Toxicity of weathered coal tar for shortnose sturgeon (Acipenser brevirostrum) embryos and larvae

Weathered coal tar collected from the Connecticut River near Holyoke, Massachusetts, was toxic to shortnose sturgeon embryos and larvae in whole sediment flow-through and elutriate static-renewal laboratory exposures. Sterile laboratory sand and clean Connecticut River sand, collected upstream from the coal tar deposits, produced no significant difference in toxicity to sturgeon embryos-larvae, while coal tar-contaminated sediment produced over 95% embryo-larval mortality. Hydrocarbon transfer and subsequent toxicity appeared to be via direct contact of the embryos with contaminated sediment, rather than via exposure to soluble hydrocarbons. This conclusion was supported by exposure of embryos and larvae to elutriates (e.g., water soluble extract) of coal-tar sediments, that resulted in embryo and larval mortality at low molecular weight PAH concentrations ≥0.47 mg/L, higher than would occur naturally. No decrease in petroleum hydrocarbon concentration was observed in sediments exposed to flowing water for 14 d, supporting the contention that soluble hydrocarbons were not responsible for the observed toxicity in whole sediment exposures under the conditions employed in this study.