to protect marine life in water and sediment have been commonly exceeded in several subsystems for several non-nutrient contaminants (for example, DeBusk et al. 2002, USEPA 2005), suggesting a potential for toxicity. This is the case for Escambia Bay, which is the most contaminated subsystem and a priority site for conservation (Beck et al. 2000). In contrast, Santa Rosa Sound is the least chemically contaminated area with- in the PBS (FDEP 2001, Lewis et al. 2007). Despite differences in environmental conditions among subsystems, it remains to be determined if the sensitivities of seagrasses and other submerged aquatic vegetation to non-nutrient contaminants is equivalent to those for zoob- enthos and fish for which most regulatory numerical guide- lines and criteria have been developed. In addition to this uncertainty is the continued absence of national and state numerical nutrient criteria which further hinders effective management of these marine angiosperms. Summary and Recommendations Despite the limitations and sources of error associated with aerial seagrass photography (see Carlson and Madley 2007), it was clear that there has been no net gain in seagrass coverage within the PBS since 1992. The few site-specific gains in coverage were overshadowed by declines in other Figure 2. Total seagrass coverage (hectares) for five subsystems in the Pensacola Bay System based on four aerial surveys. Data for 1 960, 1 980 and 1 992 surveys from Schwenning et al. (2007). subsystems which resulted in an estimated net loss of about 9% or 160 ha (~ 395 acres) system-wide. The relevance of the 2003 coverage to current coverage (2007) is unknown. Two major hurricanes, Ivan (2004) and Dennis (2005) made almost direct landfall near the PBS. Their impacts have not been reported in the scientific literature, nor have impacts associated with the ongoing urbanization of the PBS shore- line that has occurred since 2003. The rapid urbanization of the PBS watershed is expected to continue. The populations in Escambia and Santa Rosa Counties is predicted to increase 20% and 64%, respec- tively, by 2020 (Zwick and Carr 2006). The magnitude of this urban transformation on near-shore seagrasses is un- known. This uncertainty will remain until an effective and long-term resource management plan is implemented, par- ticularly for near-shore areas containing extensive seagrass coverage such as Santa Rosa Sound. Several management plans have been proposed (Rogers and Blisterfield 1975, Collard 1991, FDEP 2001), and these should include fre- quent aerial assessments (every 3 to 5 yrs) to determine coverage and more frequent insitu evaluation to determine plant condition. These assessments are important so that in the long-term biocriteria predictive of habitat quality can be developed. Other management considerations should in- clude promotion of shoreline configurations supportive of seagrass meadows and increased efforts to control coastal entry of non-point source contaminants. Of additional im- portance is the need to establish a separate designated use category to protect coastal submerged vegetation as well as the development of supportive regulatory numerical criteria for common near-shore contaminants and those of emerg- ing concern (Daughton 2005). Finally, assessment of the economical value of ecosys- 25 Lewis et al. tem services has become increasingly important to the en- vironmental policy and management process (Costanza et al. 1997, Carpenter and Turner 2000, USEPA 2006). The loss of ecological services associated with the estimated 395 acre decline in seagrass coverage for the PBS since 1992 rep- resents an approximate $8.1 million impact ($20,500/acre; Handley et al. 2007) or, if based on nutrient cycling, a $7.5 million loss ($19,000/acre; Costanza et al. 1997). Acknowledgments We thank P. Rogers (National Caucus (Sc Center for Black Aged, Washington, DC) for manuscript preparation and P. Soderlund (Computer Services Corporation, El Segundo, CA) for graphics support. Linda Harwell (U.S. Environmental Protection Agency, Gulf Breeze, FL) assisted in data analysis. Aerial photography and analysis were conducted as part of an Intraagency Agreement with the U.S. Geological Survey’s National Wetlands Research Center, Lafayette, LA. Literature Cited Beck, M.W., M. Odaya, J.J. Bachant, J. Bergan, B. Keller, R. Martin, R. Mathews, C, Porter, and G. Ramseur. 2000. 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Environmental studies in Escambia Bay and Perdido Bay systems. Final Report. Prepared for Champion International Corp., Project No. 97F299, Tallahassee, FL, USA, 210 p. Zieman, J.C. and R.T. Zieman. 1989. The ecology of the seagrass meadows of the west coast of Florida: a community profile. Biological Report 85 (7.25), Washington, DC, USA, 155 p. Zwick, P.D. and M.H. Carr. 2006. Florida 2060 - a population distribution scenario for the State of Florida. Final report, Geoplan Center, University of Florida, Gainesville, FL, USA, 25 p. 28 Gulf and Caribbean Research Volume 20 Issue 1 2008 Variability in Estimating Abundance of Postlarval Brown Shrimp Farfantepenaeus aztecus (Ives), Migrating into Galveston Bay Texas Geoffrey A. Matthews NOAA Fisheries DOI: 10.18785/gcr.2001.05 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Matthews, G. A. 2008. Variability in Estimating Abundance of Postlarval Brown Shrimp, Farfantepenaeus aztecus (Ives), Migrating into Galveston Bay, Texas. Gulf and Caribbean Research 20 (l): 29-39. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/5 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(cDusm.edu. Gulf and Caribbean Research Vol 20, 29-39, 2008 Manuscript received February 26, 2007; accepted November 16, 2007 VARIABILITY IN ESTIMATING ABUNDANCE OF POSTLARVAL BROWN SHRIMP, FARFANTEPENAEUS AZTECUS (IVES), MIGRATING INTO GALVESTON BAY, TEXAS. Geoffrey A. Matthews NOAA Fisheries, Galveston Laboratory, 4700 Ave U, Galveston, Texas 77551, e-mail: geoffrey.matthews@noaa.gov ABSTRACT: Three sets of monitoring data were used to examine the variability associated with abundance estimation of postlarval brown shrimp, Farfantepenaeus aztecus (Ives) in Bolivar Roads, Texas— the main connection between the Gulf of Mexico and Galveston Bay. Abundance of postlarvae (PL) caught with Renfro beam trawl varied greatly in different years on the same dates. A "spring peak" of brown shrimp PL migrating into Galveston Bay was found for 2 April with a quadratic regression fit to 6-day moving averages of daily mean abundance from 22 yrs of monitoring data: Ln(PL+l) = 0.8736 + 0.09037Day - 0.0004934Day 2 (adj-R 2 = 0.83, n = 159), where Day is Julian day. Abundance varied by four orders of magnitude (0 to 24,616 PL/tow) in just 4 d during a four-week intensive monitoring of PL during the 1987 spring peak. Abundance also varied by three orders of magnitude between the North and South Jetty sites during the same col- lection time. During a third study, PL abundance varied by two orders of magnitude along 360 m of the beach in < 4 hr. These investigations demonstrate that detecting significant differences in PL shrimp abundance in a pass requires substantial sampling that may not be logistically possible. However, best estimates could be obtained by including as many dates as possible, followed by including more sites, and finally by collecting during both day and night. Conclusions drawn from abundance studies of PL shrimp, fish, and crab immigrants through estuarine passes that are based on only a few samples should be reviewed. Introduction The brown shrimp, Farfantepenaeus aztecus (Ives), is a key commercial species in the shrimp fishery of the nortlv western Gulf of Mexico (GOM). Most adults inhabit water depths of 20-65 m (Darnell et al. 1983, Neal et al. 1983) and spawning and larval development occur in these wa- ters. Postlarvae (PL) migrate into the bay where they grow for about three months in salt marshes (Zimmerman and Minello 1984). Then, as advanced juveniles or sub-adults, they migrate back through the bays to the GOM, during which time they recruit to the bait and bay shrimp fisher- ies. All shrimp fisheries are valuable, are managed based on age-0 individuals (J. Nance and F. Patella, pers. comm., NMFS, Galveston, TX), and are characterized by large vari- ability in annual catches (Klima et al. 1986). It is beneficial to commercial shrimp fishers and resource managers to have a forecast of the upcoming harvest, and the abundance of im- migrating PL is a potential indicator of shrimp harvest (Bax- ter 1963, Berry and Baxter 1969, Baxter and Sullivan 1986). Various attempts to establish an early forecast using PL abundance have been unsuccessful (Williams and Deubler 1968, Berry and Baxter 1969, Sutter and Christmas 1982, DeLancey et al. 1994). These forecasting models have relied upon three important assumptions: (1) mortality rates for young brown shrimp in the estuary are either constant or vary in a regular manner seasonally from year to year; (2) the majority of recruitment of PL shrimp to estuarine nurseries occurs during the same months each year; and (3) accurate estimates of PL immigration to bays and estuaries have been obtained. Mortality rates of juvenile shrimp can be highly variable on a weekly or annual basis, but few measurements of this mortality are available (Minello et al. 1989). Accurate estimates of the influx of PL might not be possible; even the precision of such estimates has been studied only to a limited degree (Berry and Baxter 1969, Caillouet et al. 1968, 1970, Lochmann 1990). Only about 60% of the age-0 shrimp re- cruit to the fishery during the early summer, the rest recruit mostly during the next four months. The PL for the sum- mer recruitment enter the estuaries in late winter and early spring, and Berry and Baxter (1969) hypothesized that the magnitude of the spring peak immigration might control fishery recruitment for that year. However, during winter and spring Arctic frontal passages, when the water is chilled and blown out of the estuaries by north winds (i.e. during a “blue norther”), the immigration of PL is delayed (Wenner et al. 1998, Blanton et al. 1999, Benfield and Downer 2001). These events weaken temporally-dependent models, increase the variability in the rate of PL immigration, and increase the variability in estimated density obtained by sampling. Brown shrimp larvae grow and develop as plankton in shelf waters of the GOM, and many factors lead to a patchy distribution as the PL migrate towards shore and immigrate through passes into bays. As meroplankton, their distribu- tion is governed by seasonal circulation patterns, shelf gyres, wind-driven coastal and tidal currents (Temple and Fischer 1965, 1967, Temple and Martin 1979), and by wind and tem- perature controlled upwelling and downwelling (Wenner et 29 Matthews 94 ° 45 ' Figure 7. Postlarval shrimp sampling sites along Bolivar Roads, the main pass connecting Galveston Bay, Texas, with the Gulf of Mexico. Sites: A= South Jetty site, B= North Jetty site, C= Fort Point (USACE water temperature gage), D= Pier 2 1 (NOS tide gage). al. 1998, Queiroga et al. 2006). The PL stage is the last of 12 planktonic stages (Cook 1966) that develop in the GOM on a schedule dictated by food availability and environmental conditions, and larvae and PL are transported across the shelf towards shore by coastal currents (Rogers et al. 1993, Rotlv lisberg et al. 1983, 1995, Criales et al. 2006), and through passes to estuarine nurseries by tidal currents (Lochmann 1990, Herke et al. 1996, Houser and Allen 1996, Criales et al. 2000). Both types of currents can be altered seasonally by winds, particularly in the spring by Arctic frontal passages along the Gulf coast (Smith 1975, 1978). The immigration of PL would be expected to change as these currents change. The main objective of this paper is to elucidate the po- tential for drawing erroneous conclusions about the abun- dance of immigrating PL brown shrimp by looking at time and space differences in PL abundance. Three sets of collec- tions of immigrating PL were examined for variability in a “spring peak” and in short temporal and spatial variability in abundance estimates. Though the accuracy of an abun- dance estimate cannot be measured because the true num- ber of immigrating PL can never be known, the data pre- sented here demonstrate that monitoring programs also are limited in the precision of their abundance measurements. Materials and Methods Sampling Procedures The studies were conducted at Bolivar Roads (29° 20’ N, co 93° 44’ W), a jettied tidal pass forming the main entrance into ^ Galveston Bay, Texas, from the GOM (Figure 1). The South Jetty site (Figure 1, point A) and the North Jetty site (Figure 1, point B) were located along the south and north shorelines of the pass, respectively. These beach sites were sandy and mostly gently sloping ( ~ 1 : 25) with some small bottom ripples that changed weekly due to tidal currents and wave action. All PL collections were made using a modified Renfro beam trawl constructed with a 1.8 m galvanized iron pipe (12.7 mm) that spread a 1.5 m semi-conical trawl of 1 x 2 mm mesh woven nylon netting (Renfro 1963). During a tow, the net was opened by a floating head rope while the foot rope was kept on the bottom by multiple weights and the pipe beam. A standard tow involved walking the net around a 23 m radius semi-circular path from shore to shore along a central pivot point. Maximum water depth sampled was 1.2 m, and towing speed was about 1 m sec 1 . The catch was preserved in 5-10% buffered formalin. Each standard tow swept about 102 m 2 of bottom and filtered about 36 m 3 of water based on water depth, mouth opening, and distance towed. Because the vertical distribution of PL was unknown and the volume of water filtered was only approximated, the number of PL per tow (PL/tow) is used to present catch/abundance data. Spatial and temporal effects on variability in PL abun- dance were studied during intensive sampling in spring 1987. Postlarvae were collected during daylight (0800-1700) and nighttime (2000-0400), Monday through Friday from 9 March - 3 April 1987 at both South Jetty and North Jetty collection sites. Collections each week were scheduled to in- clude at least two ebb and two flood tides during daylight and darkness based on predicted tide tables (NOS 1986). For each collection three beam trawl tows were made at each site, tow paths being spread along the shoreline with 25 m between ending point of one tow and starting point of the next. During the third week, separate crews sampled both sites simultaneously, and one hour after the first col- lection, a second collection was made at the South Jetty site to discover if significant differences should be expect- ed over a 1 hr period— the usual travel time between sites. The effect of tow length (m) was examined at the South Jetty site on 17 September 1987. Ten sets of tows were made between 0840 and 1200 h. For each set, three semicircular concentric tows using radii of 11, 23, and 46 m (37, 75, and 150 ft) were made simultaneously. Only the 46 m radius tows had to be overlapped slightly because the length of shore- line shallows was limited. Because tows reached from the shore into open shallow water, variation in tow length also incorporated differences in abundance due to water depth. Hydrographic and weather data were recorded during each collection. Hourly wind speed (Kmph) and direction and air temperature (°C) data were obtained from the Na- tional Weather Service for spring 1987. Also, hourly water temperature (°C) data were obtained from the U.S. Army Estimating Postlarval Shrimp Abundance Corps of Engineer’s gauge at Fort Point (Figure 1, point C), and tide levels (cm) were obtained from the National Ocean Service gauge at the Galveston Pier 21 that is located beside the Galveston Channel (Figure 1, point D) for spring 1987. All PF in each catch were picked, identified, and counted for the normal monitoring samples. Catches were sub-sam- cr pled (> 12.5% of total catch, for a target of 200 PF) when ^ catches were large in the intensive sampling study. White shrimp, Litopenaeus setiferus (Finnaeus) PF were separated by key characteristics including presence or absence of dorsal carinal spines (Williams 1959, Cook 1966, Ringo and Zamo- ra 1968) and by size. In the year-round monitoring samples (1960-1975, 1983-1987, 1989), PFwere identified as white, pink (Farfantepenaeus duorarum (Burkenroad)), or brown shrimp. In the intensive sampling and the three radii studies PF were identified as white or brown shrimp. Any potential pink shrimp PF were pooled with brown shrimp. It is likely that over 95% of the pink and brown (grooved) PF in this research were brown shrimp based on key characteristics, season of occurrence, and the species composition of the shrimp fisheries in Galveston Bay (Baxter et al. 1988). Stud- ies to separate grooved PF and juveniles up to 7 mm carapace length are ongoing because characteristics in published keys appear to be only about 60% accurate for separating pink and brown shrimp specimens collected in the northwestern GOM estuaries (J. Ditty, pers. comm., NMFS, Galveston, TX). Analysis Regression and correlation analyses between PF abun- dance and environmental conditions were estimated using MS Excel 2000, Sokal and Rohlf (1969), and SAS (1987) for personal computers. Postlarval abundance was trans- formed using Fn(PF+l) to reduce the variance-to-mean correlation (Berry and Baxter 1969, Caillouet et al. 1970); however, an F test revealed the variances were still het- eroscedastic. Thus, Wilcoxon matched-pairs signed-ranks tests (Siegel 1956) and graphical inspections were used to compare PF abundance from tow to tow, hour to hour, day to night, day to day, site to site, and among radii. The abundance data from earliest monitoring of PF im- migration covered 1960-1966 (Baxter and Renfro 1966, Ber- ry and Baxter 1969) and has been combined here with addi- tional data collected during 1967-1975, 1983-1987, and 1989. Early collections usually did not include replicates at a site, so a daily datum for a year was from either a single sample or from the geometric mean of single samples from the South and North Jetty sites. In the 1980’s triplicate samples were taken twice per week at the South Jetty site. Daily means for all years combined were calculated using daily data or means for as many years as were sampled for that Julian day. Mul- tiple moving averages (MA) were calculated, including from 2 to 6 d. Each MA included one or more days leading up to and including the day of record; the more days included, the Figure 2. Postlarval brown shrimp sampled by NMFS monitoring of Bolivar Roads, Texas. (A) Daily mean catches for each year for January through mid-June of 1960-1975, 1983-1987, and 1989. (B) The quadratic regression line for 6-day moving average of the daily mean abundance of years combined. 95% confidence limits (dotted lines) and 95% prediction intervals (dashed lines) are indicated in each section. Julian Day 1 - January 1 ; Julian Day 150 = May 30. smoother the spring peak. A quadratic regression analysis was used to determine the spring peak in PF abundance be- cause it yields a parabolic shape with a peak and appeared to have the best potential fit to the data when viewed in a scat- ter plot. Day, the independent variable, was the Julian day of the year and ranged from 1 (1 January) to 161 (10 June). Relationships between PF abundance and water tempera- ture (°C), salinity (%o), and north-south wind vectors (see be- low) were examined graphically and by correlation analyses. North-south wind vectors were calculated using wind speeds and directions. Northwest, north, and northeast directions produced negative vectors, east and west produced zero vec- tors, and southeast, south and southwest directions pro- duced positive speed vectors (Kmph) for correlation analyses. 31 Matthews Results Postlarval Brown Shrimp Spring Peak An inspection of 22 yr of January through early June abundance data from collections in Bolivar Roads revealed that PL brown shrimp immigrated into Galveston Bay throughout the year. Immigration was found even dur- ing the coldest months, but was usually greatest during March and April (Figure 2). High abundances (> 1000 PL/ tow) were found February through May depending on the year (Figure 2A). Using Ln(PL+ 1 /transformed daily mean catches during each year a quadratic regression produced an adjusted-r 2 of only 0.27 (n = 1020). The quadratic regres- sion using 6-d moving averages (MAh) of daily means for years combined formed an acceptable spring peak that ac- counted for about 84% of the variability (Figure 2B) and established the peak on 2 April from the equation: MA6 Ln(PL+ 1) =0.8736 + 0.09037Day - 0.0004934Day 2 (adjust- ed-r 2 = 0.84, n = 159, p < 0.001). The mean and 95% confi- dence limits for Ln(PL+l)-transformed abundance data for the 62 samples (all years) collected during 30 March - 5 April, the week of the peak, were 144 PL/tow and 88-235 PL/tow, respectively, compared to the regression peak of 149 PL/tow and 95% confidence limits of 57-392 PL/tow. 1987 Intensive Spring Sampling Study Abundance of brown shrimp PL ranged from 0 to 24,616 PL/tow, with a mean of 409 PL/tow (se = 119, n = 262 samples; Table 1) during spring 1987. No white shrimp PL occurred in the samples; they were never found before May during 22 yr of monitoring in Bolivar Roads. This maxi- mum catch (24,616) was higher than any recorded catch dur- ing the 22 yr of standard monitoring. The means for tripli- cate tows ranged from 0.7 to 15,673 PL/tow and averaged 440 (se = 207, n = 77). Means for a calendar day (n = 12; 3 day and 3 night at the two sites) ranged from 18 to 4,488 PL/tow with the grand daily mean being 426 (se = 218, n = 20). The means for the North and South Jetty sites were 82 (se = 14, nr 57) and 962 PL/tow (se = 523, n = 55) for daylight, 288 (se = 42, n = 60) and 449 PL/tow (se = 110, n = 60) for night, and 188 (se = 24, n = 117) and 694 PL/tow (se = 257, n = 115) overall, respectively. For all daytime and nighttime tows the means were 514 (se = 259, n = 112) and 369 PL/tow (se = 59, n = 120), respectively. High variability in abundance found among the triplicates, day/ night, dates, and sites was not constant and may not have been obvious without intense sampling (Figure 3). Times and Sites Observing changes in PL over various periods is use- ful for understanding PL influxes through passes and for establishing sampling regimes. The largest coefficient of variation (CV) for triplicate Ln(PL+ l)-transformed abun- dance was 86.6%, and the smallest was 0.6%; both were for daytime collections at the South Jetty. Abundance in nighttime triplicates generally varied less than those North Jetty site O Day, n=3 ♦ Night, n=3 u i . 'V \i l k t f / 1— Jl O - T j n U ' 1 <0 * X G 9 11 13 16 18 20 23 25 27 30 1 3 March April Figure 3. Means and 95% confidence intervals for abundance of postlarval brown shrimp during March 1 987 in Bolivar Roads , Texas for two sites. Sampling occurred Monday through Friday for 4 weeks. Means are for triplicate tows using Renfro beam trawls. * = no data. in daytime triplicates (Table 2). Among all triplicate sam- ples, 55% had CV’s < 10% and 77% had CV’s < 20%. Postlarval abundance varied from hour to hour, and had a mean absolute difference of 104 PL/tow (se = 64) for the ten paired sets of triplicate samples. This differ- ence was less than the mean of the 20 triplicate means, 154 PL/tow (se = 40), used for the comparison. Changes occurring during half a day (-12 h) were confounded by the light factor— day becoming night and vice versa. Night abundance at each site was greater than the correspond- ing day 78% of the time (Table 1 and Figure 3). The mean absolute difference over 12 h was 650 PL/tow (se = 286, n = 66). This difference was considerably larger than the mean, 446 PL/tow (se = 212), of the 74 triplicate means used for the comparisons. Changes in abundance from day to day (-24 h) were tested by comparing means from one daytime sampling to the next and from one nighttime sam- pling to the next for each site separately. The mean absolute difference was 767 PL/tow (se = 363, n = 59). This differ- ence was also considerably larger than the mean, 451 PL/ 32 Estimating Postlarval Shrimp Abundance TABLE 7. Brown shrimp postlarval abundance in Bolivar Roads , Texas during spring 1 987 , as caught in Renfro beam trawl shoreline based tows. Each tow swept 1 02m 2 of bottom and filtered about 36m 3 of water; nd = no data; +1 Hr = samples taken one hour later at same sites. DAY NIGHT Date ( 1987 ) North Jetty Site Tow 1 Tow 2 Tow 3 South Jetty Site Tow 1 Tow 2 Tow 3 North Jetty Site Tow 1 Tow 2 Tow 3 South Jetty Site Tow 1 Tow 2 Tow 3 Daily mean 9-Mar 24 1 1 16 127 253 420 99 163 127 721 458 583 250.2 1 0-Mar 36 56 63 17 10 6 469 31 1 554 103 84 122 152.6 1 1-Mar 7 5 2 1 0 1 16 27 35 31 56 31 17.7 1 2-Mar 12 1 1 5 95 6 135 554 686 489 86 126 216 201.8 1 3-Mar 21 13 49 23 138 49 1,672 1,040 1,703 9 9 3 394.1 1 6-Mar 28 31 17 22 3 86 322 396 222 13 7 2 95.8 1 7-Mar nd nd nd nd nd nd 16 4 2 35 167 78 50.3 1 8-Mar 5 9 10 197 nd nd 201 89 182 58 94 55 90.0 1 9-Mar 73 250 191 16 82 57 173 160 160 248 76 48 127.8 20-Mar 52 53 85 729 68 254 153 205 1 15 4,503 922 746 657.1 23-Mar 219 135 376 173 37 126 255 267 213 141 270 1 15 193.9 + 1 Hr 59 20 45 154 215 175 1 1 1.3 24-Mar 8 3 7 3 35 202 434 310 344 18 10 18 1 16.0 + 1 Hr 20 93 50 128 118 119 88.0 25-Mar 59 59 64 7 17 26 156 135 82 58 66 129 71.5 + 1 Hr 23 19 34 891 912 473 392.0 26-Mar 4 2 3 70 3 99 346 175 287 162 265 348 147.0 + 1 Hr 2 1 10 124 304 220 1 10.2 27-Mar 80 91 57 109 53 90 145 175 218 345 363 453 181.6 + 1 Hr 87 36 64 528 365 155 205.8 30-Mar 3 20 16 2 2 0 71 38 161 37 52 8 34.2 31 -Mar 60 85 127 24 29 27 24 123 164 286 227 152 1 10.7 1-Apr 42 62 55 95 90 92 512 404 390 3,194 1,558 2,534 752.3 2-Apr 287 265 159 12,644 24,616 9,760 61 94 66 1,776 1,856 2,272 4,488.0 3 -Apr 457 355 260 237 589 830 384 387 522 259 130 150 380.0 tow (se = 212), of the 75 triplicate means used for the com' parisons. The increase in absolute differences with increas- ing time between collections indicates that the abundance of PL moving through the pass is extremely dynamic and that short term, even hourly, changes could be substantial. Differences in abundance between north and south jetty sites were examined by comparing means of triplicate catches for days and nights separately. The mean absolute difference was 730 PL/tow (se = 418, n = 37), and is consid- erably larger than the grand mean, 455 PL/tow (se = 215), of the 74 triplicates used in the comparisons. This differ- ence was very close to that found for changes that occurred over about 24 h, and larger than that found over 12 h. Sources of variation in PL abundance were ranked accord- ing to magnitude of CV. CV’s were calculated for abundance based on replicates (triplicates), hour to hour, day-night, sites, and dates. The CV was highest for sites, followed by dates, day-night, replicates, and hours, respectively (Table 3). How- ever, when abundance was Ln(PL+l)-transformed, the hier- archy of CV’s changed to dates and day-night being greatest, followed closely by sites, and then hours and finally replicates. Tides and Environment Weather and tides varied considerably, as is typical for spring along the northern GOM (Figure 4A). Water tem- perature (Figure 4B) ranged from 8-28°C and salinity from 15-28%o at the sampling sites. Pearson product moment correlations between Ln(PL+ l)-transformed abundance and water temperature (r = 0.22, p = 0.057, n = 77), salin- ity (r = 0.08, p = 0.464, n = 77), and wind speed vectors (r = -0.07, p = 0.527, n = 77) were weak and not significant. Postlarval abundance was depressed during two significant “blue northers”, one on 10-11 March and a larger one on 29 33 Matthews TABLE 2. Frequency distributions of coefficients of varia- tion of postlarval brown shrimp caught in triplicate samples. Collections were made along Bolivar Roads, Texas from 9 March - 3 April 1 987. Catches had been transformed using: LnfPL+l). PL = postlarvae. CV (%) NORTH JETTY Day Night SOUTH JETTY Day Night Sum Cum. % 0- 10 9 16 6 17 48 55 11-20 7 2 5 5 19 77 21 -30 2 1 4 2 9 87 31 -40 1 1 1 3 90 41 -50 1 1 2 93 51 -60 3 3 96 61 -70 1 1 97 71 -80 97 81 -90 2 2 100 90 - 100 100 n = 19 20 23 25 87 March, and rebounded as each “norther” abated (Figure 5). Flood-tides, which bring the PL into the pass from the Gulf waters, did not appear to be particularly important when weekly PL catches were examined with respect to tides, day-night, and location (Figure 6). In only 5 of 8 North Jetty cases and only 2 of 6 South Jetty cases were PL abundances greater on flood tides than on ebb tides. Eddy currents lo- cated between the ship channel and the shoreline probably added to the disconnect between abundance and tidal flows. The Effect of Tow Radius Postlarval abundances for the ten replicates of each radius differed by nearly two orders of magnitude along this short, 500 m, stretch of beach (Table 4). Among the standard 23 m radius tows, grooved shrimp, white shrimp, and total shrimp catch ranges were 48 to 3,224, 9 to 1,478, and 57 to 4,702 PL/tow, respectively. These large differences for both spe- cies were from just 360 m along the beach (Tows 1 and 8). Short tow (11 m) abundances did not correlate well with those in the standard tows (r = -0.18, p = 0.61, n = 10), and when doubled to match the tow length of the standard, they were always less than standard tow abundances. Total PL abundances from the standard and long tows (46 m) corre- lated well (r = 0.88, p = 0.002, n = 9), but when standardized for tow length, the standard tow catches were greater than those of the long tows 7 8% of the time. Such results indicate the PL were irregularly distributed out from shore as well as along shore, with more PL appearing to be in the interme- diate depth that was sampled most by the standard radius. Discussion Federal and state fishery biologists and managers in the GOM have been particularly interested in maintaining the valuable brown, white, and pink shrimp fisheries. While oth- er fisheries have been or are being over-fished and harvests declining, the shrimp harvests are holding fairly steady or de- clining only slightly through 2006 (NMFS 2007). An impor- tant correlation linking the adult shrimp harvest from the GOM with estuarine marsh nursery habitat (Turner 1977) coupled with the increase in man’s developments along the bay shores suggests dismantled or degraded salt marsh nurs- ery habitat may lead to reductions in shrimp harvests. For example, Browder et al. (1989) pointed to the insidious cor- relation between marsh break-up and shrimp populations, in that shrimp production increases as break-up increases to a point beyond which both crash. Marsh restoration efforts are not keeping pace with marsh destruction, and another few decades of marsh destruction could well lead to significant decreases in shrimp populations and harvests in the GOM. The objectives of monitoring PL brown shrimp immigra- tion are to better understand this shrimp’s annual cycle, and then to use the intensity and/ or timing of spring estuarine immigration of PL to forecast the summer harvests. High densities of immigrating brown shrimp PL have been not- Air, Galveston NWS Water, Ft. Point Figure 4. Comparison of postlarval abundance from an intensive sampling study in Bolivar Roads, just east of Galveston, Texas in 1 987 with environmental variables. A. Hourly observed and predicted water heights (NOS). B. Hourly air temperatures (NWS) and water temperatures (USACE). * = no data. 34 Estimating Postlarval Shrimp Abundance March 7 - 20, 1987 ADay, n=6 ANight, n=6 50 Kmph March 21-April 3, 1987 ADay, n=6 ANight, n=6 Figure 5. Hourly wind speed (Kmph) vectors ore compared with postlarval brown shrimp abundance (vertical arrows) from Bolivar Roads , Texas , Spring 7 987. A vertical wind vector above the horizontal axis indicates a wind from the north, and vector length may be compared with the 50 Kmph double headed arrow on the right. * = no data. ed during March and April in Texas (Copeland and Truitt 1966, Berry and Baxter 1969, Kutkuhn et al. 1969), Louisi- ana (Caillouet et al. 1971, Rogers and Herke 1985, Rogers et al. 1993), North Carolina (Williams 1964, Williams and Deubler 1968), and South Carolina (DeLancey et al. 1994). The timing of peak abundance has differed substantially from year to year, and some years the peak was absent— ex- changed for intermittent highs and lows. These variations offered potential annual differences for forecasting models. Without data from multi-year monitoring, character- ization of the “spring peak” lacks substantive form. Indi- vidually, many of the previously cited studies suggested a “spring peak” but were unable to define it. Fortunately, annual sampling by Baxter allowed calculation of a regres- sion equation to define the peak abundance which may be valid for the Texas coast. A similar regression based on long term data may also define peaks and migrations for F. aztecus PL along the north central GOM and Carolina coasts. However, one should not expect to reliably find large numbers of PL in a pass on a date based on the re- gression because many environmental and biological factors operate on PL distributions to reduce or inflate numbers on any particular day of a particular year. At present, the importance of the spring peak seems to be that it concep- tualizes the importance of the estuarine habitat during that time of year for perpetuating brown shrimp. To use its changes in magnitude and/ or timing of occurrence as fore- casting variables will depend on our ability to adequately assess and evaluate the changes, and that will require ad- dressing short-term variability in PL density measurements. Small scale variability in density estimates appears high and has a large range that is significant over time and space. Thus, this variability can cause the annual influx event to be misrepresented in small-scale sampling efforts. For Bo- livar Roads this study reported a maximum of 24,616 PL/ tow or 684 PL/m 3 whereas Baxter and Renfro (1966) re- ported a maximum of 131 PL/m 3 and Duronslet et al. (1972) reported a mean high of barely over 1 PL/m 3 . Ar- nold et al. (1960) observed in the same area that PL “... were swimming at the surface and so concentrated that several thousand could be caught with a single scoop of a dip net. On each occasion, large numbers of fish (mostly pinfish and anchovies) could be seen decimating the rela- tively helpless shrimp.” These varying reports suggest high density collections may be quite ephemeral and no more important than some intermediate density for distributing PL in the bay. Other maxima of note in Texas are: 76 PL/ m 3 along the front beach of Galveston Island during the spring (Benfield and Downer 2001), 60 PL/m 3 at Rollover Pass, Texas, from plankton tows (Berry and Baxter 1969), and 299 PL/m 3 in plankton net collections in Cedar Bay- ou that connects the GOM to Mesquite Bay (King 1971). The greatest abundance reported here, and the largest in 22 yr of sampling, was 684 PL/m 3 and occurred on the theoretical spring peak and just three days after a strong “blue norther” had blown through and reduced PL den- sity to < 1 PL/m 3 . Similar increases in PL after northers have been reported in Louisiana (Rogers et al. 1993). The norther not only pushed the water out of the bay and held it out for about a day, but also chilled the shallow water to below 10 °C which probably caused PL to bury themselves in the bottom (Aldrich et al. 1968). Postlarvae may also have TABLE 3. Sources of variation in postlarval (PL) brown shrimp catches that used Renfro beam-trawls to sample at shoreline sites in Bolivar Roads, Texas. Coefficient of varia- tion (CV) indicates the importance of the factor in contributing to the total variance. CV of Ln(PL+l )- transformed Factor n X Variance CV catches Triplicates 87 440 881,636 214 14 Hourly 10 154 23,915 100 21 Day/Night 66 472 2,869,345 359 32 Site 39 439 3,241,015 410 30 Date 18 465 3,381,709 375 32 Matthews Week: 12 3 4 □ Day-flood h Day-ebb a Night- flood a Night-ebb Figure 6. Weekly mean abundance of postlarval brown shrimp showing differences due to tidal flows, sites, and day or night conditions at two sites in Bolivar Roads, Texas, Spring 1 987. * = no doto. been concentrated in the near-offshore area by the offshore winds of the norther. Smith (1975, 1978) showed that as cold winds blow offshore they carry surface water offshore and consequently bring subsurface water towards the coast. The cold surface water may also have made PL drop into the warmer mid- and bottom water, concentrating them there, and bringing them towards shore. With the return of warm- er onshore winds from the southeast and the rising water flooding back into the emptied bay, the PL are then carried into the bay. The observed superabundance may have result- ed from the addition of PL that emerged from the bottom to join those concentrated near shore by wind and cold and those approaching the coast in the normal manner. Knott et al. (1994) found wind forcing to be important for white shrimp PL and blue crab ingress to South Carolina passes. It also appears that it might take more than one tidal flood to transport the accumulated PL through Bolivar Roads, a large pass with eddies along its sides. This could add more PL to the emerging group, if they had been trapped in the shallows during the norther as they immigrated. The fact that my data are from shoreline sampling may explain some of the lack of correlation between abundances and environ- mental and tidal conditions. By the time PL reach the sides of the pass where they were sampled tidal conditions may have changed, and their immigration slowed by slower cur- rents and more eddies. Thus, the abundances observed may represent an accumulation rather than an instantaneous oc- currence which would be reflective of environmental condi- tions when they initially arrived. Although the existence of the variability in abundance during the spring offers potential for forecasting the shrimp fishery, the numerous sources causing differences in abun- dance estimates appear not to have been accommodated in past monitoring regimes. For example, the currently non- correlative existence between environmental factors and PL abundance is not a surprise as brown shrimp PL are widely tolerant of temperature and salinity (Zein-Eldin and Aldrich 1965), but it will complicate selection of relationships for forecasting models, and will diminish the usefulness of PL abundance for forecasting unless a connection can be found. Brown shrimp PL immigration continues through the sum- mer with another smaller peak occurring in the fall, all of which offer additional potential for population modeling. A strong sampling regime will be required to address and separate the combination of biological and environmental factors that are responsible for changes in fishery harvest later in the year. Criales et al. (2006) found a similar need while studying pink shrimp PL immigration to Florida Bay. High variability in abundance of PL was observed in studies designed to examine effects of time, date, day/ night, tide, and tow distance. Some of this variability had been noted previously by Berry and Baxter (1969), Caillouet et al. (1968), Lochmann (1990), and Benfield and Downer (2001). Such extensive variability as was found over short time periods and distances illustrates that collecting only a few samples a couple of times per week or month, and at one or two sites, is likely to be inadequate to describe the dynamic PL immigration in a pass during an expanded time period. Limited data so gathered is potentially misleading, and would not likely be useful in forecasting the fishery har- vest as was noted by Benfield and Downer (2001) for shrimp, or for predicting changes in fish populations (Osenberg et al. 1994). To increase the power of a monitoring program for immigrating PL, it seems best to increase sampling to account for the factor contributing the largest variance. Our CV calculations suggest that increasing the number of dates and sites sampled would add most to a sampling regime, with both day and night sampling and replicates having less importance. This research pertained mainly to F. aztecus PL, but these high variability problems in Bolivar Roads likely ap- ply to other estuarine passes as well, and to other species of shrimp, fish, and crab larval and PL populations that immigrate through passes. The strength of PL shrimp im- migration may be a good indicator of future shrimp fishery harvest, but obtaining an accurate measurement of immi- 36 Estimating Postlarval Shrimp Abundance TABLE 4. Postlarval shrimp catches during the triple radius test at the South Jetty site in Bolivar Roads , Texas , 17 September 1987. Brown = brown shrimp ; White = white shrimp ; sd = standard deviation ; CV = coefficient of variation. Radius SET Brown 1 1 m White Total Brown 23 m White Total Brown 46 m White Total 1 24 1 25 48 9 57 182 30 212 2 29 3 32 138 28 166 142 39 181 3 76 8 84 286 51 337 244 56 300 4 95 15 110 293 65 358 289 80 369 5 30 5 35 235 61 296 269 50 319 6 46 18 64 175 72 247 318 103 421 7 90 62 152 604 208 812 1,019 294 1,313 8 27 41 68 3,224 1,478 4,702 1,616 576 2,192 9 7 7 14 2,498 821 3,319 nd nd nd 10 89 125 214 400 95 495 742 357 1,099 x: 51 29 80 790 289 1,079 536 176 712 sd: 63 1,592 684 CV (%): 79 148 96 gration may not be possible. Thus, we may need to also com and survival to provide an accurate fishery forecast, sider environmental parameters that affect juvenile growth Acknowledgments The author greatly appreciates the assistance given by D. Emiliani, G. Zamora, Jr., E. Scott-Denton, and others at the NOAA National Marine Fisheries Service Galveston Laboratory with the collecting and analysis of the many samples. Thanks are also extended to E. F. Klima and R. J. Zimmerman, who spon- sored and supported the sampling studies and research while directors of the laboratory. The author greatly appreciates the helpful critiques and discussions with T. J. Minello, R F. Sheridan, L. Rozas, R. Hart, J. Matis, A. Steel, and Z. P. Zein-Eldin. Special thanks are given to F. Patella for his assistance with the historic postlarval database, and to the late K. N. Baxter for stimulating my interest in postlarval shrimp ecology. Thanks also to the anonymous reviewers for their insight, corrections, and suggestions. Literature Cited Aldrich, D. V., C. E. Wood, and K.N. Baxter. 1968. An ecologi- cal interpretation of low temperature responses in Penaeus aztecus and P. setiferus postlarvae. Bulletin of Marine Science 18:61-71. Arnold, E.L. Jr., R.S. Wheeler, and K.N. Baxter. 1960. Observa- tions on fishes and other biota of East Lagoon, Galveston Island. United States Fish and Wildlife Service Special Scientific Report Number 344, 30 p. Baxter, K.N. 1963. 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Growth and survival of postlarval Penaeus aztecus under controlled conditions of temperature and salinity. Biological Bulletin 129: 199-216. Zimmerman, R.J and T.J. Minello. 1984. Densities of Penaeus aztecus , P. setiferus and other natant macrofauna in a Texas salt marsh. Estuaries 7:421-433. 39 Gulf and Caribbean Research Volume 20 Issue 1 January 2008 Preliminary Survey of Fish Community Composition in Seagrass Habitat in Two Back- Reef Lagoons of the Southern Mexican Caribbean Lauren A. Yeager Centro de Investigation y de Estudios Avanzados del Instituto Politecnico National, Mexico J. Ernesto Arias-Gonzalez Centro de Investigation y de Estudios Avanzados del Instituto Politecnico National, Mexico DOI: 10.18785/gcr.2001.06 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Yeager, L. A. andj. Arias-Gonzalez. 2008. Preliminary Survey of Fish Community Composition in Seagrass Habitat in Two Back- Reef Lagoons of the Southern Mexican Caribbean. Gulf and Caribbean Research 20 (l): 41-47. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/6 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(3)usm.edu. Gulf and Caribbean Research Vol 20, 41-47, 2008 Manuscript received, May 28, 2007; accepted, December 14, 2007 PRELIMINARY SURVEY OF FISH COMMUNITY COMPOSITION IN SEAGRASS HABITAT IN TWO BACK-REEF LAGOONS OF THE SOUTHERN MEXICAN CARIBBEAN Lauren A. Yeager 1 and J. Ernesto Arias-Gonzalez Centro de Investigation y de Estudios Avanzados del Instituto Politecnico National, Unidad Merida, Antigua C arretera a Progreso Km. 6, Merida, Yucatan 973 1 0, Mexico Current Address: Florida International University, Department of Biological Sciences, 11200 SW 8th Street, Miami, FL 33199, e-mail: l_yeager@hotmail.com Abstract: Little is known about seagrass fish communities in the southern Mexican Caribbean. Diurnal and nocturnal fish community structure in seagrass habitat were compared between back-reef lagoons using a visual census technique in a natural protected area within a national park (Xcalak) and an unprotected area (Mahahual). Seagrass fish communities differed significantly between the two locations in the daytime and Xcalak supported greater total fish densities. Species richness did not differ statistically between locations. Observed nighttime fish communities were characterized by low spe- cies richness and low fish abundance when compared to diurnal communities. Heavy tourist use and coastal development may have degraded seagrass habitat at Mahahual causing lower fish abundance. Also, proximity of seagrass to man- grove habitat in Xcalak may have led to increased abundance and differences in species composition between locations. More extensive analysis and monitoring of the relative functioning of back-reef habitats in these two systems is needed as coastal development and fishing pressure continue to threaten the area. ReSUMEN: No se conoce mucho sobre la comunidad de peces en pastos marinos en el sur del Caribe mexicano. La estruc- tura de las comunidades de peces nocturnas y diurnas en pastos marinos se obtuvo mediante censos visuales y se comparo entre la laguna arrecifial de un area protegida (Parque Nacional Arrecifes de Xcalak) y un area no-protegida (Mahahual). Las comunidades de peces fueron diferentes significantemente entre los dos sitios durante el dfa, Xcalak registro las mayores densidades de peces. No existe diferencia estadfsticamente significativa con respecto a la riqueza de especies entre sitios. Las comunidades de peces nocturnas presentaron valores bajos de riqueza de especies y de abundancia con respecto a las comunidades diurnas. El desarrollo turfstico y costero de Mahahual, podrian estar degradando el habitat de pastos marinos, y como consecuencia el registro de bajas abundancia de peces. En contraste, en Xcalak, la proximidad del ecosistema de manglar adyacente a los pastos marinos podrfa estar influenciando con una mayor abundancia de peces y cambios en la composicion de especies con respecto a Mahahual. Mientras en el area continue el desarrollo costero y la pesca en el area, es necesario un analisis mas extensivo (escala temporal y espacial) del funcionamiento de ambas lagunas arrecifales. Introduction Seagrass beds are among the most productive aquatic ecosystems in the world (Duarte and Chiscano 1999) and support diverse communities of fishes and inver- tebrates. These habitats are an important component of the tropical marine environment, and are linked to mangrove and coral reef habitats through fluxes of nutri- ents and organisms (Parrish 1989, Adams et al. 2006). Human use or alteration of back-reef biotopes may change their ecological functioning. Coastal development and tourist use of back-reef environments have the po- tential to degrade habitat through loss of structural com- plexity or decreased food quality. Globally, seagrass cover- ages have declined dramatically associated with human environmental degradation (Orth et al. 2006). Also, fish- ing that often targets larger piscivores may lead to shifts in trophic structure and subsequent community cascades in coastal systems (Chiappone et al. 2000, Graham et al. 2003, Mumby et al. 2006). Understanding the effects of an- thropogenic impacts on habitat function becomes a high priority as humans continue to alter many habitats im- portant to ecologically and economically valuable species. The Mexican Caribbean supports the northern extent of the Mesoamerican Barrier Reef Tract. The Parque Nacional Arrecifes de Xcalak is located on the southern Caribbean coast of Mexico, and development and fishing are restricted within this reserve. However, moderate fishing pressure still exists within the park boundaries as much of the town of Xcalak relies on artesanal fishing. Mahahual is an unprotect- ed location with increasing tourist use after the construction of a cruise ship pier in 2000. Fishing pressure has declined in Mahahual as tourism has taken over as the primary economic activity. This provides the opportunity to compare sites with- in the reserve with comparatively less coastal development to sites at an unprotected location where coastal development and use of the reef lagoon has dramatically increased. Ais development continues to threaten coastal ecosystems and 41 Yeager and Arias-Gonzalez fishing pressure persists in this region, understanding the potential impacts on back-reef habitats becomes imperative. Few studies have surveyed seagrass fish communities explicitly in the southern Mexican Caribbean. Chitarro et al. (2005) censused seagrass and mangrove habitats at Mahahual and found that juvenile reef fish densities in seagrass were lower than observed juvenile densities in mangroves. Nunez-Lara and Arias-Gonzalez (1998) surveyed lagoon fish communities at Mahahual; however they did not distinguish between lagoon habitat types (i.e. seagrass, sand, patch reefs) in their surveys. Castro-Perez (1998) censused back-reef fish communities at Mahahual, but grouped sand and seagrass habitat together. The authors are not aware of any studies which have surveyed seagrass fish communities in Xcalak. Therefore, overall, little is known about seagrass fish communities in this region. Most studies of fish communities associated with seagrass habitat have been conducted during the day. However, previous studies of tropical seagrass habitats indicate that nocturnal fish communities may differ substantially from diurnal communities (Weinstein and Heck 1979, Rob- blee and Zieman 1984, Kopp et al. 2007). Fishes from sur- rounding habitats, such as coral reefs and mangroves, are known to migrate into seagrass habitat at night to feed (Ogden and Ehrlich 1977, Burke 1995).Therefore, in order to accurately assess the value of seagrass habitat, it is im- perative to consider both diurnal and nocturnal communi- ties of fishes that may associate with this critical habitat. The primary objective of this study is to make a pre- liminary comparison of seagrass fish community structure, species richness and fish density between two back-reef lagoons with different levels of protection and human use. Additionally, a second objective is to investigate day- night shifts in seagrass fish communities at these sites. Methods Study Area Both study locations are on the southern Caribbean coast of Quintana Roo, Mexico (Figure 1). Xcalak (18° 15’ N, 87 °50’ W) is located within Parque Nacional Arrecifes de Xcalak, a marine protected area managed by the Comision Nacional de Areas Naturales Protegidas (CONAN P). The reserve encompasses 179.49 km 2 of terrestrial and marine habitats. Little coastal development exists within the park and tourist use is low. Fishing is allowed with permits with- in the reserve, and tin-permitted fishing with nets is com- mon. The study location was 2 km south of the town of Xcalak. Mahahual (18°42* N, 87°42’ W) is located 50 km north of Xcalak and is unprotected by conservation man- agement regulations. A cruise ship pier was built in Ma- hahual in 2000, which resulted in increased tourist traffic and development. Sites surveyed at Mahahual were locat- ed about 2 km south of most of the town’s development. All sites at both locations were in continuous seagrass habitat (dominated by Thalassia testudinum) with Syringodium filiforme and macroalgae (including Laurencia sp., Halimeda sp. Penicillis capitatus , Dictyota sp., Padina sp. A mphiroa sp. and Caulerpa sp.), and were characterized by sandy bot- tom. At Xcalak sites were 1.0 to 1.6 m in depth and located within the back-reef lagoon (about 1 km wide) adjacent to fringing mangroves. At Mahahual, all sites were located in seagrass habitat 1.0 to 2.0 m deep adjacent to sandy shore in a reef lagoon (lagoon width ranged from 0.25 to 0.45 km). Seagrass beds at Mahahual were patchier than those 42 Mexican Caribbean seagrass fish communities surveyed at Xcalak (L.A. Yeager, personal observation). Visual Surveys To determine the composition of the seagrass fish com- munity, visual censuses were completed during the daytime and nighttime in November and December 2006. At Xcalak and Mahahual, 15 and 19 sites were surveyed during the day and 9 and 5 sites were surveyed at night, respectively. All diurnal censuses were completed between 1120 and 1520 h and nocturnal surveys between 1830 and 2020 h. A dive light was used to illuminate the transect during nighttime censuses. Visual surveys were conducted along 20 m belt transects of 2-m width (modified from Brock 1954). All surveys were performed by the first author while snorkeling as follows: the transect line was started from a haphazardly selected point in continuous seagrass habitat and laid out perpendicular to shore. All transect starting points were at least 20 m apart and no transects overlapped within time of day (some transects between day and night in the same locations may have overlapped). Fish species abundance and estimated total length (TL) in 5-cm size classes (e.g., 0-4.9 cm, 5-9.9 cm, 10-14.9 cm) were recorded on dive slates with 5-cm increments marked on the side to aid in estimation of fish size. Members of the species Sparisoma radians , S. aurof- rentatum, and Nicholsina usta were grouped into a Scaridae complex due to difficulties distinguishing between juveniles. Data Analysis For comparisons of overall community structure, di- urnal fish community data were square-root transformed to increase contribution of less abundant species (Clarke and Green 1988). The Bray-Curtis index was used to cre- ate a similarity matrix of species-specific abundance data (Clarke 1993). A multi-dimensional scaling (MDS) plot TABLE J. List of observed taxa with mean density (# of individuals/40m 2 ± standard error) and percent community composition by location and time of day. n = number of transects per time of day and location. XCALAK MAHAHAUL Day (n = 15) Night (n = 9) Day (n = 19) Night (n = 5) Taxa Common Name x Density Percent x Density Percent x Density Percent x Density Percent Muraenidae Gymnothorax vicinus Purplemouth moray 0 0 0 0 0 0 0.20 ± 0.20 20.0 Ophichthidae Myrichthys breviceps Synodontidae Sharptail eel 0 0 0 0 0.11 ±0.07 1.2 0 0 Synodus intermedius Carangidae Sand diver 0.07 ± 0.07 0.4 0 0 0 0 0 0 Carangoides ruber Bar jack 0.33 ± 0.33 2.2 0 0 0.74 ± 0.49 8.3 0 0 Caranx crysos Lutjanidae Blue runner 0 0 0 0 0.11 ±0.11 1.2 0 0 Lutjanus griseus Gray snapper 0.20 ±0.14 1.3 0 0 0 0 0 0 Lutjanus synagris Lane snapper 0.40 ±0.13 2.6 0 0 0.26 ±0.13 3.0 0 0 Ocyurus chrysurus Gerridae Yellowtail snapper 1 .60 ± 0.85 10.3 0 0 0.63 ± 0.22 7.1 0 0 Eucinostomus sp. Mojarra 0 0 0 0 0.16 ± 0.16 1.8 0 0 Gerres cinereus Haemulidae Yellowfin mojarra 0 0 0 0 0.32 ± 0.22 3.6 0 0 Haemulon plumieri White grunt 0.13 ±0.13 0.9 0.22 ±0.15 20.0 0.05 ± 0.05 0.6 0 0 Haemulon scirus Mullidae Blue-stripped grunt 0 0 0 0 1.47 ± 1.26 16.6 0.20 ± 0.20 20.0 Pseudupeneus maculatus Chaetodontidae Yellowtail goatfish 0.8 ± 0.3 2.2 0 0 0.16 ± 0.12 1.8 0 0 Chaetodon capristratus Foureye butterflyfish 0 0 0 0 0 0 0.20 ± 0.20 20.0 Chaetodon ocellatus Spotfin butterflyfish 0 0 0 0 0.05 ± 0.05 0.6 0 0 Pomecentridae Abudefduf saxatilis Labridae Sergeant major 0 0 0 0 0.05 ± 0.05 0.6 0 0 Halichoeres bivittatus Slippery dick 9.60 ± 1.26 62.1 0 0 1 .42 ± 0.45 16.0 0 0 Halichoeres poeyi Scaridae Blackear wrasse 0.07 ± 0.07 0.4 0 0 0.79 ± 0.28 8.9 0 0 Scaridae complex Parrotfish 2.40 ± 0.63 15.5 0 0 2.21 ±0.60 24.9 0.20 ± 0.20 20.0 Scarus iserti Striped parrotfish 0.07 ± 0.07 0.4 0 0 0 0 0 0 Scarus taeniopterus Princess parrotfish 0.27 ±0.1 8 1.7 0 0 0 0 0 0 Sparisoma rubripinne Redfin parrotfish 0 0 0 0 0.26 ±0.17 3.0 0 0 Acanthuridae Acanthurus coeruleus Sphyraenidae Blue tang 0 0 0 0 0.05 ± 0.05 0.6 0 0 Sphryaena barracuda Tetradontidae Great Barracuda 0 0 0.11 ±0.11 10.0 0 0 0 0 Sphoeroides spengleri Diodontidae Bandtail puffer 0 0 0 0 0.05 ± 0.05 0.6 0 0 Diodon holocanthus Long-spine porcupinefish 0 0 0.78 ± 0.32 70.0 0 0 0.20 ± 0.20 20.0 Total 15.47 ± 2.13 1.11 ± 0.42 8.89 ± 1.70 1.00 ±0.50 43 Yeager and Arias-Gonzalez Figure 2. MDS plot comparing community structure between study loca- tions based on Bray-Curtis similarity matrix of diurnal fish com- munity data (per species density in fish/40m 2 ). Two overlapping points in the center of the cluster of gray triangles both represent transects at Xcalak. M=Mahahual and X=Xcalak. was employed based on die similarity matrix to graph i- cally explore differences in seagrass fish communities. An Analysis of Similarity (ANOSIM) was performed to test for statistical differences in fish communities between lo- cations. Importance of individual taxa in contributing to differences between locations was determined with a Similarity-Percentages (SIMPER) analysis of square-root transformed abundance data (Clarke 1993, Primer© 5). Non parametric statistics were used for all comparisons of fish abundance, species richness and length frequency be- cause variables were not normally distributed despite numer- ous transformations (Kolmogorov-Smirnov normality test, p < 0.05 in all cases). Mean total fish abundance and species richness per transect were each compared between locations for diurnal communities with a Kruskal-Wallis AN OVA. For diel comparisons, data were grouped between locations by time of day. We feel this grouping of data was justified because of the lower number of nocturnal surveys and great differences between nocturnal and diurnal communities. To- tal fish abundance and species richness per transect between night and day were compared with a Kruskal-Wallis AN OVA. Results A total of 417 individuals representing 28 taxa from 16 families were observed in seagrass habitats at the two study locations during diurnal and nocturnal censuses (Table 1). The most abundant families included par- rotfishes (Scaridae), wrasses (Labridae), snappers (Lut- janidae), grunts (Haemulidae), and jacks (Carangidae). Daytime fish communities ciiffered among locations (ANOSIM, Global R = 0.21, p = 0.002, Figure 2). Sites within Xcalak had greater similarity (57%) than sites with- in Mahahual (25%). Sites at Xcalak were characterized by two primary taxa ( Halichoeres bivitattus and Scaridae com- plex, 77.6% of all fishes observed) while sites at Mahahual were dominated by Scaridae complex, H. bivittatus , H. po - eyi, Ocyurus chrysurus, and C arangoides ruber , with these taxa making up 90% of all fishes observed (SIMPER). Sites at Xcalak were differentiated from those at Mahahual by the increased relative importance of H. bivitattus, Scaridae com- plex, O. chrysurus and L utjanus synagris and decreased relative importance of H. poeyi and C. ruber (SIMPER). Even though O. chrysurus was not one of the two most abundant species making up 90% of the fish community at Xcalak, it still was more abundant at this location than at Mahahual (Table 1). Daytime fish abundance at Xcalak (x = 15.5 ±2.1 fish/40m 2 ) was greater than that at Mahahual (x = 8.9 ±1.7 fish/40m 2 , Kruskal-Wallis, H = 6.806, p = 0.009, Table 1). However, spe- cies richness did not differ between regions in the daytime (x xcalak = 3.2 ± 0.4 fish species/transect, x mahahual = 3.7 ± 0.5 fish species/transect, Kruskal-Wallis, H = 0.150, p = 0.698). Families observed during nocturnal censuses included porcupinefishes (Diodontidae), grunts, parrotfishes, bar- racudas (Sphyraenidae), butterflyfishes (Chaetodontidae), and moray eels (Muraenidae). Nighttime fish communities exhibited much lower abundance (for both locations com- bined: x =1.1 ± 0.3 fish/40m 2 , Kruskal-Wallis, H = 26.625, p < 0.001) and lower species richness (x = 0.9 ± 0.3 fish species/transect, Kruskal-Wallis, H = 19.798, p < 0.001) when compared to daytime communities in this study. Discussion Diurnal communities of seagrass fishes differed be- tween two back-reef lagoons with physical differences that included different levels of protection. The anthropogenic influences at both sites may partially explain the observed differences in fish communities. Greater environmental degradation, reflected in patchy seagrass habitat, at Ma- hahual may have led to lower abundance of fishes within this back-reef lagoon. Mahahual village has been recently urbanized for receiving thousands of tourists brought in by cruise ships. The beach was increased with dredged sand from the reef lagoon, the reef lagoon channel was deep- ened for boat and personal water craft transit, seagrass beds were removed, and the seascape was transformed with construction of a pier, small restaurants, shops and cabins. Following construction of the cruise ship pier, coral cover has decreased and algal cover has increased on coral reefs in Mahahual (Arias-Gonzalez et al., unpublished data), a sign of habitat degradation. However, no historical data re- lated to seagrass fish communities or seagrass coverage at Mahahual are available for comparison to assess possible declines in abundance or shifts in community structure. The greater fish density at Xcalak was mainly attributed to the greater abundance of H. bivittatus. Although this spe- cies is typically considered to be a habitat generalist (Grat- 44 Mexican Caribbean seagrass fish communities wicke et al. 2006), the more extensive, less-disturbed seagrass habitat at Xcalak may have been preferable to this species. Differences in contiguous habitats at the study locations may also account for differences in fish communities. Prox- imity to surrounding habitats affects the distributions of various fish species in back-reef environments (Drew 2006). Previous studies of seagrass fishes have found that proxim- ity to mangroves and/ or coral reef habitats may affect com- munity structure or fish abundances (Robblee and Zieman 1984, Baelde 1990, Kopp et al. 2007). Mumby et al. (2004) found that coral reef sites adjacent to mangroves supported much greater biomass of fishes compared to those without mangroves nearby. Similarly, Kopp et al. (2007) observed greater fish density and biomass in seagrass habitat located adjacent to mangroves when compared to seagrass habitat near a coral reef. However, Baelde (1990) reported greater catch and greater species richness in a seagrass beds located in close proximity to mangrove and coral reef habitat com- pared to seagrass habitat only associated with mangroves. Seagrass beds at Xcalak are bordered by mangroves which may have contributed to the higher abundance of fishes found at this site. Also, the presence of L. griseus at Xcalak is likely due to the presence of mangroves at this location as this species is known for its association with mangrove habi- tats (e.g., Nagelkerken et al. 2000a, Gratwicke et al. 2006). In contrast, the close proximity of reef habitat to Maha- hual seagrass beds may have influenced community compo- sition towards reef-associated species. The lagoon is narrow- er at Mahahual than at Xcalak, which may lead to increased connectivity between the reef and seagrass habitat at Maha- hual. For example, C. ruber , a species that travels between reef and lagoon habitats, was more abundant and a more important component of the fish community at Mahahual. Even though fish densities are often reported to be lower in seagrass habitat than in surrounding coral domi- nated areas, total habitat area must be taken into account (Nagelkerken et al. 2000b, Mateo and Tobias 2004). Seagrass habitat is often quite extensive in back-reef lagoons when compared to the coverage of other habitat types (e.g., patch reefs). Therefore, even though fish densities are lower, the total contribution of seagrass beds as habitat may be greater (Nagelkerken et al. 2000b). Also, juveniles of ecologically and commercially important species (e.g., O. chrysurus , L. griseus , L. synagris ) were observed in seagrass habitat, sug- gesting this habitat may serve as a nursery area for these species. Lesser abundance of predators may make seagrass meadows the preferred feeding/sheltering habitat for a number of fishes (Shulman 1985). Additionally, habitat use only provides one measure of the value of a habitat. The function of seagrass habitat in Mahahual and Xcalak in terms of providing refuge from predation, food sources, or connectivity to other habitats is unknown. More exten- sive surveys of daytime and nighttime fish communities, as well as investigation of other aspects of ecosystem func- tions of these habitats, are needed to fully understand the importance of seagrass habitat in these back-reef systems. Diurnal seagrass fish communities of the southern Mexi- can Caribbean observed in this study were similar to assem- blages in other regions of the Caribbean, being dominated by wrasses, parrotfishes, snappers and grunts (Weinstein and Heck 1979, Nagelkerken et al. 2000b, Mateo and To- bias 2004). However, most studies only survey daytime fish communities due to logistical difficulties associated with nocturnal sampling. The preliminary surveys in this study suggest that seagrass habitat may not be as important dur- ing the nighttime in terms of total fish density or species richness. Kopp et al. (2007) also observed low abundance of nocturnal fishes in seagrass habitat near mangroves when compared to seagrass near coral reefs or to diurnal abundance. Likewise, Nagelkerken et al. (2000c) found lower fish density and species richness during nighttime in seagrass habitat in Spanish Water Bay, Curacao than dur- ing the day, but suggested that seagrass was an important nighttime feeding habitat for snappers and grunts. Wein- stein and Heck (1979) reported increased abundance of adult grunts and snappers in seagrass habitat at night and found similar or greater abundance of fishes at night than during the daytime. In this study, grunts were observed at night and snappers were observed outside of the transects at night. However, members of both of these families are highly mobile, and true patterns of their habitat use may not have been detected with the lower number of nocturnal surveys in this study. Members of other diurnally dominant fauna (e.g., wrasses) were not observed during the night- time in this study. Similarly, Robblee and Zieman (1984) found that diurnal fish communities in seagrass habitat in Tague Bay, St. Croix were dominated by small permanent residents of the seagrass bed, whereas nocturnal fish com- munities were dominated by predatory reef species. There appears to be a shift in fish communities between night and day, emphasizing the importance of considering diel chang- es in habitat use to gain a more complete understanding of the functioning of seagrass beds at these two locations. Underwater visual census is a widely used technique for surveying shallow-water fish communities. The authors ac- knowledge that some biases associated with this technique do exist (e.g., observer effect, Samways and Hatton 2001), but efforts to minimize effects of the observer and transect line were made. However, abundance of more cryptic spe- cies that hide within the seagrass canopy may be underes- timated. In this study system the relatively clear water and short seagrass canopy should have reduced this potential bias. Also, the relative efficacy of underwater visual census in quantifying fish abundance in seagrass habitat between day and night is not known. Some species may avoid the dive lights necessary for nocturnal surveys. However, a previous 45 Yeager and Arias-Gonzalez study using visual census to quantify diurnal and nocturnal fish communities in a variety of back-reef habitats including seagrass suggested dive lights did not seem to modify the be- havior of most nocturnal species (Nagelkerken et al. 2000c). Detailed conclusions about nocturnal community struc- ture at these sites are difficult to reach when considering the confounding factors of lower numbers of nocturnal surveys and decreased nocturnal fish abundance. While these poten- tial biases must be considered, qualitative differences in fish community composition at a family level as well as differences in fish abundance and species richness between night and day were so great that the overall patterns are believed to be real. A limitation of this study is the fact that both anthropo- genic influences and habitat characteristics varied between locations, so it is difficult to attribute differences in fish com- munities to any one factor. While the results presented in this paper are preliminary, and based on data collected during only one season, they do suggest both anthropogenic pres- sures and habitat differences between locations are affecting the fish communities. Additionally, this study provides an initial survey of seagrass fish communities in a little studied area that will likely continue to undergo change with increas- ing anthropogenic pressures. As coastal development and tourism continue to increase at both locations, monitoring of fish communities and bentho is recommended to better evaluate potential threats and changes in seagrass ecosystems. Acknowledgments This project was funded by a Fulbright-Garcia Robles grant, which is administered by the Institute of International Education and the U.S.-Mexico Commission for Educational and Cultural Exchange. Additional funding wsa provided through CONACYT-SEMARNAT. We thank CONANP for permis- sion to work with the Parque Nacional Arrecifes de Xcalak and support within the reserve station. We thank Global Vision International and the Universidad de Quintana Roo for their logistical support in Mahahual. Thanks to C. Layman and two anonymous reviewers who provided valuable comments on the manuscript. Also, we thank G. Acosta-Gonzalez, J. C. Fuentes-May, and C. Gonzalez-Salez for their support with logistics and K. Arana-Alonso, S. Emily, M. Gonzalez, W. Hadad-Lopez, N. 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Ichthyofauna of seagrass meadows along the Caribbean coast of Panama and in the Gulf of Mexico: Composition, structure and commu- nity ecology. Marine Biology 50:97-107. 47 Gulf and Caribbean Research Volume 20 Issue 1 2008 Shell Utilization Pattern by the Hermit Crab Isocheles sawayai Forest and Saint Laurent, 1968 (Anomura, Diogenidae) from Margarita Island, Caribbean Sea, Venezuela Lee A. Galindo Universidad de Oriente, Venezuela Juan A. Bolanos Universidad de Oriente, Venezuela Fernando L. Mantelatto University ofSao Paulo DOI: 10.18785/gcr.2001.07 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Galindo, L. A., J. A. Bolanos and F. L. Mantelatto. 2008. Shell Utilization Pattern by the Hermit Crab Isocheles sawayai Forest and Saint Laurent, 1968 (Anomura, Diogenidae) from Margarita Island, Caribbean Sea, Venezuela. Gulf and Caribbean Research 20 (l): 49-57. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/7 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(cDusm.edu. Gulf and Caribbean Research Vol 20, 49-57, 2008 Manuscript received, May 5, 2007; accepted, December 1 1 , 2007 SHELL UTILIZATION PATTERN BY THE HERMIT CRAB ISOCHELES SAWAYAI FOREST AND SAINT LAURENT, 1 968 (ANOMURA, DIOGENIDAE) FROM MARGARITA ISLAND, CARIBBEAN SEA, VENEZUELA Lee A. Galindo 1 , Juan A. Bolanos 1 , and Fernando L. Mantelatto 2 * 1 Laboratorio de Carcinologia, Escuela de Ciencias Aplicadas del Mar, Universidad de Oriente, Apartado postal 147, Nueva Esparta, Venezuela 2 Laboratory of Bioecology and Crustacean Systematics, Postgraduate Program in Comparative Biology, Department of Biology, Faculty of Philosophy, Science and Letters of Ribeirao Preto, University of Sao Paulo, 14040-901 Ribeirao Preto (SP), Brazil, e-mail: flmantel@usp.br * corresponding author ABSTRACTS Isocheles sowoyoi is a hermit crab that is occasionally mentioned in the literature, and recently its distribu- tion was extended to Venezuelan waters. Because no information on the biology and shell use patterns of this species inhabiting Caribbean waters is available, we provide the first information on shell occupation patterns of I. sawayai from Venezuela. Specimens were collected monthly from January to December 2000 along the sandy shore of Margarita Island, Venezuela. The 942 specimens collected showed different shell use patterns between the sexes and according to the reproductive condition of the females. The gastropods Leucozonio nasso (37.37%), Engoniophos unicinctus (25.37%), Nassarius vibex (4.88%), Melongena melongeno (4.25%), and Stromonita haemastoma (3.82%) represent 76% of the total occupied shells. Of the total of 26 different shell species occupied by I. sowoyoi , males were found occupying 21 , while females were found occupying all 26 shell species. In general, both sexes most frequently occupied L. nassa and E. unicinctus. However, the percentage of females occupying these shells was significantly higher than that of the males. Regression analyses showed the best correlation between crab size, shell aperture width, and shell internal volume. The current comparative investigation, in combination with other South Atlantic populations of I. sawayai, provided further evidence of shell use adaptation in hermit crabs from different areas, and increases our insight into shell use of shallow- water hermit crabs. Introduction Hermit crabs are an interesting group from a biological and evolutionary viewpoint, especially in regard to their intriguing mechanisms of shell use. The borrowed shells of gastropods provide protection against predators and physical stress, and often constitute a limiting resource for hermit crabs (e.g., Reese 1969, Vance 1972, Fotheringham 1976a, Bertness 1981a) in terms of growth, reproduction, and social behavior. Although many studies have been published on hermit crab shell occupation worldwide, the parameters by which a particular shell is chosen by a hermit crab are not completely known (Meireles and Mantelatto 2005). Studies on gastro- pod shell availability, patterns of shell use and selection, and the relationship between these factors constitute an initial part of a long-term effort undertaken to identify and clarify important parameters affecting this process (Mantelatto and Meireles 2004). The patterns of shell use vary among hermit crab populations and are influenced by several factors, such as the type and size of available shells, the inhabited area (inter- tidal or sublittoral area), and the hermit crabs’ shell preference (Garcia and Mantelatto 2000, Mantelatto and Garcia 2000). The genus Isocheles Stimpson, 1858 is known taxonomi- cally, but there is a lack of basic biological information. For the five species in the genus reported in American tropical and subtropical waters, there are only brief refer- ences concerning their distributions (see Forest and Saint Laurent 1968, Nucci and Melo 2000, Guzman 2004), and a recent study on molecular phylogeny (Mantelatto et al. 2006). In relation to Isocheles sawayai Forest and Saint Lau- rent 1968, the available information is restricted to data on specimens from the Brazilian coast that deals with the mor- phology of larval stages (Negreiros-Fransozo and Hebling 1983), shell use (Pinheiro et al. 1993, Fantucci et al. 2008), and records of intersex individuals (Fantucci et al. 2007). Although shell use by hermit crabs has been examined in other areas of the world (see Mantelatto and Garcia 2000 for review), to our knowledge no detailed and systematic study has been carried out on the hermit crab fauna of the Carib- bean or Atlantic region of Venezuela. Here we report the first observations on the patterns of gastropod shell occupa- tion by a population of I. sawayai inhabiting the sandy shore of Isla Margarita, Venezuela, with emphasis on morpho- metric relationships between hermit crabs and their shells. 49 Galindo et a Materials and Methods Study Area La Restinga Beach is located in a northern cornice of Margarita Island, Venezuela on the Caribbean Sea (10°57’ N - 11°03’ S, 64°01’ - 64° 12’ W; Figure 1) and is open to north- west trade winds. The beach is formed by a flat sand fringe that separates a hypersaline lagoon from the ocean, has a total surface area of about 30 km 2 , and is the largest beach in Nueva Esparta Province. The mean water temperature during collections was 26 °C and the salinity was 34 ppt. Sampling Procedures Specimens of I. sawayai were collected monthly during daytime on La Restinga Beach from January to December 2000 at random locations along the beach over a distance of about 200 m. A minimum of 70 individual hermit crabs were captured by hand each month. After collection, the animals were transported to the Crustacean Laboratory of the Universidad de Oriente and preserved in a 5% solution of formalin in sea water. Each individual was removed from its occupied shell, sexed, wet weighed (WW, g), and the ce- phalothoracic shield length (CSL, mm) was measured to the nearest 0.05 mm using a caliper. The reproductive condition of each female (ovigerous, non-ovigerous) was also recorded. Shell Study Shell species were identified according to the descriptions in Warmke and Abbott (1962), Abbott (1974), and Morris (1975), and confirmed by a specialist. The measurements were made according to Imafuku and Ando (1999) and Man- telatto and Garcia (1999): Total Shell Length (TSL, mm); Shell Maximum Width (SMW, mm); and Shell Dry Weight (SDW, g). Shell Internal Volume (SIV, cc 3 ) was measured by the method suggested by Bertness (1981b), and involved determining the volume of sand (known weight) required to fill an empty shell. Shell Angle Tip (SAT, degree) was measured according to Asakura (1995). An empirical scale was used to evaluate the physical state of shell condition, from 1 for perfect shell condition to 6 for severely damaged. Data Analysis To determine correlations among hermit crab dimensions and shell variables, regressions Y = a • X b and correlation co- efficients were calculated. The percentage of occupied gas- tropod shells was estimated based on the total number of individuals collected. The Shannon-Weaver Diversity Index (Margalef 1974), based on the number of gastropod species Figure 7. Map showing the sampling location (star) at an exposed sandy beach at La Restinga , Margarita Island, Venezuela (10°57'N - 1 l°03'S, 64°0V- 64°I2'W). Potential sources of shells: La Guardia (dotted arrow) and El Saco (striped arrow). 50 Shell occupation by I. sawayai in Venezuelan waters TABLE I. Species, number, and percentage (monthly and total) of gastropod shells used by Isocheles sawayai from January to December 2000 at La Restinga Beach, Venezuela. Occurrence is expressed as the number of shells found per number of collections. Shell Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Occurrence °/o Leucozonia nassa 52 39 23 14 31 29 26 30 30 42 21 15 352 12/12 37.37 Engoniophos unicinctus 9 13 11 12 15 26 18 22 17 32 38 26 239 12/12 25.37 Nassarius vibex - 1 4 1 1 5 5 1 1 2 4 10 2 46 11/12 4.88 Melongena melongena 3 2 5 8 6 5 3 3 2 1 2 40 11/12 4.25 Stramonita haemastoma 10 3 6 5 3 4 1 1 2 1 - - 36 10/12 3.82 Stramonita rustica - 6 6 2 - 2 2 1 3 4 2 1 29 10/12 3.08 Natica canrena 2 6 2 3 4 1 4 - 3 1 1 2 29 11/12 3.08 Bursa granularis 4 4 2 2 2 1 2 3 2 2 2 1 27 12/12 2.87 Pisania tincta 5 - - 2 2 1 - 3 - 5 2 - 20 7/12 2.12 Clathrodrillia gibosa 3 3 3 1 - - 3 1 - 2 1 1 18 9/12 1.91 Murex chrysostoma 1 3 2 1 1 1 3 - - 3 - 3 18 9/12 1.91 Turritella variegata 1 - - 1 1 - - 3 3 2 3 3 17 8/12 1.80 Conus spp. - - 1 - 2 1 2 - 5 - - - 1 1 5/12 1.17 Chicoreus brevifrons 2 - 1 1 1 1 1 - - - 1 1 9 9/12 0.96 Marginella prunum 1 - 2 1 1 1 - 1 - - 1 1 9 8/12 0.96 Others 1 7 3 1 5 5 3 3 3 2 3 3 4 42 - 4.46 Total number of species per month 17 13 14 18 15 15 15 13 12 15 14 14 17 species and % occurrence included in Other category: Fusinus closter (0.74%), Cancellaria reticulata (0.53%), Olivia reticula - tus (0.42%), Terebra cinerea (0.32%), Fasciolaria tulipa (0.21%), A ncilla tankervilli (0.11%), Cymatium parthenopeum (0.11%), Mur- ex spp. (0.11%), C eritium eburneum (0.11%), Conus jaspideus (0.11%), and Tegula lividomaculata (0.11%), 2 unidentified (1.58%). used by I. sawayai , was also calculated. The occupancy of shell species by hermit crabs (males, non-ovigerous females, and ovigerous females) was tested by the chi-square test and the mean size of both sexes was compared by Mann-Whitney Li- te st (Zar 1996). The level of significance was 0.05 for all tests. Results Of 942 hermit crabs collected, 171 were males (18.15%), 164 were non-ovigerous females (17.41%), 600 were oviger- ous females (63.69%), and the sex of 7 was undetermined (0.74%). Males and females had a CSL ranging from 1.70 to 7.35 mm and from 2.15 to 8.75 mm, respectively. Males were significantly larger than non-ovigerous (U = 17167.6, p < 0.01) and ovigerous females (U = 18985.3, p < 0.01). Isocheles sawayai occupied shells of 26 gastropod spe- cies. Leucozonia nassa, Engoniophos unicinctus, Nassarius vibex , M elongena melongena, and Stramonita haemastoma rep- resented 75.69% of the total shells obtained. The great majority of hermit crabs (95.55%) occupied 15 of the 26 shell species (Table 1). The shell species used least fre- quently were Fusinus closter (0.74%), C ancellaria reticulata (0.53%), Olivia reticulatus (0.42%), Terebra cinerea (0.32%), Fasciolaria tulipa (0.21%), A ncilla tankervilli (0.11%), C yma- tium parthenopeum (0.11%), Mure* spp. (0.11%), C eritium eburneum (0.11%), Conus jaspideus (0.11%), and Tegula livb domaculata (0.11%). These 9 species of infrequently used shells plus 2 unidentified ones were designated as “others.” The number of shell species occupied per month by I. sawayai ranged from 12 (September) to 18 (April). Leucozonia nassa, S. haemastoma, and Stramonita rustica showed the highest frequency of occurrence (12/ 12) during the study period (Ta- ble 1). Of the total shells analyzed, 16% were covered external- ly by epibionts (bryozoans in most cases), 50% were generally damaged, and only 34% were in a perfect state of condition. Morphometric relationships between hermit crabs and used shells were statistically significant, but with low correla- tion coefficients (Table 2, Figure 2). Of these, the relationships SMW versus CSL and SIV versus CSL turned out to best de- scribe the association between hermit crabs and their shells. Although significant, SAT versus CSL (r = 0.29) did not seem to generate much information concerning the population. Males and females (% 2 = 90.71; p < 0.001; permutation test = 0) as well as ovigerous and non-ovigerous females (/ 2 = 30.59; p < 0.001; permutation test = 0) showed different shell use patterns (Figure 3). Males were found occupying 21 of the 26 collected gastropod shells, whereas females (ovigerous Galindo et a as well as non-ovigerous) used all die shell species collected. The mean Shannon-Weaver diversity (hP) of shells occupied by L sawayai was 1.67 ± 0.16 bit/ind and ranged from 1.51 to 2.07 bit/ind. High values of H’ indicate the population occupied a wider variety of shell species. In general, males and females of I. sawayai inhabit L. nassa (19% □; 42% □, respectively) and E. unicinctus (16% 28% □, respectively) most frequently; the percentage of females using these two shells was significantly higher than that of males (% 2 = 25.23; p < 0.001; permutation = 0.006 and x 2 = 14.92; p < 0.01; permutation = 0.05; respectively). The use of E. unicinctus by ovigerous and non-ovigerous females was statistically dif- ferent (x 2 = 16.49; p < 0.01; permutation = 0.01). However, there was no evidence of a difference between the reproduc- tive state of females and their occupation of L. nassa (x 2 = 7.09; p < 0.31; permutation = 0.34). The variability of shell species used decreased as the hermit crab size increased (Fig- ure 4). However, in the smallest size class of hermit crab the shell variability was limited by the availability of small shells. 8 1 6 0 -j , , , , 0 2 3 5 6 8 9 CSL {mm) 4 , 3 0 -j , , , ■ ■ , 0 2 3 5 6 8 9 CSL (mm) Discussion In general, I. sawayai occupied a wider variety of shell spe- cies compared with other hermit crabs from tropical and sub- tropical areas (Table 3). Although shell availability was not evaluated, intense occupancy of some species of gastropod shells would indicate active selection behavior in I. sawayai in the field. Isocheles sawayai is a medium-sized hermit crab; this size may increase the possibility of finding adequate shells com- pared to larger crabs that are forced to look for larger shells. Judging from the large number of shell species used, it could be expected that high gastropod shell diversity is avail- able at La Restinga Beach; however, neither living gastro- pods nor empty shells were found in the field during the present study. The present study revealed a high variation of shell use in this hermit crab population. Generally, when there is good availability of resources (i.e., empty shells, live TABLE 2, Shell dimensions of gastropods occupied by Isocheles sawayai from January to December 2000 at La Restinga Beach, Venezuela. TSL = Total Shell Length; SMW = Shell Maximum Width; SDW = Shell Dry Weight; SIV = Shell Internal Volume ; SAT = Shell Angle Tip; N = Number of Shells; Min = Minimum Value; Max = Maximum Value; X = Mean; sd = Standard Deviation; CV = Coefficient of Variation. N Min Max X sd CV TSL (cm) 941 0.005 0.729 0.235 0.068 28.80 SMW (cm) 938 0.019 0.441 0.143 0.043 29.68 SDW (g) 942 0.07 16.90 1.72 1.46 85.01 SIV (cm 3 ) 899 0.02 8.12 0.69 0.86 124.48 SAT (°) 937 12 135 60.60 18.70 30.90 8 0 2 3 5 6 8 9 CSL (mm) 0123456789 CSL (mm) Figure 2. Regression plots between cephalothoracic shield length (SL) of Isocheles sawayai and total shell length (TSL), shell maximum width (SMW), shell dry weight (SDW), shell internal volume (SIV), and shell angle tip (SAT). 52 Shell occupation by I. sawayai in Venezuelan waters 100% 80 % 60 % -o 0 VI =3 0 a> ro § 40 % 0 Q_ 20% 0% HR EJ Others B Pisania tincta S Bursa granulans El Stramonita rustica □ Natica canrena Q Stramonita haemastoma S Melongena melongena □ Nassarius vibex O Engoniophos unicinctus □ Leucozonia nassa Males Non-ovigerous females Ovigerous females Figure 3. Percent use by Isocheles sawayai of different species of gastropod shells by demographic category. gastropods, and high diversity of occupied shells), the most common pattern observed is an occupation of adequate and undamaged shells by the hermit crabs (Mantelatto and Meireles 2004). However, this condition was not observed in the population studied: a large number (76%) of dam- aged shells were found, and no preference for occupation of these shells by either sex or ovigerous females was ob- served. A similar pattern has been described for other her- mit crabs from different areas worldwide (Vance 1972, Bach et al. 1976, Martinelli and Mantelatto 1999, Mantelatto and Meireles 2004). According to Scully (1979), the occupation of damaged shells increases the probability of interactions and shell exchanges within a population, affecting both protection and reproduction of the resident hermit crabs. For example, in situations where shell availability is limited, we expect to find a greater use of damaged shells (Hazlett 1966, 1970, Childress 1972, Bertness 1981b). Specimens of I. sawayai need heavy shells to survive the strong waves on an exposed sandy beach. The observed pattern of occupation of damaged shells suggests that competition for shell resources made occupation of inadequate shells essential. The natu- ral occurrence of hermit crabs in specific gastropod shells may be a consequence of a preference for such shells and of their relative abundance in the appropriate size range with respect to crab abundance (Conover 1978). We can con- clude that the population of I. sawayai at La Restinga Beach most probably displays intense shell exchange mechanisms. One intriguing question arising from this study is, where does I. sawayai obtain shells? The crabs may obtain their shells from several different sources: 1) empty shells could be available from El Saco to the West via migratory movements parallel to shore (see Figure 1); 2) the action of waves and currents have an important role in shell transportation from different areas (rocks, mud sediments, and lagoons) such as northwest of La Guardia Bay to the east (see Figure 1), where the most frequently available shells are those more susceptible to physical action (waves and currents); 3) shells may come from older shells deposited in the sediments in the area; and 4) shells may come from intraspecific exchanges. These factors may influence shell availability at La Restinga Beach. Provenzano (1959) reported a high occupation rate of Stramonita gastropod shells by I. wurdemanni in Bermuda. Similar results were reported for I. wurdemanni in Stra- monita floridana shells (95.6% occupancy; Caine 1978) in Florida, and in Brazil (49.9% occupancy; Fantucci et al. 2008). The genera Stramonita, Leucozonia, and C ymatium oc- cur over a wide latitudinal range, and their shells are com- monly occupied in noticeably high percentages by pagurid and diogenid hermit crabs (Grant and Ulmer 1974, Bert- ness 1982, Negreiros-Fransozo et al. 1997, Mantelatto and Garcia 1999); thus it is not surprising that they would also be suitable for the hermit crab population studied here. 53 Galindo et a The presence of live individuals of Stramonita and Leucozonia in die rocky shore regions of El Saco and La Guardia peripheral to the study area (see Figure 1) can be considered as potential sources of shells appropriate for I. sawayai, although proper studies have yet to be done. The genera Terebra, Murex, and M elongena are frequent, but not abundant, in some other reports of shell use by tropical hermit crabs (Provenzano 1959, Fotheringham 1976a, Caine 1978, Bertness 1982), reflecting a similar pattern found in the population studied here. Unfortu- nately, there are no data or detailed studies available on gastropod species in this area for comparative analysis. From the results obtained here, we can infer that I. sawayai inhabits a wide variety of shell species, but tend to occupy shells of specific species (L. nassa and E. unicinctus ). From published reports it is evident that, in nature, each species of hermit crab preferentially occupies one or a few species of shells, as reported for Paguristes tortugae by Mantelatto and Dominciano (2002), C alcinus tibicen by Garcia and Mantelat- to (2000), Pagurus brevidactylus by Mantelatto and Meireles (2004), and I. sawayai by Fantucci et al. (2008). These patterns of occupation are related to preferences for specific shells and/ or the abundance of appropriate shells in the habitat. However, in the case of I. sawayai , the reasons cannot be pre- cisely determined by the study methods used, so further ex- perimental studies dealing with these questions are necessary. Differences in shell weight are known to encourage use patterns and may affect reproduction of hermit crabs. Ac- cording to Fotheringham (1976a), shell weight directly af- fects the amount of energy available for reproduction; crabs carrying heavier shells must shift energy to activities such as locomotion and the search for food. Males of I. sawayai were found occupying heavier shells than females and juveniles, probably because of their larger size as well as their numeri- cal dominance or status in the population (Garcia and Man- telatto 2000). Furthermore, larger shells are less subject to displacement by water movements. Larger males preferential- ly occupied M. melongena, probably because of both its orna- mental shape (triangular-ovate body and triangular aperture) and medium size. Ovigerous females clearly preferentially oc- cupied L. nassa and E. unicinctus, but only up to 6.5 mm CSL. Males also showed a higher diversity of shells used (2.27 bit/ ind) compared with non-ovigerous females only (1.66 bit/ ind). It is possible that males change shells more frequently as a consequence of their faster growth (Mantelatto et al. 2005) as they increase in size and require new and larger shells. For females, the tendency to occupy larger and heavi- er shells is related to the space available to contain more eggs (Mantelatto and Garcia 1999). Ovigerous females < 4.7 mm CSL clearly preferred L. nassa and E. unicinctus shells compared to non-ovigerous females. These observa- tions are supported by Bach et al. (1976), Fotheringham TABLE 3. Comparative data on gastropod shell species occupation in hermit crab species of the family Diogenidae from tropical and subtropical zones. Hermit species Number of shell species Locality Reference Calcinus seurati 5 Hawaii, USA Hazlett (1989) Calcinus tibicen 21 Randolf Reef, Panama Bertness (1982) Calcinus tibicen 7 Ubatuba, Brazil Mantelatto and Garcia (2000) Calcinus tubularis 15 Mediterranean Sea, Italy Pessani et al. (2000a) Clibanarius albidigitus 7 Golfo Dulce, Costa Rica Childress (1972) Clibanarius antillensis 22 Randolf Reef, Panama Bertness (1982) Clibanarius tricolor 18 Florida, USA Bach et al. (1976) Clibanarius vittatus 8 Texas, USA Fotheringham (1976a) Clibanarius zebra >9 Hawaii, USA Hazlett (1989) Dardanus insignis 7 Ubatuba, Brazil Negreiros-Fransozo et al. (1997) Diogenes nitidimanus 26 Kyushu, Japan Asakura (1995) Diogenes pugilator 10 Ligurian Sea, Italy Pessani et al. (2000b) Isocheles sawayai 4 Ubatuba, Brazil Negreiros-Fransozo et al. (1997) Isocheles sawayai 17 Ubatuba, Brazil Fantucci (2008) Isocheles sawayai 26 La Restinga, Venezuela Present study Loxopagurus loxochelis 6 Ubatuba, Brazil Martinelli and Mantelatto (1999) Paguristes tortugae 21 Ubatuba, Brazil Mantelatto and Dominciano (2002) Petrochirus diogenes 12 Ubatuba, Brazil Bertini and Fransozo (2000) 54 Shell occupation by I. sawayai in Venezuelan waters K ^ 0> ib t- In- rt m in r- ih- ^ « m ri uS in © co h-P>OlU 3 T-l^{T 50 )tPf- h-rt ^NWW^ITIO lDffiNN GB ** N W' ffl t ID B O N N CD Crab si2e classes (mm) □ fit/rsa guanufari? Q Engorooptass wnr&iriqJus O L&ucpjEOft.'fl nasss BMeiongenarpefongena □ Wassarws vibex G NaSica c a arena Q Others m Pisania Iincta 9 Stramonita haemastoma □ Stramontia rustics Figure 4. Percent use of gastropod species shells by Isocheles sawayai in each size class and demographic category. A. Males. B. Non-Ovigerous females. C. Ovigerous females. (1976b), and Mantelatto and Garcia (1999, 2000). We infer that ovigerous females of I. sawayai are more selec- tive regarding shell use in order to 1) reach optimal shell size, 2) use a shell shape that provides a better fit for the crab body shape/ size, and 3) allows a better space to carry their broods, as observed in other pagurids of similar size (Dominciano and Mantelatto 2004). In other words, non- ovigerous females may go through a transition period when they look for the appropriate shell to brood their eggs. In conclusion, we postulate that I. sawayai in the La Restinga Beach area shows intense competition for ap- propriate shells through shell exchange, but concern trated on two gastropod species. The shell use pattern of this species varies between the sexes and the reproductive condition of females. In general, the population inhabits shells of L. nassa and E. unicinctus, but this occurs mainly for all the ovigerous females. There was a significant size relationship between the hermit crab and its shell, prim cipally with respect to shell width and internal volume. Acknowledgements Special thanks go to those who collaborated during the course of this study, especially J.C. Capelo for help- ing in shell identification and the fishermen for support during field activities. FLM received direct support from the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for an ongoing research fellow- ship and during the International Cooperative Project - CNPq - Prosul Program (490340/2004-0), which pro- vided financial support to FLM and JCB during a Brazil- Venezuela visiting program. We are also thankful to A.L. Meireles, R. Biagi, two anonymous reviewers, and the editorial committee for their criticism and suggestions on an early version of the manuscript. Janet W. Reid (Vir- ginia Museum of Natural History) revised the English text. Literature Cited Abbott, R.T. 1974. 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Tobias Division of Fish and Wildlife , U.S. Virgin Islands DOI: 10.18785/gcr.2001.08 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Mateo, I. and W. J. Tobias. 2008. Seasonal Patterns of Juvenile Fish Abundance in Seagrass Meadows in Teague Bay Bank Barrier Reef Lagoon, St. Croix, U.S. Virgin Islands. Gulf and Caribbean Research 20 (l): 59-65. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/8 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(cDusm.edu. Gulf and Caribbean Research Vol 20, 59-65, 2008 Manuscript received, July 16, 2004; accepted, January 14, 2008 SEASONAL PATTERNS OF JUVENILE FISH ABUNDANCE IN SEAGRASS MEADOWS IN TEAGUE BAY BANK BARRIER REEF LAGOON, ST. CROIX, U.S. VIRGIN ISLANDS Ivan Mateo* and William J. Tobias USVI Division of Fish and Wildlife, Rainbow Plaza 45 M arshill Fredericksted, St Croix USVI 00840 * Current address: Dept, of Fisheries, Animal and Veterinary Science, University of Rhode Island, Kingston RI 02881 USA, e-mail: imateo32@hotmail.com ABSTRACTS Considerable knowledge has been gained regarding fish use of nearshore habitats such as seagrass mead- ows or mangrove lagoons in the Caribbean (e.g., evaluation of nursery value, trophic linkages). However, few stud- ies have been conducted on fish recruitment to seagrass habitat around the Caribbean. Juvenile reef fish in seagrass meadows at Teague Bay, St Croix, U.S. Virgin Islands were surveyed from October 1998 through September 1999 using a visual census technique. Grunts (Haemulidae) were the most abundant juveniles observed (60% of all fish), fol- lowed by wrasses (Labridae, 20%) and parrotfishes (Scaridae, 13%). French grunt, Haemulon flavolineatum, were the most numerous species (59.5% of all fish), followed by slippery dick, Halichoeres bivittotus (18.5%), and bucktooth parrotfish, Sparisoma radians (10.4%). Most numerically abundant fish species demonstrated peaks in recruitment dur- ing late summer and fall. Our results imply that the functioning of seagrass beds incorporates strong seasonal patterns of small-fish abundance that need to be accommodated in any study wishing to understand their importance to fisheries. Introduction Seasonal patterns of recruitment have been studied extern sively in coral reef habitats at various locations, such as Great Barrier Reef, French Polynesia, Hawaii, and the Caribbean (Williams and Sale 1981, Eckert 1984, Walsh 1987, Doherty 1991, Dufour 1993, Casselle and Warner 1996, Planes 1997, Robertson and Kauffman 1998). However, there have been no studies on seasonal fish recruitment patterns within dif- ferent coastal habitats such as seagrass beds, mangroves, and backreefs, despite the widely accepted view of these habi- tats as juvenile nursery grounds (Nagelkerken et al. 2000a, 2000b, Cocheret et al. 2002, Mumby et al. 2004). Ogden and Gladfelter (1983) claim these nearshore habitats act as nurs- eries for three main reasons: 1) they are located away from the heavy predation pressure characteristic of coral reefs, 2) they offer protection to small fishes due to the structural complexity of masses of leaves and roots, and 3) they provide a rich food supply based on plant detritus and associated microorganisms and small invertebrates. In addition, most studies of nearshore tropical fish habitat use (Nagelkerken et al. 2000a, 2000b, 2001, Cocheret et al. 2002, Halpern 2004, Mumby 2004, Chittaro et al. 2005) were conducted in short periods of time (1 to 4 months) without taking into consid- eration the seasonality of these species. Thus, it is critical to investigate seasonality of fish recruitment in seagrass beds in order to refine our knowledge of coastal fish habitat use. Because critical seagrass habitats are generally close to shore, they are susceptible to anthropogenic disturbances such as storm-water and pollutant runoff and spills and me- chanical damage by boats. With growing fears that stock res- toration efforts are being compromised more by habitat loss from coastal development and by pollution than by overex- ploitation, conservation of habitats (such as seagrass mead- ows) is becoming an important part of fisheries management. In order to support informed decisions for the sustain- able management of marine fish and their habitats, there is a vital need for more documentation on the seasonality of habitat use by small juveniles. The goal of this study was to document temporal recruitment patterns in the fish as- semblages in seagrass meadows in the U.S. Virgin Islands. This study was designed to answer the following ques- tions: (1) Are there significant variations (order of magni- tude) in recruitment patterns among the most abundant seagrass fish species? (2) Are there clear seasonal patterns in recruitment among seagrass-associated fish species? Materials and Methods The three embayments sampled in this study (Cottongar- den Bay, Teague Bay, and Yellowcliff Bay) are part the Teague Bay bank-barrier reef system that extends from Pull Point to Lamb Point on the Northeast coast of St. Croix (Figure 1). This lagoon is described in Mateo and Tobias (2001). All seagrass meadows were found at similar depths (0.5 m to 3 m), and the vegetation within beds was dominated by tur- tlegrass Thalassia testudinum and manatee grass Syringodium filiforme with percent seagrass coverage at about 80%. From October 1998 through September 1999, fish recruits (re- cently settled post-larvae and juveniles) were counted along 50 m x 2 m strip transects (Fowler et al. 1992). For each bay, a 20 m x 20 m grid pattern was laid over a nautical chart. Grid intersecting points were labeled with consecutive num- bers and were the bases for selecting transect starting points for each embayment. Ten randomly selected starting points were surveyed per month for all three embayments, based 59 Mateo and Tobias 64 * 36 ” 00 I [Seagrass Study Site Reef Habitats Figure 7. Location of seagrass meadows study site at Yellowcliff Bay (YC), Teague Bay (TG), and Cottongarden Bay (CG) at the Northeast coast of St. Croix, USVI. on a preliminary fish census that used cumulative species/ transect counts Rogers et al. (1994). At each of the starting points, a single 50-m transect line (marked at 1 cm inter- vals) was laid out on a randomly selected compass bearing for each transect. On each transect, 100 m 2 were visually surveyed for fish by two divers swimming parallel but on opposite sides of the transect in a 1 m x 50 m belt transect. At each transect site, a fish census and a benthic survey were done. Each diver recorded fish species and estimated the size classes (<5 cm, 5-10 cm, and > 10 cm total length [TL]) of individuals for each species. For most species, ju- veniles < 5 cm were recorded as recruits. For smaller spe- cies, such as wrasses, grunts, and damselfishes, juveniles < 3 cm were considered recruits. Only juvenile recruits were considered for analysis in the remainder of this study. Identification of grunt recruits was verified by both divers during each dive using an underwater guide of early life history of grunts taken from Findeman (1997). To mini- mize the potential bias of counting the same individual twice along the belt transect, divers conferred with each other using hand signals to make sure fish were counted only once (Eberhardt 1978), and divers were trained to maintain constant swimming speed along the transect and to not count fish that entered the census area after the visual census had started (Samoylis and Carlos 2000). Statistical Analysis Prior to conducting data analyses, fish density estimates from both divers were checked for independence with a Pear- son product-moment correlation coefficient (r) (Zar 1984). If uncorrelated, the paired transects could be considered in- dependent samples. We considered r < 0.50 to indicate in- dependence. Correlation between paired divers was low (r = 0.41, p = 0.243, n = 360), and we interpreted the data gener- ated from the two divers as separate and independent census data sets. Data were standardized by month by pooling belt transects from all three embayments by habitat type. This allowed for equal sample size (n = 24) for the one year study. The assumption of homogeneity of variance was tested prior to each analysis using the Fevene Median test (Zar 1984) for data on number of fish per transect and density of the most abundant species. If this assumption was vio- lated, we log (x+l)-transformed data to satisfy assumptions of homogeneity of the variances (non-transformed data were used in graphs for clarity). Monthly variation in density of the most abundant species recorded on transects were exam- ined with a two-way ANOVA (Sokal and Rohlf 1981). If the overall F-value was significant, Tukey’s pair-wise multiple comparison procedure was used to compare mean values. Results A total of 8,243 juveniles of 23 species were counted during the study (Table 1). Grunts (Haemulidae) were the most abundant family comprising 60.1% of all juveniles observed. Wrasses (Fabridae) were the second most abun- dant family with 19.4% of the total, followed by parrot- fishes (Scaridae, 13.3%). Eight other families comprised the remaining 7.2% of juveniles observed. Of 23 species ob- served, the French grunt, Haemulon flavolineatum, was over- whelmingly dominant, accounting for 59.5% of all recruits, followed by slippery dick, Halichoeres bivittatus (18.5%), and bucktooth parrotfish, Sparisoma radians (10.4%) (Table 1). Significant differences in fish recruit density were found among species (F = 23.175, p < 0.001) and month (F n = 20.737, p < 0.001) for all taxa. Significant interactions among 60 Seasonal patterns of juvenile fish species and month (F ? u = 1.791, p < 0.003) were also found in this study. Recruit densities of H. flavolineatum, H. bivittatus, and S. radians were significantly higher than those for the re- maining species (Tukey test, p < 0.001). There were also sig- nificant differences in small fish abundance of H. flavolinea- tum, H. bivittatus, S. radians, Ocyurus chrysurus, Scams iseri, and Acanthurus chirurgus among months (Tukey test, p < 0.001). Major recruitment peaks for H. flavolineatum were ob- served in November 1998 and July 1999 (Figure 2a). Because sampling was only conducted for 12 months, it is uncertain whether these peaks indicate annual or semi-annual pulses. The second most abundant species (H. bivittatus ) exhibited abundance peaks in October 1998 and September 1999 and lower recruitment during other months (Figure 2b), indicat- ing a prolonged recruitment period with a peak during au- tumn. Bucktooth parrotfish, S. radians, clearly exhibited hi- modal recruitment, with peaks in October 1998, May 1999, and September 1999 (Figure 2c). Doctorfish, A. chirurgus, exhibited continuous recruitment from April to November and no recruitment from December to March (Figure 2d). Yellowtail snapper, O. chrysurus, recruits exhibited an annual peak in August and September of 1999 (Figure 2e). A simi- lar pattern was observed for beaugregory, Stegastes leucostic- tus, with continuous recruitment from April to January and no recruits seen from February to March (Figure 2f). Black- ear wrasse, Halichoeres poeyi , (Figure 2g) followed the same recruitment pattern as H. bivittaus. The striped parrotfish, S. iseri, showed a large peak in October 1998 (Figure 2h). Discussion Although conclusions cannot be drawn from only one year of data, some of the common seagrass fishes in St. Croix appeared to show seasonal variation in recruitment pulses. Within our eight most abundant species we found that H. flavolineatum, H. bivittatus, S. radians, O. chrysurus, S. iseri, and H. poeyi had major recruitment pulses from late summer to late fall. In the Caribbean region, studies focusing on entire reef fish assemblages (not just those in seagrass) have documented seasonal recruitment, primar- ily during spring through fall. In Barbados, Tupper and Fiunte (1994) found that assemblage-wide recruitment was high between May and November and low between Decem- ber and April. Luckhurst and Luckhurst (1977) reported semi-annual recruitment pulses, primarily in the spring and fall, for sixteen species within seven families in the Netherlands Antilles. Beets (1997) found abundance peaks of fish recruits on artificial reefs in St. Thomas US VI in April and June. Finally, late spring-summer peaks in recruit- ment were documented for four of the five most abundant families (Gobiidae, Labridae, Haemulidae, Pomacentridae) in a fringing reef in St. John USVI (Miller et al. 2001). The recruitment patterns exhibited by H. bivittatus, H. poeyi, A. chirurgus, and S. iseri contrasted with those found TABLE 7. Abundance of fish recruits on seagrass meadows in Teague Bay, St. Croix, U.S. Virgin Islands, October 1998 to September 1 999 using visual census. Total area surveyed was 36,000 m 2 . Family and Species Total Recruits Percent of Total Synodontidae Synodus foetens 1 0.01 Lutjanidae Ocyurus chrysurus 214 2.60 Lutjanus synagris 1 1 0.13 Lutjanus mahogoni 7 0.09 Haemulidae Haemulon flavolineatum 4,901 59.51 Haemulon plumierii 56 0.68 Mullidae Pseudupeneus maculatus 29 0.35 Chaetodontidae Chaetodon capistratus 30 0.36 Pomacentridae Stegastes leucostictus 123 1.49 Stegastes partitus 6 0.07 Labridae Halichoeres bivittatus 1,524 18.51 Halichoeres poeyi 72 0.87 Xyricthys martinicensis 7 0.09 Doratonotus megalepsis 4 0.05 Scaridae Sparisoma radians 860 10.44 Scarus iseri 155 1.88 62 0.75 Acanthuridae Acanthurus chirurgus 122 1.48 Acanthurus bahianus 22 0.27 Monacanthidae Monacanthus ciliatus 9 0.11 Tetradontidae Canthigaster rostrata 11 0.13 Sphoeroides spengleri 7 0.09 Sphoeroides testudineum 2 0.02 TOTAL 8,235 100.00 in other studies in the Caribbean. Luckhurst and Luck- hurst (1977) reported year-round labrid recruitment with spring pulses in the Netherlands Antilles, whereas in our study H. bivittatus abundance peaks occurred during Sep- tember and October. Adams and Ebersole (2002) report- ed recruitment peaks in June and February for acanthu- rid species on lagoonal patch reefs in St. Croix, while in 61 Mateo and Tobias 300 250 200 150 100 50 0 Haemulon flavolineatum (a) i 6 - 5 - 4 - 3 - 2 - 1 - 0 - Halichoeres poeyi (g) ll llllll l ooooooa > iO'iO'\0'\a'iO'iO'iO''a'> ^ ^ ^ ' < CO cu Q 25 20 15 10 5 0 Scarus iseri (h) u i i i i i r oooooo^O'O'2'cj'cjnc^ o'0'oio\0'0'9°'0'0\ S t & k & k 9-k kt Month Month Figure 2. A/lean monthly abundance (± standard error) of dominant recruit species observed using visual census on seagrass meadows in Teague Bay from October 1 998 to September 1 999. n= i 0 transects per month (area of each transect = 100m 2 ). 62 Seasonal patterns of juvenile fish our study we found comparable densities of A. chirurgus recruits from spring through fall. For S. iseri, Miller et al. (2001) found recruitment peaks in summer, while we found more S. iseri recruiting from late summer to late fall, with a major recruitment peak during the month of October. Significant geographical variation in seasonality of juve- nile abundance seems likely to occur throughout the Carib- bean (Victor 1991, Robertson and Kauffman 1998). Distinct intraspecific geographical variation in spawning seasonal ity has been reported within the Caribbean, with a tendency to- wards less seasonality in the more tropical parts of that region in some species and spawning peaks at different times of the year at different locations in others (Victor 1991, Robertson and Kauffman 1998). Reef fish species differ in the extent to which their recruitment seasonality varies in different parts of the Caribbean (Robertson and Kauffman 1998): for ex- ample, while four Stegctstes species have somewhat strong late summer peaks of recruitment in the Northwest Caribbean (Booth and Beretta 1994, Mcghee 1995), they have weaker seasonality in the Southwest Caribbean, with their recruit- ment peaks at least 6 months earlier in the year (Robertson 1990). Furthermore, pomacentrid species may have differ- ent seasonal recruitment peaks at different locations on a single island in the same year (Booth and Beretta 1994, Ca- selle and Warner 1996). Damselfish recruitment occurs dur- ing September in Puerto Rico (McGehee 1995), year-round with fall pulses in the Netherlands Antilles (Luckhurst and Luckhurst 1977), and from June to September in Barbados (peak for Stegctstes partitus; Tupper and Flunte 1994). In our study, damselfish exhibited summer/ fall recruitment pulses. Other species appear to have consistent recruitment patterns throughout the Caribbean. For example, H. flavolineatum has been found to recruit throughout the year in St. Croix (McFarland et al. 1985, Shulman and Ogden 1987), with reports of recruitment peaks in summer and fall throughout the Caribbean (Miller et al. 2001, Appeldoorn et al. 1997, this study). For O. chrysurus , recruitment peaks found in the present study (during August-October) were similar to those found by Watson et al. (2002) in seagrass habitats in Tortola. In recent years, considerable knowledge has been gained regarding fish use of nearshore habitats such as seagrass meadows or mangrove lagoons in the Caribbean (e.g., evalu- ation of nursery value or trophic linkages) (Nagelkerken et al. 2000a, 2000b, Cocheret et al. 2003, Mumby et al. 2004, Chittaro et al. 2005); however, few studies have been conducted on fish recruitment to seagrass habitat around the Caribbean. This is a component that is often overlooked in studies characterizing the nursery roles of seagrass and mangroves for tropical fishes in the Carib- bean (Nagelkerken et al. 2000a, 2000b, 2001, Cocheret et al. 2002, Mumby et al. 2004, Chittaro et al. 2005). Our study has demonstrated differences in recruitment intensity among species and months within a year of study. We recognize that this is a short-term study. It may or may not be indicative of typical recruitment patterns but provides valuable comparative information on recruitment from the Caribbean region. 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Prentice Hall, Up- patterns of recruitment of juvenile coral reef fishes to coral per Saddle River, NJ, USA, 718p. habitats within One Tree Lagoon, Great Barrier Reef. Ma- rine Biology 64:245-253. 65 Gulf and Caribbean Research Volume 20 Issue 1 January 2008 Carpoapseudes heardi N. Sp. (Tanaidacea: Apseudomorpha) from Caribbean Waters Near Tobago Tom Hansknecht Barry A. Vittor and Associates, Inc. Katia Christol dos Santos Universidade de Sao Paulo DOI: 10.18785/gcr.2001.09 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Hansknecht, T. and K. Christol dos Santos. 2008. Carpoapseudes heardi N. Sp. (Tanaidacea: Apseudomorpha) from Caribbean Waters Near Tobago. Gulf and Caribbean Research 20 (l): 67-74. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/9 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(cDusm.edu. Gulf and Caribbean Research Vol 20, 67-7 4, 2008 Manuscript received, October 29, 2007; accepted, January 23, 2008 CARPOAPSEUDES HEARDI N. SP. (TANAIDACEA: APSEUDOMORPHA) FROM CARIBBEAN WATERS NEAR TOBAGO Tom Hansknecht 1 and Katia Christol dos Santos 2 l Barry A. Vittor and Associates, Inc., 8060 Cottage Hill Rd. Mobile, AL 36695, USA, e-mail: bvataxa@bvaenviro.com 2 Laboratorio de Carcinologia, Museu de Zoologia, Universidade de Sao Paulo, Av. Nazare, 481, Ipiranga, Caixa Postal 42494, CEP 04218-970 Sao Paulo, SP, Brazil ABSTRACTS Corpoopseudes heardi n. sp. is described from samples collected from depths of 421 and 537 m off Tobago and is the first Caribbean record for the genus. The new species bears a resemblance to Corpoopseudes serratospinosus Lang, 1968 and other related species in the shortened dactylus unguis combination of pereopod 1, but has parallel eyespines like Corpoopseudes bocescui Gu^u, 1975 and Corpoopseudes simplicirostris (Norman and Stebbing, 1886). Other diagnostic characters include pereopods 2 and 3 with basal spurs, labrum with paired lobes, labial palp with two terminal setae, maxillipedal bases with outer crenulations, and pleopods with 1 -articled rami. It was found to lack an epistomal spine and has an unusual form of the third pereopod short propodal spine. ReSUMOI Corpoopseudes heardi sp. nov. e descrito de amostras coletadas em profundidades entre 421 e 537 m ao largo de Tobago, o primeiro registro do genero no Caribe. A nova especie se assemelha a Corpoopseudes serratos- pinosus Lang, 1968 e outras especies no encurtamento da combina^ao datilo-unguis no pereopodo 1, mas possui lobos oculares paralelos como Corpoopseudes bocescui Gu^u, 1975 and Corpoopseudes simplicirostris (Norman e Stebbing, 1886). Outros caracteres diagnosticos incluem pereopodos 2 e 3 com esporas basais, labrum com lobos pareados, palpo labial com duas cerdas terminals, base do maxilfpede com crenula<;6es externas e pleopodos com ramo uniar- ticulado. E diferenciada pela ausencia do espinho do epistoma e possui urn curto e incomum espinho no propodo do terceiro pereopodo. Introduction Recent deep-sea sampling efforts in the Caribbean Sea near Trinidad and Tobago conducted by Continental Shelf Associates (CSA) International Inc. under contract to Petro- Canada Trinidad and Tobago Ltd. have revealed a rich as- semblage of tanaidaceans and other peracarideans. Samples were collected by CSA in the wet (November-December 2006) and dry (May-June 2006) seasons, and both collec- tions included specimens of a new species of C arpoapseudes. Several other new apseudomorphs and tanaidomorphs were also found which will be the subject of future reports. Recent studies have shown that the ranges of some Caribbean deep- sea tanaids overlap with those in the Gulf of Mexico (GOM; T.J. Hansknecht, unpublished data), although no published records of the genus C arpoapseudes have been reported for GOM waters (Larsen 2005) or the Caribbean Sea. The nearest reported species (Larsen 1999) in the genus is C arpoapseudes prospectnes Larsen, 1999 from the South Atlantic off Brazil. Gupi (1972) originally proposed the subfamily Leiopinae to include the genera C arpoapseudes and Leiopus Beddard, 1886 that have a first pereopod stronger than the follow- ing ones and a maxillipedal endite bearing a specialized in- ner distal seta with a leaf-shaped form. The genus C arpoap- seudes Lang, 1968 consists of a group of 17 large, deep-sea apseudomorphs, from all major oceans. These tanaids are characterized by a lengthening of the carpus on pereopod 1 as compared to the merus (Gutn, 1980). In contrast, Bacescu (1982) reported C arpoapseudes curticarpus from the NE Atlan- tic which is the first known species with a pereopod 1 carpus shorter than the merus, and C arpoapseudes prospectnes Larsen, 1999 as the first member of the genus with the carpus of pe- reopod 1 equal to the merus in length (Larsen 1999). Mem- bers of this genus also share a characteristic male cheliped morphology with a large triangular tooth on the propodal fixed finger. Gupi (1996) later presented a key to the thirteen known species of C arpoapseudes based, in part, on a compari- son of the rostral lengths, pereopod 2 carpal length relative to that of the merus, and the length of the exopod relative to that of the basis of the cheliped. Other key characters included the number of antennule and antenna articles of the flagella and the presence or absence of branchial spines. Other members of the genus have been described world- wide. For example, C arpoapseudes caraspinosus Dojiri and Sieg, 1997 was described from California and was the second species of the genus to be found with lateral spines on the carapace, and C arpoapseudes spinigena Bamber, 2007 and C arpoapseudes varindex Bamber, 2007 have recently been described from the Kurile-Kamchatka and the Japan trenches. The purpose of this study was to report the first occurrence of this genus in the Caribbean Sea and describe a new species of C arpoapseudes. Materials and Methods Shipboard samples were collected by CSA using a 0.35-m 2 box corer, and infaunal samples were preserved in 10% formalin, stained with Rose Bengal, sorted, and then Hansknechtand Santos Figure 7 . Carpoapseudes heardi n. sp. (a) ovigerous female (1 1 .2 mm) paratype dorsal view, (b) male holotype (8.3 mm) lateral view, (c) anten- nule, (d) antenna, (e) labrum, (f) left mandible, (g) same, spine row enlarged, (h) molar process, (i) labium, (j) maxillule palp and outer endite, (k) maxillule inner endite, and (I) maxilla. stored in 70 % isopropyl alcohol. Samples were sorted Mobile, Alabama. Slide mounted specimens were studied and identified by Barry Vittor and Associates (BVA), with a Leica MZ6 and illustrated with a Leitz camera luci- 68 Carpoapseudes heardi taxonomy da-equipped Nikon Optiphot. All measurements are given in millimeters. Types are deposited in the United States National Museum (USNM) in Washington, D.C. and ad- ditional material is retained at BVA. The terminology of Wading (1989) and Larsen (2003) is followed, with the ex- ception that spiniform setae on the pereopod articles are called spines. The terms parallel and divergent are proposed for the orientation of the eye spines. Anteriorly directed eye spines, in relation to the carapace, are referred to here as parallel, whereas outward directed spines are divergent. SYSTEMATIC ACCOUNT Suborder Apseudomorpha Sieg, 1968 Family Apseudidae Leach, 1814 Subfamily Leviapseudinae Sieg, 1980 Genus Carpoapseudes Lang, 1968 Diagnosis (modified from Lang (1968), Gupi (1996) and Larsen (1999)) Carapace with rostrum and eye lobes bearing a terminal spine. Pereonites 3-5 with lateral spines; pereonite 6 shorter than pereonites 3-5, trapezoidal in shape. Pleotelson cylin- drical and long. Antenna with 5-articled peduncle; squama well-developed. Mandible with 3-articled palp. Maxillule with 2-articled palp. Endite of maxilliped with a leaf-like spine. Chela and pereopod 1 with exopodites. Pereopod 1 coxa with spine. Pereopod 1 with carpus and propodus, dor- sal and ventral margins lined with numerous finely attenuate setae. Chelipeds sexually dimorphic, with triangular tooth on fixed finger in males. Pleopods well-developed, five pairs. Described species included in genus: Carpoapseudes auri- tochelis Kudinova-Pasternak, 1975; C. austroafricanus (Bar- nard, 1940); C. bacescui Gupi, 1975; C. caraspinosus Dojiri and Sieg, 1997; C. curticarpus Bacescu, 1982; C. kudinovae Bacescu, 1981; C. laubieri Bacescu, 1982; C. longissimus Lang, 1968; C. menziesi Gufll, 1975; C. oculicornutus Lang, 1968; C. prospectnes Larsen, 1999; C. romanae Bacescu, 1987; C. rotundirostris Kudinova - Pasternak, 1989; C. serratosipino - sus Lang, 1968; C. simplicirostris (Norman and Stebbing, 1886); C. spinigena Bamber, 2007; C. varindex Bamber, 2007. Carpoapseudes heardi n. sp. Material Examined Holotype (USMN 1110765) 8.3mm male, Offshore Toba- go, Block 22, 30 November 2006, Station SLCA-MDFD-1, ll o 29 , 39.012” Latitude, 60 0 37 , 57.1494”Fongitude, 537 m, mud. Paratypes 4 specimens (11.2, 10.5 mm ovigerous females, 10 mm male, 6.4 mm juvenile) Offshore Tobago, Block 22, 30 November 2006, Station SLCA-MDFD-1, 1U29’39.012” Fatitude, 60°37’57.1494” Fongitude, 537 m, mud. USMN 1110766 2 specimens (10.3 mm male, 8.5 mm female) Off- shore Tobago, Block 22, 16 November 2006, Station ASC- FRFD-6, 11 °29’50.3394” Fatitude, 60°47’56.3214” Fongi- tude, 421 m, sandy mud. USMN 1110767 Diagnosis Rostrum triangular, acuminate, extending beyond eye lobes, carapace without lateral apophyses. Eye lobes acuminate, anteriorly projecting. Epistome without spine. Fabrum with two lobes on article 1. Male chela with ven- tral process on carpus. Pereonite 1 with bulbous expansion housing coxa. Pereonites 2 and 6 with small anterolateral spines Pereopods 2 and 3, basis with dorsoproximal spur- like apophysis. Pleopods inserted midlaterally, bearing exopods, endopods 1-articulate. Female with five pairs of oostegites located on cheliped and pereopods 1-4. Etymology This species is named for our friend and tanaid expert, Richard W. Heard. Description of male holotype (Figures 1-3) Body (Figure lb) 8.3 mm long, glabrous, white, iridescent, tapering posteriorly, with long, narrow pleotelson. Carapace about 0.9 times as long as wide, with slightly downturned, triangular rostrum extending about 1/3 length of antennu- lar article 1, inflated branchial lobes lacking spines, delin- eated dorsally by shallow furrows. Pereonite 1 widest, with large bulbose lateral lobes surrounding coxa of pereopod 1. Pereonites 3-5 with strong lateral spines located slightly ante- rior to the midpoint of the somite. Pereonites 2 and 6 with smaller anterolateral spines. Pleonites with epimera bearing spines and short setae. Hyposphenia present between che- liped bases, on all pereonites and on pleonites 1-5. Geni- tal cone broadly rounded. Pleopods inserted midlaterally. A ntennule (Figure lc) with 4-articulate peduncle, article 1 longer than remaining three combined, with several broom setae on outer margin, two adjacent setae distally. Inner mar- gin with two long and several short setae. Article 2, outer margin with cluster of setae and aesthetascs on distal third. Article 3 shorter than article 2, with long seta on outer dis- tal margin and shorter paired setae on inner distal margin. Article 4 common with outer flagellum of 20 articles, with strap-like aesthetascs on inner margins of articles 4, 6, 8, 9, 10, 11-18, on outer margins of articles 11, 13, and 17. Single setae on outer margins of articles 5, 7 and 9. Tip of outer flagellum with four simple setae and one broom seta. In- ner flagellum of six articles with single simple and broom seta on third article, two simple setae on fifth article, strap- like aesthetasc and three simple setae on terminal article. Antenna (Figure Id) with 5-articulate peduncle. Article 1 with broad inner lobe, article 2 with squama and three setae on outer margin, article 3 shortest, with single inner distal seta, articles 4-5 with several broom setae. Squama bearing five setae, with one on inner margin and four on outer mar- gin. Flagellum 9-articulate, with 5 terminal setae. Articles 1, 2 and 4 with long outer seta, article 7 with broom setae. Labrum (Figure le) with article 1 bearing two ventral 69 Hansknechtand Santos Corpoopseudes heard i n. sp. (a) male holotype (8.3 mm) maxilliped palp , (b) male paratype(10 mm) maxilliped endite, (b') endite oppo- site, (c) epignath, (d) ovigerous female paratype (1 1 .2 mm) cheliped, (e) cheliped, (f) male paratype (10 mm) cheliped, (g) pereopod 1 . lobes, each with long setal cluster on outer margin, article 2 process bearing oval, smooth triturative surface with outer with broadly excavate mid-margin. cusp and fine setules. Pars incisiva with five broad denticles. Mandible (Figures lf-h). Left mandible with broad molar Lacinia mobilis narrow, with four denticles. Spine row con- 70 Carpoapseudes heardi taxonomy sisting of five setae, four with multifurcate tips, one with bifurcate tip. Palp 3-articulate, article 1 shortest, bearing two setae. Article 2 longer than articles 1 and 3 combined, distal inner margin bearing row of seven serrated setae, decreasing in length distally, with six smaller, curved, subequal setae. Article 3, distal two thirds bearing inner row of thirteen curved setae, distal margin bearing two longer setae. Right mandible not illustrated but similar to left. Labium (Figure li). Basal endite not illustrated. Palp, mar- gins with long setules, with two distal setae. M axillule (Figures lj-k). Outer endite with nine distal spiniform setae, two subterminal setulate setae. Palp 2-ar- ticulate, distal article longer than proximal, bearing facial row of four elongate subterminal setae with serrated tips and single larger terminal spine (broken). Inner endite with five distal setae with fine setules on inner and outer margins Maxilla (Figure 11). Movable endite, outer lobe with sev- en setae, outermost pair setulate, inner lobe with five stout curved setae. Fixed endite, outer lobe with two subterminal setae, one palmate, three multifurcate setae, six setae with serrate tips. Inner lobe with comb row of about 25 curved, basally inflated setae, with one to two straight guard setae. M axilliped (Figures 2a-b,b0- Coxa very short, nearly as wide as basis. Basis large, quadrate, distal outer margin crenulate, sculptured. Palp article 1, outer lobe bearing large, distally setulate seta, inner margin with single simple seta. Article 2, outer margin bearing three stout curved setae, lateral sur- face with single seta, inner margin with two rows of setulate setae, dorsal row consisting of six short and single, atypical, thick, blunt seta, ventral row with eleven setae. Article 3 with six distally attenuate setae on inner margin. Article 4 with seven setae. Endite, inner margin serrate, with three coupling hooks, three circum-plumose setae. Inner surface with subterminal, apically inflated serrate spine (“leiopid spine”) and subterminal simple setae. Distal inner margin with five truncate setae, outermost seta distally setulate. Dis- tal outer margin of endite with five setae, distally flattened. Epignath (Figure 2c). Cup-shaped, with large setulate seta and two basal lobes. C heliped (Figures 2d-f). Basis short, bearing 2-articlulate exopod, article 2 with four plumose setae. Ventral margin of basis without spine, with five ventrodistal setae. Merus with three ventrodistal setae and short spine. Carpus, ventral margin with three long and one short seta, dorsodistal mar- gin with spinous apophysis and single strong seta (broken). Propodus, fixed finger with ventral margin bearing four short setae, distal margin with small setae and claw, setal row extending onto cutting surface, triangular tooth on cutting margin followed by row of short spines. Dactylus, cutting margin bearing short spines, dorsal margin with two setae. Pereopod 1 (Figure 2g). Coxal process bulbous, as long as pereonite 1, with anterolaterally directed spine. Basis 3.7 times longer than wide, with 2-articulate exopod, article 2 with five plumose setae (illustrated for 2 setae). Dorsoproxi- mal margin of basis with apophysis and short setae. Ischium with ventral seta. Merus about 4/5 length of carpus, ven- trodistal margin with eight setae, one stronger spine, dor- sodistal margin with two setae. Carpus, both margins lined with row of long attenuate setae, ventrodistal margin with two spinulate spines. Propodus about 2/3 length of carpus, dorsal margin with eleven attenuate setae, ventral margin with six antennuate setae, seven spinulate spines, and single short distal spine bearing seven ventral denticles. Dactylus plus unguis short, 1/3 length of propodus. Dactylus, ven- tral margin with two spines, one distal seta, dorsodistal margin with two setae. Unguis thick, shorter than dactylus. Pereopod 2 (Figure 3a). Basis with spur on dorsoproximal margin, numerous short setae on both margins. Ischium with ventrodistal seta (broken). Merus shorter than car- pus, with six ventral and three dorsal setae. Carpus with ventral margin with nine long attenuate setae and dorso- distal margin with distal cluster of four setae. Lateral sur- face of carpus with six setae with raised bases. Propodus shorter than carpus, with ventral row of six setae and short distal spine. Propodal spine with six teeth on ventral margin and with fine dorsal denticles. Distal half of dor- sal margin of propodus with closely spaced row of eight long, attenuate setae. Dactylus about Vi length of propo- dus, with single dorsal and ventral setae. Unguis broken. Pereopod 3 (Figure 3b). Basis with dorsoproximal spur, longer than combined length of ischium, merus and carpus. Ischium short, with dorsodistal broom seta. Merus shorter than carpus, with few setae. Carpus similar to pereopod 2, but without row of lateral setae, ventral margin with six se- tae, one ventrodistal spine. Propodus with setae and broom seta on dorsodistal half. Ventral margin of propodus with five setae and short distal spine spine with three ventral teeth. Unguis plus dactylus slightly longer than propodus. Dactylus with one ventral fixed spine and three dorsal se- tae. Unguis slightly shorter than dactylus, weakly curved. Pereopod 4 (Figure 3c). Basis like pereopod 3, but without spur and with constriction near middle (artifact?) with strong ventrodistal seta (broken). Ischium with two ventrodistal se- tae. Merus about Vi length of carpus with single dorsodistal and three ventrodistal setae. Carpus longer than all other ar- ticles except basis, with lateral oblique row of seven setae on distal margin and with four setae on ventral margin. Propo- dus with dorsoproximal broom seta, distal margin truncate, bearing five attenuated setae. Ventral margin with three setae. Dactylus plus unguis shorter than that of pereopod 3, about 2/3 length of propodus. Dactylus longer than unguis, dorsal margin with two setae, ventral margin with one distal seta. Pereopod 5 (Figure 3d). Basis bearing large mid-dorsal broom seta, two ventrodistal setae. Ischium similar to pereo- pod 2. Merus shorter than carpus, with single ventrodistal and dorsodistal setae. Carpus with single strong ventrodistal 71 Hansknechtand Santos Figure 3. Carpoapseudes heardi n. sp. (a) male holotype (8.3 mm) pereopod 2 with enlarged spine, (b) pereopod 3 with enlarged spine, (b') ovigerous female paratype (1 1 .2 mm) pereopod 3 spine, (c) pereopod 4, (d) pereopod 5, (e) pereopod 6, (f) pleopod 1 , (f') male paratype ( 1 0 mm) pleopod endopod specialized seta, (g) female paratype uropodal exopod, and (h) male paratype endopod. seta and four weaker setae. Dorsal margin of carpus with four attenuated setae on distal half. Mesiodistal margin of carpus with two setae. Propodus about equal to length of merus, with ventrolateral row of six spines on inner margin. Mesiodistal margin of propodus with four setae. Ventral margin of propodus with four setae. Dactylus plus unguis equal to length of propodus. Dactylus, with two dorsal and single ventral setae. Unguis slightly shorter than dactylus. 72 Carpoapseudes heardi taxonomy Pereopod 6 (Figure 3e). Coxa toroidal-shaped, distal margin bearing single seta. Basis with two large middorsal broom setae with smaller and distal broom setae present. Ischium with single ventrodistal seta. Merus with ventrodis- tal seta. Carpus longer than merus, with few setae. Propo- dus with midventral indention (artifact?), 10 spines, two setae. Dorsal margin with broom seta on distal third, with five distal setae. Dactylus plus unguis longer than propo- dus. Ventral margin of dactylus with four setae and dor- sal margin with two setae. Unguis shorter than dactylus. Pleopod (Figures 3f,C). Peduncle 2-articled, article 1 short, naked, rectangular, article 2 with four plumose setae on inner margin. Endopod slightly longer than exopod, 1-articled, mar- gins lined with 20 or more long plumose setae. First proximal seta of inner margin of endopod highly modified (Figure 3f ). Exopod Particulate, margins bearing about 20 plumose setae. Uropod (Figures 3g-h). Protopod attached near dorsal margin of pleotelson, dorsal margin with two distal setae, ventral margin with single distal seta. Exopod with seven articles, including three pseudosegments, bearing one seta on article 5. Tip with four setae. Endopod with 33 articles, including about three pseudosegments. Articles 2-4, 7- 12, 16, 19, 27, and 26 with setae, usually paired. Ar- tides 7 and 13 with 2-3 broom setae. Tip with five setae. Sexual and developmental differences Females are similar to males in dorsal view (Figure la). Cheliped merus of female has two ventrodistal setae (Figure 2d). Large males have a tubercle on the ventroproximal mar- gin of the carpus of the cheliped that is absent in younger males and all females (Figure 2f). Propodus of largest males has more setae on the ventral margin of the fixed finger. The large propodal tooth on the cheliped fixed finger is ab- sent in the female. The female cheliped of the C. heardi n. sp. lacks the propodal tooth although this is prominent in the younger and older males. In the largest adult males, a second smaller cheliped tooth is also found near the articu- lation with the dactylus (Figure 2f). Large males have pro- portionally short exopods on the chela when compared to the length of the basis. In the ovigerous female pereopod 3 has a short propodal spine bearing smaller denticles. Hypo- sphenial spines are stronger in the large adults. Numerous aesthetascs, strapdike in shape, are also found on the male outer antennular flagellum, although these are absent in the female. With regards to the base of the maxilliped, the outer margin of article 2 of mature C. heardi n. sp. has strong cren- ulations as also illustrated for C. auritochelis Kudinova -Pas- ternak, 1975. These and the size of the cheliped propodal tri- angular tooth are likely related to the maturity of the tanaid. Ovigerous females with a marsupium have five pairs of oostegites present including one on the cheliped and one on pereopods 1-4. Large males also have five plumose setae on the inner margin of the protopodite of the pleopod rather than four. The highly modified seta on the endopod of the pleopod also seems to be found only in mature individuals (Figure 3F). Discussion Carpoapseudes heardi n. sp. differs from all other known species in the genus by a combination of characters, the prominent being presence of parallel eyespines and the lack of an epistomal spine. Carpoapseudes bacescui Gu^u, 1975 and C. simplicirostris (Norman and Stebbing, 1886) also have parallel or anteriorly directed eyespines plus epis- tomal spines. Carpoapseudes heardi n. sp. further differs from these two species by the presence of a larger rostrum. In C. simplicirostris the rostrum is very narrowed and stick-like while the rostrum of C. bacescui is shorter than that of C. heardi n. sp. Like C. heardi n. sp., C. longissimus Lang, 1968 and C. oculicornutus Lang, 1968 lack epistomal spines, but they differ from the new species by having divergent rather than parallel eyespines. A comparison of the first pereo- pod of C. heardi n. sp. to other related species reveals that this leg has a shortened dactylus similar to that of C. sen ratospinosus Lang, 1968, but the merus of C. heardi n. sp. lacks the dorsal setae as characteristic of the former species. Carpoapseudes prospectnes Larsen, 1999 which was described from Brazilian waters and is the only other member of the ge- nus known from the western Atlantic, is distinguished from C. heardi n. sp by the having an epistomal spine and lacking parallel eyespines. With the description of C. heardi n. sp. the genus Carpoapseudes now contains 18 species, most of which are reported from depths greater than 1000 m. Three species of Carpoapseudes, C. heardi, n. sp., C. prospectnes, and C. sen ratispinosus however, are known from depths < 900 m, with C. prospectnes having the shallowest occurrence (295-360 m). An examination of the mouthparts of the new species reveals that the inner distal seta on the maxilliped endite of C. heardi n. sp. is long, serrated, and not leaf-like, but can be considered a “leiopid spine” based on its size and position, indicating a relationship with Leviapseudes Sieg, 1983 and related genera. The labial palp of C. heardi n. sp. has two ter- minal spines as in C. spinigena Bamber, 2007 and C. prospect - nes whereas three spines are present in most other species. The mandibular palp of the new species has an interesting arrangement of setae on the second article of the palp, with the setae steadily decreasing in size distally on the article. The shape of the pereopod 3 propodal spine of C. heardi n. sp., with regards to the size and number of ventral denti- cles, also varies between the sexes. Females have smaller and more numerous ventral denticles than males (Figure 3b 0- The number of oostegites present in members of Can poapseudes is controversial. Gutri (1981) and Dojiri and Sieg (1997) reported that the genus Carpoapseudes had five pairs of oostegites; however, Larsen (1999) reported only 4 pairs. It is possible that some authors did not have fully ovigerous female material available to study. Based on our observations, the cheliped oostegite of C. heardi n. 73 Hansknechtand Santos sp. does not form until the marsupium is present. For in- stance, one ovigerous female (11.2 mm; Figure la) did not have a cheliped oostegite whereas another (10.5 mm) had a fully formed marsupium with the cheliped oostegite. Fi- nally, on C. heardi n. sp. the oostegite forms posterior and medial to the insertion of the cheliped and not near the exo- pod as in other apseudid genera examined by the authors. Like most species of the genus, C. heardi n. sp. has simple non-plumose setae of the lateral epimera of the pleonites; in contrast, C. bacescui Gutxi, 1975 has long plumose setae. Acknowledgments The authors thank Barry Vittor and Associates Inc., Petro - Canada Trinidad and Tobago Ltd., and CSA International, Inc. with special thanks to B. Balcom (CSA-West), and the MZUSP - Museu de Zoologia - Lab. Carcinologia. We also thank the anonymous reviewers for improving the manuscript. Literature Cited Bacescu, M. 1982. Carpoapseudes laubieri sp. n. et C. curticarpus sp. n. de 1 ' Atlantique de NE (Bassin ouest-europeen) et quel- ques details nouveaux sur La calabilite Du genre. Travaux du Museum national d’Histoire naturelle “Grigore Antipa” 24:55-68. Bamber, R N. 2007. Suborders Apseudomorpha Sieg, 1980 and Neotanaidomorpha Sieg, 1980 In: K. Larsen and M. Shimo- mura, eds. Tanaidacea (Crustacea: Peracarida) from Japan III. Tbe deep trenches; the Kurile- Kamchatka Trench and Japan Trench. Zootaxa Monograph # 1599, Magnolia Press, Auckland, New Zealand, p. 13-40. Beddard, F.E. 1886. Report on the Isopoda collected by H.M.S. Challenger during the years 1873-1876. Part II. The Voyage of H.M.S. Challenger. Zoology 17: 1-175, Pis I-XXV. Dojiri, M. and J. Sieg. 1997. The Tanaidacea. In: J.A. Blake and P.H. Scott, eds. Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and Western Santa Barbara Channel. Volume 11. The Crustacea Part 2. The Isopoda, Cumacea and Tanaidacea. Santa Barbara Museum of Natural History. Santa Barbara, CA, USA, p. 181-278. Gupa, M. 1972. Phylogenetic and systematic considerations upon the Monokonophora (Crustacea-Tanaidacea) with the sug- gestions of a new family and several new subfamilies. Revue Roumaine de Biologie (Serie Zoologie) 17:297-305. Gupa, M. 1975. Carpoapseudes bacescui n. sp. and C. menziesi n. sp. from the Peru-Cbile trench. Revue roumain de Biologie (Biologie animale) 20:93-100. Gupa, M. 1980. On the status of the “groups” Leiopus and Carpoapseudes (Crustacea, Tanaidacea) and their systematic position. Travaux du Museum national d’Histoire naturelle “Grigore Antipa” 22:385-392. Gutu, M. 1981 A new contribution to the systematics and phylogeny of the suborder Monokonophora (Crustacea, Ta- naidacea). Travaux du Museum national d’Histoire naturelle “Grigore Antipa” 23:81-108. Gupa, M. 1996. The description of Spinosapseudes n. g., and amended diagnoses of two genera of Tanaidacea (Crustacea). Revue Roumaine de Biologie (Serie de Biologie Animale) 41:87-93. Kudivova-Pasternak , R.K. 1975. Tanaidacea (Malacostraca) of the deep-sea Romansh and Guinea Hollow. Zoologicbeskii Zhurnal 54:682-687. Lang, K. 1968. Deep-sea Tanaidacea. Galathea Report 9:23-209. Larsen, K. 1999. A new species of the deep-sea genus Carpoap- seudes Lang from tbe southwestern Atlantic (Crustacea, Tanaidacea) Zoostema 21:647-659. Larsen, K. 2003. Proposed new standardized anatomical termi- nology for the Tanaidacea (Peracarida). Journal of Crustacean Biology 23:644-661. Larsen, K. 2005. Deep sea Tanaidacea (Peracarida) from the Gulf of Mexico. Crustaceana Monographs 5, Brill, Boston, MA, USA, 381 p. Norman, A.M and T.R.R. Stebbing. 1886. On the Crustacea Isopoda of tbe ‘Lightning, ‘Porcupine’ and ‘Valorous’ Expedi- tions. Transactions of the Zoological Society of London 12 (Part IV, No. 1): 7-141, Pis 16-27. Sieg, J. 1983. Tanaidacea. In H.-E. Gruner and L.B. Holthuis, eds. Crustaceorum Catalogus, Vol 6, Dr. W. Junk Publishers Inc., Hague, The Netherlands, 552 p. Watling, L. 1989. A classification system for crustacean setae based on the homology concept. In: B.E. Felgenhauer, L. Watling, and A.B. Thistle, eds. Functional Morphology of Feeding and Grooming. Crustacean Issues 6, Balkema, Rot- terdam, The Netherlands, p. 15-27. 74 Gulf and Caribbean Research Volume 20 Issue 1 January 2008 An Unusual Reaction and Other Observations of Sperm Whales Near Fixed-Wing Aircraft Mari A. Smultea Joseph R. Mobley Jr. University of Hawaii, West Oahu Dagmar Fertl Geo-Marine, Inc. Gregory L. Fulling Geo-Marine, Inc. DOI: 10.18785/gcr.2001.10 Follow this and additional works at: http://aquila.usm.edu/gcr o Part of the Marine Biology Commons Recommended Citation Smultea, M. A., J. R. Mobley Jr., D. Fertl and G. L. Fulling. 2008. An Unusual Reaction and Other Observations of Sperm Whales Near Fixed-Wing Aircraft. Gulf and Caribbean Research 20 (l): 75-80. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/10 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(o)usm.edu. Gulf and Caribbean Research Vol 20, 75-80, 2008 Manuscript received March 29, 2007; accepted July 27, 2007 SHORT COMMUNICATION AN UNUSUAL REACTION AND OTHER OBSERVATIONS OF SPERM WHALES NEAR FIXED-WING AIRCRAFT Mari A. Smultea 1 , Joseph R. Mobley, Jr. 2 , Dagmar Fertl 3 *, and Gregory L. Fulling 3 1 29333 SE 64th Street, Issaquah, Washington 98027 USA 2 University of Hawaii-West Oahu, 96-129 Ala Ike Street, Pearl City, Hawaii 96782 USA 3 Geo-Marine, Inc., 2201 K Avenue, Suite A2, Plano, Texas 75074 USA * Corresponding author, e-mail: dfertl@geo-marine.com Introduction Data on the reactions by cetaceans to aircraft flying over- head (or in the near vicinity) are limited (e.g., Richardson et al. 1995, Patenaude et al. 2002). This information is im- portant for assessing potential effects of aircraft on feder- ally protected species, such as sperm whales (Physeter mac- rocephalus ) particularly in association with offshore oil and gas exploration in the northern Gulf of Mexico (NGOM) and elsewhere. As noted in the draft recovery plan for the sperm whale, “the severity of the threat is unknown for sound-producing factors (including aircraft) related to the oil and gas industry” (NMFS 2006). Sperm whales in the NGOM are well-known to occur in areas of intense oil and gas exploration and development activities (e.g., Jochens et al. 2006). Helicopters (as well as work boats) are used to transport workers to and from operating offshore platforms in the NGOM. These helicopter operations occur between the water’s surface and altitudes of — 2,135 m (e.g., Daska- lakis and Martone 2004). Low altitudes are flown during approaches to and departures from offshore platforms. The NOAA Fisheries currently includes in its biological opinions, a conservation recommendation that permit holders maintain helicopter traffic over the NGOM at al- titudes above 305 m, if practicable, to avoid disturbance to whales and sea turtles. It is projected that an average rate of 25,000-55,000 helicopter operations will occur annually in the Central Planning Area (including the Mississippi River Delta area, a known high-use area by sperm whales, particularly females and their calves) (MMS 2006). The fre- quency of such flights is anticipated to continue increasing as the number of operating offshore structures increase. Reported behavioral reactions by sperm whales to air- craft are sparse, highly variable, and largely anecdotal as summarized in Table 1. Observers since the whaling era began have noted that sperm whales tend to be skittish (Whitehead 2003). When documented, sperm whale reac- tions to both planes and helicopters range from no reac- tion (Clarke 1956, Gambell 1968, Green et al. 1992) to reactions such as increased surface intervals and dramatic behavioral changes (Clarke 1956, Fritts et al. 1983, Mullin et al. 1991, Wiirsig et al. 1998, Richter et al. 2003, 2006). Given the lack of supporting data for either case, it is impor- tant that these types of data are collected and consolidated into a cohesive document. Therefore, the specific objec- tives of our paper are to report our visual observations of sperm whale reactions to straight-line aircraft fly-bys (i.e., passes), to report a unique observation of a recognized “stress behavioral reaction” exhibited by sperm whales dur- ing an overhead circling by small fixed-wing aircraft, and to provide a summary review of published related studies. Materials and Methods Cetacean observations were made during a series of multi-year, line-transect aerial surveys for cetaceans conduct- ed within 45 km from shore of the main Hawaiian Islands. Specifics of the survey protocol and general area descrip- tions are detailed in Mobley et al. (2000). Briefly, surveys occurred over waters less than 2,000 m in bottom depth (Mobley et al. 2000) using small aircraft (1993, Cessna 172; 1994 and 1995, Skymaster; and 1998, Partenavia) at an al- titude of 245 m and a speed of 185 km/hr. Four personnel were aboard the aircraft during all flights: a pilot, a data re- corder, and two observers. Time, location and altitude infor- mation were recorded in real time using a computer linked to an altimeter and global positioning system every 30 sec and manually whenever a sighting occurred. A Hi 8-mm video camera and a 35-mm camera with 300 mm telephoto lens were used to document unusual sightings and behavior. Response (reaction or no reaction) by cetaceans dur- ing an initial pass was noted as required by the NMFS re- search permit obtained for the surveys. A “reaction” to the aircraft was defined as an overt change in the initially ob- served orientation or behavior of at least one animal in a group; for example, an abrupt dive associated with a splash or display of the tail flukes, a breach, a tail slap, etc. (sim- ilarly described by Green et al. 1992, Wiirsig et al. 1998, Patenaude et al. 2002). After the initial pass of a sighting, the aircraft sometimes circled over or near (usually within ~ 200 m lateral distance) the sighting so that observers could verify species, group size, and species composition. For the purposes of this report, “adult” refers to non-calf whales. 75 Smultea et a TABLE 7. Summary of available information on reactions of sperm whales to low altitude overflying aircraft. Location Aircraft Altitude (m) Behavior Description Reference the Azores Sikorski S55 helicopter -4.6-27 m 4 sperm whales marked with 'Discovery-type' marks shot from a standard rifle during two different flights; apparent "unconcern" until a down-draught of rotors caused much agitation of the water, causing the whales to quickly dive and simultaneously defecate Clarke (1956) South Africa Cessna 31 OH -150 m Whales seemed unaware of aircraft flying overhead (number not specified) 0 Gambell (1968) northern Gulf of Mexico Beechcraft (Model AT-1 1) alternating altitudes of 91 m and 229 m Circling often (number not specified) disturbed whales by causing changes in direction, dive patterns, and increased speed of movement; one observation of breaching possible response Fritts et al. (1983) northern Gulf of Mexico Twin Otter -230 m Some (number unspecified) whales affected by flyovers and dove immediately while other animals remained at the surface Mullin et al. (1991) Oregon and Washington DeHavilland Twin Otter -65 m No reaction by 24 observed groups Green et al. (1992) northern Gulf of Mexico Twin Otter Usually -230 m 7 (28%) of 25 groups changed behavior when approached to within 305 m Wursig et al. (1998) the Bahamas Cessna 172 50-245 m Group of six sperm whales (including one calf) closed ranks and one whale turned on its side to apparently look up towards aircraft circling overhead C. MacLeod, pers. comm., Beaked Whale Research Project, University of Aberdeen, Lower Right, 59 Jute Street, Aberdeen, AB24 3 EX, U.K. Kaikoura, New Zealand Fixed-wing aircraft Aircraft recorded as present when flying circular pattern at least 1 50 m above whale(s) Study of impacts of aircraft-based whale-watching on male sperm whales from small vessel (n=l 1 6) and from shore (n=29). Transient males delayed time to first click (vocalization) and reduced surfacing time near aircraft, while residents slightly increased their surface time near aircraft. No alteration of frequency of heading changes by residents or transients. Results indicated aircraft presence combined with other factors (e.g., season, year) contributed to slight changes in behavior. Richter et al. (2003, 2006) Kauai, Hawaii Cessna 172, Skymaster, Partenavia -233-269 m 3 of 8 groups (<360 m lateral distance) reacted to fly-by by abruptly diving. One group of 1 1 (including one calf) closed flanks, slowed down, formed a reverse marguerite with calf in middle, then dove while aircraft circled overhead for 6 min. Present study a General statement based on review of daily diaries kept by pilots operating spotting aircraft associated with whaling operations during 1966, 1967 and 1968. Results Data were obtained from observations of 24 sperm whale groups totaling 109 individuals (mean = 4.6 whales, sd = 5.3, range 1-20). An additional three sightings with no later- al distance data were excluded from analyses; none of these groups demonstrated a visible reaction to the aircraft. Nine calves were sighted in six of the 24 groups. Most (n = 13) of the 24 sightings were made from the Skymaster, 10 from the Partenavia, and 1 from the Cessna. During initial passes, aircraft altitude ranged from 233-269 m and lateral dis- tance to whale sightings ranged from 103-3,427 m (n = 24). Responses to aircraft passes A reaction to the initial pass of the aircraft was observed during three (12%) of 24 sightings: two from the Skymaster (both single adult whales) and one from the Cessna 172 (a group of four adult whales). All three reactions consisted of a hasty dive and occurred < 360 m lateral distance from the aircraft. Of the eight groups seen < 360 m lateral dis- 76 Sperm Whale Reactions to Aircraft tance from the aircraft, three (38%) reacted to the passing aircraft; no reactions were noted for the remaining 16 sight- ings at lateral distances > 360 m from the aircraft (n = 21). No reaction was observed during the two closest (103 m and 208 m lateral distance) initial passes (both by the Skymas- ter) (Figure 1A). However, a reaction by the closest of these initial sightings (103 m lateral distance) occurred during a subsequent resighting 3 min later while the Skymaster cir- cled overhead. This response is described below and is based primarily on Hi 8-mm video, photographs, and field notes. Response to circling aircraft While surveying at 235 m altitude (50 km north of Kaua’i), a single sperm whale was sighted from the Skymaster and no reaction to the initial pass was seen. Subsequently, the air- craft turned to estimate group size and confirm species iden- tification. During this time, the aircraft increased altitude and began circling the location of this individual to look for more animals. About 3 min later, a group of 11 sperm whales (10 adults plus 1 calf) surfaced in the same area. The aircraft continued circling this group for - 6 min at distances of 0-500 m (laterally) and altitudes of 245-335 m. All whales were visible at or near the water’s surface throughout most of the observations. One adult estimated to be - 1/3 longer than the other adults and not associated closely with the calf was assumed to be a mature male (bull) based on its rela- tive body length (Rice 1989). After the aircraft circled over- head for about 4 min, the whales ceased forward movement, moved closer together in a parallel flank-to-flank formation (Figure IB), and formed a fan-shaped semi-circle with heads facing out and flukes toward the middle of the semi-circle (Figure 1C). The bull was on the left outer edge of the semi- circle and the calf remained near the middle of the group. Maximum distance between individuals over the course of the observation decreased from about six body lengths to one, thereby, concentrating the group as a whole around the calf. During this time, one whale was seen on its side with its mouth agape. The entire episode lasted about 9 min from initial sighting to the unique behavioral observation. Discussion We interpreted the aforementioned group’s formations as an agitation, distress, and/ or defense reaction to our cir- cling aircraft. This interpretation is based upon behavioral events displayed by sperm whales in situations of distress, reacting to perceived or actual threats, such as killer whales ( Orcinus orca ) (e.g., Arnbom et al. 1987, Pitman et al. 2001), false killer whales ( Pseudorca crassidens ) (Palacios and Mate 1996), short-finned pilot whales ( Globicephala macrorhynchus ) (Weller et al. 1996, Pitman et al. 2001), sharks (Best et al. 1984), whalers (Nishiwaki 1962, Caldwell et al. 1966, Berzin 1971), and vessel approaches (Palacios and Mate 1996). The characteristic responses to killer whales are individuals com- ing to the surface, swimming fast toward one another, and clustering actively and tightly (Whitehead 2003), similar to the behavior we observed. The semi-circle “fan” forma- tion we describe is similar to defensive “marguerite”- and “spindle”-like formations reported by other researchers (Nishiwaki 1962, Berzin 1971, Arnbom et al. 1987, Weller et al. 1996, Pitman et al. 2001). Weller et al. (1996) ob- served open-mouth behavior (akin to our observation) by sperm whales, and interpreted this as a discrete distress re- sponse to harassment by short-finned pilot whales, based on obvious distress behavior reported by other research- ers. In our observations, the mouth agape may have been a distress response to our aircraft. This same whale was swimming on its side, possibly to look up at the aircraft. The tight parallel formation we observed is often a pre- cursor to socializing events (during which animals huddle together and rub against each other), but also to defensive responses such as the fan formation we observed (D.M. Palacios, NMFS/Pacific Fisheries, Environmental Labora- tory, Pacific Grove, California, pers. comm.). Thus, hud- dling may provide an opportunity for information transfer and reassurance between group members. For the group we observed, this behavior might have increased defensive capabilities by minimizing exposure of the flanks (particu- larly the calf) to a perceived threat. Similar behaviors by a group of six sperm whales (including one calf) in the Ba- hamas occurred when a Cessna 172 passed, then circled directly over the group at an altitude of about 50-245 m (C.D. MacLeod, Beaked Whale Research Project, Lower Right, Aberdeen, AB24 3EX, United Kingdom, pers. comm.). The group closed ranks and one individual turned on its side to apparently look up towards the aircraft. In general, it is difficult to identify behavioral reactions during brief observation periods such as short overflights by aircraft; furthermore, some subtle changes in behavior (i.e., in respiration) are not evident without statistical analysis (e.g., Richardson et al. 1995). Thus, it is possible that sperm whales we observed may have exhibited reactions we did not recognize or see because they occurred after we had passed. Reactions of sperm whales to perceived threat stimuli may be context dependent. Berzin (1971) described three separate fright reactions related to the level of the perceived threat: dive, aggregate at surface, and flight/flee. Pitman et al. (2001) further suggested that sperm whales often dive in the presence of boats (perhaps a mild response) vs. ag- gregate if the threat is immediate, forming a rosette when groups are small (typically < 9 whales). The three apparent dive responses we reported may have been a “mild fright” response to the brief passes by our aircraft. In contrast, the two group formations we described appear to have been fright responses to persistent overhead circling by the air- craft and resemble the “spindle” group formed in response to an immediate perceived threat (Pitman et al. 2001). Received sound levels of our aircraft near sperm whale 77 Smultea et a Figure 7 . Chronological group formations exhibited by a group of 1 1 sperm whales (including one bull and one calf) while a Skymaster aircraft circled overhead on 9 April 1 994 from 1 146h to 1 155h (see text): (A) No reaction , 1 151 h; (B) Flank to flank parallel formation, 1 153h; (C) Semicircle formation, 1 154h. Scale is approximate. sightings were not available, and cannot be realistically cab culated for our data, given the variation and complexities involved in estimating aircraft-to-surface and sub-surface sound propagation (see Richardson et al. 1995). However, available data indicate that the expected frequency range and dominant tones of sound produced by our aircrafts overlap with the known low-end frequency range of sperm whale vo- calizations (< 0.1 to 30 kHz; see summaries by Richardson et al. 1995 and Ketten 1998). Snell’s Law predicts a 26° sound cone from the vertical for the transmission of sound from air to smooth-surface water (Urick 1972, Richardson et al. 1995). The angle of this cone becomes greater in Beaufort wind force > 2. Based on altitudes, the group of 11 sperm whales with the unusual reaction described above presum- ably received both acoustic and visual cues (the aircraft and/ or its shadow) from the circling aircraft, as they were located directly under the aircraft and/or well within Snell’s pre- dicted sound cone. The other 24 sperm whale groups that were passed once by our aircraft were outside (104-3,427 m lateral distance) the theoretical 26° sound cone (lateral distance 54-62 m); however, whales near this sound cone (within roughly several hundred meters) may have heard the overflying aircraft via scattering associated with the rough sea surface at the time (Beaufort wind force 3-4). Based on other studies of cetacean responses to sound (Richardson et al. 1995, Patenaude et al. 2002), we believe that our observed reactions to brief overflights by the air- craft were short-term and probably of no long-term biologi- cal significance. Although isolated occurrences of this type are probably not biologically significant, repeated or pro- longed exposures to aircraft overflights have the potential to result in significant disturbance of biological functions, especially in important nursery, breeding or feeding areas (Richardson et al. 1995). Activities involving aircraft that might result in harassment of sperm whales include mili- tary training exercises, helicopter overflights associated with offshore oil and gas exploration and development (for ex- ample, in the NGOM), recreational/ecotourism flights (for example, off Hawaii and New Zealand) and research surveys. This limited description sheds light on the need to sys- tematically document behavioral responses by cetaceans to aircraft, particularly by protected species, such as the endan- gered sperm whale. There is also a need to document re- ceived sound levels of aircraft by whales, and to record and 78 Sperm Whale Reactions to Aircraft compare whale behavior before, during and after controlled overflights, ideally of the same individual(s), to provide in- creased statistical power to account for the inherent varia- tion among individuals. The latter approach has been used during land-based observations of humpback whales circled by research aircraft near Hawaii (Smultea et al. 1995) and to some extent from land-based sites and small vessels where sperm whales occur near shore (Richter et al. 2003). It is typically difficult to determine the reactions of cetaceans to overflights, since most observations have been from the disturbing aircraft itself (Richardson and Wiirsig 1997) or a small nearby vessel. These observation platforms limit and potentially confound what can be observed, and can pre- clude isolated comparison of behavior before, during, and after aircraft disturbance. Such data could also be collected by tracking whales with non-invasive tags (such as the D-tag developed by Johnson and Tyack 2003) capable of recording received sound levels and water depth among other data (such as changes in orientation of the animal in the water); this technique could ideally be combined with non-intrusive be- havioral observations (e.g., theodolite tracking from shore). In summary, based on our and others’ observations, the biological significance or consequences of the potential im- pact of aircraft overflights on cetaceans warrants further, ide- ally systematic studies. These studies should be conducted with the following goals: consideration with respect to envi- ronmental planning purposes; implementation of monitor- ing and mitigation measures; and deliberation in decision- making regarding regulations affecting marine mammals. Acknowledgments This work was performed as part of the Acoustic Thermometry of Ocean Climates Marine Mammal Research Program (ATOC-MMRP) funded by the Advanced Research Projects Agency. Data collection assistance was provided by T. Norris and D. Weller. Whale sketches were made by T. Fertl; D. Davis, M. Repaci, and K. Knight created the whale graphics. Observation interpretations were assisted by D. Palacios. We thank A.S. Frankel, T.A. Jefferson, T. Norris, D. Weller, and S. Yin for providing helpful comments on various drafts of this paper. Observed sperm whale reactions were counted as non-lethal “take” as permit- ted under the National Marine Fisheries Service (NMFS) permit No. 810 issued to J.R. 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Aquatic Mammals 24:41-50. 80 Gulf and Caribbean Research Volume 20 Issue 1 January 2008 Occurrence of Larval and Juvenile Fish in Mangrove Habitats in the Sian Ka'an Biosphere Reserve, Quintana Roo, Mexico Matthew Campbell Texas A&M University Corpus Christi Kim Withers Texas A&M University, Corpus Christi James Tolan Texas Parks and Wildlife Department DOI: 10.18785/gcr.2001.11 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr O Part of the Marine Biology Commons Recommended Citation Campbell, M., K. Withers andj. Tolan. 2008. Occurrence of Larval and Juvenile Fish in Mangrove Habitats in the Sian Ka'an Biosphere Reserve, Quintana Roo, Mexico. Gulf and Caribbean Research 20 (l): 81-86. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/ 1 1 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(o)usm.edu. Gulf and Caribbean Research Vol 20, 81-86, 2008 Manuscript received August 1, 2007; accepted December 14, 2007 SHORT COMMUNICATION OCCURRENCE OF LARVAL AND JUVENILE FISH IN MANGROVE HABITATS IN THE SIAN KA'AN BIOSPHERE RESERVE, QUINTANA ROO, MEXICO Matthew Campbell 1,2 , Kim Withers 1 2 , and James Tolan 3 Center for Coastal Studies. Texas A&M University-Corpus Christi, 6300 Ocean Dr., Corpus Christi, Texas 78412 and 3 Texas Parks and Wildlife Department - Coastal Fisheries, 6300 Ocean Dr., Corpus Christi, Texas 78412 2 Current address: Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409, e-mail: matthew.d.campbell@ttu.edu Introduction Mangrove forests are ubiquitous in low lying coastal areas of tropical and subtropical zones of the world, in- cluding the lagoons of the Sian Ka’an Biosphere Reserve, Quintana Roo, Mexico. Mangroves are habitat for juve- nile fish of both oceanic and estuarine origin (Vasquez- Yoemans 1992, Vasquez-Yoemans et al. 1992, Laegdsgaard and Johnson 1995). Development of the Caribbean coast of Mexico north and south of the Sian Ka’an Reserve is in large part focused on tourism-related endeavors such as destination resorts, scuba diving and fishing. While some of the development is innocuous, land acquisition for de- velopment of resorts has fragmented mangrove habitats in the region and likely altered their function. It has been shown in other mangrove estuaries that habitat fragmen- tation negatively impacts fish assemblages (Layman et al. 2004). Because of the importance of mangrove estuaries as juvenile fish habitat, loss of mangrove habitat may result in noticeable effects on adult recruitment to fisheries in tropi- cal regions. Very little is known about the composition of larval and juvenile fish communities within the reserve. Ichthyofaunal surveys of mangrove-lined estuaries world- wide have shown broadly similar taxonomic composition, including Eleotridae (sleepers), Gerreidae (moj arras), Mugi- lidae (mullets), Poeciliidae (livebearers), Gobiidae (gobies), Clupeidae (herrings) and Belonidae (needlefish) (Austin 1971, Blaber et al. 1989, Wright 1986, Thayer et al. 1987, Yanez-Arancibia et al. 1988, Chong et al. 1990, Vasquez- Yoemans 1992; Vasquez-Yoemans and Gonzalez 1992). In this research, we describe the juvenile fish community of two connected mangrove lagoons within the Sian Ka’an Biosphere Reserve at the end of the dry season (May). Study Area The Sian Ka’an Biosphere Reserve includes two bays, Bahia de la Ascension and Bahia Espiritu Santo, and two shallow lagoons, Laguna Campechen, and Laguna Boca Paila (Figure 1). All sampling in this study took place in the shallow lagoon system. The two shallow water lagoons are created by a long narrow sand bar, are separated from the bay systems, and are connected to the Caribbean Sea through Boca Paila inlet. The lagoon system is about 1 m deep with deeper (2-3 m) channels, with fringing red mangrove (Rhizophora man- gle), algal flats and seagrass beds. Shoal grass (Halodule sp.) was dense in the ocean pass (Boca Paila) and became sparse past the bridge and as the lagoon system extended inland. Materials and Methods Light trap sampling was conducted nightly from 7-20 May 1999, excluding 16 May 1999. Neuston net sam- pling was conducted during daylight hours on 9, 16 and 21 May 1999. Sampling included parts of two lunar cycles but not an entire cycle due to time constraints. Three light trap sampling (LTS) stations were selected at increasing distances from Boca Paila inlet (Figure 1), but could not be spread too far due to the difficulties of navigat- ing the lagoons at night. Microhabitats were red mangrove adjacent to seagrass beds (LTS 1), red mangrove adjacent to sandy bottom (LTS 2), and fringing red mangrove in a secondary channel (LTS 3). Light trap design followed that of Mueller et al. (1993). Electric diving lights (similar to cy- alume sticks) were used as a light source. Two light traps were set at each site at sunset and retrieved about 1 h later. One trap was set within the red mangrove prop root com- plex and the second was located in the channel, about 1 m from the interior trap to ensure no overlap of illuminated areas. Upon retrieval, LTS samples were washed into 0.5 mm mesh biobags and fixed in 10% formalin overnight . Four neuston net sampling sites were also selected at in- creasing distances from Boca Paila inlet and could be spread out further into the system since sampling occurred during the day (Figure 1). Microhabitats sampled were a secondary channel with sandy bottom fringed by red mangrove (NNS 1) rocky/ sandy bottom adjacent to red mangrove, near a cenote (NNS 2), sandy bottom adjacent to red mangrove (NNS 3), and a seagrass bed adjacent to red mangrove (NNS 4). These sites were located in sufficient water depths (at least 1 m) to prevent the net from dragging the bottom. Neuston sam- pling was conducted with a 3: 1 aspect ratio 60 cm net of 0.33 81 mm mesh. On each sampling day three net tows were com ducted at each site and in haphazard directions for varying lengths of time. A high speed flowmeter was secured inside the neuston ring to calculate linear distance from the flow- meter coefficient. After each sampling effort, samples were washed down the net into the cod end (0.33 mm mesh) with buckets of seawater, and fixed in 10% formalin overnight. Formalin-preserved samples from both gear types were transferred to 45% isopropyl alcohol for transporta- tion and storage. Fish were identified to the lowest pos- sible taxon and counted using keys in Ditty et al. (1994), Farooqi et al. (1995), Fritzsche (1978), Johnson (1978), Jones et al. (1978), Martin and Drewry (1978), Moser et al. (1984), Powles (1977), and Richards et al. (1994). Raw data was standardized for both light trap and neuston net data. Mean set time was calculated for LTS samples, and total numbers of fish were then standardized to this unit of time for each sample (total fish/ total minutes x mean min- utes = standardized fish). NNS sampling was standardized to 100 m 3 (total fish/total volume x 100 m 3 ). Volume was calculated using the area of the neuston net ring multiplied by the distance sampled (volume = area x linear distance). Results and Discussion A total of 2,457 individuals representing 26 families and 50 species were collected during the sampling period. Light trap sampling captured 1,977 individuals from 42 species and 23 families (Table 1). The most commonly captured species in light traps were Eucinostomus spp., Harengula jag- uana, C yprinodon variegatus and an unidentified Gobiid. Neuston net sampling collected 480 individuals from 20 species and 13 families (Table 2), with the most commonly captured species including 2 unidentified goby species and an unidentified atherinid. Family dominance was similar between gears with Gobiidae, Atherinidae (silversides), and Gerreidae representing nearly 70% of the total catch in both. Other important families included Clupeidae and Cyprinodontidae (killifish) in light trap collections and Belonidae and Syngnathidae (pipefish) in the neuston net collections. Families exclusive to light trap collections were Balistidae (trigger fish), Lambrisomidae (lambrisomid blennies), Clupeidae, Eleotridae, Elopidae (ladyfish), Mega- lopidae (tarpon), Mugilidae, Ophichthidae (snake eels), Opistognathidae (jawfish), Pomacentridae (damselfish), Scaridae (parrotfish), Scorpaenidae (scorpionfish), Sparidae Figure I. Mops showing the location of the Sion Ko'on Biosphere Reserve on the Yucatan Peninsula ; in Quintana Roo, Mexico (A), with detail of the study oreo (denoted by the hatched square; B) and location of sampling sites (C). 82 Sian Ka'an Mangrove Juvenile Fish TABLE I. Mean catch per unit effort (CPUE; fish/minute) of species in light trap stations, with standard error in parenthesis. Phylogenetic order, family and species names follow McEachran and Flechhelm (1998) and McEachran and Flechhelm (2005). LTS 1 LTS 2 LTS 3 LTS 1 LTS 2 LTS 3 Elopidae Carangidae Elops saurus 0.04 (0.06) 0.00 0.06 (0.06) Trachinotus falcatus 0.04 (0.06) 0.00 0.00 Megalopidae Gerreidae Megalops atlanticus 0.04 (0.06) 0.00 0.00 Eucinostomus spp. 17.21 (6.41) 10.12 (3.91) 9.64 (4.06) Ophichthidiae Sparidae Myrophis punctatus 0.04 (0.06) 0.03 (0.05) 0.00 Sparidae species A 0.00 0.2 (0.2) 0.00 Clupeidae Pomacentridae Harengula jaguana 0.04 (0.06) 10.87 (10.22) 2.57 (1.98) Stegastes spp. 0.00 0.03 (0.05) 0.00 Jenkinsia lamprotaenia 0.00 0.59 (0.49) 0.16 (0.22) Scaridae Clupeidae species A 0.00 0.1 (0.1) 0.00 Scarus vetula 0.00 0.03 (0.05) 0.00 Engraulidae Lambrisomidae Anchoa lamprotaenia 0.00 0.1 (0.1 1) 0.00 Starksia lepicoelia 0.18 (0.25) 0.00 0.00 Belonidae Gobiesocideae Strongylura notata 0.44 (0.26) 0.14(0.11) 0.06 (0.06) Gobiesox spp. 0.49 (0.58) 0.00 0.00 Strongylura spp. 0.27 (0.16) 0.15 (0.1) 0.03 (0.04) Gobiesocidae species A 0.09 (0.13) 0.03 (0.05) 0.00 Belonidae species A 0.09 (0.09) 0.00 0.00 Eleotridae Hemiramphidae Dormitator maculatus 0.87(0.50) 0.13 (0.15) 0.06 (0.06) Hyporhamphus unifasciatus 0.49 (0.35) 0.00 0.00 Gobiidae Mugilidae Species A 5.85 (2.23 1 .02 (0.78) 0.56 (0.67) Mugil curema 0.00 0.00 0.03 (0.04) Species B 0.9 (0.54) 0.14 (0.15) 0.03 (0.04) Atherinidae Species C 0.05 (0.07) 0.00 0.00 Atherinimorus sp. 0.18 (0.25) 0.11 (0.15) 0.00 Species D 1.42 (1.18) 0.2 (0.16) 0.00 Atherinomorus stipes 0.00 0.33 (0.18) 0.23 (0.23) Species E 0.08 (0.08) 0.07 (0.07) 0.00 Atherinidae species A 1 .29 (0.97) 1 .4 (0.74) 0.21 (0.13) Species F 0.36 (0.36) 0.00 0.00 Cyprinodontidae Species G 0.04 (0.06) 0.00 0.00 Cyprinodon variegatus 3.84 (1.98) 0.32 (0.2) 0.04 (0.05) Balistidae Syngnathidae Balistidae species A 0.04 (0.06) 0.00 0.00 Syngnathus dunckeri 0.23 (0.13) 0.00 0.00 Monacathidae Syngnathus spp. 1.12 (1.20) 0.00 0.00 Stephanolepis setifer 0.04 (0.06) 0.00 0.00 Syngnathidae species A 0.00 0.23 (0.33) 0.00 Tetraodontidae Scorpaenidae Sphoeroides parvus 0.09 (0.08) 0.00 0.00 Scorpaena plumieri 0.04 (0.06) 0.00 0.00 Sphoeroides spp. 0.04 (0.06) 0.00 0.00 Scorpaena spp. 0.09 (0.09) 0.00 0.00 Unidentified 0.00 0.03 (0.05) 0.00 Opistognathidae Overall 36.16(7.9) 26.43(12.95) 13.68 (5.0) Opistognathus spp. 0.00 0.05 (0.07) 0.00 Species Richness 32 23 13 (porgies) and Tetraodontidae (puffers). Families exclusive to neuston net collections were Blenniidae (combtooth blen- nies), Fistulariidae (cornetfish) and Haemulidae (grunts). In light traps, both fish CPUE and species richness de- creased as distance from the Boca Paila inlet increased (Ta- ble 1). Gerreids ( Eucinostomus spp.) dominated the catch at all sites, and represented 48% of total catch. Gerreids are typically abundant along sandy shorelines, bays, and estu- aries, a few species are found in freshwater, and they are important components of fish communities in many estuar- ies (Bohlke and Chaplin 1993). Eucinostomus spp. comprised the largest year-round population of juvenile fishes in saline mangroves bordered by coral reefs in Puerto Rico (Austin 1971). Gerreids were also the dominant species in man- grove-lined bays in the Ten Thousand Islands, Florida (Tabb and Manning 1961, Carter et al. 1973, Colby et al. 1985). Clupeids represented 20% of the total light trap collec- tion and were the second most abundant family. However, of the total clupeids collected at light trap sites, 77% were captured on 10 May 1999, and were either Harengula jaguana 83 Campbell et a TABLE 2 . Mean density (fish/ 100 m 3 ) of species in neuston net stations, with standard error in parenthesis. Phylogenetic order, family and species names follow McEachran and Flechhelm (1998) and McEachran and Flechhelm (2005). NNS 1 NNS 2 NNS 3 NNS 4 Engraulidae Engraulidae species A 0.00 0.23 (0.23) 0.00 0.75 (0.75) Belonidae Strongylura spp. 0.29 (0.10) 0.00 0.00 0.15 (0.15) Hemiramphidae Hyporhamphus unifasciatus 0.27 (0.09) 0.76 (0.40) 0.14 (0.14) 0.00 Fistulariidae Fistulariidae species A 0.00 0.00 0.00 0.10 (0.10) Atherinidae Atherinomorus stipes 0.00 0.16 (0.16) 0.00 0.00 Atherinidae species A 1 .76 (0.59) 7.71 (3.08) 1 .06 (0.48) 1.95 (1.00) Cyprinodontidae Cyprinodon variegatus 0.00 0.37 (0.37) 0.00 0.00 Syngnathidae Syngnathus spp. 0.21 (0.07) 0.25 (0.25) 0.80 (0.48) 1 .59 (0.63) Syngnathidae species A 0.00 0.00 0.00 1.58 (1.58) Carangidae Oligoplites saurus 0.00 0.00 0.29 (0.19) 0.57 (0.45) Gerreidae Eucinostomus spp. 0.21 (0.07) 0.16 (0.16) 0.00 1.8 (1.35) Haemulidae Haemulon spp. 0.00 0.00 0.28 (0.28) 0.00 Blenniidae Blennius spp. 0.00 0.00 0.00 0.23 (0.23) Blenniidae species A 0.00 0.28 (0.19) 0.37 (0.25) 2.56 (1.70) Gobiesocidae Cobiesox spp. 0.27 (0.09) 0.12 (0.12) 0.00 0.00 Gobiesocidae species A 0.00 0.50 (0.50) 0.21 (0.21) 0.00 Gobiidae Gobiidae species D 0.00 0.20 (0.20) 0.92 (0.70) 0.26 (0.26) Gobiidae species H 0.00 0.00 0.43 (0.31) 0.00 Gobiidae species 1 2.49 (0.83) 4.53 (1.75) 24.46 (15.96) 4.45 (2.54) Gobiidae species J 0.29 (0.10) 1.10 (0.73) 4.06 (3.13) 3.13 (1.86) Unidentified 2.84 (0.95) 1.35 (0.78) 4.45 (3.65) 2.49 (1.0) Yolk sac larvae 0.00 0.00 0.00 0.12 (0.12) Overall 8.63 (2.09) 17.72 (4.74) 37.46 (19.6) 21.73 (6.88) Species Richness 8 13 11 13 or Jenkinsia lamprotaenia. Jenkinsia sp. and Harengula sp. also dominated mangrove estuaries in Puerto Rico (Rooker et al. 1996) and Bahia de la Ascension (Vasquez-Yoemans 1992). Gobiids were dominant in this study and are generally important components of shallow water communities. In this study, Gobiidae represented one-half of the abundance in neuston net collections, with 73% of individuals col- lected on the same day at NNS 1 and NNS 2. Elsewhere, gobiids dominated catch from shallow coral reef habitat at One Tree Island, Great Barrier Reef (Kingsford and Finn 1997), and in a lagoon reef at Moorea Island, French Polynesia (Dufour and Galzin 1993). In Florida (USA) estuaries, gobiids are important components of fish com- munities (Odum and Heald 1972). Gobiids were abundant and widely distributed in Bahia de la Ascension (Vasquez- Yeomans 1992) and represented 8.5% of the Bahaman 84 Sian Ka'an Mangrove Juvenile Fish shore-fish fauna. Worldwide, they form a significant ele- ment of the tropical fish faunas (Bohlke and Chaplin 1993). Due to the spatial and temporal limitations of the study the role of microhabitats in the lagoons could not be eas- ily examined. However, larval and juvenile fish diversity and abundance within the mangrove estuary may have been enhanced by habitat contiguity. For example, species rich- ness and CPUE were greater at LTS 1, where mangroves grew adjacent to dense seagrass beds, than it was in other LTS sites where mangroves were adjacent to bare bottoms. In contrast, the greatest density of fishes at neuston net sites was collected where the bottom was sandy (NNS 3), but species richness was greatest where there was a sandy/ rocky bottom and a cenote (NNS 2) and seagrasses (NNS 4). Mangrove estuaries are significant in supporting local and global species diversity, and tropical fisheries are highly dependent on their continued healthy functioning. Main- taining the productivity of the mangrove estuaries within the Sian Ka’an Biosphere Reserve should be considered a high priority. Further analysis of fish recruitment in La- guna Boca Paila and Laguna Campechen is recommended with amendments to the spatial and temporal components of experimental design. Future studies should correct sam- pling design shortfalls from this study: for example, sam- ple all sites with both gears and on the same days. Effects of lunar periodicity, currents, tides, and on-shore wind on recruitment of larval fish also need to be investigated. Acknowledgements This research was conducted with the permission of then-director of the Sian Ka’an Biosphere Reserve, Alfredo Arellano Guillermo, under Secretaria de Medio Ambiente Recursos Naturales y Pesca (SEMAR- NAP) Scientific Permit D00.02.3014 which was obtained through collaboration with the Centro de Inves- tigacion y de Estudios Avanzados del IPN-Universidad Merida. We thank P. Watson for the use of Rancho Pedro Paila within the reserve as a base for field operations and lab work. Numerous people were involved in field collections and sample sorting, but special thanks go to J. and K. Tunnell, E. (Albert) Hill and T. Bates. This project was funded by the Center for Coastal Studies, Texas A 250 m for the next 8-h period. 98 Escolar pop-up satellite archival tagging Figure 2. Depth range of a PSAT tagged escolar in the Windward Passage by 8-h summary data bins. Dark grey bars indicate the "night" binning periods from the PSAT data , while light grey bars indicate the "day" and "cre- puscular" periods (combined). Temperature stratifications at depth (thin lines) were generated from transmitted PDT data with a combination of recorded and interpolated temperature measurements. Following this second period, the animal began a diel move- ment pattern for the remaining deployment length: during daylight hours the time-at-depth histograms indicate that the vast majority of time was spent at depths > 250 m, while the nighttime period was characterized by much shallower depth preferences (Figure 2). The 8-h crepuscular period included both light and dark photoperiods and had the broadest depth range, spanning from the shallow nighttime and deep daytime depth distributions (generally < 100 to > 800 m). Although the unequal binning process in the tag pro- gramming precludes statistical comparisons between peri- ods, the PDT profiles do allow for generalized reconstruc- tions of the habitat preferences of the tagged animal. The PDT data provided depth maxima and minima for each 8-h binning period and allowed the reconstruction of both the inhabited water column and thermal layers using a combi- nation of recorded and interpolated depth and tempera- ture values (Figure 2). Overall depth and temperature use percentages were compared as day versus night periods and scaled to the proportion of total time over the course of the deployment period (Figure 3). The PDT data were also used to roughly reconstruct the vertical structure of the water column, which showed a relatively shallow mixed layer, fol- lowed by a weak thermocline that extended to about 250 m. The U.S. Naval Observatory data indicate that sunrise in the Windward Passage during the tag deployment oc- curred at 0516 (± 2 min) and sunset at 1839 (± 2 min). The general agreement between programmed periods and local times of sunset and sunrise prompted an initial naming of period #1 as “night,” period #2 as “crepuscular,” and pe- riod #3 as “day.” However, the similarity of the distribu- tions of “crepuscular” and “day” periods prompted the col- lapse of both into one “day” period. Multiple comparisons of minimum temperatures (a proxy for maximum depth, which was not recorded) with the Tukey test for unequal sample sizes (Zar 1999) indicated significant differences between periods 1 and 2 and periods 1 and 3, but not periods 2 and 3. The three 8-h periods per day from the tag programming roughly corresponded to one night and two daylight photoperiods during the deployment, allow- ing for descriptive comparisons between the two periods. The depth and temperature distributions from this 99 Kerstetter et. a I Utilization Figure 3. Scaled habitat utilization of time of depth and temperature (x ± se) for a PSAT tagged escolar in the Windward Passage. Open bars are daylight (two 8-h summary periods per 24-h period) and dark bars are at night (one 8-h summary period per 24-h period). Due to the binning structure of the tag programming , depths between 250 and 1000 m were binned into the last depth category and temperatures < 1 2°C were similarly binned into the last tempera- ture category. fish show strong diel patterns in movement (Figure 3). The majority of the nighttime period (70%, ± 8.2% se) was spent above 150 m depth, while the majority of the daytime period (82.5%, ± 5.1% se) was spent below 250 m. Depth data from PDTs indicate that on at least one night, the escolar came within 5 m of the surface, although there was not a significant relationship between depth at night and available moonlight (r = -0.530, p = 0.093). Temperature minima and maxima for each 8-h period were examined for temperature range and then grouped by 24-h period to obtain an estimate of total daily temperature range. The mean temperature range per 8-h period was 17.0°C (±0.73 se). Over the 11 deployment days with all three 8-h periods, the animal had a daily temperature range of 21.3°C (± 0.38 se). Discussion Although PSAT technology has been successfully applied to other deep-diving animals (e.g., sperm whales, Physeter macrocephalus; Amano and Yoshioka 2003 and Humboldt or jumbo squid, Dosidicus gigcts; Gilly et al. 2006), this tag- ging represents the first successful deployment of this tech- nology for a mesopelagic teleost. The available data do not allow the determination of why the tag released pre- maturely, but additional research with tagging techniques on mesopelagic fishes may identify specific techniques that differ from those used with epipelagic animals, such as not including a RD-1500 device. As with most mesope- lagic species, there is little available information on the behavior of escolar other than that based on incidental interactions with fisheries, such as the commercial pelagic longline fishery or the recreational swordfish fishery off the southeast coast of Florida. Through the use of this fisher- ies-independent PSAT technology, about 14 d of recorded behavior were obtained from an escolar for the first time. This fish exhibited clear diel differences in depth pref- erence. Unfortunately, the binning structure of our tag programming did not allow the reconstruction of short- duration movements within each pre-determined time pe- riod. For example, the reported time-at-depth histograms for this escolar could represent broad movements up to shallow depths, similar to the “U-shaped” depth record re- ported by Carey and Robison (1981) for tracked swordfish. Alternatively, the histograms could represent serial vertical movements, such as those seen in bigeye tuna Thunnus ohe- sus (Musyl et al. 2003). Regardless of the vertical movement pattern these histograms actually represent, the data suggest that escolar do not remain within a single depth regime. Ad- ditional investigations may determine that a revision in the species depth distribution to “nictoepipelagic” is warranted. The crepuscular period included the most time at depth of the three 8-h bins, rather than the daylight period, even though the sunrise and sunset times roughly corresponded with the bin start and end times. In Kerstetter and Graves (2006a), all of the escolar catches on hook-time recorders (HTRs) occurred at night or nautical twilight (dusk), sug- gesting that the species follows an isolume similar to other mesopelagic predators. HTRs during the present study simi- larly indicated that all escolar were captured between 2100 and 0500 local time (RH. Rice, unpubl. data). Carey and Robison (1981) observed that swordfish frequently moved from depth to near-surface waters within a 1-h period. It is likely that escolar follow the isolume, resulting in behavioral patterns similar to that demonstrated in sword- fish. Data from the U.S. Naval Observatory indicate that nautical twilight for this location occurs about one hour prior to actual sunrise. The clear, oligotrophic waters of the northern Caribbean Sea and the absence of artificial light has been demonstrated to allow the transmission of 100 Escolar pop-up satellite archival tagging light to depth prior to sunrise (D.W. Kerstetter, unpubl. data), which may serve as a visual cue to an animal like the escolar that preferentially forages in low light-level condi- tions. The eyes of escolar are also large and very sensitive to light (E. Landgren, Lunds University, pers. comm.). Al- though the overlap in the programming of the tag allowed about 25% of the 8-h period to include nominal darkness, such short-duration use of shallow waters by a downward migrating fish following the isolume would presumably be masked by the larger percentage of time spent at depth. The first data recording period of the track is shallower than subsequent identical time bins, and the next preceding period shows less depth variation than other periods dur- ing the same diel cycle. The disproportionately large size of the last bin in the tag programming might mask some of the intra-bin vertical movements, however, and PDT data indeed indicate a depth range during this second period be- tween 272 and 784 m. It is unclear whether these first two time periods of the deployment were indicative of a so-called “recovery period” for the animal, similar to aberrant behav- iors noted for other large pelagic fishes following tagging (e.g., Nelson 1990, Loefer et al. 2005, Kerstetter and Graves 2006b). Although briefly resuscitated prior to release, the fish was hooked for about 2.5 h, and little has been pub- lished on the time required for full physiological recovery for large pelagic fishes under various stress related conditions. This particular individual was also pale brown, rather than the common dark brown seen on other escolar at haulback, perhaps showing an additional sign of physiological stress. The large water temperature extremes experienced by this animal on a daily basis are beyond those known for most fishes. The known exceptions all include species with some physiological mechanism to compensate for loss of body temperature at depth. Although Brill et al. (1999) and Brill and Lutcavage (2001) have suggested a maximum tempera- ture range of about 8 °C for short-duration movements, the available summary data do not permit such an analysis for this individual escolar. Carey and Robison (1981) observed a temperature range of 19 °C in two hours for a tagged sword- fish. Although similarly broad water-temperature ranges were observed for the tagged escolar, it is currently unknown what physiological mechanisms - if any - maybe used by this species to allow for effective foraging at these temperature extremes. As opposed to more epipelagic species such as tunas and istiophorid billfishes, very few mesopelagic fishes have been tagged with satellite tag technology. This paper presents new information on the movements and temperature preferences of an escolar based on one pop-up satellite archival tag de- ployment. The patterned movements to and from depth sug- gest that these behaviors were not abnormal, but instead like- ly represent regular, diel feeding migrations similar to those seen in swordfish. Further study of this species will improve our understanding of its biology and thermal adaptations. Acknowledgments This research was supported by the NMFS Southeast Fisheries Science Center. The authors wish to thank Captain Greg O’Neill and the crew of the F/V Carol Ann for their assistance with the tagging and Eric Orbesen of NMFS for his assistance with Figure 1. Mention of commercial products does not imply endorsement by Nova Southeastern University, NMFS, the University of Miami, or the authors. Literature Cited Amano, M. and M. Yoshioka. 2003. Sperm whale diving behav- ior monitored using a suction-cup-attached TDR tag. Marine Ecology Progress Series 258:291-295. Berkeley, S.A., E.W. Irby Jr., and J.W. Jolley Jr. 1981. Florida’s commercial swordfish fishery: longline gear and methods. 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Zar, J.H. 1999. Biostatistical analysis, 4 th edition. Prentice Hall, Upper Saddle River, NJ, USA, 663 p. 102 Gulf and Caribbean Research Volume 20 Issue 1 January 2007 Editorial Mark S. Peterson University of Southern Mississippi , mark.petersonf® usm.edu DOI: 10.18785/gcr.2001.01 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Recommended Citation Peterson, M. S. 2008. Editorial. Gulf and Caribbean Research 20 (l): iv-iv. Retrieved from http://aquila.usm.edu/gcr/vol20/issl/l This Editorial is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contactJoshua.Cromwell@usm.edu. EDITORIAL As one famous Mississippi songwriter exclaims “Changes in latitudes, changes in attitudes, nothing appears quite the same” applies not only to life but to the Gulf and Caribbean Research . Since I became Editor-in-chief starting with the 1997 issue, many changes and attitudes have changed regarding what the “Scope” of the journal should be (see Gulf Research Reports , volume 11 editorial), its scholastic and scientific value, and how it is managed and produced. We have come a long way from the first issue in 1961. Much of those changes were directly influenced by the expert guidance and energy of Sigrid “Dawne” Hard, who recently retired as Managing Editor of this journal. Dawne was integral to all aspects of this journal and brought it to a higher level of scholarship by her dedication to how the journal looked and her persistence on how it was edited. She could be a task- master but always with the goal of a better product. I miss her and her energy and talents and she made this journal better for all her dedicated work. Luckily (for me) I was able to replace her with other talented and hard working professionals; Diana Reid (Graphic Designer), Angela R. Bone (Administrative Assistant) and Nancy J. Brown- Peterson (Assistant Editor) who share the duties of layout of manuscripts, tracking manuscripts, and editing for style and format, respectively. We are also lucky to continue to have Joyce M. Shaw (Librarian) to assist us with literature accuracy issues. We have made this transition with limited difficulties and have made some additional modifications in the journal. We have changed the format and style to make it more contemporary, have changed the cover to better reflect our “Scope,” and now have additional early editing making the final product more consistent and accurate. All of this has allowed me to better focus on manuscript quality for the journal. As we continue to evolve at Gulf and Caribbean Research our gratitude is extended to Dr. William Hawkins (GCRL Director) for his guidance and support of this 47 year old journal! Mark S. Peterson Editor-in-Chief and Professor Department of Coastal Sciences The University of Southern Mississippi Gulf Coast Research Laboratory 703 East Beach Drive Ocean Springs , MS 3 9564