Florida Museum of Natural History

Abstracts of AES Scientific Papers

American Elasmobranch Society 2001 Annual Meeting
State College, Pennsylvania
ABSTRACTS - Part 3: Manire through Purdy

(CAM, JG) 1600 Ken Thompson Parkway, Mote Marine Laboratory, Sarasota, FL 34236; (LR) P.O.Box 91000, Oregon Graduate Institute, Portland, OR 97291; (EC) 3500 Delwood Beach Road, National Marine Fisheries Service, Panama City, FL 32408

Infertility in Bonnethead Sharks, Sphyrna tiburo, in the Eastern Gulf of Mexico May Be Caused by Endocrine Disrupting Chemicals in the Environment

Previous studies have demonstrated a high frequency of infertile ova in the uterus of pregnant bonnethead sharks along the central Gulf coast of Florida. We hypothesized that this infertility was caused by disruption to the endocrine system and that this infertility could be correlated with the presence of environmental contaminants, especially organochlorines. To test these hypotheses, we collected samples from bonnethead sharks from three areas that represented three different levels of organochlorine contamination. These included Florida Bay in the Florida Keys (the least contaminated control area), Anclote Key near Tampa Bay (highly contaminated area), and Apalachicola Bay in the Florida Panhandle (intermediate contamination). Differences were found in serum concentrations of reproductive steroid hormones, sperm counts and sperm viability, concentrations of various organochlorines, growth and reproductive parameters, and resultant population intrinsic rates of increase. Estradiol concentrations in mature females from Tampa Bay were found to be one half the concentrations found in the Florida Bay (control) females. There were significant differences in serum concentrations of estradiol and testosterone from immature females (Tampa Bay << Florida Bay). It is likely that these differences in hormone concentrations are caused by endocrine-disrupting organochlorine compounds present in the marine environment inhabited by these sharks. (Session 16, Sunday, July 8, Penn Stater, Room 207, 8:45)



(FAM) Aquatic Ecology Lab, The Ohio State University, Columbus, OH 43212; (CLB) 3000 NE 151 Street AC1 378, Florida International University, North Miami, FL 33181

Cortisol Mediated Movement in the Sedentary Coral Reef Fish (Dascyllus albisella)

Cortisol has long been recognized as a ªstress hormone in vertebrates and has been implicated in dominance and social behavior in fish species. In this study, we propose that the reception of agonistic behavior in the damselfish Dascyllus albisella can result in elevated levels of cortisol, which in turn trigger migration out of their social group. To test whether cortisol induces movement in D. albisella, we exposed individuals to a cortisol-seawater solution and compared their movement behavior over time (within a 3 x 2 cells grid) in 380 l aquaria against untreated control fish. We found that both treatment and time elapsed from removal of treatment had effects on the movement rate of individuals. However, there was no interaction between the two factors. Cortisol treated fish moved between cells more often than control fish during the observation periods and thus spent less time than control fish in any given cell. While not a definitive study, our results suggest that this is an appropriate direction for further study. (Session P-32, Monday, July 9, Penn Stater, Deans Hall)



621 Charles E. Young Drive South, University of California, Los Angeles, Los Angeles, CA 90095

Mechanism of inflation behavior in the swellshark, Cephaloscyllium ventriosum (Elasmobranchii: Scyliorhinidae)

Numerous lower vertebrates (e.g., chuckwallas, Sauromalus obesus) are capable of defensive inflation, whereby an increase in body volume affords some anti-predatory advantage. Sharks of the genus, Cephaloscyllium, are also reported to exhibit inflation behavior, although the morphological and physiological details were not previously described. The northeastern Pacific species, C. ventriosum, was therefore studied to i) determine the mechanics of the inflation response, ii) identify any associated anatomical modifications, and iii) elucidate the ecological significance of this atypical elasmobranch behavior. Whole body radiographs of deflated and inflated specimens were performed to confirm the body region responsible for housing the engulfed medium and describe general differences between the deflated and inflated states. Swellsharks were also induced to inflate in a novel experimental aquarium after surgical implantation of miniature pressure transducers in the cardiac stomach as well as buccal and parabranchial cavities. Digital footage of inflation events was taken to correlate external phenomena related to inflation with recorded internal pressure changes. A model of inflation behavior is advanced that explains how super-ambient pressures are created within the buccal cavity in order to force water through the esophagus and into the fore portion of the stomach. (Session 29, Monday, July 9, Penn Stater, Room 105, 8:30)



6342 Hawthorne Terrace, independent, Norcross, GA 30092

Sharks in land. The symbolism of freshwater sharks and sawfishes in north Australian Aboriginal societies

An important metaphor in Aboriginal religion is that of rivers flowing to the sea. Rivers link the lands of independent cultures and clans, symbolizing social alliances, profound knowledge, and the soul&'s journey in death. Family groups trace their origin to supernatural ancestral beings (totems) who often assumed the form of animals. During epic journeys, these ancestors shaped the landscape, created humanity, and bestowed land and culture upon their descendants. Revered for their euryhaline power, carcharhinid sharks and sawfishes appear prominently as ancestral creators of river systems throughout Arnhem Land, and are associated with concepts of diplomacy, rites of passage, and lawful vengeance. While each sacred site founded by ancestral sharks is owned by a distinct cultural entity, the disparate clans owning estates along the shark&'s path recognize a shared heritage as children of their shark mother. In tracing the origin of human social groups to facets of the natural world, totemic ancestry empowers Aboriginal people to recognize personal kinship ties to virtually any natural species, members of other totemic societies, and even to the land itself. As the embodiment of the sacred rivers which they created, euryhaline sharks remain central religious symbols in Arnhem Land societies. (Session 26, Monday, July 9, Penn Stater, Room 207, 9:00)



114 Hofstra University, Hofstra University, Hempstead, NY 11549

Reproductive biology of gulper sharks from the Cayman Trench, Jamaica

Gulper sharks (Centrophorus: Squalidae: Squaliformes) typically are gray to brown, with large green eyes, spines anterior to both dorsal fins, and pectoral fins that often have a free rear tip that extends well under the first dorsal origin. They are most abundant below 200 meters depth. Specimens were obtained via horizontal longline at depths between 400-900 meters. The reproductive biology of 6 male and 38 female Centrophorus cf. uyato have been examined. The smallest mature male was 81.2 cm total length whereas the smallest mature female was 91.5 cm total length. The sharks exhibit aplacental viviparity with a maximum of two pups per litter. Ova continued to develop throughout gestation. Most females carrying developing embryos had two large (>4.9 cm), equally developed ovarian ova, which leads us to believe that they ovulate soon after parturition. This species seems to exhibit complete sexual segregation during the non-mating season with males being completely absent from the study site during the summer months. (Session P-14, Saturday, July 7, Penn Stater, Deans Hall)



WHOI, Woods Hole Oceanographic Institution, Woods Hole, MA 02543

Are elasmobranchs susceptible to dioxins?

Anthropogenic pollutants in marine environments include many planar halogenated aromatic hydrocarbons (PHAH). These compounds are toxic and carcinogenic, and bioaccumulate in elasmobranchs. The toxic effects of TCDD (2, 3, 7, 8-tetrachlorodibenzo-p-dioxin) and related PHAHs (e.g., non-ortho-substituted PCBs) are mediated through the aryl hydrocarbon receptor (AHR) pathway. Differences in ligand binding affinity of AHRs underlie some species- and strain-specific differences in the toxicity of TCDD. Objectives are to clone and characterize AHRs in elasmobranchs and to assess their TCDD-binding affinity. We used reverse transcription polymerase chain reaction (RT-PCR) with degenerate primers to isolate fragments of the AHR. Previous work in this lab identified partial sequences of two forms of the AHR from spiny dogfish Squalus acanthias and smooth dogfish Mustelus canis, and one AHR from little skate Raja erinacea. Recently we cloned fragments of two AHR forms each from Greenland shark Somniosus microcephalus and sandbar shark Carcharhinus plumbeus. We are using rapid amplification of cDNA ends (RACE) to obtain the 5&'- and 3&'- ends of AHRs from all five species. The divergence and conservation of AHR genes in elasmobranchs will be discussed in the context of functional domains of the receptor. (Supported in part by NIH Grants ES06272 and ES05935). (Session 16, Sunday, July 8, Penn Stater, Room 207, 8:30)



Feldbergstrasse 22, University Basel, Switzerland, Basel, Basel 4057 Switzerland

Temporal and spatial variations in shark abundance and distribution in the estuary of the Ten Thousand Islands, Florida.

Sharks were collected at regular intervals from May through October 1999 and 2000 from three different habitats throughout the Ten Thousand Island Estuary. The habitats comprised gradients mainly defined by substrate, depth, salinity and temperature. The objectives of the present study were, 1) to determine the structure of shark communities; 2) to evaluate temporal trends in community structure; 3) to evaluate spatial trends in community structure and 4) to verify the physical factors responsible for the temporal and spatial patterns found. Spatial and temporal segregation of shark species was observed within the estuary during the wet season. Overall trends included an avoidance of the backwater area by Carcharhinus limbatus, whereas Carcharhinus leucas showed a preference for this habitat. These two species also differed in their temporal use of the estuary. C. limbatus was most abundant from May through August and C. leucas from August through October. Sphyrna tiburo turned out to be an spatial-opportunist, most abundant from July through September. Correlation between intensity of shark use and salinity, temperature and depth was also observed. The study should help arguing about possible impacts of the planned change of the water run-off in this area on the local shark community. (Session 10, Saturday, July 7, Penn Stater, Room 207, 1:45)



(PM) 4202 East Fowler Avenue, University of South Florida, Tampa, FL 33620; (RH) 1600 Ken Thompson Parkway, Mote Marine Laboratory, Sarasota, FL 34236; (TT) 2538 McCarthy Hall, University of Hawaii at Manoa, Honolulu, HI 96822; (AS) Univ. of Cal., University of California, Berkeley, CA 97720

Suction feeding in elasmobranchs: functional and evolutionary considerations

Prey capture in elasmobranchs may involve ram, biting, filter feeding, compensatory suction, inertial suction or a combination of these behaviors. Morphological and physiological specializations for inertial suction feeding, as exemplified by the nurse shark Ginglymostoma cirratum, include a small terminal mouth with prominent labial cartilages that direct the gape anteriorly, small teeth, rapid mouth opening, and a modified kinematic prey capture sequence involving a fast opening phase that often lacks cranial elevation. Paleontological evidence suggests ancestral sharks were morphologically specialized for seizing and tearing their prey and primarily used ram prey capture. If this is correct, inertial suction feeding has repeatedly arisen within numerous elasmobranch lineages, often nested within groups of ram and compensatory suction feeding sharks. These inertial suction feeding elasmobranchs are predominantly benthic associated predators on smaller prey. We predict that inertial suction specialists will in general be shallow water dwellers that are weak or intermittent swimmers, be compressiform in shape, have more stereotyped kinematic and motor patterns of prey capture, and utilize ambushing and stalking of their smaller prey. Furthermore, inertial suction prey capture should predominate in the benthic associated batoids. A notable exception to this morphotype, the pulsatile suction-filter feeding whale shark Rhincodon typus, is discussed. (Session 29, Monday, July 9, Penn Stater, Room 105, 8:15)



Greate Rd., Va. Inst Mar. Sci., Gloucester Pt., VA 23062

Distribution and abundance of sharks in the Chesapeake Bight, U.S.A.

Scientific long-line survey data collected in the Chesapeake Bight from 1973-2000 were analyzed to describe the distribution and abundance of sharks. The most abundant species was Carcharhinus plumbeus which migrates into the region in late Spring when water temperatures rise to 16-18C. Migration out of the region to south of Cape Hatteras usually occurs in late September or early October. Neonates and juveniles up to 4 or5 years of age use Chesapeake Bay as a nursery. Older juveniles occupy <10m depths along the coast but move further off shore (10-20m) as they get older. After pupping adult females move to depths>20m.Dusky sharks (C.obscurus exhibit the same seasonal migratory patterns, but utilize nearshore (<10m) areas for pupping.Blacktip (C.limbatus), spinner (C.brevipinna) and sharpnose (Rhizoprionodon terraenovae) sharks usually immigrate in June and seem to prefer higher temperatures (>22C) than the previous two species.Other species of importance are tiger (Galeocerdo cuveri), sand tiger (Carcharias taurus) sharks, and the grey smoothound (Mustelus canis). Seasonality and depth and temperature distributions are described for all species as well as size and sexual segregation. Another community of sharks occupys the outer continental shelf (>100m) in summer. Sharks taken there include bignose (C. altimus), mako (Isurus oxyrinchus) and blue (Prionace glauca). (Session 10, Saturday, July 7, Penn Stater, Room 207, 1:30)



Wetland Resources Building, Louisiana State University, Baton Rouge, LA 70803

Barrier island restoration and beach renourishment in coastal Louisiana: altering essential fish habitat?

Annual land loss in coastal Louisiana is between 20-35 square miles/year and accounts for up to 80% of the national coastal loss. In response to this rapid land loss, Federal and state programs have been instigated to rebuild and restore Louisiana&'s coastal wetlands and barrier islands. Restoration projects have at times focused on restoring the physical environment without in-depth analysis of the ecological function of the habitat. Biological considerations, such as possible loss of valuable habitat for organisms using these areas, as well as the evaluation of restoration efforts for aquatic organisms, need to be more carefully considered. We discuss possible consequences of habitat alternation due to restoration projects, utilizing shark nursery habitat as an example. Research findings suggest that the Gulf of Mexico side of East Timbalier Island may function as a shark nursery, as may all Louisiana barrier islands. We have observed neonates, young-of-the-year, juveniles and/or adults for six species of sharks on the front island platform. Several shark species utilize the shallow surf zone, another potentially important habitat for sharks. We discuss possible effects of restoration/renourishment projects as they relate to these essential shark habitats. (Session 16, Sunday, July 8, Penn Stater, Room 207, 9:30)



6525 N. Sheridan Rd., Loyola University Chicago, Chicago, IL 60626

Forces of Nature: Sharks in Eighteenth and Nineteenth Century European and American Art

The purpose of this talk is to examine the manner in which sharks are portrayed in eighteenth and nineteenth century Western art in the context of changing attitudes concerning the relationship between humanity, religion and nature. Between 1700 and 1900 Western views of nature and the relationship of human experience to nature experienced radical change. The European colonial experience was driven by a perception of nature as a force to be dominated by humans, who were seen as being at the earthly pinnacle of the scala naturae. In this context, nature was viewed as hostile and implacable, to be constantly striven with and overcome. By the mid-to-late nineteenth century, changes in Western scientific and philosophical outlooks resulted in changing attitudes about the relationship between humanity and nature. In this latter view, humanity was seen more as an integral part of nature and in harmony with its forces. We will demonstrate that these changes in attitude are reflected in various paintings from this period that depict sharks representing forces of nature, including John Singleton Copley's Watson and the Shark, J.M.W. Turner's The Slave Ship and Winslow Homer's The Gulf Stream. (Session 26, Monday, July 9, Penn Stater, Room 207, 11:00)



(SMN) 8272 Moss Landing Road, Moss Landing Marine Laboratories, Moss Landing, CA 95039; (JG, CAM) 1600 Ken Thompson Parkway, Mote Marine Laboratory, Sarasota, FL 34236

Calcitonin: potential roles in the bonnethead shark, Sphyrna tiburo

Calcitonin is a phylogenetically ancient hormone that is produced in the parafollicular C cells of the thyroid gland in mammals and the ultimobranchial gland in all other jawed vertebrates. This hormone has been historically believed to be a major factor in calcium regulation. However, recent studies indicate that perhaps its primary role is in reproduction and/or development. The current study presents data on calcitonin bioactivity during the female reproductive cycle and embryonic development of the bonnethead shark, Sphyrna tiburo. Serum calcitonin concentrations within the mature female bonnethead shark over the reproductive cycle were determined using an enzyme-linked immunosorbent assay (ELISA) for salmon calcitonin. The presence of calcitonin in the reproductive tissues of the mature female bonnethead shark and within the developing embryo was demonstrated via immunohistochemical techniques. Results from ELISA demonstrate an elevation in serum calcitonin levels during the later stages of the reproductive cycle. Calcitonin bioactivity within the uterine tissue is present during the later stages of reproduction, paralleling the changes in serum calcitonin concentration and indicating a possible role in matrotrophy. Calcitonin bioactivity within the developing embryo demonstrates a possible role in the gastrointestinal tract and the pancreas. (Session 20, Sunday, July 8, Penn Stater, Room 207, 2:45)



(JJN) PO Box 110880, University of Florida, Gainesville, FL 32611; (MJS) University of Central Florida, University of Central Florida, Orlando, FL 32816; (GB) University of Florida, Florida Museum of Natural History, Gainesville, FL 32611

The Influence of Tidal Stage and Lunar Phase on the Frequency of Shark Attacks

Worldwide Sharks present a potential danger to swimmers entering the ocean. Past studies trying to rationalize and prevent shark attacks have focused on single, isolated parameters such as water temperature, water depth, water turbidity, and activities of the victim. They have not yet looked into the ecology of the environment in which the attacks occurred. This study addresses the ecological basis behind shark attacks. Tides have a large effect on the coastal environment, influencing the daily activities of many organisms, including sharks. If tides influence the behavior of sharks, attack frequencies will increase when the tides put them in closer proximity to humans. The tides are influenced by the moon, which is also said to play a major role in the activity patterns of animals. Therefore, attack frequency will increase during the phases of the lunar cycle that intensify the feeding behavior of sharks. The International Shark Attack File (ISAF) provided attack records for the analysis. Data from each case (date, time, and location) were used to find the tidal stage during the attack. An analysis of the patterns shown in histograms depicted the degree to which shark attacks are influenced by tidal stage and lunar phase. (Session P-14, Saturday, July 7, Penn Stater, Deans Hall)



1600 Ken Thompson Parkway, Mote Marine Laboratory, Sarasota, FL 34236

Growth inhibition of mammalian tumor cell lines by conditioned media from in vitro cultures of immune cells from the epigonal organs of bonnethead sharks Sphyrna tiburo

Cell culture supernatants (conditioned media, CM) from 2-4 day serum-free cultures of unstimulated immune cells from epigonal organs of bonnethead sharks Sphyrna tiburo demonstrate a consistently high inhibitory activity against two mammalian tumor cell lines sensitive to different immune regulatory factors. At initial concentrations of 5x104cells/mL, A375.S2 human malignant melanoma (interleukin-1 sensitive) and WEHI 164 murine fibrosarcoma (tumor necrosis factor sensitive) cells were co-cultured with various dilutions of bonnethead epigonal CM. Percent growth inhibition (%GI) was assessed after 96 h of culture by comparing the conversion of MTT to purple formazan by live cells in experimental and control cultures. Equal volume co-culture of CM (total protein - SEM, 9.16 - 0.63 mg/mL, n=21) with A375.S2 cells resulted in a mean %GI - SEM of 84.8 - 1.1, while co-culture of CM (total protein - SEM, 9.45 - 0.65 mg/mL, n=19) with WEHI 164 cells resulted in a mean %GI - SEM of 93.6 - 0.4. Preliminary characterization of bonnethead epigonal CM using SDS polyacrylamide gel electrophoresis indicates three major protein bands, one of which is consistent with the approximate molecular weight reported for both interleukin-1 and tumor necrosis factor from mammalian species. (Session P-14, Saturday, July 7, Penn Stater, Deans Hall)



(HLP) 28 Tarzwell Drive, NOAA/NMFS, Narragansett, RI 02882; (JCC) East Porter St, Albion College, Albion, MI 49224

Wild mating of the nurse sharks Ginglymostoma cirratum: Courtship behaviors, possible cooperation, and mechanisms of mate choice in an elasmobranch.

Elasmobranch copulation is often preceded by courtship activity. Ongoing life history studies of nurse sharks in the Dry Tortugas, FL have provided an opportunity for repeatable observations of shark courtship and mating behaviors. Ten reproductive behaviors are examined: refuge (23 occurrences), follow (4), shoal (6), grasp (11), avoidance (58), wait (10), carry (18), male competition (3), male cooperation (blocking) (3), and insertion and copulation (32). These behaviors are defined and documented, and clarified with video records that supplement past observations by the authors and others, and provide information about the timing and dynamics of nurse shark reproductive behaviors. (Session 7, Saturday, July 7, Penn Stater, Room 207, 9:45)



(RWP) National Museum of Natural History, Smithsonian Institution, Washington, DC 20560; (MF) P. O. Box 14-901, National Institute of Water and Atmospheric Research, Wellington, New Zealand

Ontogenic Development of Teeth in Embryos of Lamna nasus

The dental ontogeny in 21 embryos (7 male/14 female), ranging in size from 215-670 mm FL, was examined to trace the development of teeth in various tooth positions, to determine the variation in tooth form and to determine the polarity of tooth characters.In embryonic dentitions from individuals 413 mm FL or less, the teeth have a morphology very similar to those of some of the earliest chondrichthyans in the fossil record. Some of these smaller dentitions possessed upper and lower parasymphyseal teeth. In larger embryos, the dentition changes abruptly to a lamniform type resembling an that of an Odontaspis, but lacking lateral denticles; the first upper anterior tooth is also absent in all dentitions. These dentitions provide important information about the wide range of dental variation and provide information about which dental characters represent primitive or derived states. (Session P-14, Saturday, July 7, Penn Stater, Deans Hall)