Reproductive and early life stage effects of bioaccumulative contaminants: PCBs and mercury

This research determined the potential for mercury or PCBs to disrupt reproduction and sexual development in fish. Fundulus heteroclitus , and two species of trout (Oncorhynchus mykiss and O. clarki clarki) were exposed to mercury and/or polychlorinated biphenyls (PCBs) via contaminated food, immersion in solutions, or exposure to whole sediment or sediment extracts. Endpoints included survival, growth, fecundity, fertilization success, hatch success, larval survival, sex ratios, and the prevalence of gonadal or spinal abnormalities.; PCBs were highly bioavailable. Exposure of rainbow trout larvae to Aroclor 1260 altered female gonads. Exposure of trout eggs or larvae to sediment extract containing PCBs prevented hatching and reduced larval survival in both species of trout. Exposure of cutthroat trout eggs to PCB-contaminated sediment reduced larval survival.; When trout eggs were exposed to Aroclor 1260, growth at six months of age was affected. Exposure of cut-throat trout eggs to a PCB metabolite reduced larval survival. Exposure of rainbow trout eggs to a PCB metabolite reduced growth at six months of age. In summary, there was some evidence that PCB exposure disrupted sexual development and caused early life-stage mortality (particularly between hatch and yolk absorption) and growth effects. Both direct effects on exposed fish and transgenerational effects were observed.; Exposure to mercury increased mortality in male Fundulus (possibly as a result of behavioral alterations). Exposure of Fundulus to mercury-contaminated food reduced fertilization success in offspring. Offspring of exposed fish also had altered sex ratios, with treatment at moderate concentrations producing fewer females and treatment at the highest concentration producing more females than expected. In summary, mercury exposure reduced male survival, reduced the ability of offspring of exposed fish to reproduce successfully, altered sex ratios, and altered growth in Fundulus. Both direct effects on exposed fish and transgenerational effects were observed.; The overarching purpose of this research was to determine the potential for methylmercury or PCBs to disrupt reproduction and sexual development in fish. Low levels of methylmercury or PCBs accumulated in tissues may disrupt normal reproduction and sexual development in Fundulus heteroclitus or rainbow or cutthroat trout, which could have serious effects at the population level.