RAPID: Resolving higher trophic-level change within the northern Gulf of Mexico ecosystem as a consequence of the Deepwater Horizon oil spill

Marine Environmental Sciences Consortium, Dauphin Island AL

Investigators

Abstract

Intellectual Merit: On April 22, 2010, the semi-submersible drill platform Deepwater Horizon sank in nearly 1,200 m of water in the northern Gulf of Mexico. After several attempts to close a failed blowout preventer valve, it became clear that tremendous amount of oil was being released each day. Pre-approval of undisclosed chemical dispersants was made based on knowledge of the dispersant application over limited areas and for limited time at the sea surface. An unprecedented volume of dispersant has been applied both at the surface and through direct injection into the wellhead leak at 1,200 m depth. The result is the release of large, but unquantified concentrations of organic carbon available for microbial degradation. To date, there is no plan for understanding functional ecosystem baseline shifts as a consequence of this magnitude of application of dispersants or the resulting re-distribution of oil or released compounds within the water column. Scientists posed the questions: Do these baseline shifts in resource (heterotrophic microbes versus autotrophic phytoplankton) permeate through the classical food web or remain largely within the microbial web? If material enters the classical food web, does it favor fish or gelatinous zooplankton? It is vital to understand in this in both the short- and long-term because secondary producers represent the major link between primary production and higher trophic levels (e.g., piscivorous fish) by which energy (and contaminants) are incorporated into grazer food webs. Dr. Monty Graham will work with colleagues on a project aimed to characterizing ecosystem-level changes to the pelagic system of the northern Gulf of Mexico. This effort will specifically contribute a temporal component to a separately funded spatial component. The group will employ a trophic assessment using both gut contents and Carbon/Nitrogen stable isotope ratios of pelagic filter-feeding invertebrates (jellyfish) and vertebrates (planktivorous fish). These will be compared to SI and gut content information collected over the previous two years in the spill-impacted area east and west of the Mississippi River. Broader impacts The Dauphin Island Sea Lab is uniquely organized to provide educational experiences from kindergarten (Discovery Hall Programs) through Ph.D. (University Programs). This RAPID will provide an immediate educational benefit to an existing Ph.D. student, Ms. Isabella D'Ambra (University of South Alabama, Marine Sciences Dept.) who is currently working on the trophic structure of nearshore pelagic communities using stable isotopes of carbon and nitrogen. In addition, one new scientist, Dr. Rob Condon will begin employment in June specifically to address trophic exchanges between microbial/detritus fractions to upper food-chain organisms. Moreover, this study will have an impact on the wider food-chain impacts of a major, chronic oil spill beyond what is noted by the simple acute damage to ecosystems.