COS 117-8 - Insights into Blue crab larval ecology from the Deepwater Horizon oil spill

Thursday, August 11, 2011: 4:00 PM
18A, Austin Convention Center
Erin Grey1, Caz M. Taylor2, Susan Chiasson2 and Michael Bartlein2, (1)Ecology & Evolutionary Biology, Tulane University, New Orleans, LA, (2)Ecology and Evolutionary Biology, Tulane University, New Orleans, LA

The Deepwater Horizon oil spill offered a unique opportunity to gain insights into larval dispersal in the Gulf of Mexico.  Starting prior to the spill, we are developing a particle-tracking model to simulate the dispersal of Blue crab (Callinectes sapidus) larvae in the Gulf of Mexico (GOM) and to estimate larval connectivity among bays and estuaries.  Our goal is to determine how connectivity influences the population variability of this commercially and ecologically important species.

The Deepwater Horizon oil spill coincided with the peak spawning period of Blue crabs.  Since Blue crab larvae inhabit surface waters and feed on a variety of plankton, it was likely that they would be exposed to both crude oil and dispersants that were applied widely to dissipate oil slicks.  To determine the effects of the oil spill on Blue crab larvae, we sampled megalopae (post-larvae) at coastal sites from Texas to Florida.  Megalopae recruitment rates were compared to baseline data when possible and samples were tested for spill-related compounds.  Dispersal simulations were used to determine which estuaries likely received spill-exposed larvae. 


Megalopae recruitment was highly variable in 2010, but we found no evidence that recruitment rates were significantly different from previous years.  Megalopae did, however, contain unusual orange lipid droplets underneath their carapaces that had not been observed in 40+ years of prior research in the GOM.  The proportion of megalopae with these droplets varied over time and space, as did the presence of spill-related compounds.  The spatio-temporal patterns of droplets and spill-related compounds and the simulations greatly enhance our understanding of Blue crab larval dispersal in the GOM.  Implications for fisheries management, oil spill remediation, and usefulness of particle-tracking models will be discussed.

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