Stimulation of microbial activities and polycyclic aromatic hydrocarbon degradation in marine sediments inhabited by Capitella capitata

Abstract

The effect of the polychaete Capitella capitata on a variety of sediment microbial activities was determined for 5 months in marine microcosms with or without chronic treatment with the polycyclic aromatic hydrocarbon anthracene. Rates of microbial D[U-14C] glucose assimilation and respiration as well as rates and total amounts of [9-14C] anthracene mineralization were consistently greater in sediments with resident populations of Capitella. Anthracene treatment only affected 14C-anthracene mineralization such that after 5 months all sediments under chronic anthracene treatment mineralized 14C-anthracene more rapidly than sediments without anthracene or those containing only Capitella. Microbial incorporation of [methyl-3H] thymidine showed no consistent pattern among treatments. The colonization of sediments by total numbers of meiofauna and meiofauna-sized larvae was suppressed in microcosms dosed with anthracene, in contrast to the increased numbers in Capitella-inhabited microcosms. However, when Capitella was also present in anthracene-dosed microcosm sediments, the suppression of total meiofauna numbers was partially offset. These results indicate that the presence of infauna may significantly stimulate certain microbial activities and meiofauna colonization in marine sediments. As a result, mitigation of the effects of organic pollutants, as well as their elimination from sediments, may be enhanced in systems with robust microbe-infauna associations.