Toxicity of sediment-associated PAHs to an estuarine copepod: Effects on survival, feeding, reproduction and behavior

The toxicities of sediment-associated phenanthrene, fluoranthene and diesel fuel to the estuarine copepod Schizopera knabeni Lang were investigated. The 4-d LC50 was lowest for diesel fuel (194 μg/dry g), followed by phenanthrene (473 μg/dry g) and fluoranthene (> 2,100 μg/dry g). Sublethal effects on grazing rate were assessed in 30 h exposures using 14C-labeled microalgae. Feeding was inhibited at concentrations well below the 96 h LC50 values (50% decrease at concentrations ranging from 48 to 94 μg/dry g), probably due to the narcotizing effect of PAH. PAH effects on offspring production were examined by exposing individual copulating pairs to sediment treatments for 14 d. No significant effect on clutch size was observed; however, PAHs decreased nauplii and copepodite production at sublethal sediment concentrations (50% decrease at concentrations ranging from 38 to 64 μg/dry g). Schizopera knabeni actively detected and avoided PAH-amended sediment, as determined in preference/avoidance experiments. Although mortality only occurs at exceedingly high concentrations, PAH sublethal effects will likely reduce fitness and alter S. knabeni distribution and abundance in heavily contaminated sites.