Summary:
We propose to continue and expand what has been a very successful NGI Phase I project, which is focused on determining if and where oil has reached the seafloor below the intertidal zone and if at these sites it has affected benthic ecosystems. Oil has been observed over large areas of the ocean surface and has been reported in thin, discrete layers on subsurface isopycnals. To date, there have been a number of qualitative observations reported indicating that some oil may have reached the sea floor at neritic to bathyal depths; however, comprehensive and quantitative data on this and related subjects remain lacking. Consequently, the crucial questions of if, where, and to what degree petroleum hydrocarbon and chemical dispersant contamination has had an impact on bottom sediment ecosystems across a very large area of the sea floor remain unanswered.
The proposed research is comprehensive and strongly multi-disciplinary by necessity. Field sampling has and will continue to include sedimentary environments in high-turbidity, coastal settings including the Mississippi, Chandeleur, and Breton Sounds, the continental shelf (LA, MS) and the deeper water environments of the continental slope and upper rise, nearer to the site of the Macondo well. Analytical elements will include organic geochemistry, to characterize the various biomarker compounds to assist in determining the source, primary degradation pathways, and degradation rates of the hydrocarbons; sedimentology, to determine how hydrocarbon contamination may alter sediment textures, geotechnical properties, and carbon storage capacity; radiochemistry, to quantify sediment mixing, rates of accumulation and chronology, which will ultimately allow for fluxes of oil to the seafloor to be determined; the collection and characterization of marine snow particulates from the water column, which may provide critical information on the impacts of oil pollution on benthic-pelagic coupling; and benthic ecology, specifically of meio- and macro-fauna, which will allow for the impacts of hydrocarbon contamination on ecosystem health to be assessed by examining changes in and recovery of overall biomass, species diversity, and community structure.
In addition to supporting multiple NGI Phase II investigators via ship time, this project will continue to integrate sampling and data sharing efforts with a substantial number of regional and national academic partners, and to serve the needs of a diverse group of stakeholders. Shared ship time and co-sampling will continue with those at the University of North Carolina (UNC, A. Teske, B. MacGregor), Texas A&M University (TAMU, P. Louchouarn), the University of Georgia (UGA, S. Joye), and Florida State University (FSU, J. Chanton). Cooperation and open communications with both NOAA and the federal multi-agency response consortia [Subsurface Monitoring Unit (SMU), Operational Science Advisory Team (OSATI)] will also continue.