Corexit 9500A, the chemical dispersant used in the DWH oil spill, increases the toxicity of crude oil to marine microzooplankton

We conducted laboratory experiments to determine the effects of Corexit 9500 and dispersed crude oil on marine microzooplankton. We collected plankton samples in the field that were sieved and sorted to obtain individuals from 7 taxa that were then cultured in the lab for use in the study: Strombidum sp., Spirostrombidium sp., Eutintinnus pectinis, Favella ehrenbergii, Gyrodinium spirale, Protoperidinium divergens, Protoceratium sp. An additional species for use in this study, Oxyrrhis marina, was obtained from the University of Texas Culture Collection of Algae. 24 and 48 hour experiments were conducted exposing a single species to one of four conditions: control, crude oil emulsions, dispersant-treated crude oil emulsion, or a solution of dispersant alone in seawater. This dataset reports the cells counted for 2 –4 replicates of each species and treatment. Additionally, the EC50 is calculated for each species and treatment.