Resolving Changes in Zooplankton Biomass and Community Composition During the DWH Oil Spill

The Deepwater Horizon (DWH) oil spill was unprecedented in virtually all measures of magnitude and duration of petroleum hydrocarbon loadings to the northern Gulf of Mexico. One of the lesser considered consequences of the release is the total load of organic carbon to an extremely productive system. Without minimizing the potential toxicological consequences, the DWH provided a unique opportunity to explore the nature trophic linkages between dissolved organic material, microbes, zooplankton and higher trophic levels. Here we present a summary of research activities that show rapid utilization of oil-carbon by microbes, yet while this carbon signal reached zooplankton, total nearshore mesozooplankton biomass was reduced during the spill. In addition, a striking shift in zooplankton community composition also occurred. We discuss these changes in terms of a shift in the forage base for important Gulf marine fishery species.