The Gulf of Mexico is an oceanic basin characterized by extensive hydrocarbon reserves. The western and central portions of the Gulf's continental slope are subject to natural seepage of oil and gas into overlying sediments and waters. The daily dose of hydrocarbon from these sources is at most 3% of the daily discharge from the recent Macondo well blowout. Natural seeps provide valuable laboratories for studying how chemical and biological processes respond to hydrocarbon inputs. These seeps provide modest inputs of oil and gas over hundreds to thousands of years of ecological integration. In contrast, the Macondo blowout injected massive quantities of oil and gas into a focused area, impacting Gulf of Mexico deep waters and sediments, as well as coastal ecosystems. An integrated project will compare the impacts of natural seepage and Macondo blowout hydrocarbon releases on foodwebs, biological signatures, and carbon and sulfur cycling at natural seeps near the Macondo wellhead, and at sites impacted directly by the Macondo blowout. The findings of this project will be compared with results from prior studies of Gulf sites not impacted by either natural or Macondo hydrocarbon releases. At natural seeps, experimental studies will include amendments of water column and sediment samples with various oil/gas/dispersant mixtures to document the response of microbial communities to hydrocarbon inputs and to dispersants. The investigator group is uniquely positioned to evaluate both impacts and ecosystem recovery trajectory of Macondo-impacted sites because of an extensive post-Macondo time- series data set (May 2010 through July 2011, so far, via re-direction of previously scheduled cruises) and through prior studies of hydrocarbon-rich sites throughout the northern Gulf over several preceding decades.

The proposed studies will address GRI research themes 1 through 4 and will generate data to advance substantially the understanding of microbial as well as physical processing and redistribution of hydrocarbons in northern Gulf slope deepwater ecosystems. Such studies are highly relevant for quantifying the ecological impacts of the Macondo blowout while advancing scientific knowledge to help understand and predict the impacts of future hydrocarbon releases. Specific objectives include:

1. elucidating the effects of biological activity and physical processes versus dispersant application on oil transfer between surface waters, deep water, and sediments;
2. quantifying the impact of oil inputs on water column biological community composition, activity, carbon flow, and food webs;
3. defining how sedimented oil influences benthic (microbial and invertebrate) and water column (microbial) community composition and performance;
4. tracking recovery and documenting the controls on recovery for benthic and pelagic systems impacted by the Macondo Blowout; and,
5. developing tools and techniques to track and characterize hydrocarbons as they are biologically processed.

This project brings together an interdisciplinary, highly qualified research team from fourteen institutions (Florida State University (FSU), Georgia Institute of Technology (GT), J Craig Venter Institute (JCVI), Columbia - Lamont Doherty Earth Observatory (LDEO), Penn State University (PSU), University of Georgia (UGA), University of Mississippi (UM), University of North Carolina (UNC), Oregon State University (OSU), University of Southern Mississippi (USM), Temple University (TU), University of California Santa Barbara (UCSB), University of Maryland (UM-CBL) and University of Texas (UT); a detailed description of the institutional components and investigator expertise are provided in section 4c (Partnership Table) with expertise ranging from biology (GT, LEDO, UCSB, UT) to microbiology (JCVI, UGA, UNC) and molecular biology (JCVI, UGA, UNC) to analytical (LDEO, UGA, UNC, OSU) and isotopic (FSU, GT, UNC) chemistry and biogeochemistry (UGA, UNC) to megafauna (PSU, TU, UM), systems ecology (PSU, TU), numerical modeling (GT, UGA) and remote sensing (FSU, GT, LDEO, UNC, UM-CBL, USM). Cutting-edge techniques will be employed to quantify the fluxes of hydrocarbons and other chemical species from the seafloor through the water column, to constrain composition of biological communities and their functional response to these hydrocarbon inputs, and to understand the return flux of hydrocarbons, introduced into the water column, to the seafloor (e.g., "oil snow"). We will maintain a persistent observational presence on the seafloor using remote cameras, chemical sensor arrays, and in situ samplers deployed on benthic lander systems, lagrangian profilers in the water column, and satellite remote sensing of surface waters. These observations will provide the long term, continuous data sets needed to document the biological, chemical, and physical dynamics at natural seeps and at sites recovering from impacts of the Macondo Blowout.

By spanning a range of sites - from natural seeps and to areas impacted and influenced significantly by the Macondo blowout - this project will provide an unprecedented opportunity to characterize the biological response to hydrocarbon inputs across a range of depths, to elucidate the environmental parameters that regulate the growth and activity of hydrocarbon degrading microorganisms in nature, and to quantify the extent to which hydrocarbon-based production of energy and carbon impacts other organisms in the habitat. These efforts, which build up from microscale processes, will provide critical insights for understanding biogeochemical cycles at the macro scale, including the responses of rich marine ecosystems to any potential future oil release.

This novel and uniquely multidisciplinary effort quantifies the impacts of hydrocarbon seepage on biological processes through a comprehensive program of field and laboratory studies. A broad range of ongoing and planned studies of microbial biogeochemistry, biodiversity, and microbial hydrocarbon processing, will be integrated with the larger Northern Gulf marine ecosystem response to hydrocarbon inputs at different trophic levels in water column and sediment. For example, hard-ground megafaunal communities occur over a large region of the northern Gulf and this work will contribute to understanding resilience and responses in those communities. This integrated ecosystem trajectory, from microorganisms to megafauna, from pre- to post-Macondo blowout at multiple sites in the Northern Gulf, will be the major focus of education, training of postdoctoral fellows, graduate and undergraduate students and public outreach. Not limiting itself to retrospective understanding, the proposed work will generate predictive modeling capabilities to constrain hydrocarbon impacts on biological processes throughout the world ocean. Knowing the biogeochemical and biological consequences, feedback mechanisms, and geospatial dynamics of the Macondo blowout in its relation to the Northern Gulf of Mexico ecosystem will help better prepare the scientific community and emergency responders to delineate potential impacts of accidental hydrocarbon releases in the future.