Project Overview

Summary:

Overview

Florida State University (PI, Dr. Eric Chassignet) received an RFP-I award from GoMRI of $20,245,000 for the Deep Sea to Coast Connectivity in the Eastern Gulf of Mexico (Deep-C) Consortium that consisted of 14 collaborative institutions and 306 researchers. The goals included: (1) generating quantitative data on the physical, chemical, and biological systems of the northeastern Gulf of Mexico, including regions affected by the Deepwater Horizon (DwH) oil spill; and 2) integrating these data into earth system and food web models to improve prediction of the path, fate, and consequences of crude oil and gas released from the northeastern deep Gulf through natural or anthropogenic causes to support improved responses to future incidents.

Research Highlights

As of December 31, 2015,Deep-C researchers (including 91 students) conducted 75 research expeditions, produced 156 datasets resulting in125 peer-reviewed publications, and made more than 500 scientific presentations. The datasets, residing in the GoMRI Information and Data Cooperative, are available to the public. Below are significant outcomes.

Theme 1: Physical Processes

• Deep-C research found that large-scale, low-frequency downwelling events can move isopycnals more than 100m vertically up or down the De Soto Canyon continental slope and that these events are two to four times more likely than upwelling events to occur when the Loop Current impinges on the slope along the southern West Florida Shelf. Loop Current contact with the slope spawns a high-pressure sea-surface height (SSH) anomaly that transits the slope toward the Mississippi Delta in the topographic Rossby wave direction. This high SSH suppresses isopycnals below, causing downwelling and/or hindering upwelling.
• Deep-C research revealed that the geostrophic eddy field significantly affects upwelling response to tropical cyclones. In addition to translation speed, this response is a function of the curl of wind-accelerated geostrophic currents, rather than just the curl of wind stress. Results underscore the need for initializing coupled numerical models with realistic ocean states to correctly resolve the three-dimensional upwelling-downwelling responses and improve intensity forecasting. Vertical velocities over the upper ocean play a key role in transporting and dispersing nutrients, larvae, suspended matter, and oil products throughout the water column. Velocities peak during and in the wake of major wind-forcing events.
• Impacts of the DwH oil spill on benthic communities were observed by Deep-C researchers in the outer shelf regions, implying that (1) oil reached the impacted area via the surface layers, not the mid-water plume; and (2) recovery of slow-growing corals will be lengthy.
• Deep-C and the NOAA Ocean Exploration collaborated to conduct a high-resolution bathymetric survey of the De Soto Canyon. Results informed selection of an array of sampling sites subsequently occupied by Deep-C and C-IMAGE consortia members.
• Deep-C scientists developed a unique survey platform, modular instrument lander, and equipment toolsled (MILET) for collecting geo-located images and sub-bottom profiles. An opportunistic MILET survey of a small mound at 2000m depth, where the Ocean Explorer cruise reported gas bubbles, yielded discovery of an asphalt seep, the first reported in the eastern Gulf (seeps are rare in the eastern Gulf area surveyed).

Theme 2: Chemical/Biological Processes

• Deep C radiocarbon research provided indirect evidence that 3-5% of the oil released by the DwH spill was deposited on the sea floor as oil-derived carbon. Further, some carbon from the oil spill entered the food web primarily via methanotrophy, the impact of which is also revealed in methane assimilation in particulate organic matter. Isotopic signature of particulate organic carbon appears to be a good indicator of seepage impacts.
• Deep-C researchers identified a new pool of non-native, transformational products — oxygenated hydrocarbons in the weathered Macondo well oil by two-dimensional gas chromatography and catalyzed numerous fields of investigation. Results indicate a previously underreported chemodynamic process in oil spill weathering.
• Deep-C research demonstrated that impact studies using only unweathered Macondo well oil grossly underestimate the complexity and chemistry of the environmentally relevant Macondo oil contaminant. It  developed methods to isolate the transformation products as a function of structure (aromatic vs. nonaromatic) and chemical functionality (ketone, alcohol, carboxylic acid, etc.), revealing that Macondo well oil was quickly oxidized after entering the environment, generating tens-of-thousands of ketones, alcohols, and carboxylic acids. Separation methods now allow for isolation and subsequent dosing of microcosms with structurally and chemically defined fractions to ascertain each variable’s effect on toxicity.
• Deep-C found that environmental transformation generates tens-of-thousands of new compounds previously unobservable at the molecular level. Using the Fourier transform ion cyclotron resonance mass spectrometer, which successfully targets polar, high-boiling compounds in environmental samples, they found (1) that weathering generates nearly 20,000 new basic compounds not native to the parent Macondo well oil; and (2) that the same samples contain another 30,000 new acidic species. These new species are not gas chromatography-amenable.

Theme 3: Ecological Effects

• Deep-C scientists completed the largest GoM survey of deep-sea demersal fishes conducted to date, with this goal: to determine species diversity, distribution, abundance, life history, trophic interactions, and the physiological effects of pollutant exposure. The life history data collected represent the first records for many of these species. They examined spatial and temporal differences in PAH biomarker levels (cytochrome P4501a1, glutathione-S-transferase; biliary PAH metabolites) in fishes collected 1-2 y post spill, including the more abundant sharks and bony fishes. Results indicate: 1) higher biomarker levels in fish collected from oiled sites than those collected from non-oiled sites; 2) in some species, biomarker levels declined with distance from the DwH site; and 3) biomarker levels in elasmobranchs increased 2-3 y post spill and declined thereafter, whereas biomarker levels in bony fishes were higher earlier (1.5 y post spill) and then declines. These trends support the hypothesis linking differences in PAH exposure between oiled and non-oiled sites to the DWH oil spill.
• Oil contamination from the DwH spill profoundly affected the abundance, structure, and metabolic potential of sedimentary microbial communities along the NE Gulf coast. The microbial bloom appearing in beach sand immediately post-spill exceeded pre-spill levels by orders of magnitude. Microbes degraded weathered oil and succession of indigenous microbial populations paralleled degradation of petroleum hydrocarbons, leading to decreased taxonomic diversity and increased functional diversity. Pre-spill microbes were adapted to oligotrophic conditions. Oil degraders, latent in the sand and surface waters pre spill, appeared immediately post-spill, shifting from oil-eating to aromatic hydrocarbon decomposing microbes whereas function shifted between generalists and specialists.
• Deep-C research revealed differences in the response of hydrocarbon-degrading bacteria to Macondo crude oil and Corexit 9500A-dispersed oil. Corexit significantly inhibited both growth and crude oil degradation potential in some species, and enhanced it in others. The same species that enhance crude oil toxicity by producing biosurfactants can reduce dispersed-oil toxicity through degradation or sequestration. Crude oil attaches readily to sand grains to limit the depth of oil transport into marine sands. Corexit reduces adhesion of oil to sands thereby allowing PAHs to penetrate deeper into sediment, reaching groundwater levels.   
• The Deep-C Atlantis NEGoM food web model can incorporate yearly variability in water patterns. Scientists developed in the process:  (1) a food web Rglobi package that can pull data from the Global Biotic Interaction Database, speeding up model development and enhancing comparisons; and (2) an R package to allow rapid development and execution of future Atlantis model. Deep-C assisted C-IMAGE in adding an oil exposure functionality to Atlantis and collaborated with economists outside of GoMRI to merge new economic fishery models with large-scale ecological models.

Theme 4: Technology Developments

• The incorporation of wave models and the carbon, silicate, and nitrogen (CoSiNE) ecosystem model component into the coupled COAMPS ocean-atmosphere modeling system involved a long and overarching development and testing cycle. Once accomplished, Deep-C model experiments revealed that air-sea coupled simulations generate much more realistic conditions as compared to satellite estimates, which may offer improved spill response support. Further, sensitivity simulations conducted with the coupled Earth System Model in the Mississippi Bight revealed three important points:  1) the inclusion of river nutrient fluxes is critical, especially in the vicinity of the Mississippi River; 2) data assimilation in ecosystem models continues to be a challenge; and 3) the ecosystem (biological blooms) responded much more energetically to air-sea coupled (vs. non air-sea coupled) simulations.
• Deep-C’s analysis of historic observations and a high-resolution nested simulation of the De Soto Canyon revealed high-speed (30–50 cm/s or higher) near-bottom (1000 – 2000 m) currents during and following hurricane passages. Currents of this magnitude could suspend and transport oil deposited on the sea floor and could be damaging to oil and gas infrastructure. Model simulations show the strongest currents are linked with steep topographic features and persist for days to weeks as near-inertial oscillations. These observations will assist further characterization of these deep water regimes, as well as improve spill response and remediation efforts.
• Use of the Deep-C developed West Florida Coastal Ocean Model (WFCOM) demonstrated that coupled deep-ocean and local forcing drives the coastal ocean (defined as continental shelf and estuaries). Thus, accurate coastal ocean circulation modeling requires the nesting of unstructured and structured grid models, including, for example, nesting an estuary-specific model into WFCOM to demonstrate connectivity between shelf and estuary waters. This allows modeling how contaminants, such as spilled oil, flow within an estuary system, improving mitigation for and responses to oil spills.

Outreach

Deep-C organized more than 900 outreach activities or products, including:

• The Gulf of Mexico Multidisciplinary Curriculum for High School Students was developed around the five research areas of Deep-C: geomorphology, geochemistry, ecology, physical oceanography, and modeling. Each module includes five lessons, background information on the topic, relevant supplementary reading materials, a glossary, and an assessment.
• Deep-C ROV Competitions taught students about ROV use in marine industry and their importance in the DwH oil spill response; and ROV design, construction and operation. Training Workshops preceding the Competition showed educators how to integrate ROVs and marine science into STEM education efforts.
• The Gulf Oil Observers (GOO) Project trained students and others to be effective citizen scientists. The curriculum included lesson plans in the classroom and coastal expeditions to enhance knowledge of ocean science and oil spill research and put knowledge into action.
• Scientists in the Schools is a program placing researchers in local middle and high school classrooms to provide students with insights into the issues faced and the research conducted on the long term effects of the DwH oil spill.

Proposal Abstract - Deep-C