Meeting Abstract

36.1  Sunday, Jan. 5 08:00  Combinatorial effects of Corexit EC 9500A with abiotic and biotic stressors in the rotifer Brachionus plicatilis WILLIAMS, M.B.*; POWELL, M.L.; WATTS, S.A.; Univ. of Alabama at Birmingham, Birmingham, AL; Univ. of Alabama at Birmingham, Birmingham, AL; Univ. of Alabama at Birmingham, Birmingham, AL micwilli@uab.edu

Corexit EC 9500A (Corexit) is a surface acting agent that was implemented to facilitate ecosystem recovery following the recent Deep Water Horizon oil spill. Corexit acts to destabilize and disperse oil rafts, leading to enhanced degradation by naturally-occurring microbes. The direct chemical action of Corexit may also affect lipid components of living cells in lower trophic level marine fauna, endangering their populations. Toxic effects of Corexit dispersant on these primary producer/consumer populations can affect higher trophic level dynamics by altering carbon and energy transfer, thereby influencing ecosystem stability. Therefore, we examined the effects of Corexit on Brachionus plicatilis, a representative species of zooplankton in marine and estuarine ecosystems. Corexit exposure at standard husbandry conditions (17.5ppt salinity, 23 C, 200 rotifer/mL density) produced an LC50 value of 113 ppm for cultured B.plicatilis (probit analysis). At temperatures above annual Gulf coast shallow water medians (>22 C), the susceptibility of cultured populations to Corexit was substantially increased with the populations reaching an upper thermal survival temperature at lower temperatures as Corexit concentrations increased. In addition, increases in acclimation salinity and increases in rotifer population densities resulted in reduced survivorship when exposed to Corexit. These data suggest that outcomes associated with the exposure of wild populations of zooplankton to dispersant will vary depending on physical factors and community structure. These data can also be used to develop policies regulating the application of dispersants in future spills.