COMPARISONS OF THE EFFECTS OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN ON CHEMICALLY IMPACTED AND NONIMPACTED SUBPOPULATIONS OF FUNDULUS-HETEROCLITUS .1. TCDD TOXICITY

A subpopulation of Fundulus heteroclitus inhabiting the chemically imp acted estuary of Newark Bay, New Jersey, was found to be resistant to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as compared to a chemically non-impacted subpopulation of F. heteroclitus in Tuck erton, New Jersey. The Newark/Raritan Bay estuary is a major site of T CDD contamination. The Newark F. heteroclitus embryos, when exposed to 12 to 100 parts per trillion (pptr) [H-3]TCDD/acetone (nominal water concentrations) did not exhibit TCDD-dependent lesions or death. In co ntrast, the Tuckerton embryos exhibited both TCDD concentration-relate d lesions and death that was associated with the lesions. The Newark e mbryonic resistance to TCDD toxicity could not be attributed to a less er absorption of [H-3]TCDD as compared to the Tuckerton embryos. The N ewark F. heleroclitus adult fish, when dermally treated with 0.30 to 6 0 ng/g [H-3]TCDD/DMSO, did not exhibit TCDD treatment-related increase s in death, lesions, or liver-to-body-weight ratios, whereas the Tucke rton adult fish did. The Newark fish did exhibit greater parasitic inf estations of the liver, greater hepatic neoplasias, and greater liver- to-body-weight ratios, all of which were independent of laboratory TCD D treatment, as compared to the Tuckerton fish. These hepatic effects in the Newark fish may be indicative of the chronic chemical exposure of this F. heteroclitus subpopulation.