Toxicological Impacts of Oil on Blue Crab (Callinectes sapidus) Megalopae Following the Deepwater Horizon Oil Spill

Blue crabs, Callinectes sapidus, are an important ecological species in Mississippi and Louisiana.  Blue crab life history includes a marine larval stage vulnerable to environmental changes in the Gulf of Mexico, particularly on the continental shelf from March through October.   At it’s peak, the Deepwater Horizon (DWH) oil spill on the continental shelf extended from the Louisiana to Florida.  There is high spatial and temporal overlap between blue crab larvae and the DWH oil spill area and it is critical to examine effects of the oil spill on larval survival and recruitment.  We report on results of our NSF-funded research into toxicological impacts of crude oil and dispersant on larval blue crab growth and survival, as well as a field study in 2010 to assess recruitment success of blue crabs in coastal Mississippi as compared to historical patterns.  Laboratory assays of larval survival as a function of crude and dispersed oil concentration and exposure time were conducted using cultured blue crab larvae.  Blue crab megalopal settlement rates were measured daily using simple settlement collectors between July 1 and Oct 31, 2010.  The results of this study are a test of the hypothesis that recruitment was significantly lower in 2010 than in any previous year for which we have data.  Further the assay data will be combined with published data on oil concentration in the Gulf of Mexico in a population matrix model to establish a link between changes in megalopal delivery to the coastal zone in 2010 and the possibility of oil-induced larval and megalopal mortality.