Distinguishing between contaminant and reef effects on meiofauna near offshore hydrocarbon platforms in the Gulf of Mexico

Abstract

Offshore hydrocarbon production effects are localized in the Gulf of Mexico extending only 200 m from platforms. Effects are caused by the contaminant gradient or the fouling community on platform legs. To distinguish between contaminant and reef effects, meiofauna were sampled at production platforms (reef and contaminant effects), artificial reefs (reef, but no contaminant effects), platform removal sites (contaminant, but no reef effects), and controls (no contaminants or reef effects), and replicated in three blocks. The removal sites had higher concentrations of many contaminants than reef or control sites, but lower concentrations than platform sites. Reduced meiobenthic abundances and altered Harpacticoida community structure were primarily a function of reef effects, not contaminant effects. The habitat influence is likely a result of complex ecological interactions near platforms. The reef effect appears to be important in controlling meiofauna near platforms where contaminants are low because of drilling and production techniques used in the Gulf of Mexico. The finding that contaminants alone do not explain faunal patterns around offshore platforms indicates that future studies should include appropriate artificial reef control sites.