ECOLOGICAL CONSEQUENCES OF ENVIRONMENTAL PERTURBATIONS ASSOCIATED WITH OFFSHORE HYDROCARBON PRODUCTION - A PERSPECTIVE ON LONG-TERM EXPOSURES IN THE GULF-OF-MEXICO

A synthesis of the Literature on benthic responses to marine pollution suggests that macroinfaunal and meiofaunal communities exhibit repeat able patterns of response to sedimentary contamination generally detec table at high taxonomic levels (even phylum). These responses appear t o be jointly driven by intrinsic physiological and ecological characte ristics of higher taxa, such that crustaceans (especially amphipods an d harpacticoids) and echinoderms are sensitive to toxics whereas polyc haetes, oligochaetes, and nematodes (especially non-selective deposit feeders) are enhanced by organic enrichment. Application of this model to the GOOMEX results implies involvement of both toxicity and organi c enrichment. Results of toxicity tests and comparisons of observed co ntaminant concentrations to known effects levels imply that metals dri ve the toxicity response. We conclude that (1) long-lasting effects of drilling activity exist in the sedimentary environment around gas pro duction platforms, (2) dual effects of toxicity and organic enrichment probably drive readily detectable responses in benthic meiofauna and macroinfauna to 100-200 m, and (3) the failure to detect evidence of e xposure or sublethal impacts on fishes and most larger invertebrates i s a joint consequence of their mobility over the relevant scales of en vironmental change and their negligible exposure to hydrocarbons and o ther contaminants.