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 w hole sediment flow-through and elutriate static-renewal laboratory exp osures. Sterile laboratory sand and clean Connecticut River sand, coll ected upstream from the coal tar deposits, produced no significant dif ference in toxicity to sturgeon embryos-larvae, while coal tar-contami nated 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 so luble hydrocarbons. This conclusion was supported by exposure of embry os and larvae to elutriates (e.g., water soluble extract) of coal-tar sediments, that resulted in embryo and larval mortality at low molecul ar weight PAH concentrations greater than or equal to 0.47 mg/L, highe r than would occur naturally. No decrease in petroleum hydrocarbon con centration was observed in sediments exposed to flowing water for 14 d , supporting the contention that soluble hydrocarbons were not respons ible for the observed toxicity in whole sediment exposures under the c onditions employed in this study.