We propose to assess the impact of Deepwater Horizon oil and dispersants on sediments and benthic communities on the West Florida Shelf and Slope. In particular, assessing sub-surface oil and dispersants will gauge the effects on benthic habitat critical to nearby fisheries and marine protected areas. We propose to use a new Ocean Instruments MC-800 multicore system to sample sediments in three depth transects that intersect suspected layers of subsurface oil at approximately 400 m and 1400 m water depth.
The transects will be aligned with those identified in the College of Marine Science’s Initial Baseline Survey. One transect will sample areas currently influenced by the spill, and probably extend from offshore Pensacola to approximately 1600 m in DeSoto Canyon. The second and third transects will sample areas not yet affected by the spill, extending from the Appalachicola and Tampa Bay regions across the West Florida Slope normal to the isobaths. We plan to collect samples from these transects on an eight-day cruise aboard the R/V Weatherbird II, at no cost to this proposal. Core samples will be dated by radioisotope methods and analyzed for oil and dispersants by organic and inorganic geochemistry, including organic compounds and metals specific to Deepwater Horizon petroleum. In addition, benthic foraminiferal assemblages and their stable isotope geochemistry will be quantified to assess the impact on benthic communities. In this way we seek to document possible “bathtub rings” of sub-surface oil and dispersants and their effects on benthic habitats, as a baseline for future monitoring studies.