The Deepwater Horizon oil spill is effectively a large-scale tracer release. The large pulse of carbon from the spill that has entered the marine environment provides an opportunity to both better understand the functioning of coastal ecosystems and investigate the effects of the spill on coastal food webs and fisheries. This material is unique in terms of its isotopic composition, both in terms of 13C, 14C, and possibly 34S. We hypothesize that this pulse of radiocarbon-free dead carbon will be assimilated into the food web, with potential long-term effects on the capacity of coastal ecosystems to support living resources including fisheries.
We propose to investigate the effects of the spill on Gulf coast ecosystems with a particular emphasis on the trophic interactions and food web dynamics that support major fisheries in the Gulf. We will concentrate our efforts on the natural abundance 14C, 15N & 34S to trace the fate of the oil, its derivatives, and associated dispersants into and through the coastal and offshore food web.
1. Baseline pre-impact samples have been obtained in Louisiana, Mississippi, Alabama, and Florida
2. Post-impact samples have been collected along the Gulf Coast from May to November 2010 at a variety of sites from the Texas border to the Big Bend region of Florida
3. Offshore samples have been collected across the Gulf in September and in October on cruises by our collaborators, Dr. Samantha Joye (UGA), Dr. Charlotte Bruner (USM), and Dr. Chuck Fisher (PSU)
Our sampling scheme allows us to characterize the 14C signature of coastal food webs prior to, during, and after oil impact as well as across a spatial gradient in impact severity, thus allowing us to effectively trace its effects through the food web. Our work will examine both offshore and coastal animal communities and sediments. We have also identified archived samples from ongoing monitoring efforts that can be used to extend our analysis months to years before the spill.