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EDC RESEARCH AT EPA ATLANTIC ECOLOGY DIVISION: DO ENVIRONMENTAL EDCS IMPACT FISH POPULATIONS
Citation:
Mills, L J., R E. GutjahrGobell, D B. Horowitz, C Norwood, AND G Zaroogian. EDC RESEARCH AT EPA ATLANTIC ECOLOGY DIVISION: DO ENVIRONMENTAL EDCS IMPACT FISH POPULATIONS. Presented at Endocrine Disruption Research Seminar: Collaborative Between NIESH, Superfund and Basic Research Program in EPA New England, Boston, MA, November 29, 2000.
Description:
The Atlantic Ecology Division, Office of Research and Development, EP A is a marine laboratory situated on Narragansett Bay, Rhode Island. Researchers at AED are investigating the effects endocrine disrupting chemicals (EDCs) in the aquatic environment might have on reproductive success of oviparous fish. An initial series of experiments were conducted to evaluate whether there are reliable indicators in fish that reflect exposure to EDCs. In these experiments, male juvenile summer flounder were exposed in the laboratory to established estrogenic (17 -estradiol, o,p '-DDT; octylphenol) or anti-androgenic (p,p '-DDE) chemicals.
After four weeks, male flounder exposed to estrogenic chemicals uniformly exhibited decreased gonadosomatic index [GSI = (gonad wt/(body wt -liver w)) x 100], changes in gonad development, and decreased plasma testosterone levels relative to controls. Changes in hepatosomatic index [HSI = (liver wt/body wt) x 100], plasma estradiol, and plasma vitellogenin were observed with some estrogenic EDCs but not others. p,p '-DDE treatment did not significantly alter any indicator.
To determine whether indicators that reflect exposure to EDCs are also indicative of impacts on reproductive success, reproducing male and female adult cunner (Tautogolabrus adspersus) were exposed to either l7 -estradiol or ethinyl estradiol in laboratory experiments. Reproductive success of treated fish was assessed through daily measurements of egg production, number of viable eggs, and percent fertilization. Gonadosomatic index (GSI) was recorded at termination of each two week exposure; blood was also drawn to analyze for plasma steroid hormones and vitellogenin. In a preliminary experiment, fish treated by subcutaneous implantation of 0.5 mg/kg estradiol in a slow-release matrix showed indications of reduced total egg production and egg viability, although the decrease was not statistically significant compared to control fish. A low level of the female protein vitellogenin was detected in males from this estradiol treatment. Percent fertility of eggs was not different than in controls. In fish implanted by a similar method with 2.5 mg/kg ethinyl estradiol, a significant reduction in total egg production and egg viability was observed. Female GSI was also significantly decreased. Plasma vitellogenin levels in males were extraordinarily high, yet neither percent fertile eggs nor male GSI was significantly different than in controls. Plasma steroid hormone levels have not yet been determined.