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ASSESSEMNT OF GONAD SIZE IN TAUTOGOLABRUS ADSPERSUS AS AN INDICATOR OF REPRODUCTION AND EDC EXPOSURE
Citation:
GutjahrGobell, R, G Zaroogian, D B. Horowitz, AND L J. Mills. ASSESSEMNT OF GONAD SIZE IN TAUTOGOLABRUS ADSPERSUS AS AN INDICATOR OF REPRODUCTION AND EDC EXPOSURE. Presented at Society of Environmental Toxicology and Chemistry, Portland, OR, November 14-18, 2004.
Description:
Cunner habitat includes estuarine and marine areas where sewage treatment and other discharges containing estrogenic (EDCs) are likely.
Endocrine-disrupting chemicals (EDCs) in the environment may disturb the population dynamics of wildlife by affecting their reproductive output. We hypothesized that there is an allometric relationship between cunner (Tautogolabrus adspersus) gonad weight and body size, and that exposure to EDCs affects this allometric relationship. We also hypothesized that gonadosomatic index (GSI) can predict egg production, so that if an EDC affects GSI, it can also be expected to affect egg production. We tested these hypotheses in field collected and laboratory exposed female cunner. In order to determine the relationship of gonad weight to body size, length, weight, and gonad weight were measured weekly in cunner collected from a control field site (April - December). There was a statistically significant positive allometric relationship between cunner size and gonad weight in both spawning and non-spawning cunner. We also compared body size, GSI and egg production during two week laboratory studies with spawning cunner. With laboratory-generated data, gonad weight in control fish also exhibited an allometric relationship with length (p = 0.018) and weight (p = 0.0002). Reproductive output and female GSI were positively correlated (p = 0.06). To test the effects of estrogenic exposures on fecundity, reproductively active cunner were exposed in three separate experiments by implanting test estrogens (17b-estradiol, estrone and 17a-ethynylestradiol) subcutaneously in a slow-release matrix at 0.05, 0.5 and 2.5 mg/kg. In EDC exposed fish, gonad weight still exhibited an allometric relationship with length (p = 0.0004) and weight (p = 6.6E-5), but there was no significant correlation between female GSI and reproductive output (p = 0.161). Gonads from cunner exposed to estrogens in the laboratory were also evaluated histologically. Our data indicate short-term exposure to estrogenic EDCs does not affect the allometric relationship between gonad and body size in cunner, but EDC exposure can alter the relationship between female GSI and egg production.