The Mechanisms and Effects of Endocrine Disruption on Infertility in the Bonnethead Shark on Florida's Gulf Coast

EPA Grant Number: R826128
Title: The Mechanisms and Effects of Endocrine Disruption on Infertility in the Bonnethead Shark on Florida's Gulf Coast
Investigators: Manire, Charles A. , Cortes, Enric , Rasmussen, L. E.L.
Current Investigators: Manire, Charles A. , Cortes, Enric , Gelsleichter, James , Rasmussen, L. E.L.
Institution: Mote Marine Laboratory , Florida State University , Oregon Graduate Institute of Science & Technology
Current Institution: Mote Marine Laboratory , National Marine Fisheries Service , Oregon Graduate Institute of Science & Technology
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1998 through December 31, 2001
Project Amount: $399,653
RFA: Endocrine Disruptors (1997) RFA Text |  Recipients Lists
Research Category: Economics and Decision Sciences , Endocrine Disruptors , Health , Safer Chemicals


Objectives/hypotheses: The objectives of this proposed study are: 1) to determine the degree to which the infertility observed in the bonnethead shark (Sphyrna tiburo) in the Tampa Bay/Anclote River area of Florida is caused by disruption of the shark's endocrine system; 2) to determine the mechanism[s] of such disruption; 3) to determine if this infertility is correlated with organochlorine levels in the shark's serum and/or liver; and 4) to estimate the effects that the infertility rates, as well as other possible effects of the contaminants, observed in three different geographical areas, may have on the rate of population growth of the species in the different areas. With regard to these objectives, field observations, published data and preliminary studies have allowed the formulation of the following hypotheses: 1) infertility observed in female bonnethead sharks, in the form of infertile ova maintained in the uterus throughout gestation, is caused by a disruption to the endocrine system, either in the male during sperm production or storage, or in the female during sperm storage; and 2) infertility in bonnethead sharks is correlated with the presence of environmental contaminants, especially organochlorines.


This study will involve the collection of samples from S. tiburo populations in three different geographical areas exposed to three different levels of human impact. One is a highly populated, highly industrialized area, the second is less populated and non-industrialized, and the third is a relatively uncontaminated habitat. The study will utilize histological and immunocytochemical techniques, radioimmunoassay of steroid hormones (reproductive and glucocorticoids), sperm counts and sperm viability measurements, gas chromatography/mass spectrometry, routine ageing techniques and demographics to compare the reproductive attributes, stress levels, organochlorine levels in the shark's serum and liver in these three populations, and to assess the impact of the infertility, as well as other possible effects of the contaminants, on the population parameters of each population.

Expected Results:

The successful completion of the study will allow for the determination of whether infertility is correlated with an environmental contaminant, the determination of risk assessment for populations of these sharks in the Florida Gulf coastal areas, and will allow for the estimation of possible effects on other commercially and ecologically important shark species, other marine life and humans that share contaminant exposure with S. tiburo. Upon the successful completion of this study, this species could be used as an indicator species to monitor the contaminants and thereby be useful in risk assessment and management in these and other areas where the species occurs.

Publications and Presentations:

Publications have been submitted on this project: View all 13 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 8 journal articles for this project

Supplemental Keywords:

marine environment, estuarine habitat, risk assessment, elasmobranchs, organochlorines, histology, reproduction, hormones, infertility, RFA, Environmental Exposure & Risk, Health, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Limnology, exploratory research environmental biology, wildlife, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Risk Assessments, Ecological Effects - Environmental Exposure & Risk, Southeast, Biochemistry, Children's Health, Histology, Endocrine Disruptors - Human Health, EPA Region, Ecological Indicators, ecological effects, risk assessment, region 4, Anclote River, Gulf Coast, Florida Bay, elasmobranchs, ecological exposure, fish, infertility, estuarine habitat, bonnethead shark, organochlorine compounds, Tampa Bay, ecological impacts, Apalachicola Bay, reproduction, reproductive processes, Florida, reproductive health, Florida Gulf Coast

Progress and Final Reports:

  • 1998
  • 1999 Progress Report
  • 2000 Progress Report
  • Final Report