Resilience of the zooplankton community in the northeast Gulf of Mexico during and after the Deepwater Horizon oil spill

Abstract

We evaluated the resilience of the zooplankton community to the Deepwater Horizon oil spill in the northeast Gulf of Mexico, by assessing abundance, biomass, spatial distribution, species composition, and diversity indices during spring, summer, and winter, May 2010 to August 2014. SEAMAP samples collected between spring and summer 2005–2009 were analyzed as a baseline. Our results did not indicate that there was a long-term impact from the oil spill, but did demonstrate that environmental variability and riverine processes strongly governed zooplankton community dynamics. Zooplankton abundances during the oil spill (spring 2010) were not significantly different from abundances during spring 2011 and 2012. Summer 2010 abundances were the highest observed for the 2005 to 2014 period, due to high river discharge, high chlorophyll, and aggregation in eddies. High densities of the dinoflagellate, Noctiluca, during the oil spill, and the copepod, Centropages velificatus, and larvaceans in all years, suggest that these taxa warrant further investigation. Ecosystem connectivity (zooplankton transport by currents into the oil spill region), high fecundity, relatively short generation times, and refugia in deeper depths are key factors in zooplankton resilience to major perturbations. This study serves as a baseline for assessment of future impacts to this system.