Endocrine disrupting chemicals (EDCs) are exogenous synthetic and natural compounds or their metabolites that alter endocrine function and cause deleterious effects at the level of the organism, its progeny, and/or populations. The adverse effects of EDCs probably result from their ability to mimic the structure and elicit the biological activities of natural hormones, often estradiol (E2). A wide variety of synthetic chemicals found in municipal, industrial, and agricultural effluents including alkyl phenol ethoxylates, PCBs, dioxins, pesticides, and PAHs, and others have been found to induce strong estrogenic activities in vertebrate animals, most often fishes.
Exposure of fish populations to EDCs may result in reproductive impairment and histologi-cal pathologies. In situ exposure of fish to effluents from sewage treatment plants alters sex ratios, induces hermaphroditism, andimpairs kidney function. Controlled laboratory experiments have demonstrated that some EDCs can reduce the fertilization rate of sperm from exposed males and the survivorship of larval offspring of crosses with exposed males. Therefore, environmental exposure to suites of EDCs can compromise recruitment success of impacted populations.
Biomarkers have been developed to allow for rapid and sensitive assessments of exposure of fishes to EDCs. Expression of biomolecules, including steroids and vitellogenin (Vtg), maybe altered by exposure to EDCs. Vtg is an egg-yolk precursor protein that is normally synthesized in the liver of reproductively active females andis transported via the bloodstream to the developing oocytes where it serves as a nutritional source. Expression of Vtg is normally high in reproductively mature females and is much lower in males and reproductively immature females. The gene encoding for Vtg is present in males and immature females-it just is not active.
A limited survey of gene expression in native YOY striped bass collected at HR RM20 andin adult male killifish collected from Newark Bay failed to detect Vtg while female and male killifish injected with E2 did (McArdle, McElroy, and Elskus, 2004). Studies comparing Vtg expression and levels of circulat ing male and female specific hormones in winter flounder Pleuronectes americanus from two sites in Jamaica Bay and a reference site showed only minor evidence of endocrine disruption (McElroy et al., 2004). These data suggest that endocrine disruption is not widespread in resident fish in the Harbor Estuary. Correlations between induced Vtg and higher level effects in HR populations' reproductive impairment or histological alterations have not yet been conducted. Also, the abundance of striped bass and recruitment to the HR population are at or near historical peaks, suggesting that reproductive impairment from EDCs may not be a problem for HR fishes.
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