Short-Term Effects of an Oil Spill on Marsh-Edge Fishes and Decapod Crustaceans

On 19 April 2005, an oil spill occurred in southeastern Louisiana's Barataria Bay estuary. We used a drop sampler to characterize the marsh-edge nekton community. Thirty-six locations were sampled in pre- and post-spill time frames from March through May 2005. Before-after control-impact (BACI) analyses of the total number of individuals (fishes + decapod crustaceans), total fishes, and sensitive species found significant interactions between the temporal (before/after) and spatial (control/impact) treatments and indicated an effect of the oil spill. Nonparametric analyses detected varied faunal assemblages across temporal treatments, but were similar in species composition among spatial treatments. While the BACI analyses showed event effects, differences were not strongly detected in nonparametric analyses of community structure. Fish are mobile and left the spill area after the disturbance, whereas the less mobile but more numerous benthic decapod crustaceans remained. The overall community structure appears to be robust and quickly recovered from the localized spill event.