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This research determined the potential for methylmercury or Aroclor 1268 to disrupt reproduction and sexual differentiation in Fundulus heteroclitus. The research determined whether fish that are exposed to mercury or Aroclor 1268 survive and successfully reproduce; whether offspring of exposed fish hatch, survive, produce eggs, and fertilize them; and whether the second-generation offspring of exposed fish hatch and survive. Fundulus heteroclitus were exposed to mercury or Aroclor 1268 via contaminated food. Endpoints evaluated included survival, growth, fecundity, fertilization success, hatch success, larval survival, sex ratios, and the prevalence of gonadal abnormalities. In general, polychlorinated biphenyls were highly bioavailable and accumulated well through feeding. The only statistically significant effect observed as a result of treatment with Aroclor 1268 was an increase in growth in the offspring of exposed fish. Mercury was accumulated in a dose-dependent fashion via food exposures. Exposure to mercury in food increased mortality in male F. heteroclitus, which possibly occurred as a result of behavioral alterations. Increased mortality was observed at body burdens of 0.2 to 0.47 microgram/g. Offspring of F. heteroclitus fed mercury-contaminated food were less able to successfully reproduce, with reduced fertilization success observed at egg concentrations of 0.01 to 0.63 microgram/g, which corresponds with parent whole-body concentrations of 1.1 to 1.2 micrograms/g. 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. Alterations in sex ratios were observed at concentrations of less than 0.01 microgram/g in eggs or between 0.44 and 1.1 micrograms/g in parents. Offspring of mercury-exposed fish also had increased growth in moderate treatments, when egg concentrations were less than 0.02 microgram/g, or when parent whole bodies contained 0.2 to 0.47 microgram/g. In summary, exposure to mercury reduced male survival, reduced the ability of offspring to successfully reproduce, and altered sex ratios in offspring. Both direct effects on exposed fish and transgenerational effects were observed.

Abstract-Soils and sediments contaminated with residues of technical toxaphene may require remedial action to reduce human health and ecological risks. Sediments were collected from a coastal wetland impacted by discharge from a former toxaphene production facility and analyzed by gas chromatography-electron capture detection and conventional and enantioselective gas chromatography-mass spectrometry in the electron capture negative ion mode. The prominent chlorobornanes (CHBs) in all samples were 2-exo,3-endo,6-exo,8,9,10-hexachlorobornane (B6-923 or Hx-Sed) and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane (B7-1001 or Hp-Sed), metabolites of higher chlorinated components of technical toxaphene (CTTs). Pentachlorobornanes, toxaphene homologs not previously reported in environmental samples, and likely precursor CTTs were also detected. Several CHB congeners were enantioresolved, the majority of which exhibited racemic composition. These results indicate that the profile of CHBs persisting in estuarine sediment is highly modified relative to the technical mixture, and also provides strong evidence of in situ reductive dechlorination, a process that if enhanced could act to reduce bioaccumulation and toxicity of sediment-bound CTTs at toxaphenecontaminated sites.

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