Abstracts of AES Scientific Papers
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American Elasmobranch Society 1999 Annual Meeting
State College, Pennsylvania
ABSTRACTS - Part 3: Manire through Purdy
*Manire, Charles A., Rasmussen, L. E. L.
(CAM) Mote Marine Laboratory, Mote Marine
Laboratory, Sarasota, FL 34236; (LLR) Department of Biochemistry and Molecular
Biology, Oregon Graduate Institute, Beaverton, OR 97006
Do shark reproductive steroid hormone
concentrations exhibit a diurnal cyclical pattern?
Despite the recent increased understanding
of the patterns and roles of steroid hormones in elasmobranch reproduction,
little is known regarding short-term cycles in these animals. Diel cycles in
reproductive steroid hormones have been described in a wide variety of
vertebrates including mammals, reptiles, amphibians, and teleost fishes. To
determine whether the bonnethead shark, Sphyrna tiburo, undergoes a
similar diurnal cycle, blood was collected from mature females from the wild at
three hour intervals over a two day period. The serum derived from this blood
was then analyzed for 17-beta estradiol, progesterone, testosterone,
dihydrotestosterone and corticosterone. These hormone concentrations were
determined using standard radioimmunoassay techniques. Results of these analyses
and implications of the findings will be presented.
*Manire, Charles A., Rasmussen, L. E. L.,
Tricas, Tim
(CAM) Mote Marine Laboratory, Sarasota, FL
34236; (LLR) Department of Biochemistry and Molecular Biology, Oregon Graduate
Institute, Beaverton, OR 97006; (TT) Department of Biological Science, Florida
Institute of Technology, Melbourne, FL 32901
Elasmobranch corticosterone
concentrations: related to stress or sex or what?
The steroid 1-alpha hydroxycorticosterone
is known to be the major stress hormone in elasmobranchs, but the related
steroid corticosterone that serves as a stress hormone in many other groups of
animals is also present in elasmobranch serum. To determine whether
corticosterone might function as a secondary stress hormone, blood samples were
collected from bonnethead sharks, Sphyrna tiburo, in the wild when
the exact time of first contact with the net for capture was known. Some of the
sharks sampled in this way were taken into the laboratory for monitoring of
hormone levels over a longer time frame as well. No change in corticosterone
concentration was detected either for short term stress (acute stress) or for
longer term stress (chronic stress) in these animals. To assess the possibility
of a reproductive role for this steroid, samples were taken from immature and
mature male and female bonnetheads in the wild, and a number held in the
laboratory over a large portion of the reproductive cycle, as well as from
mature male and female Atlantic stingrays, Dasyatis sabina, from
the wild. There was a significant difference between male and female
corticosterone concentrations, but no difference between immature and mature
sharks. There were also significant differences for both mature male and female
sharks and stingrays at different reproductive stages.
*Marshall, Allan, Smith, Mark, Correia,
Joáo P., Oliveira, Miguel de Esplanada D. Carlos I.
Oceanário de
Lisboa, Lisboa, 1998 Portugal
Development of elasmobranch transportation
techniques
An overview of techniques utilized to
transport elasmobranchs to the Oceanário de Lisboa is undertaken. Specifically,
techniques to capture, restrain and transport elasmobranchs are examined. In
addition, anaesthetic regimes and profilactic protocols are reviewed. The
efficacy of different techniques is discussed.
Martin, Andrew P.
Dept EPOB, University of Colorado,
Boulder, CO 80309
Rates of organelle and nuclear gene
evolution follow same rules: continuing lessons from sharks
Rates of nucleotide substitution for
organelle and nuclear genes are thought to follow different sets of rules. Rates
of nucleotide substitution for nuclear genes may be governed primarily by the
number of germ line replication events (the so called "generation
time" hypothesis) whereas rates of mitochondrial DNA evolution appear to be
controlled primarily by DNA damage pathways of mutation mediated by mutagenic
by-products of oxidative phosphorylation (the so called "metabolic
rate" hypothesis). Comparison of synonymous substitution rates estimated
for dlx, hsp70, and RAG-1 genes in mammals and sharks, two taxa with similar
generation times but differing metabolic rates, shows that rates of molecular
evolution in sharks are approximately an order of magnitude slower than mammals
for both nuclear and mitochondrial genes. In addition, there is significant
positive covariation of substitution rate for mitochondrial and nuclear genes
within sharks. These results, interpreted in the light of differences in life
history and metabolic rate between taxa, and coupled with increasing evidence
for cross-genome activity of DNA repair enzymes, suggests that molecular clocks
for mitochondrial and nuclear genes follow the same set of rules.
*Mattos, Sérgio, Pereira, José, Ferreira,
Beatrice
(SM) Pç Min Joáó Gonçalves de Souza,
SUDENE, Renewable Natural Resources, Recife, Pernambuco 50670-900 Brazil; (JP,
BF) Departamento de Oceanografia, Federal University of Pernambuco, Recife,
Pernambuco 50670-901 Brazil
Growth parameters of the Caribean
sharpnose shark Rhizoprionodon porosus (poey, 1861) off
Pernambuco State (Brazil) continental shelf
The Caribbean sharpnose shark, Rhizoprionodon
porosus (Poey, 1861), is a tropical specie found in Caribbean waters,
along all Brazilian coast, until Uruguay waters. The present paper aim to
present a preliminary result of growth parameters of the Caribbean sharpnose
shark, from specimens caught by the artisanal fishery of Pernambuco
State-Brazil, relevant for the adequate resources administration. The growth
curves for females as much as for males, in length and weight, demonstrate that
females grow larger, but males grow faster, and that K, t0 and
L(infinite) values, are close if compared to other genus species, and even if
compared with other small and medium groups size sharks. The obtained growth
curves in centimeters, from von Bertalanffy (1938) mathematics equation, are:
Lt = 87.13 [1 - e -0.42
(t + 1.10) ] (males) and
Lt = 106.82 [1 - e -0.30
(t + 1.12) ] (females).
There was a high significant difference
among the growth curves in length for males and females. For the gutted weight /
total length relationship for males and females, the mathematics equations are:
We = 0.0054 Lt 2.8993
(males) and
We = 0.0017 Lt 3.1666
(females).
It was observed a significant difference
among gutted weight / total length relationship for males and females. From the
mathematics expression of the growth curve in length and the gutted weight /
total length relationship, it was obtained the growth curve in weight in grams,
for males and females:
We = 2,277.9 [1 - e-0.42
(t + 1.10) ]2.8993 (males) and
We = 4,512.6 [1 - e -0.30
(t + 1.12) ]3.1666, (females).
*Mattos, Sérgio, Nunes, Danillo, Hazin,
Fabio
(SM) Pç Min João Gonçalves de Souza,
SUDENE, Renewable Natural Resources, Recife, Pernambuco 50670-900 Brazil; (DN,
FH) Av Dom Manoel de Medeiros, s/n, Federal Rural University of Pernambuco,
Recife, Pernambuco 52171-900 Brazil
Reproductive biology of the Caribean
sahrpnose shark Rhizoprionodon porosus (Poey, 1861) off
Pernambuco State (Brazil) Continental Shelf
The Caribbean sharpnose shark,
Rhizoprionodon porosus (Poey, 1861), is a tropical specie found in the Caribbean
waters, along all Brazilian coast, until the Uruguay waters. The present paper
aim to describe the preliminary results on the reproductive biology of the
Caribbean sharpnose shark. A total of 264 specimens were analysed, 161 been
females, with total length (TL) ranging from 33.5 to 100.5 cm, and 103 been
males, with TL ranging from 33.5 to 80.0 cm. The total body weight (TW) range
from 128.0 to 5,010.0 g for females and from 131.5 to 1,907.0 g for males. Among
the females, 80 were pregnant, with TL ranging from 63.0 to 100.5 cm. The
Diameter of the largest ovarian follicle in these pregnant females showed a
growth at the same rate of the embryos growth, indicating that probably they
should be ready for another ovulation immediately after parturition. The
sub-adult and pre-ovulatory females presented a TL near to the pregnant females.
The actual data suggest that females first mature at approximately 65 cm in the
Pernambuco State waters. Concerning males, the clasper length showed a sharp
increase in the 60-65 cm length class, and together with the data on clasper
calcification, suggest that male first mature at these length.
*McCandless, Camilla T., Pratt, Harold L.,
Kohler, Nancy E.
(CTM) Department of Fisheries, Animal and
Veterinary Sciences, University of Rhode Island, Kingston, RI 02881; (HLP, NEK)
NOAA/NMFS/NEFSC Narragansett Lab, National Marine Fisheries Service,
Narragansett, RI 02882
Preliminary Results of the 1998
Cooperative Atlantic States Shark Pupping and Nursery Survey (COASTSPAN)
Understanding coastal shark nursery
habitat is critical to effective management and necessary for defining essential
fish habitat (EFH). The Apex Predators Program (APP) formed the Cooperative
Atlantic States Shark Pupping and Nursery Survey (COASTSPAN), an alliance of
state cooperators to investigate shark nursery grounds along the east coast of
the United States. Cooperative researchers in selected coastal states conducted
a comprehensive and standardized investigation of putative shark nursery areas.
North Carolina DMF, South Carolina DNR, Savannah State College with cooperation
from Georgia DNR, Florida DEP and NMFS/University of Rhode Island in Delaware
Bay all participated to sample a total of 1104 sharks in east coast waters in
1998. Seven hundred seventy three of these sharks were tagged with fin tags and
released. Sharks commonly caught by these states were: sandbar, Carcharhinus
plumbeus, Atlantic sharpnose, Rhizoprionodon terraenovae,
smooth dogfish, Mustelus canis, bonnethead, Sphyrna tiburo,
finetooth, Carcharhinus isodon, spinner, C. brevipinna,
and bull shark, C. leucas .
*Morris, Julie A., Wyffels, Jennifer,
Snelson Jr., Franklin F.
(JAM) University of Central Florida,
Winter Park, FL 32792; (JW) ADVSC Dept., Clemson University, Clemson, SC 29634;
(FFS) Department of Biology, University of Central Florida, Orlando, FL 32816
Confirmation of embryonic diapause in the
bluntnose stingray Dasyatis
say
The female reproductive cycle of Dasyatis
say has been confirmed for the Indian River Lagoon system population (Brevard
County, FL). D. say exhibits embryonic diapause, arresting
development of its embryos at the blastoderm stage. In the summer, mating
activity immediately precedes ovulation and fertilization of the eggs.
Encapsulated, diapausing embryos are maintained in the uterus for approximately
10 months. When embryogenesis resumes in the spring, development is rapid,
lasting 10-12 weeks. Pupping is followed by ovulation and mating, then the cycle
repeats. There is no period of reproductive inactivity.
*Naylor, Gavin, Ryburn, Julie A., Fedrigo,
Olivier, Lopez, Andres
Zoology and Genetics, Iowa State
University, Ames, IA 50011
Toward a molecular phylogeny for
Galeomorph sharks: A progress report.
Representatives of each of the eight
orders of sharks were sequenced for 3 mitochondrial and one nuclear gene in an
effort to determine the evolutionary branching order among the major lineages of
sharks. Comparisons between mitochondrial and nuclear inferences are presented.
*Neal, Ashley E., Bodine, A. B., Wourms,
John P.
(AEN, JPW) Clemson University, Clemson, SC
29634; (ABB) AVS Department, Clemson University, Clemson, SC 29634
Protein Analysis of the Uterine
Histotrophe of Rays
Stingrays display a form of aplacental
viviparity in which embryos develop in utero without
connection to maternal tissues. In most species, yolk reserves are exhausted
early in development and uterine fluid, termed histotrophe, is the putative
source of nutrients for the remainder of gestation. Uterine fluid from several
species of stingrays was analyzed for total protein content. Fatty acid
components were removed and soluble and insoluble protein was isolated. The
molecular weight of the proteins was determined using SDS-PAGE. The majority of
the soluble protein present in histotrophe has a molecular weight of less than
10 KD, although a substantial amount has a weight that exceeds 100KD.
Quantitative and qualitative comparisons were made of protein content at
different phases of the reproductive cycle. In some species, protein content is
low early in gestation and increases during mid-gestation. Work continues on the
identification of specific proteins in histotrophe such as immunoglobulin M,
vitellogenin, albumin, and transferrin or other iron-binding proteins.
*Neal, Ashley E., Wyffels, Jennifer T.,
Wourms, John P.
(AEN, JPW) Clemson University, Clemson, SC
29634; (JTW) AVS Department, Clemson University, Clemson, SC 29634
Virtual Embryology: 3D Reconstruction of
Skate Embryos ( Raja erinacea )
The most notable use of 3 dimensional
reconstruction of serial sections of elasmobranchs dates back to the 1911
monograph of Scammon on Squalus acanthias embryos. Since then
few authors have attempted reconstructions because early methodologies were so
labor intensive. Recent advances in computer technology, however, have made this
form of morphological analysis more feasible. Our work represents one component
in a comprehensive series of studies on the embryology of Raja erinacea .
Using a combination of video microscopy and computer techniques we seek to
visualize development of this species in the three dimensions of space as well
as the fourth dimension of time.
O'Donnell, Erin E.
Biology Department, University of
Massachusetts Dartmouth, North Dartmouth, MA 02747
A comparative study of time-place learning
in skates and stingrays
Few studies have been conducted on the
learning abilities of elasmobranchs and fewer still have examined comparative
learning abilities in these animals. Yet, distinctive differences in brain
morphology and relative brain size suggest that differences in learning
abilities may exist among them. The most disparate brains, in terms of relative
size and morphological complexity are found in two groups of batoids - skates (Rajiformes)
and stingrays (Myliobatiformes). This study compared the abilities of skates Raja
erinacea and stingrays Dasyatis sabina in learning
a simple time-place task. The results of four sets of experiments based upon the
presence or absence of a light cue at a specific time of day provided evidence
that D. sabina are capable of time-place learning. Under the
same conditions in paired experiments, R. erinacea did not
respond in a manner that statistically demonstrated their ability to make a
time-place association.
*Pardini, Amanda T., Jones, Catherine S.,
Noble, Leslie R.
(ATP) Department of Aberdeen, University
of Aberdeen, Aberdeen, Aberdeenshire AB24 2TZ United Kingdom; (CSJ, LRN)
Department of Zoology, University of Aberdeen, Aberdeen, Aberdeenshire AB24 2TZ
United Kingdom
Molecular population genetics of the Great
white shark, Carcharodon carcharias
The Great White Shark (GWS), Carcharodon
carcharias, is considered a threatened species. However, the true
conservation status of this predator is uncertain, due to its intractability as
a research organism. Aside from the inherent problems of working in a marine
environment GWS are elusive and uncommon. The difficulty of undertaking research
on this species is evident from the paucity of information on most aspects of
its biology, in particular population dynamics, encouraging speculation about
its conservation status.
Molecular based approaches are now
routinely used on a variety of organisms to address previously intractable
questions pertaining to their population biology. Application of these
approaches to GWS research promises to significantly improve our knowledge of
shark population biology and behaviour. The potential to use minute tissue
samples for identification of individuals will circumvent many of the problems
current in GWS research programmes on natural populations, in addition to making
fragmentary museum material susceptible to robust genetic analysis.
*Piermarini, Peter M., Evans, David H.
University of Florida, Gainesville, FL
32611
Effect of salinity on Na,K-ATPase
expression in the gills, rectal gland, and kidneys of the Atlantic stingray ( Dasyatis
sabina )
The influence of environmental salinity on
osmoregulatory mechanisms of elasmobranch fishes has not been well studied. One
of the most important enzymes associated with ion balance is the sodium,
potassium-ATPase (Na-pump). The goal of this study was to describe and/or
quantify the branchial, rectal gland, and renal expression of the Na-pump, using
immunocytochemistry and Wesern blotting, in the euryhaline Atlantic stingray ( Dasyatis
sabina ). In fresh water, the Na-pump was localized to both filamental
and lamellar cells of the branchial epithelium, but was only localized to cells
of the filament in marine ( D. sabina ). Results from Western
blots demonstrated that the overall branchial expression of the Na-pump was
lower in sea water animals. Rectal glands from marine ( D. sabina )
were larger and expressed more overall Na-pump than those from freshwater
animals. Western blots of kidney tissue showed a similar amount of expression
for the Na-pump in fresh and sea water animals. We suggest that the differential
expression of the Na-pump in the gills and rectal gland of ( D. sabina )
may be a key component to its euryhaline life style. Supported by American
Elasmobranch Society Student Research Award (PMP), EPA STAR Grant U-915419-01-0
(PMP) and NSF Grant IBN-9604824 (DHE).
*Prodóhl, Paulo A., Stanhope, Michael J.,
Shivji, Mahmood S.
(PAP, MJS) School of Biology and
Biochemistry, The Queen's University, Belfast, Northern Ireland BT9 7BL UK;
(MSS) Oceanographic Center, Nova Southeastern University, Dania, FL 33004
Microsatellite DNA profiling in the blue
shark Prionace glauca : development and potential application
for population studies.
The world-wide increase in shark fisheries
is thought to be resulting in declining population numbers of many species. The
blue shark ( Prionace glauca ), possibly the most abundant of
the larger pelagic sharks, is no exception. In addition to a directed fishery,
large numbers of blue sharks make up the bycatch in the tuna and swordfish
fishery. Increased fishing pressure and inadequate management strategies have
prompted concerns about the sustainable health of blue shark populations. The
main reason for inadequate management measures is the paucity of information on
population genetic structure and life history strategy for this species.
Traditional methods used to gather this type of information such as allozyme
electrophoresis and RFLP analysis of mitochondrial DNA have proved to be only of
limited use due to the apparent low rate of molecular evolution in this and
other shark species. Recently, microsatellite DNA profiling techniques have been
proposed as an alternative source of highly informative molecular makers. This
new class of markers has not yet been fully exploited for shark population
studies. Here we report on the development of blue shark microsatellite markers
from an enriched library. Their potential for blue shark population genetic
studies with examples is also discussed.
*Purdy, Robert W., Applegate, Shelton P.
(RWP) National Museum of Natural History,
Smithsonian Institution, Washington, DC 20560; (SPA) Universidad Nacional
Autonoma de Mexico, Instituto de Geologia, Mexico City, Mexico D. G. 04510
Mexico
The Phylogenetic Importance of Fossil
Shark Teeth
Since the classic work of Louis Agassiz
(1835-1843), paleontologists have given much attention to the taxonomic
description and interpretation of fossil shark teeth, which occur mainly as
isolated teeth. Most of this work has been done without the benefit of knowledge
of the great variation present in the teeth of living sharks. Although Leriche
recommended reconstructing fossil shark dentitions as means of reducing the
number of unneeded taxonomic names, his advice has gone unheeded. As a result of
this, for fossil lamniform sharks close to 1000 names alone exist in the
literature. Recently the importance of fossil shark teeth to our understanding
of their phylogenetic history has been questioned. We review briefly dental
variation in lamnid sharks, discuss its impact on the taxonomy of fossil forms,
demonstrate the usefulness of reconstructed dentitions to taxonomic studies, and
discuss their strengths and weaknesses. Finally we discuss the importance of
selecting the correct outgroup for the cladistic analysis of shark dental
characters.
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