This is a RAPID response to the Deepwater Horizon Oil Spill. The PIs will assess the impact of Deepwater Horizon oil and dispersants on sediments and benthic communities of 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. They will acquire a MC-800 multicorer system to sample the sediments along three depth transects, one where subsurface oil is suspected and two transects where the areas are not yet affected by the spill. Samples will be collected on an 8-day cruise aboard R/V Wetherbird II. Core samples will be dated by radioisotopes and chemically analyzed for oil and dispersants.
Broader impacts: Assessing the impact of the oil spill from Deepwater Horizon and the subsequent use of dispersants on the West Florida slope and shelf is an important component of the regions disaster assessment program. The study will also provide a pre-impact baseline for future monitoring. A graduate student will be involved in outreach at the 9th grade level by conducting hands-on exercises to assess the impacts of oil spill. Results will also be used in marine science courses.
We proposed 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 to gauge the effects on benthic habitat critical to nearby fisheries and marine protected areas. We proposed to acquire a new Ocean Instruments MC-800 multicore system to sample sediments along three depth transects that intersect suspected layers of subsurface oil at approximately 400 m and 1400 m water depth. The transects were aligned with those identified in the College of Marine Science’s Initial Baseline Survey. Two transects sampled areas influenced by the spill (PCB and DSH), extending from offshore Pensacola and Panama City to approximately 1600 m in DeSoto Canyon. The third transect sampled areas not affected by the spill, extending from the Tampa Bay region across the West Florida Slope. We collected samples from these transects on four cruises aboard the R/V Weatherbird II. Core samples were 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 (single celled zooplankton) and their shell chemistry were quantified to assess the impact on benthic communities. A pulse of sediment was detected at the surface of the sediment cores collected during and following the Deepwater Horizon event (higher rates of deposition relative to the pre-deepwater horizon period). This pulse of sediment included higher concentrations of petrochemical. The increased deposition of petrochemical and potentially their direct contact with the sediments caused a decline in the number of single-celled zooplankton (foraminifera) that live in the sediments. The foraminiferal contact with increased concentrations of petrochemical also changed the chemical composition of their shells. Overall, the detection of a sediment pulse (flocculent blizzard) and the direct contact of petrochemical plumes (bathtub ring) on the sediments lends evidence for two fundamental ways petrochemical can be deposited during petrochemical releases, yields better understanding of the chemical, physical, biological, and geological processes that occur during these events, and aids decision making and response efforts for future petrochemical release events.
