VIRGINIA JOURNAL OF SCIENCE OFFICIAL PUBLICATION OF THE VIRGINIA ACADEMY OF SCIENCE Vol. 61 No. 4 Winter 2010 TABLE OF CONTENTS ARTICLES PAGE Functional Feeding Groups, Species Richness and Spatial Distributions of Fishes in Rocky and Sandy Beach Habitats of St. John, U.S. Virgin Islands. Eugene G. Maurakis, George E. Maurakis, and Demetri E. Maurakis. 127 A Habitat Model for the Detection of Two-lined Salamanders at C. F. Phelps Wildlife Management Area, Fauquier and Culpeper Counties, Virginia. Jay D. McGhee and Michael D. Killian. 151 2010 UNDERGRADUATE RESEARCH AWARD WINNERS 157 Virginia Journal of Science Volume 61 Number 4 Winter 2010 Functional Feeding Groups, Species Richness and Spatial Distributions of Fishes in Rocky and Sandy Beach Habitats of St. John, U.S. Virgin Islands Eugene G. Maurakisl’% George E. Maurakis^, and Demetri E. Maurakis^ 1 Department of Biology, University of Richmond, VA 23173 ^Science Museum of Virginia, 2500 W. Broad St., Richmond, VA 23220 ^Math Science High School at Clover Hill, 13301 Kelly Green Lane, Midlothian, VA 23112 ^Midlothian Middle School, 13501 Midlothian Turnpike, Midlothian, VA23113 ABSTRACT Objectives were to identify and compare fish species richness, functional feeding group richness and diversity, and delineate distributions of fishes at rocky and sandy beach habitats at St. John, U.S. Virgin Islands. Visual observations using snorkel and mask were made at 3-m intervals seaward from shore during daylight hours. A total of 69 taxa (67 species) representing 33 families of fishes were observed. Total (53) and average fish species richness (32.7) at rocky beach habitats were greater than those (total=43; average=24.3) at sandy beach habitats. Twelve functional feeding groups were identified (diurnal planktivores. excavators/eroders, macroalgae browsers, macrocarnivores, mobile benthic invertivores, general omnivores, strict piscivores, sand invertivores, scrapers, coral/colonial sessile insectivores, territorial algae/detritus, and turf grazers). Total numbers of functional feeding groups (range=10-12) and species (range=29-46) per functional feeding groups at distances greater than 1 m from shore at rocky beach habitats were consistently higher than those (functional feeding group range^S-lO; species per functional feeding group=T9-30) at sandy beach habitats. Information on the number and composition of functional feeding groups in rocky and sandy beach habitats from this study can serve as a baseline for future investigations as changes in Caribbean habitats continue to occur. Keywords: fish species richness, fish functional feeding group, Caribbean beach habitats INTRODUCTION Substrate complexity such as that offered by coral reefs is significant in providing diverse habitats that harbor a variety of fishes, particularly reef fishes (Christensen et al., 2003; Claro et al., 2001; Friedlander and Parrish, 1998; Gratwiche and Speight, 128 VIRGINIA JOURNAL OF SCIENCE 2005; Mac et al., 1998; Monaco et al., 2003; 2007; Nero and Sealey, 2005; Ohman and Rajasuriya, 1998). Other habitat areas, such as Caribbean mangroves and seagrass beds, are also important habitats as they serve as nursery and feeding areas for a variety of juvenile reef fishes (Faunce and Serafy, 2006; Nagelkerken and van der Velde, 2002). Focus on the decline of coral reefs and mangroves and the various ecological functions they provide to reef fishes has overshadowed habitats (i.e., sandy and rocky nearshore habitats) considered to be lesser important in understanding the health and dynamics of tropical ecosystems and their ichthyofaunas (Nero and Sealey, 2005). Granted, fish communities in sandy and rocky beaches have relatively depauperate ichthyofaunas compared to those of reef systems. Sandy and rocky nearshore habitats, however, harbor some of the same fish species common to reefs, mangroves, and seagrass beds (Valdez-Munoz and Mochek, 2001; Ortiz and Lalana, 2008). Except for some observational data on selected species in nearshore sandy and rocky Caribbean habitats provided by Valdez-Munoz and Mochek (2001), there is a paucity of published information on the fishes in sandy and rocky beach habitats in the Caribbean. Knowledge of species richness and distributions of fishes in nearshore sandy and rocky-shore habitats can also serve as baseline data for future comparisons as changes occur in reef, mangroves, and seagrass habitats related to chronic anthropogenic impacts (e.g. overfishing, habitat degradation) and climate change. For example, upwards of 90 % of reefs of the U.S. Virgin Islands (USVI) experienced bleaching in 2005 when sea surface temperatures were higher than the previous 14 years (Rothenberger et al., 2008). Of particular importance may be the number and composition of functional feeding groups in these habitats, where the loss of one or two functional feeding groups represented by one or few species could be critical to the functioning of the ecosystem (Halpern and Floeter, 2008). Objectives of this study were to identify and compare fish species richness, functional feeding group richness and diversity, and delineate distributions of fishes at sand- and rock-shoreline beach habitats at St. John, U.S. Virgin Islands in the Caribbean Sea. MATERIALS AND METHODS Fish species richness and spatial distributions were surveyed by visual census using snorkel and mask at each of 1, 3, 6, 9, 12, 15, and 20 m from shore at each of 30 transects (14 sandy- and 16 rocky-shoreline habitats) at Little Lameshur (18.32026 N, -64.72551 W), Great Lameshur (18.31822 N, -64.72427 W), and Francis Beach (18.36537 N, -64.74365 W), St. John, USVI, during daylight hours (i.e., 0800-1800) from 12-18 July 2007 and 8-18 July 2008. Transects were established randomly at each rocky or sandy beach habitat, and none were re-sampled during the second year. Low light conditions and poor visual acuity at greater depths precluded the recording of species beyond 30 m from shore. The vertical observational zone was from the bottom substrate to the surface, including boulder ledges and crevices. No substrate material was overturned or dislodged. Fishes within an estimated 3-m horizontal circumference of the observer were identified by visual observation. Some identifications were verified by examining digital photographs made underwater with an Olympus Stylus 770 SW or Olympus 850 SW camera at each distance per transect. Water depth (m) was measured with a weighted cord marked in 1-m increments. Relative percents of habitat composition (i.e., sand, gravel, cobble, boulder, seagrass, VIRGIN ISLAND FISH ECOLOGY 129 and coral) were estimated by observation and recorded at each distance from shore. These percents were transformed to their arcsin equivalents prior to statistical analysis. Fish census data are available upon request. Assignment of species to functional feeding groups (diurnal planktivores, excavators/eroders, macroalgae browsers, macrocarnivores, mobile benthic invertivores, general omnivores, strict piscivores, sand invertivores, scrapers, coral/colonial sessile insectivores, territorial algae/detritus, and turf grazing) follows the designations in Halpem and Floeter (2008). Species richness, and functional feeding group richness, Shannon-Weiner diversity and evenness were compared among (general linear model followed by Duncan’s Multiple Range Test at p=0.05, SAS, 2009) and between (t-test at p=0.05, SAS, 2009) rocky and sandy shore habitats. RESULTS Average water depths (1.6-4.6 m) at each distance from shore (3, 6, 9, 12, 15, and 20 m) at rocky transects were significantly greater than those (0.94-2.5 m) at sandy transects (Table 1). Percent occurrences of coral, boulder and seagrasses at rocky habitats were significantly higher than those from 3-20 m from shore at sandy habitats with three exceptions (Table 1). Percent occurrence of coral at 15 and 20 m and that of seagrasses at 20 m from shore did not vary significantly between rocky and sandy habitats (Table 1). Conversely, percent occurrences of cobble, gravel, and sand at rocky habitats were significantly lower than those at sandy habitats from 3-20 m from shore with two exceptions. Occurrence of sand and gravel at 20 m from shore did not vary significantly between rocky and sandy habitats (Table 1). A total of 69 taxa (67 species + 2 families) representing 33 families of fishes were observed (Table 2) in the 30 sandy and rocky transects at Little Lameshur, Francis Beach, and Great Lameshur, St. John, US VI. The most speciose families were Scaridae (8), Haemulidae (7), Pomocentridae (6), Labridae (4), and Lutjanidae (4). Seventeen families were each represented by one species. Total fish species richness at rocky habitats was 53; that at sandy habitats was 43. Average number of species (32.7) at rocky habitats was significantly greater than that (24.3) at sandy habitats (t=6.18; p=0.0016). Species richness (avg. range=l 1-20) at combined rocky habitats did not vary significantly at distances 6-20 m from shore (Table 3). In contrast, at combined sandy habitats, species richness (avg. ranges 1-5.9) did not vary significantly at distances 1-20 m from shore (Table 4). Species richness (avg. range 3-20) at each distance from shore at rocky habitats was significantly greater than those (avg. range=l-5.9) at sandy habitats (Table 5). Numbers of functional feeding groups encountered at rocky habitats were consistently higher than those at sandy habitats (Tables 6-7). On average, rocky habitats from 3-20 m from shore had two more functional feeding groups (avg =11.3) than sandy habitats (avg =9.3; Tables 6-7). Two species (Archosargus rhomboidalis and Sparisoma radians) of the macroalgae browser functional feeding group occurred frequently at rocky habitats. No macroalgae browsers were observed at sandy habitats. The most speciose functional feeding groups were mobile benthic invertivores (11 species at 9 m in rocky habitats), scrapers and piscivores (each 9 species at 6 m in rocky habitats), and macrocarnivores (6 species at 6 m in sandy habitats)(Table 2). Total numbers of functional feeding groups (range=10-12) and species (range=29-46) per functional feeding groups at distances greater than 1 m Rom shore at rocky habitats 130 VIRGINIA JOURNAL OF SCIENCE were consistently higher than those (functional feeding group range=8-10; species per functional feeding group= 19-30) at sandy habitats (Tables 1,6-7). At the 1-m distance, functional feeding group richness at rocky habitats was five; that of the 1-m sandy habitat was one. Except at 20 m from shore, functional feeding group richness (avg. range=6.67-10) and Shannon diversity (avg. range= 1.84-2.05) from 3-15 m from shore at rocky habitats were significantly higher than functional feeding group richness (avg. range=5.3 3-8.33) and Shannon diversity (avg. range=l .43-2.02) at sandy habitats (Table 8). In contrast, functional feeding group richness (avg.=7.3) and diversity (avg.=1.86) at 20 m from shore at sandy habitats were significantly greater than functional feeding group richness (avg.=6.67) and diversity (avg.= 1.53) 20 m from shore at rocky habitats (Table 8). Functional feeding group evenness indices (avg. range=0.8896-0.9171) at distances 6- 20 m from shore at rocky habitats were significantly lower than those (avg. range=0.9226-0.9551) at sandy habitats (Table 8), indicating greater variability in numbers of species comprising the functional feeding groups in rocky habitats. For example, at 6 m from shore at rocky habitats, mobile benthic invertivores and scrapers totaled 10 and 9, respectively, whereas other functional feeding groups were composed of 1-5 species. At 3 m from shore, the average functional feeding group evenness index (0.9764) at rocky habitats was significantly greater than that (0.9539) at sandy habitats (Table 8). DISCUSSION Comparison of rocky and sandy beach habitats The more complex habitats of the intermingled boulder, rock, and coral substrates at rocky habitats exhibited higher species richness and functional feeding group richness than did less complex sandy habitats. Rocky shore habitats, where fish species richness was correlated with increasing water depth and the presence of coral, boulders, cobble, and gravel, harbored more fish species (avg.=32.7) than did sandy habitats (avg.=24.3). Even at greater distances from shore (i.e., 15 and 20 m) at sandy habitats where the percentages of coral (6.0-6.2) and seagrass (26.0 at 20 m) were comparable to those (coral=5.5-7.4; seagrass=23.5 at 20 m) at the same depths at rocky beaches, species richness (avg. range=3.73-5.89) still was significantly lower than those (avg. range=l 1.0-12.8) at rocky habitats. That more complex habitats support greater fish species richness has been documented repeatedly in the literature (Christensen et al., 2003; Claro et ah, 2001; Friedlander and Parrish, 1998; Gratwiche and Speight, 2005; Monaco et al., 2003; 2007; Nero and Sealey, 2005; Oilman and Rajasuriya, 1998; Valdez-Munoz and Mochek, 2001). Results from the present study are comparable to those of Gratwicke and Speight (2005) who studied the relationship between fish species richness and habitat complexity in a series of shallow tropical marine habitats in the British Virgin Islands. The lower species richness (range = 1 -30) at sandy beach habitats is comparable to the findings of Valdes-Munoz and Mochek (2001) who reported low fish species diversity in non-estuarine sandy beach areas of Cuba where species richness was 25. Although vertical relief of substrates (e.g. boulder rock substrates) was not measured in the present study, average depth, distance from shore and percentage of rock were correlated with high species richness at rocky habitats. These results are not unlike those of Brokovich et al. (2006), who indicated that reef fish assemblages in the northern tip of the Red Sea varied between habitats, and that VIRGIN ISLAND FISH ECOLOGY 131 fish community structure was best explained by average depth, distance from shore, vertical relief, percent cover by rock, and cover complexity index. Species richness and both the number and composition of functional feeding groups in rocky and sandy habitats may have applications in future studies as changes in Caribbean habitats continue to occur. For example, Halpern and Floeter (2008) point out that knowledge of the functional feeding groups provide insight into the assembly, structure and dynamics of ecological communities, and that the addition or loss of a few species can have significant to minimal impacts on ecosystem function. On average, rocky habitats from 3-20 m from shore had two more functional feeding groups (avg = 11.3) than did sand habitats (avg.=9.3). Flowever, the numbers of species comprising the functional feeding groups at rocky habitats averaged 13.3 species (range 5-46) more than those at sandy habitats (range 1 -30). In both rocky and sandy habitats, many functional feeding groups (i.e., turf grazer, excavator eroder, macroalgae browser, and territorial algae detritivore) were represented by only one or two species, with most single species functional feeding groups occurring in sandy habitats (Table 2). Spatial and behavioral comparisons of fishes Spatial and behavioral descriptions, and occurrences of diurnal inshore pelagic fishes, epibentic pomacentrids, suprabenthic resident reef fishes, and territorial benthic fishes of the Cuban shelf provided by Valdes-Munoz and Mochek (2001) present the single most detailed source for comparisons with fishes in rocky and sandy beach habitats in our study. Diurnal inshore pelagic fish es Valdes-Munoz and Mochek (2001) reported the diurnal, transient belonid, carangid, and sphyraenid species common in the inshore upper water column at study sites in Cuba. We encountered these same transient taxa at our inshore rocky and sandy habitats, but also observed atherinid, engraulid, and clupeid (e.g. Harengula humerali ) schools in the upper water column at these habitats as well. Diurnal Epibenthicpomacentrids The epibentic pomacentrid, Abudefduf saxatilis (sergeant major) was reported by Valdes-Munoz and Mochek (2001) to be common on irregular bottom types and frequently formed large schools 95 % of the time they were observed. In contrast, we encountered individual A. saxatilis and never observed schools of A, saxatilis over nearshore rocky or sandy substrates. Valdes-Munoz and Mochek (2001) observed the epibenthic pomacentrid (blue chromis), Chromis cyanea (abundant in the Caribbean), forming large schools. We never observed a single C. cyanea at any of our rocky or sandy habitats, suggesting that these habitat substrates are not favorable to this species. Diurnal suprabenthic fishes Suprabenthic fishes (i.e., scarids, acanthurids, labrids, and chaetodontids), diumally foraging above the bottom, were the resident fishes living over reefs serving as the primary representatives of the reef fish community studied by Valdes-Munoz and Mochek (2001). They reported scarids occurring in small groups or alone, constantly moving over great distances during the day while foraging on coral; in sea grass beds; however, some scarid species (e.g. Sparisoma radians) showed some behavioral elements of nomadic fishes, a high degree of motor activity, and the formation of large schools. We never observed large schools of any of the scarids (i.e., Scarus iserti, Scarus taeniopteryx , Sparisoma viride, Sparisoma aurofrenatum, Sparisoma 132 VIRGINIA JOURNAL OF SCIENCE frondosum, Sparisoma radians, and Sparisoma rubripinne) in our study. We observed these species foraging on coral singly or within close proximity of other scarids. Three scarid species (S. aurofrenatum, S. frondosum , and S. radians) occurred at rocky habitats but were never observed at sandy habitats in our study. Our observations of the acanthurids (Acanthurus bahianus, Acanthurus chirurgus, and Ac-anthurus coeruleus), spending most of their tune on the bottom while grazing during the day, are consistent with the behaviors of the species reported by Valdes- Munoz and Mochek (2001). Whereas we observed some intraspecific aggression between individuals in these species, we never observed the formation of schools reported by Valdes-Munoz and Mochek (2001) probably because of the low density of individuals in the rocky and sandy habitats we studied. Labrids, reported by Valdes-Munoz and Mochek (2001) to be one of the most common families foraging during the daytime, were common in both rock and sand beach habitats in our investigation. Five Labrid species, Halichoeres bivittatus, Halichoeres maculipinnia, Halichoeres radiatus (juveniles only), Lachnolaimus maximus , and Thalassoma bifaciatum, were constantly on the move in search of food. In particular, our observations of H. bivittatus and T. bifaciatum are consistent with the movements and behaviors described by them, where the latter species was reported to be in a fast and constant motion for 99 % of their time while foraging over reefs on the Cuban shelf. We cannot, however, confirm their observations of group formation in T. bifaciatum. Our observations of diurnal feeding behaviors near the bottom by Chaetodon striatus, Chaetodon capistratus, and Chaetodon ocellatus are consistent with those described by Valdes-Munoz and Mochek (2001). We did not observe any of these chaetodontids protecting territories, consistent with the report by Valdes-Munoz and Mochek (2001). Diurnal territorial benthic fishes Juvenile to adult Stegastes leucostictus (beaugregory) were observed to protect their territories against conspecific individuals during the daytime. These observations are consistent with descriptions of aggression of this territorial benthic species reported by Valdes-Munoz and Mochek (2001). Stegastes diencaeus (longfin damselfish) were commonly observed defending the confines of basket sponges in both rocky and sandy beach habitats. Diurnal observations of nocturnal suprabenthic fishes This group of primarily nocturnal species is composed of lutjanids, haemulids, and holocentrids. Valdes-Munoz and Mochek (2001) indicated that grunt and snapper aggregations are the largest among the species associated with the bottom, and are most active at night when they move off reefs and forage in neighboring areas. In our daytime study, small to large (>300 individuals) motionless or slow moving schools of juvenile to adult Haemulon flavolineatum (French grunt) and juvenile Haemulon sciurus (bluestripe grunt) occurred at both rocky and sandy beach habitats, usually in areas of cover such as overhanging boulders, submerged trunks of fallen trees or rock ledges. Adult H. sciurus, Haemulon melanurum (cottonwick) and Haemulon parra (sailor’s choice) were observed usually as single individuals, not in schools. Only once did we obseive two adult H. parra under a boulder. Juvenile Lutjanus synagris (lane snapper) and juvenile Ocyurus chrysurus (yellowtail snapper) were observed in schools hovering over the bottom. Adult L. synagris and O. chrysurus, as well as adult VIRGIN ISLAND FISH ECOLOGY 133 Lutjanus analis (mutton snapper) and Lutjanus apodus (schoolmaster) were observed individually, not in schools. These observations of juvenile and adult grunts and snappers in our study areas are consistent with the findings of Valdes-Munoz and Mochek (2001) who reported the activities of these species in Cuban reef systems. The nocturnal holocentrids, Holocentrus rufus (longspine squirrelfish) and Myripristis jacobus (blackbar soldierfish) were common to both rocky and sandy habitats. They were seen underneath overhanging rock ledges or under boulders where they remained motionless. They were frequently accompanied in these protected areas by juvenile and adult H. flavoUneatum and H. sciurus. Notes on other species at beach habitats Individual Synodus sciurus (bluestripe lizardfish) frequented sandy nearshore areas where they buried themselves tail first into the sand. Remaining motionless with only their eyes exposed, they ambushed small fishes that were within striking range, which was about equal to their total body length. Also common in sandy substrates were two bothids, Bothus lunatus and Both us ocellatus. These flatfishes buried themselves in the sand at nearshore sandy habitats too, where they laid motionless with only their eyes exposed above the sand to ambush passing fishes. Individual or groups of up to three Pseudopeneus maculates (spotted goatfish) were common foragers in sand areas of both habitats studied. Two carangids, Caranyx ruber (bar jack) and Trachinotus goodei (palometa) were also common pelagic species at both beach habitats. Although the blenniid ( Scartella cristata) and the gobiid ( Bathygobius soporator) were recorded from both rocky and sandy habitats less than three times each, their occurrences were probably underrepresented because of their cryptic behaviors and small sizes. Similarly, low frequencies of blenniid and gobiid species were also reported by Lindeman and Snyder (1999) in a study of nearshore hard bottom fishes of southern Florida. ACKNOWLEDGMENTS We sincerely thank Rafe Boulon, Chief of Resource Management of the Virgin Islands National Park, for collecting permits; Dr. Robert E. Knowlton for significant comments which greatly improved the manuscript; and Penelope G. Maurakis for her assistance in the field. The authors made all observations together in the field. The first author analyzed data and prepared the manuscript. LITERATURE CITED Brokovich, E., A. Baranes, and M. Goren. 2006. Elabitat structure determines coral reef fish assemblages at the northern tip of the Red Sea. Ecological Indicators. 6:494-507. Christensen, J. D., C. F. G. Jeffrey, C. Caldow, M. E, Monaco, M.S. Kendall, and R. S. Appeldoorn. 2003. Cross-shelf utilization patterns of reef fishes in Southwestern Puerto Rico. Gulf and Caribbean Research. 14(2):9-27. Claro, R., K. C. Lindeman, and L. R. Parenti. 2001. Ecology? of the Marine Fishes of Cuba. Smithsonian Institution Press, Washington, DC. 253 p. Faunce, C. H. and J. E. Serafy. 2006. Mangroves as fish habitat: 50 years of field studies. Marine Ecology Progress Series 318:1-18. Friedlander, A. M. and J. D. Parrish. 1998. Habitat characteristics affecting fish assemblages on a Hawaiian coral reef. Journal of Experimental Marine Biology 134 VIRGINIA JOURNAL OF SCIENCE and Ecology. 224(1998): 1-30. Gratwicke, B., and M. R. Speight. 2005. The relationship between fish species richness, abundance and habitat complexity in a range of shallow tropical marine habitats. Journal of Fish Biology. 66:650-667. Halpern, B. S. and S. R. Floeter. 2008. Functional diversity responses in changing species richness in reef fish communities. Marine Ecology Progress Series. 364:147-156. Findeman, K. C. and D. B. Snyder. 1999. Nearshore hard bottom fishes of southeast Florida and effects of habitat burial caused by dredging. Fishery Bulletin. 97:508- 525. Mac, M. J., P. A. Opler, C. E. Puckett Hacker and P. D. Doran (eds.). 1998. Status and trends of the nations biological resources. U.S. Department of the Interior, U.S. Geological Survey, Washington DC. Monaco, M.E., A.M. Friedlander, C. Caldow, J.D. Christensen, C. Rogers, J. Beets, J. Miller, and R. Boulon. 2007. Characterizing reef fish populations and habitats within and outside the Virgin Islands Coral Reef National Monument: A lesson in MPA Design. Fisheries Management and Ecology. 14:33-40. Monaco, M. E., J. D. Christensen, A. M. Friedlander, M. S. Kendall, and C. Caldow. 2003. Quantifying habitat utilization patterns of U.S. Caribbean and Hawaii reef fish to define marine protected area boundaries: The coupling of GIS and ecology. Proceedings of the 13th Biennial Coastal Zone Conference,Baltimore, MD, July 13-17. Nagelkerken, I. and G. van der Velde 2002. Do non-estuarine mangroves harbour higher densities of juvenile fish than adjacent shallow-water and coral reef habitats in Curasao (Netherlands Antilles). Marine Ecology Progress Series. 245:191-204. Nero, V.L and K. S. Sealey. 2005. Characterization of tropical near-shore fish communities by coastal habitat status on spatially complex island systems. Environmental Biology of Fishes. 73(4):437-444. Ohman, M. C. and A Rajasuriya. 1998. Relationships between habitat structure and fish communities on coral and sandstone reefs. Environmental Biology of Fishes. 53:19.31. Ortiz, M. and R. Lalana. 2008. Marine Biodiversity of the Cuban Archipelago: An overview. Center for Marine Research. In Caribbean Marine Biodiversity: The Known and the Unknown, P. Miloslavich and E. Klein (Eds), DEStech Publications, Inc., Lancaster PA, University of Havana, Cuba. 20 p. Available from: http://cbm.usb.ve/CoMLCaribbean/pdf/I-03_Cuba_fmal.pdf Rothenberger, P., J. Blondeau, C. Cox, S. Curtis, W. S. Fisher, V. Garrison, Z. Hillis- Starr, C. F.G. Jeffrey, E. Kadison, I. Lundgren, W. J. Miller, E. Muller, R. Nemeth, S. Paterson, C. Rogers, T. Smith, A. Spitzack, M. Taylor, W. Toller, J. Wright, D. Wusinich-Mendezand J. Waddell. 2008. The state of the coral reef ecosystems of the U.S. Virgin Islands. In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. SAS. 2009. SAS 9.2 for Windows. Statistical Analysis Systems, Cary, NC. Valdes-Munoz, E. and A. D. Mochek. 2001. Chapter 3: Behavior of marine fishes of VIRGIN ISLAND FISH ECOLOGY 135 the Cuban Shelf. In: Claro, R., K. C. Lindeman, and L. R. Parenti. 2001. Ecology of the Marine Fishes of Cuba. Smithsonian Institution Press, Washington, DC. 253 p. TABLE 1. Comparison of water depth (m), and percent cover of substrate type between rocky and sandy beach habitats at combined Little Lameshur, Francis and Great Lameshur beaches, St. John, USVI in July 2007 and July 2008. Parameter Distance from Rocky Sandy F p > F shore (brO Depth 1 0.20 0.17 0.14 0.7247 Coral 0.0 0.0 - - Boulder 81.7 0.0 2.21 0.007 Cobble 3.3 0.0 1.0 0.3739 Gravel 0.0 10.0 3.0 0.1583 Sand 15.0 90.0 135.0 0.0003 Seagrass o. 0.0 0.0 - - Depth 1.56 0.94 6.40 <0.0001 Coral 1.10 0.00 3.91 0.0514 Boulder 49.60 0.00 392.47 <0.0001 Cobble 10.60 32.20 21.99 <0.0001 Gravel 4.40 30.00 19.58 <0.0001 Sand 17.80 33.80 8.00 0.0059 Seagrass £ 12.60 0.00 60.32 <0.0001 Depth u 1.91 1.10 23.97 <0.0001 Coral 3.42 0.00 34.00 <0.0001 Boulder 48.30 0.00 3105.74 <0.0001 Cobble 11.40 40.70 69.47 <0.0001 Gravel 4.02 10.68 8.29 0.0045 Sand 13.84 43.18 76.09 <0.0001 Seagrass Q 12.68 5.15 17.88 <0.0001 Depth y 2.84 1.22 103.28 <0.0001 Coral 2.92 0.00 33.21 <0.0001 Boulder 43.00 1.50 4957.44 <0.0001 Cobble 5.17 22.29 40.24 <0.0001 Gravel 2.50 6.88 28.39 <0.0001 136 VIRGINIA JOURNAL OF SCIENCE TABLE 1 continued Parameter Distance from shore (m) Rocky Sandy F p > F Sand 17.17 64.00 282.35 <0.0001 Seagrass 12 24.58 5.57 64.46 <0.0001 Depth 2.76 1.29 89.87 <0.0001 Coral 7.46 0.00 104.02 <0.0001 Boulder 48.31 0.00 5870.34 <0.0001 Cobble 6.76 34.17 33.87 <0.0001 Gravel 3.38 5.42 3.99 0.0484 Sand 12.54 58.47 115.23 <0.0001 Seagrass 15 7.18 0.97 10.32 0.0017 Depth 4.10 2.00 175.68 <0.0001 Coral 5.47 6.23 0.20 0.6532 Boulder 38.52 6.23 362.87 <0.0001 Cobble 4.06 31.98 44.00 <0.0001 Gravel 1.02 3.02 18.43 <0.0001 Sand 22.42 40.28 14.23 0.0003 Seagrass 20 33.52 12.26 34.64 <0.0001 Depth 4.61 2.49 180.83 <0.0001 Coral 7.39 6.00 0.53 0.4681 Boulder 34.89 7.00 122.92 <0.0001 Cobble 4.32 36.33 33.31 <0.0001 Gravel 0.00 0.56 3.71 0.0574 Sand 18.07 24.11 1.85 0.1771 Seagrass 23.52 26.00 0.20 0.6576 VIRGIN ISLAND FISH ECOLOGY 137 TABLE 2. Comparisons of functional feeding groups (FFG) and taxa per group by distance from shore (m) between rocky and sandy beach habitats at St. John US VI, July 2007 and July 2008. Functional feeding group designations from Halpern and Floeter (2008). Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats 1 Diurnal planktivore 2 1 Atherinidae X Engraullidae X X Macrocarnivore 1 Gerres cinereus X Piscivore 1 Eucinostomus jonesi X Territorial algae 1 Stegastes leucostictus X detritivore Group Total 5 1 3 Diurnal planktivore 3 2 Atherinidae X Engraullidae X X Thallasoma bifasciatum X Opistognathis macrognathus X Macrocarnivore 5 5 Dasyatus americana X Gerres cinereus X X Lutjanus apodus X Lutjanus synagris X X Ocyurus chrysurus X X Sphyraena barracuda X X Mobile benthic 6 2 Haemulon flavolineatum X X invertivore Haemulon sciurus X Myripristis jacobus X Halichoeres bivittatus X X Halichoeres maculipinna X Halichoeres radiatus X General omnivore 2 1 A budefduf saxatil is X X Abudefduf taurus X Piscivore 4 1 Ablennes hians X X 138 VIRGINIA JOURNAL OF SCIENCE TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Carcharhinus perezi X Eucinostomus jonesi X Holocentrus rufus X Sand invertivore 1 0 Pseudupeneus maculatus X Scraper 4 4 Acanthurus bohianus X X Acanthurus chirurgus X Scarus taeniopterus X Sparisoma aurofrenatum X Scartella cristata X Bathygobius soporator X Synodussaurus X Coral colonial 2 1 Chaetodon capistratus X sessile invertivore Chaetodon striatus X Sphoeroides testudineus X Territorial algae 1 2 Stegastes diencaeus X detritivore Stegastes leucostictus X X Turf grazer 1 1 Acanthurus coemleus X X Group Total 29 19 6 Diurnal planktivore 2 5 Atherinidae X Engraullidae X Harengula humerali X Thallasoma bifasciatum X X Mugil curema X Opistognathis macrognathus X Excavator eroder 1 0 Sparisoma viride X Macroalgae browser 2 0 Archosargus rhomboidalis X Sparisoma radians X Macrocarnivore 5 5 Dasyatus americana X VIRGIN ISLAND FISH ECOLOGY 139 TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Gerres cinereus X X Lutjanus apodus X Lutjanus synagris X X Ocyurus ch rysurus X X Sphyraena barracuda X X Mobile benthic 10 4 Trachinotus goodei X X invertivore Haemulon aurolineatum X Haemulon flavolineatum X X Haemulon sciurus X Haemulon striatum X Myripristis jacobus X Halichoeres bivittatus X X Halichoeres maculipinna X Halichoeres radiatus X Scarus iserti X X General omnivore 1 1 A budefduf saxatilis X X Piscivore 3 2 Ablennes hians X X Eucinostomus jonesi X Holocentrus rufus X Caranyx ruber X Sand invertivore 1 3 Pseudupeneus maculatus X X Bothus lunatus X Bothus ocellatus X Scraper 9 4 Acanthurus bohianus X X Acanthurus chirurgus X Scartella cristata X X Bathygobius soporator X X Gymnothorax funebris X 140 VIRGINIA JOURNAL OF SCIENCE TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Holacanthus ciliaris X Scarus taeniopterus X Sparisomci aurofrenatum X Sparisoma rubripinne X Synodus saurus X Coral colonial 3 2 Chaetodon capistratus X sessile invertivore Chaetodon striatus X X Sphoeroides testudineus X X Territorial algae 2 3 Stegastes diencaeus X X detritivore Stegastes leucostictus X X Stegastes variabilis X Turf grazer 1 1 Acanthurus coeruleus X X Group Total 40 30 9 Diurnal planktivore 3 4 Atherinidae X Harengula humerali X Cheilopogon melanurus X Thallasoma bifasciatum X X Mugil curerna X X Excavator eroder 1 1 Sparisoma viride X X Macroalgae browser 2 0 Archosargus rhomboidalis X Sparisoma radians X Macrocarnivore 5 6 Dasyatus americana X Gerres cinereus X X Lutjanus apodus X Lutjanus synagris X X Ocyurus chrysurus X X Sphyraena barracuda X X VIRGIN ISLAND FISH ECOLOGY 141 TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Urolophus jamaicensis X Mobile benthic 11 6 Trachinotus goodei X X invertivore Haemulon aurolineatum X Haemulonflavolineatum X X Haemulon sciurus X X Haemulon striatum X Myripristis jacobus X Halichoeres bivittatus X X Halichoeres maculipinna X X Halichoeres radiatus X Lachnolaimus maximus X Scarus iserti X X General omnivore 3 0 A budefduf saxatil is X Abudefduftaurus X Diploclus argenteus X Piscivore 6 2 Ablennes hians X X Caranyx ruber X Eucinostomus jonesi X Holocentrus rufus X Acanthostracion quadricornis X Nicholsina usta X Pareques acuminatus X Sand invertivore 1 2 Pseudupeneus maculatus X X Bothus ocellatus X Scraper 7 4 Acanthurus bohianus X X Acanthurus chirurgus X X Gymnothoraxfunebris X Holacanthus ciliaris X Scarus taeniopterus X X 142 VIRGINIA JOURNAL OF SCIENCE TABLE 2. Continued Distance Functional Feeding FFG Richness Taxa Occurrence from Group shore (m) Rocky beach habitats Sandy beach habitats Rocky beach habitats Sandy beach habitats Sparisoma aurofrenatum X Sparisoma ntbripinne X X Coral colonial 4 1 Chaetodon capistratus X sessile invertivore Chaetodon striatus X Epinephelus striatus X Sphoeroides testudineus X X Territorial algae 2 1 Stegastes diencaeus X detritivore Stegastes leucostictus X X 12 Diurnal planktivore 3 2 Harengula humerali X Cheilopogon melanurus X Thallasoma bifasciatum X X Mugil curema X Macroalgae browser 2 0 Archosargus rhomboidalis X Sparisoma radians X Excavator eroder 1 1 Sparisoma viride X X Macrocarnivore 4 5 Dasyatus americana X Gerres cinereus X Lutjanus apodus X Lutjanus synagris X X Ocyurus chrysurus X X Sphyraena barracuda X X Mobile benthic 10 4 Trachinotus goodei X invertivore Haemulon aurolineatum X Haemulon flavolineatum X Haemulon melanurum X Haemulon sciurus X Haemulon striatum X Anisotremus surinamensis X VIRGIN ISLAND FISH ECOLOGY 143 TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Halichoeres bivittatus X Halichoeres maculipinna X Myripristis jacobus X Halichoeres bivittatus X Halichoeres maculipinna X Lachnolaimus maximus X Scarus iserti X General omnivore 3 0 A budefduf saxatil is X Abudefduf taunts X Diplodus argenteus X Piscivore 5 1 Ablennes hians X X Holocentrus rufus X Acanthostracion quadricornis X Nicholsina usta X Pareques acuminatus X Sand invertivore 2 1 Pseudupeneus maculatus X X Calamus calamus X Scraper 7 3 Acanthurus bohianus X X Acanthurus chirurgus X Bathygobius soporator X Holacanthus ciliaris X Scarus taeniopterus X X Sparisoma aurofrenatum X Sparisoma rubripinne X X Coral colonial 3 0 Chaetodon capistratus X sessile invertivore Chaetodon striatus X Epinephelus striatus X Territorial algae 2 1 Stegastes diencaeus X detritivore Stegastes leucostictus X X 144 VIRGINIA JOURNAL OF SCIENCE TABLE 2. Continued Distance Functional Feeding FFG Richness Taxa Occurrence from Group shore (m) Rocky beach habitats Sandy beach habitats Rocky beach habitats Sandy beach habitats Turf grazer 1 1 Acanthurus coeruleus X X Group Total 43 19 15 Diurnal planktivore 3 3 Engraullidae X Harengula humerali X Cheilopogon melanurus X Thallasoma bifasciatum X X Mugil curema X Macroalgae browser 2 0 Archosargus rhomboidalis X Sparisoma radians X Excavator eroder 0 1 Sparisoma viride X Macrocarnivore 4 5 Dasyatus americana X Gerres cinereus X X Lutjanus analis X Lutjanus apodits X Lutjanus synagris X X Ocyurus chrysurus X X Mobile benthic invertivore 10 6 Anisotremus surinamensis Trachinotus goodei X X Haemulon aurolineatum X Haemulon flavolineatum X X Haemulon m elan urum X Haemulon sciurus X X Haemulon striatum X Myripristis jacobus X Halichoeres bivittatus X X Halichoeres maculipinna X X Lachnolaimus maximus X Scarus iserti X VIRGIN ISLAND FISH ECOLOGY 145 TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats General omnivore 3 2 A budefdufsaxatil is X X Abudefduf taunts X Diplodus argenteus X Lactophrys triqueter X Piscivore 3 0 Ablennes hians X Holocentrus rufus X Pareques acuminatus X Sand invertivore 2 0 Pseudupeneus maculatus X Calamus calamus X Scraper 5 3 Acanthurus bohianus X X Acanthurus chirurgus X Holacanthus ciliaris X Scants iserti X Scarus taeniopterus X X Sparisoma ntbripinne X Coral colonial 2 0 Chaetodon striatus X sessile invertivore Epinephelus striatus X Territorial algae 1 1 Stegastes leucostictus X X detritivore Turf grazer 1 1 Acanthurus coeruleus X X Group Total 36 22 20 Diurnal planktivore 2 4 Atherinidae X Engraullidae X Harengula humerali X Thallasoma bifasciatum X Cheilopogon melanurus X Mugil curema X Macroalgae browser 2 0 Archosargus rhomboidalis X Sparisoma radians X 146 VIRGINIA JOURNAL OF SCIENCE TABLE 2. Continued Distance Functional Feeding from Group shore (m) FFG Richness Taxa Occurrence Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Excavator eroder 0 1 Sparisoma viride X Macrocarnivore 3 4 Lutjanus apodus X X Lutjanus synagris X Ocyurus chrysurus X X Sphyraena barracuda X Urolophusjamaicensis X Mobile benthic 8 5 Trachinotus goodei X invertivore Haemulon aurolineatum X Haemulon flavolineatum X Haemulon melanurum X Haemulon parra X Haemulon sciurus X X Haemulon striatum X Myripristis jacobus X Halichoeres bivittatus X X Lachnolaimus maximus X Scams iserti X General omnivore 2 1 A budefdufsaxatil is X X Abudefduf taunts X Piscivore 4 1 Ablennes hians X X Holocentrus rufus X Nicholsina usta X Pareques acuminatus X Sand invertivore 2 1 Pseudupeneus maculatus X X Calamus calamus X Scraper 6 3 Acanthurus bohianus X X Holacanthus ciliaris X Scartella cristata X Scarus iserti X VIRGIN ISLAND FISH ECOLOGY 147 TABLE 2. Continued Distance Functional Feeding FFG Richness Taxa Occurrence from Group shore (m) Rocky Sandy Rocky Sandy beach beach beach beach habitats habitats habitats habitats Scants taeniopterus X X Sparisoma aurofrenatum X Sparisoma rubripinne X Coral colonial 2 0 Chaetodon striatus X sessile invertivore Epinephelus striatus X Territorial algae 2 1 Stegastes diencaeus X detritivore Stegastes leucostictus X X Turf grazer 2 1 Acanthurus coeruleus X X Sparisoma rubripinne X Group Total 35 22 148 VIRGINIA JOURNAL OF SCIENCE TABLE 3. Average numbers of fish taxa observed in combined transects of nearshore rocky habitats at Francis, Great Lameshur, and Little Lameshur beaches of St. John USVI, July 2007 and July 2008. Underscored means do not differ significantly (p=0.05). Distance from shore (m) 15 6 9 20 12 3 1 Avg. no. species 5.9 5.0 4.8 4.1 3.3 2.7 1.0 F=1.42; p=0.2025 TABLE 4. Average numbers of fish taxa observed in combined transects at sandy habitats at Francis, Great Lameshur, and Little Lameshur beaches on St. John, USVI, July 2007 and July 2008. Underscored means do not differ significantly (p=0.05). Distance from shore (m) 9 6 12 15 20 3 1 Avg. no. species 20.0 18.0 17.8 12.8 11.0 9.0 3.0 F=2.93; p=0.0254 TABLE 5. Comparison of average number of species at nearshore rocky and sandy habitats at Francis, Great Lameshur and Little Lameshur beaches, St. John, USVI, July 2007 and July 2008. Distance from Shore Average number of species Rocky habitat Sandy habitat F p value 1 3.00 1.00 99.99 <0.0001 3 9.00 2.67 8.43 0.0104 6 18.00 5.00 79.85 <0.0001 9 20.00 4.89 56.38 <0.0001 12 17.75 3.27 37.54 <0.0001 15 12.80 5.89 4.93 0.0464 20 11.00 3.73 6.73 0.0159 VIRGIN ISLAND FISH ECOLOGY 149 TABLE 6. Frequency of occurrence of taxa per functional feeding group at combined nearshore rocky habitats at Francis, Great Lameshur, and Little Lameshur beaches at St. John USVI, July 1 3 Distance from shore (m) 6 9 12 15 20 Diurnal planktivores 3 6 6 6 4 4 2 Excavators/eroders 0 0 1 1 1 0 0 Macroalgae browsers 0 0 1 1 1 1 1 Macrocamivores 1 10 17 15 8 9 3 Mobile benthic invertivores 0 12 31 33 21 17 12 General omnivores 0 5 5 7 4 8 5 Strict piscivores 1 4 7 11 7 5 5 Sand invertivores 0 3 4 4 2 2 2 Scrapers 0 4 19 20 11 9 7 Coral/colonial sessile insectivores 0 3 6 7 5 2 2 Territorial algae/detritivores 1 5 5 8 2 2 2 Turf grazers 0 2 6 6 4 4 2 Total 6 54 108 119 70 63 43 TABLE 7. Frequency of occurrence of taxa per functional feeding group from combined nearshore sandy habitats at Francis, Great Lameshur, and Little Lameshur beaches at St. John USVI, July 2007 and July 2008. Functional feeding group 1 Distance from shore (m) 3 6 9 12 15 20 Diurnal planktivores 2 3 8 7 4 5 5 Excavators/eroders 0 0 0 2 1 2 1 Macrocarnivores 0 7 12 17 8 8 6 Mobile benthic invertivores 0 8 11 15 9 14 11 General omnivores 0 1 1 0 0 3 2 Strict piscivores 0 1 8 4 1 0 1 Sand invertivores 0 0 7 7 4 4 3 Scrapers 0 4 6 9 6 9 6 Coral/colonial sessile insectivores 0 1 4 1 0 0 0 Territorial algae/detritivores 0 4 5 4 2 4 7 Turf grazers 0 3 4 4 1 4 3 Total 2 32 66 70 36 53 45 150 VIRGINIA JOURNAL OF SCIENCE TABLE 8. Comparison of taxa richness, diversity (H), and evenness of functional feeding groups between rocky and sandy habitats at combined Little Lameshur, Francis Beach, and Great Lameshur, St. John USVI, July 2007 and July 2008. Distance from shore (m) 3.00 6.00 9.00 12.00 15.00 20.00 Richness Rocky 7.00 10.00 10.00 8.67 8.00 6.67 Sandy 5.33 8.33 7.33 5.67 6.67 7.33 t value 5.57 16.89 11.4 6.14 10.26 6.22 p>t 0.0020 <.0001 <.0001 0.0017 0.0002 0.0016 HIndex Rocky 1.84 2.04 2.05 1.91 1.90 1.53 Sandy 1.43 2.02 1.82 1.55 1.77 1.86 t value 8.05 60.02 26.46 10.23 18.96 7.82 p>t 0.0005 <.0001 <.0001 0.0002 <.0001 0.0005 Evenness Rocky 0.9764 0.8896 0.8927 0.8939 0.9171 0.9061 Sandy 0.9539 0.9551 0.9226 0.9309 0.9606 0.9425 t value 60.03 53.53 89.59 67.62 62.84 77.93 p>t <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 Virginia Journal of Science Volume 61 Number 4 Winter 2010 A Habitat Model for the Detection of Two-lined Salamanders at C. F. Phelps Wildlife Management Area, Fauquier and Culpeper Counties, Virginia Jay D. McGhee , 1 Randolph-Macon College, Ashland, Virginia, 23005 and Michael D. Killian, Department of Biological Sciences, University of Mary Washington, Fredericksburg, Virginia 22401 ABSTRACT Aquatic salamanders represent an important component of Virginia river watersheds, but despite potential declines, few specifics are known about their habitat preferences. We surveyed the habitats of the northern two-lined salamander and collected data on an array of habitat variables associated with the species. We used a logistic regression analysis to develop a model predicting its presence or absence for a given SOm-transect. Our final model incorporated the variation in stream depth and direction of stream flow and accounted for 25% of the variation in our data. We conclude that stream depth variation is an important feature of salamander habitat ecology, and surmise that direction of flow is of site-specific importance possibly related to stream order. Both features may be behavioral adaptations to avoid fish predation. INTRODUCTION Stream-dwelling salamanders are an important component of aquatic ecosystems. They account for a significant proportion of the biomass of a stream ecosystem, and act as a key trophic link, important as both predators and prey (Spight 1967, Burton and Likens 1975, Rocco and Brooks 2000). Consequently, these salamanders have potential to act as an indicator of stream health (Rocco and Brooks 2000, Barr and Babbitt 2002). This is particularly true for headwater streams were salamanders may act as the dominant vertebrate predator (Davie and Welsh 2004). Accordingly, it would be beneficial to better understand how these species make use of their available habitat. This is especially important in the face of on-going amphibian declines (Alford and Richards 1999). Knowledge of this type may provide better insights into the conservation of these species and their associated ecosystems (Cushman 2005). Previous surveys of stream and terrestrial amphibian diversity have been carried out in the Rappahannock River watershed of northern Virginia; however, more needs to be done to quantify the habitat preferences of important stream species (Mitchell 1998, McGhee and Killian 2010). To begin addressing this need, we conducted a preliminary study of salamander habitat at C.F. Phelps Wildlife Management Area (WMA) located in the Rappahannock River watershed and developed a simple habitat model for the 1 Corresponding author. E-mail: jaymcghee@rmc.edu 152 VIRGINIA JOURNAL OF SCIENCE northern two-lined salamander (Eurycea bislineata ), a common stream species for the area (McGhee and Killian 2010). Northern two-lined salamanders are common to northern Virginia forest streams within the Rappahannock River watershed (Mitchell and Reay 1999). While they are considered potentially important components of the local ecosystems in which they occur, few studies have developed predictive models of habitat use (Davie and Welsh 2004). They occupy stream margins and seeps, using submerged rocks and woody debris for cover; but may periodically be found in upland terrestrial sites (Petranka 1998). Females attach eggs beneath submerged rocks of varying surface area in headwater streams (Jakubanis et al. 2008). Larvae of this species are benthic predators associated with stream pools with low silt (Smith and Grossman 2003, Petranka 1998). Two-lined salamanders are able to access low-order streams typically inaccessible to predatory fishes, and have become adapted to these headwater stream environments (Vannote et al. 1980, Davie and Welsh 2004). We hypothesized that two-lined salamanders would be detected in or near cool narrow, shallow streams. From this hypothesis, we predicted that important habitat variables in a logistic regression model would be stream temperature, stream depth, and stream width. METHODS We chose sampling sites by randomly selecting a GPS starting location constrained to occur within C. F. Phelps WMA, and moving from that point to the nearest stream. We then moved upstream or downstream a randomly selected distance of up to 50m, and laid a 50m transect running downstream. We sampled stream transects by searching five 1-m 2 quadrats placed within each of the five 10-m sections of the transect. The particular location of the quadrat within these 10-m sections was randomly selected (Jaeger 1994, Jaeger and Inger 1994). We searched quadrats by looking under larger cover objects such as rocks or decaying logs, leaf pack, leaf litter, and using a standard-mesh aquarium dip net (1/16 inch mesh size) to sample stream bottoms (Mitchell 2000). We identified captured salamanders to species (Petranka 1998). Data were collected at both transect and quadrat levels (Table 1). We used logistic regression to select models with those predictive variables most associated with salamander captures at the transect level. Variables measured at the quadrat level were averaged and averages and standard deviations were used as separate predictor variables. As synergistic effects may occur between the variables we measured, we created a priori multiplicative variables for testing as well (Table 1). We used forward stepwise selection (P = 0.05 to enter and 0.10 to remove) in SPSS (SPSS Inc., Chicago IL). We assessed variable coefficients using the change in -2 loglikelihood and evaluated the explanatory value of models using Nagellcerke’s r (Ryan 1997, Hosmer and Lemeshow 1989, Nagelkerke 1991). For all statistical analyses a = 0.05. RESULTS From 13 April 2007 - 21 April 2009, we sampled 78 stream transects with 390 stream quadrats. We located 256 two-lined salamanders, 203 of which were larval. Two-lined salamanders were detected in 45 of the 78 stream transects, for a 58% encounter rate. Logistic regression selected two predictor variables: the standard deviation of maximum stream depth (SDMD: -0.12 ± 0.06 SE, change in -2 log TWO-LINED SALAMANDER HABITAT MODEL 153 Table 1. Habitat variables for stream and terrestrial transect sites at C. F. Phelps Wildlife Management Area, Virginia. For variables that had a standard deviation (SD) associated with them, the SD was included in the analysis as a separate predictor. Transect-Level Quadrat-Level Season 3 Mean Maximum Depth Relative Humidity Maximum Depth SD Vapor Pressure Deficit Mean Stream Width Air Temperature (C) Stream Width SD Air Pressure Mean Depth*Width Weather b Depth*Width SD Bank Habitaf Mean Water Temperature Direction of Stream Flow Slope of Stream Flow Water Temperature SD a Spring: Mar 20/21, summer: June 20/21, fall: Sep 22/23, winter: Dec 21/22 b Clear, partly cloudy, overcast, light rain, medium rain c Deciduous, coniferous, mixed deciduous/coniferous, open field/shrub likelihood = 5.331,df=l,P = 0.021), and direction of stream flow (Direction: 0.10 ± 0.01 SE, change in -2 log likelihood = 4.301, df = 1, P = 0.038, Figure 1). The model explained 25% of the variation in data (r 2 = 0.25). Probability of predicting the detection of a two-lined salamander within a stream transect was equal to 1 This model would correctly predict the presence of two-lined salamanders in 84% of cases in our study site, and correctly predict the absence in 48% of cases. The standard deviation and the average of the maximum stream depth were positively correlated r = 0.75, P « 0.0001), and so the majority of transects with low variability in depth also tended to be shallow. Two-lined salamanders tended to be found in streams flowing both south and west (logistic regression (3 = 0.10, P = 0.05). No other variables or combinations thereof produced models of significant predictive value. DISCUSSION Our model indicated that two-lined salamanders are sensitive to variation in stream depth. As those streams with high depth variation tended to be generally deeper, we interpret this as a preference for shallower sites in avoidance of fish predators (Sih et al. 1992). The maj ority of our captures were larval, and Barr and Babbitt (2002) found that larval two-lined salamanders occurred in negative association with brook trout (Salvelinus fontinalis ), a fish predator. Average maximum depth also tended to be chosen by models if depth SD and direction of stream flow were removed, reinforcing the likely importance of depth. Variation in depth may provide refuges for predators to feed on larvae, or larvae and adults may simply tend to avoid deeper sites. No salamanders were found in our study site at depths greater than 20 cm. 154 VIRGINIA JOURNAL OF SCIENCE 400 350 E 300 v 60 « 250 TJ | 200 Li¬ 'S 150 c 100 < 50 0 • Detected • <>■ Not Detected • • • t • ° * O ♦# o <5*0 o o O o o + o 5 10 15 20 25 0 Stream Depth Standard Deviation (cm) 30 FIGURE 1. The relationship between angle of stream flow and stream depth variation for transects at C. F. Phelps Wildlife Management Area, Virginia. Salamanders were typically detected (circles) in streams with relatively low variability, flowing southwest. The model’s selection of stream flow direction as a predictor of the presence of two-lined salamanders is difficult to interpret. Individuals were most easily detected in streams flowing towards the south and west, towards the general direction of the bordering Rappahannock River. South and west flowing streams tended to flow either close to the Rappahannock or to be a 2 nd or 3 rd order stream, and larvae, which often drift downstream, may be attempting to find slow moving, shallow, or low depth- variance pools with sufficient cover (Petranka 1998, Barr and Babbitt 2002). Bruce (1986) found that first-year two-lined larvae tended to dominate downstream samples compared to upstream samples. Unfortunately, direction of stream flow is unlikely to translate this effect to other sites very well. Interestingly, the model failed to include stream temperature. Grant et al. (2005) also failed to detect a water temperature effect for two-lined salamanders in the Shenandoah National Park, Virginia. Barr and Babbitt (2002) and Rocco and Brooks (2000), however, detected a positive relationship between two-lined salamander presence and temperature, but they may have found a greater range of temperatures concurrent with the greater elevation variability at their sites (300 - 1200 m and 358 - 752 m compared to our 200 - 400 m). Our model was able to provide significant information on the habitat used by two- lined salamanders using only two relatively easily acquired variables, and recommends itself for use as a preliminary predictor for presence/absence surveys when relatively few man-hours are available. It does tend to discount sites where the species does occur (false absences) about half the time, however, so more complete models are required to better understand the habitat ecology of the species. TWO-LINED SALAMANDER HABITAT MODEL 155 ACKNOWLEDGMENTS We thank Joe Ferdinandsen, manager of C. F. Phelps WMA for his cooperation, along with R. Hughes & Jerry Sims. We thank University of Mary Washington students Carly Byers, Sarah AJmahdali, Jennifer Clary, Hillary Adams, and Ramsey Hanna for their assistance in the field. We thank the students of J. D. McGhee’s animal ecology classes for Fall 2007 and 2008 for their help in field sampling. This work was made possible through a grant by the University of Mary Washington. LITERATURE CITED Alford, R. A., and S. J. Richards. 1999. Global amphibian declines: a problem in applied Ecology. Annual Review of Ecology and Systematics 30:133-165. Barr, G. E. and K. J. Babbit. 2002. Effects of biotic and abiotic factors on the distribution and abundance of larval two-lined salamanders (Eurycea bislineata) across spatial scales. Oecologia 133:176-185. Bruce, R. C. 1986. Upstream and downstream movements of Eurycea bislineata and other salamanders in a southern Appalachian stream. Herpetologica 42:149-155. Burton, T. M. and G. E. Likens. 1975. Energy flow and nutrient cycling in salamander populations in the Hubbard Brook Experimental Forest, New Hampshire. Ecology 56:1068 - 1080. Cushman, S.A. 2005. Effects of habitat loss and fragmentation on amphibians: A review and prospectus. Biological Conservation 128:231-240. Davie, R.D., and H.H. Welsh, Jr. 2004. On the ecological roles of salamanders. Annual Review of Ecology, Evolution, and Systematics 35:405^134. Grant, E. H. C., R. E. Jung, and K. C. Rice. 2005. Stream salamander species richness and abundance in relation to environmental factors in Shenandoah National Park, Virginia. American Midland Naturalist 153: 348 - 356. Hosmer Jr., D. W. and S. Lemeshow. 1989. Applied Logistic Regression. John Wiley and Sons, New York. Jaeger, R. G. 1994. Transect sampling. Pages 103-106 in W. R. Heyer, M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster, editors. Measuring and monitoring biological diversity: standard methods for amphibians. Smithsonian Institution Press, Washington, D. C. Jaeger, R. G. and R. F. Inger. 1994. Quadrat sampling. Pages 97-102 in W. R. Heyer, M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster, editors. Measuring and monitoring biological diversity: standard methods for amphibians. Smithsonian Institution Press, Washington, D. C. Jakubanis, J., M. J. Dreslik, and C. A. Phillips. 2008. Nest ecology of the southern two- lined salamander (Eurycea cirrigera ) in eastern Illinois. Northeastern Naturalist 15:131-140. McGhee, J.D. and M.D. Killian. 2010. Salamander diversity at C. F. Phelps wildlife management area, Fauquier and Culpeper counties, Virginia. Northeastern Naturalist 17:629 - 638. Mitchell, J. C. 1998. Amphibian decline in the Mid-Atlantic Region: monitoring and management of a sensitive resource. Final Report, Legacy Resource Management Program, U. S. Department of Defense, Arlington, Virginia. Mitchell, J. C. 2000. Amphibian monitoring methods & field guide. Smithsonian 156 VIRGINIA JOURNAL OF SCIENCE National Zoological Park Conservation and Research Center, Front Royal, Virginia. Mitchell, J.C., and K.K. Reay. 1999. Atlas of Amphibians and Reptiles in Virginia. Special Publication Number 1, Virginia Department of Game and Inland Fisheries, Richmond, Virginia. Nagelkerke, N. J. D. 1991. A note on the general definition of the coefficient of determination. Biometrika, 78:691-692. Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, D. C. Rocco, G. L. and R. P. Brooks. 2000. Abundance and distribution of a stream Plethodontid salamander assemblage in 14 ecologically dissimilar watersheds in the Pennsylvania central Appalachians. Final Report No. 2000-4. Pennsylvania State Cooperative Wetlands Center, Forest Resources Laboratoiy, Pennsylvania State University. Prepared for U.S. Environmental Protection Agency, Region III. Ryan, T. P. 1997. Modem regression methods. John Wiley and Sons, Inc. New York. Sih, A., L. B. Kats, and R. D. Moore. 1992. Effects of predatory sunfish on the density, drift, and refuge use of stream salamander larvae. Ecology 73:1418-1430. Smith, S., and G.D. Grossman. 2003. Stream microhabitat use by larval SouthernTwo- lined Salamanders (Eurycea cirrigera ) in the Georgia Piedmont. Copeia 2003:531-543. Spight, T. M. 1967. Population structure and biomass production by a stream salamander. American Midland Naturalist 78:437-447. Vannote, R.L., G. W. Minshall, K.W. Cummins, J.R. Sedell, and C.E. Cushing. 1980. The river continuum concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130-137. 2010 UNDERGRADUATE RESEARCH AWARDS 157 VAS Winners - Fall 2010 Undergraduate Research Awards Grants of $500 were awarded as follows: Brandon Newmyer Radford University Faculty Advosor: Mark Cline Project title: Determining the Hypothalamic Mechanisms of Neuropeptide AF-Induced Anorexia in a Mammalian Model Collette Dougherty Radford University Faculty Advisor: Mark Cline Project title: Central Mechanisms of Gastrin-Releasing Peptide-Induced Anorexia in Chicks Andre Han, Virginia Tech Faculty Advisor: Pablo Sobrano Project title: Biomedical Characterization of Flavin Adenine Dinucleotide Dependent Monooxygenase from Aspergillus fumigates 158 VIRGINIA JOURNAL OF SCIENCE Erin A. Haynes and Bowyn A. Wang University of Mary Washington Faculty Advisor: Theresa Grana Project title: Nematodes in Virginia: Comparative Development and Model Organism Characteristics Anum Shaikh University of Mary Washington Faculty Advisor: Deborah O’Dell Project title: Effects of Combined Vitamin C & E Treatment on Plaque Formation in Alzheimer’s Disease NOTES Virginia Academy of Science 2500 W. Broad St., Richmond, VA 23220-2054