Project Overview

Summary:

Overview

In January 2015, Dr. Nancy Rabalais and the Louisiana Universities Marine Consortium was awarded an RFP-IV grant at $16,113,929 to lead the GoMRI Coastal Waters Consortium (CWC-II) which consisted of 14 collaborative institutions and 194 research team members (including students). CWC-II builds on results from RFP-I and continues to provide a better understanding of the fate and continued degradation of oil, its influence on food web structure, how the resulting shifts influence populations, individuals, and ecosystem functions during the recovery phase, and the interaction of oiling impacts with the other ecosystem stressors.

Outreach

Over its award period (3 years, plus a 12-month no-cost extension), CWC-II organized approximately 200 outreach activities or products, including:

• Development of the Science and Technology Advisory Team (STAT) for the Region 6 Regional Contingency Plan (Ann Hayward Walker). This plan addresses contingency planning and partnership gaps, especially with academia and other external technical specialists.  Having the capability to engage with all stakeholder groups will help cultivate a broad capability to understand, monitor, characterize, and model hazards that can inform all levels of preparedness and response decisions.
• Participation of CWC researchers in seminar in Biloxi: How does science help manage oil spills? What information could help us strengthen oil spill response? How can we improve data sharing so it is early and often and collected in a format that can be used by all?
• One National Academies of Science, Gulf Research Program 2018 Gulf Research Program Fellow (Elizabeth Robinson, Nancy Rabalais) and one National Academies of Science, Gulf Research Program Early-Career Research Fellowships, Dr. J. Cameron Thrash, mentored by Dr. Nancy Rabalais.
• Development of Seafood Industry Liaison Specialist (SIL) Regional Contingency Plan by Ann Hayward Walker that addresses contingency planning and partnership gaps, especially with the seafood industry and related technical specialists.  Having the capability to engage with all stakeholder groups will help cultivate a broad capability to understand, monitor, characterize, and model hazards that can inform all levels of preparedness and response decisions.
• Continued experiential learning experiences for elementary, middle school and high school students, including field trips and science camps.

Research Highlights

As of January 31, 2019, CWC-II research, which entailed around 200 research cruises/expeditions, resulted in 37 peer-reviewed publications, more than 180 scientific presentations and 120 datasets being submitted to the GoMRI Information and Data Cooperative (GRIIDC), which are/will be available to the public. CWC-II engaged 29 Masters and PhD students over its award period. Significant outcomes of CWC-II research according to GoMRI Research Themes are highlighted below.

Theme 1. Physical distribution, dispersion and transport of petroleum

• FVCOM models focusing on nearshore water transport within the Louisiana bight accurately reproduced the observed transport of oil slicks from the coastal waters into the Barataria estuary.
• Model experiments with river diversions to the east of the Mississippi River delta at the levels used in 2010 indicated that such actions would not prevent oil from entering those estuaries.
• Model experiments with river diversions into the Barataria Bay complex as envisioned by the Louisiana Coastal Protection Authority indicated major changes in estuarine and coastal water freshwater effects and circulation.
• Continued development including waves and sediments simulate oil and sediment transport, resuspension and deposition processes in the Barataria system, and marsh shoreline erosion rates.
  
  

Theme 2. The chemical evolution and degradation of petroleum hydrocarbons from the Deepwater Horizon oil spill

• CWC determined background levels of oil hydrocarbons in Louisiana marshes, pre-spill.
• There were multiple re-oiling of marsh habitats with storms and sediment resuspension and transport.
• Oil redistribution during Hurricane Isaac (2012) and other storms moved DWH oil residue farther into the marsh, up to 90 m.
• There was a degradation of the DWH oil signal and a shift from petrogenic to pyrogenic hydrocarbons with time.
• Total alkanes and total aromatics were not at background levels (but higher) in 2018 compared to pre-oiling in 2010.
• Pockets of fresh oil residue persist in marsh sediments, primarily in crab burrows.
  
  

Theme 3. The environmental effects in the Gulf of Mexico offshore, nearshore and marsh environments

• There is no evidence that DWH oil residues affected the typical seasonal development of bottom-water hypoxia in 2010.
• The 2010 shelf phytoplankton community composition differed from the longer-term data. Some shifts were lower abundance for some phytoplankton groups and higher abundance for other groups.
• Epifaunal and macroalgal communities were depressed at shelf edge banks closest to the well site.
  
  

Marsh Environments

• Heavily-oiled marsh shorelines eroded at a faster rate than those moderately- or lightly-oiled. Eroded marshes will not recover.
• Marsh sediment cohesion (shear strength measurements) was less in oiled than in unoiled marshes, but also less where nitrogen and phosphorus loads were higher.
• Shifts in ratios of specific hydrocarbon components in marsh sediments were reflected in marsh microbial communities.
• Marsh processes, e.g., phosphorus absorption, greenhouse gas fluxes, nitrogen and denitrification rates, were established over multiple habitats, seasons, and years, for the benefit of baseline data in the event of future oil spills
• Microbial community diversity increased over time post-spill as it approached that of unoiled reference sites.
  
  

Organisms and Populations

• Many observational and field experiments began at a time of declining or decreased total alkanes and total aromatics. Marsh organism and population dynamics were more broadly defined by marsh vegetation than reflections of oil residues.
• Some faunal groups did not recover for 5 years or longer; faunal recovery was related to vegetation recovery.
• Marsh nekton distribution did not differ in oiled vs unoiled marshes because of their ability to move, reduced exposure compared to experimental conditions, and population compensatory mechanisms.
• Seaside sparrows reproductive biology was decreased following exposure to DWH oil residues.
  
  

Food Webs

• There was evidence of petroleum hydrocarbon influence or uptake in several marsh organisms.
• A detailed marsh food web based on stable isotopes and fatty acid isotopes was developed for inclusion in larger models.

 Proposal Abstract - CWC-II