Project Overview

Summary:

In January 2018, Dr. Nancy Rabalais at the Louisiana Universities Marine Consortium, was awarded an RFP-VI grant totaling $4,799,897 to lead the GoMRI project entitled “Coastal Waters Consortium-III: Oil Spills as Stressors in Coastal Marshes - The Legacy and the Future (CWC-III)” which consisted of 14 collaborative institutions and approximately 89 research team members (including students).

The following broad goals for this project were intended to conclude the momentum that was started in the CWC-I and -II GoMRI-funded projects: 

1. 1. Finalize oil transport and fate models, assess their predictive skill, and provide model support for other CWC researchers;
      Track the chemical evolution and biological degradation of the petroleum/dispersant components in marsh and mesocosms;
   2. Finalize a seven-year baseline of oil contamination at the key sampling sites, and measure shoreline erosion, vegetation, and soil characteristics;
   3. Conclude mesocosm experiments of oiling on multiple ecosystem components, including oil degradation, soil characteristics, vegetation, microbes, organisms, predator-prey responses, and biogeochemistry;
   4. Complete a field and modeling study of the fluxes of water, sediment, nutrients, carbon and oil through Barataria Pass over an annual cycle and use it to evaluate the predictive skill of CWC models;
   5. Conclude individual and population food webs models using a variety of isotopic, compound specific, and fatty acid tracers for birds and marsh rats, and overall food webs;
   6. Focus specific sub-model attention on the effect of freshwater diversions on fish food webs;
   7. Synthesize data, tools and perspectives through workshops that transcend individual component groups to include other researchers (phytoplankton and microphytobenthos, modeling, nutrients and oil, carbon flux); and
   8. Prepare additional outreach activities, including a web-based interactive teaching/research project on a 2-dimensional Predictor Project, and a specific activity for transfer of research knowledge to practitioners.

Outreach Highlights

As of June 30, 2020, CWC-III research team members have participated in more than 40 outreach-related activities including school presentations and activities, workshops, field trips, scientific presentations, and stakeholder outreach.  Here are a few of our key outreach products and activities:

• A series of workshops led by Ann Hayward Walker engaged scientists and oil spill responders on Oil Spill Preparedness and Response, Tradeoff Decisions in the Gulf of Mexico, Facilitated Application of Science Results to Oil Spill Practitioners, and two new preparedness and response documents approved for the Region 6 Regional Contingency Plan (Appendices 41 and 42).
  
  
• The hallmarks of public education by CWC-III educators were experiential learning in the wetlands of south Louisiana. CWC-III educational programs were taken out of the LUMCON Marine Center to schools across the state to reach students who would not otherwise have a chance to learn about the marine environment. Much of the CWC-III educational support funds were used to reach underprivileged and underrepresented students, by paying for their transportation costs, substitute teachers, room and board, and use of vessels at the LUMCON Marine Center.

Research Highlights

As of June 30, 2020, this project’s research resulted in 23 peer-reviewed publications (with at least 17 near in press or accepted), 1 book chapter, 79 scientific presentations, and 63 datasets being submitted to the GoMRI Information and Data Cooperative (GRIIDC), which are/will be made available to the public. The project also engaged 11 PhD and 5 Masters students over its award period. Significant outcomes of this project’s research are highlighted below.

The 8-year funding of the Coastal Waters Consortium, over three competitive cycles, earlier NGI and NSF-RAPID funding, and the initiative of researchers before the oil came onshore provided a unique opportunity to study the effects of a large-scale oil spill in Louisiana coastal waters and salt marsh environments. Aspects of the research programs changed and evolved, but several components remained the same through the course of the GoMRI funding. Long-term data, short-term experiments, comparative studies, and large marsh mesocosms differentially dosed with crude oil provided much insight into the effects of the Deepwater Horizon oil spill on south Louisiana natural environments.

 The levels of hydrocarbons, particularly alkanes and aromatics, reached a peak from background levels within one month of oil coming onshore Louisiana. There was a steady decrease in the hydrocarbon concentrations until a new baseline was reached. The new baseline was well above the background prior to the spill. The chemical signature of the Macondo oil was absent within four years of sampling. With the initial delay in development of the GoMRI research program, some hydrocarbons had already changed in concentration and components when in field studies of marsh habitats began. Many of the CWC measurements began at that time and indicated a lessening of the effects of the oil spill, but may not have captured the full extent of the oil exposure. For instance, benthic macroinfauna increased after the first year of CWC collections then reached a plateau. It is possible that the initial, expected lower abundances might not have been captured as part of the delayed study.

Modeling of nearshore coastal circulation patterns provided clear patterns of oil movement onshore, into the Louisiana bight, and movement into Barataria Bay. Further model scenarios indicated that release of fresh water to the east of the Mississippi River did not work to keep oil out of the Chandeleurs or Lake Borgne. Further, the anticipated large diversions of fresh water into Barataria Bay on the west side of the Mississippi River will dramatically change circulation patterns and salinity in Barataria Bay and may result in changes to offshore circulation patterns.

Multiple long-term measurements from several groups should have, by now, demolished the idea that the coast is homogeneous in many aspects, including biogeochemical signals (microbial turnover, enzyme assays, morphometrics, marsh elevation, and historical of oiling before 2010).

We learned more about the susceptibility of marshes to oiling than was anticipated: 

1. 1. As expected, marshes that were heavily oiled suffered from high erosion rates and permanent loss of land.
   2. Other oiled marshes eroded but the rates were within the background marsh erosion rates of coastal Louisiana.
   3. The process of oiled shoreline erosion included an initial phase of rapid erosion followed by the loss of marshes on exposed promontories as a legacy effect.
   4. Hurricane Isaac in 2011 suspended and dispersed Macondo oil into marshes that were previously unoiled and to nearly 100 m into the marsh than the initial 5- to 10- m of oiling.
   5. Marshes were back to pre-spill conditions eight years later, although they are still recovering.
   6. There were no oil exposure versus oil exposure related changes to nitrogen cycling within Terrebonne Bay, but the experiments were conducted 2.5 to 3.5 years post-spill, indicating no loss of microbially-mediated nitrogen removal services the salt marshes provided. There were potential processes for which no differences were found including the time post-exposure that the studies began and marsh edge erosion.
   7. A baseline data set was established for many metrics that transcended various oil-specific measurements. These include diverse biological components, microbial population diversity and function, plant morphometrics, soil percent organic content, bird reproductive success, and marsh sediment microphytobenthos.

In nearshore waters, although oiling was visually repulsive and caused significant loss to wildlife, there was no measurable or inferred effect on the size of the summertime low oxygen event in 2010. There was as 2-3 year lifetime of oiling on the continental shelf before concentrations were at pre-spill conditions. Oil caused significant dolphin deaths across the northern Gulf of Mexico. Baseline data were developed for dolphin strandings indicating a strong dependency on menhaden as prey. Menhaden accumulated oil and their consumption may have been a major pathway for oil to enter into dolphin populations, which will not recover for decades.

It was difficult to tease apart natural variability and the migratory nature of many organisms from effects of oil exposure. Controlled experiments of experimental oil exposure in the laboratory with simulated marsh habitats or sea grass beds did result in lethal and sublethal impacts, including behavioral modifications, predator-prey interactions, and swimming and searching responses.

The large marsh mesocoms at the LUMCON Marine center, while difficult to develop and populate with plants and organisms within the time limits of CWC-III, are beginning to generate a wealth of data on the effects of different levels of oil exposure to plants, animals, microbes, and marsh processes. There will be a one-year post-exposure sampling in July 2020, with samples being worked up outside of GoMRI funding. These results will continue to be documented post-GoMRI. In addition, Dr. Roberts is finding and seeking funding to keep the mesocosms operating post-GoMRI.

There are many more reports/analyses/publications to be finished to add to the GoMRI and CWC legacy. The research projects were ambitious and productive, but not always able to complete their results within the funding cycles. They will continue to be presented in the scientific literature.

 Proposal Abstract - RFP-VI PI Nancy Rabalais