Variations in benthic fauna underneath an effluent mixing zone at a marine oil terminal in Port Valdez, Alaska.

The distributions of hydrocarbons and infauna in sediments below a permitted mixing zone for the disposal of treated ballast waters in Port Valdez, Alaska were examined annually, 1999-2001. The associations of biological measures and the abundance of selected benthic organisms to total aromatic hydrocarbons (TARO) ranged up to large-sized effects, as compared against minimum-effect criteria (/r/> or =0.63). The apparent sensitivity of three polychaete worms to low levels of hydrocarbons makes them particularly useful as indicators of future changes in spatial distributions of hydrocarbons associated with discharged effluent. In 2001, sediment TARO concentrations decreased and the correlation values of TARO to biotic variables were generally less than in 1999 and 2000. Evidence supports a conclusion of a strong but spatially limited association of some fauna with accumulations of petroleum hydrocarbons in these sediments.