SENSITIVITY OF LARVAL AND ADULT ALASKAN SHRIMP AND CRABS TO ACUTE EXPOSURES OF THE WATER-SOLUBLE FRACTION OF COOK INLET CRUDE OIL

Abstract

ABSTRACT The sensitivity of adult and larval Alaskan shrimp and crabs to the water-soluble fraction (WSF) of Cook Inlet crude oil was measured by tests using 96-hour static bioassays at the water termperatures that these animals normally encounter. Larval crustaceans were found to die more slowly than adults, making it necessary to measure sensitivity in terms of concentrations causing moribundity (death imminent) instead of in terms of concentrations causing death during exposure. The cessation of all motion and reaction was found to indicate moribundity in adults, and the cessation of swimming was found to indicate morbundity in larvae exposed for 96 hr. Ninety-six-hour LC50's for moribundity for stage I larvae ranged from 0.95 to 1.8 ppm depending on species, while 96-hr LC50's for adults ranged from 1.9 to 4.2 ppm oil. Sensitivities for stage I-VI larvae of coonstripe shrimp ranged between 0.24 ppm and 1.9 ppm. Larvae were more sensitive to oil than adults. The sensitivity of larvae depended on species and developmental stage. Larvae are probably more vulnerable than adults to oil exposure because of greater sensitivity to oil and greater susceptibility to predation. Cold-water species may be particularly vulnerable because of increased time spent as developing larvae.