RESPONSES OF EMBRYONIC AND LARVAL INLAND SILVERSIDES, MENIDIA-BERYLLINA, TO A WATER-SOLUBLE FRACTION FORMED DURING BIODEGRADATION OF ARTIFICIALLY WEATHERED ALASKA NORTH SLOPE CRUDE-OIL

Weathered Alaska North Slope crude oil (ANS 521) was stirred for 2 and 14 days in 20 parts per thousand salinity sterile seawater or for 14 days in seawater with nutrients and a group of three (G03) microorgani sms from Prince William Sound, Alaska, that were capable of biodegradi ng hydrocarbons. A total of 0.65 and 0.69 mg/L water soluble fraction (WSF) of neutral fraction hydrocarbons was recovered from the 2- and 1 4-day stirred sterile systems, respectively. In comparison, a total of 7.5 mg/L WSF neutral fraction hydrocarbons was recovered from systems containing ANS 521 that were stirred and biodegraded by the G03 micro bes for 14 days. Toxicity/teratogenicity tests were conducted with neu tral fraction hydrocarbons recovered from the sterile and biodegraded systems using embryonic inland silversides, Menidia beryllina. Hydroca rbons from the sterile systems did not cause statistically significant teratogenic responses at concentrations of 1%, 10%, and 100% (w/v) of recovered fractions (redissolved in 20 parts per thousand salinity st erile seawater). Counts of heart contraction rates were significantly lower (alpha less than or equal to 0.05) at the 100% WSF concentration of hydrocarbons on days 5 and 6 of embryogenesis. In contrast, recove red and redissolved neutral fraction hydrocarbons from ANS 521, that w ere biodegraded for 14 days, caused statistically significant (alpha l ess than or equal to 0.05) teratogenic responses at the 1, 10, and 100 % WSF concentrations. Measurement of heart contraction rates showed st atistically significant (alpha less than or equal to 0.05) reductions at the 100% WSF concentration on days 2 through 6 of embryogenesis, co mpared to controls.