EXPERIMENTAL INVESTIGATION OF THE EFFECTS OF POLYNUCLEAR AROMATIC-HYDROCARBONS ON AN ESTUARINE SEDIMENT FOOD-WEB

The influence of polynuclear aromatic hydrocarbons (PAH) on a benthic estuarine sedimentary salt-marsh food web was examined using a microco sm system to simulate natural conditions. Microcosms were dosed with s ublethal concentrations of PAH-contaminated sediment collected from a produced-water site at Pass Fourchon, Louisiana, USA (final PAH concen trations ranged from 0.3 to 3 mg PAH/kg dry sediment). Bacterial activ ity, physiological condition and abundance were not influenced by PAH, but microalgal activity and physiological condition were. Crazing by meiobenthic copepods on benthic microalgae was not significantly influ enced by PAH concentration, nor was the physiological condition of cop epods, as determined by their lipid-storage material. Meiofaunal commu nity composition was influenced by PAH, as nematodes became disproport ionately abundant, and the nauplius/copepod ratio increased in High-PA H treatments, Overall, however, sublethal effects of PAH were not pron ounced at the concentrations examined. Considering that coastal Louisi ana has been exposed to chronic contamination by petroleum hydrocarbon s for decades, it is suggested that the sedimentary microbial/meiofaun al community may have adapted to elevated PAH concentrations.