Our vision is to understand how the presence of oil in the marine environment will trigger the production of substances by bacteria and phytoplankton that increases the formation of marine snow. Furthermore, we seek to understand how marine snow can impact the fate and transport of oil and dispersants in the ocean.
The explosion of the Deepwater Horizon (DwH) drilling rig in the northern Gulf of Mexico on April 20, 2010 released ~ 4.1 million barrels of oil over 84 days with an estimated 60% of this reaching the sea surface. It is known that weathering and the physical forces in the ocean affect both the distribution and properties of the oil released, and that opportunistic microbes play an important role in its degradation. However, there are few studies examining the interactions between oil, microbes (phytoplankton, bacteria) and the mucous they secrete. ADDOMEx brings together a group uniquely qualified to study the molecular-level chemistry of sparingly-soluble substances in complex systems and the associated microbial communities.
Our vision is to understand how the presence of oil in the marine environment triggers the production of exopolymeric substances (EPS) that may protect organisms from the oil, emulsify the oil, or both, which can result in the alteration of its degradation. The interaction among EPS, oils and the local environmental factors plays a critical role in determining the fate of oil (e.g., degradation, dispersion or sedimentation) from oil spills. The mission of this proposal is to develop a process-based understanding of the role that the secretions from marine microbes play in the fate of oil (e.g., degradation, dispersion or sedimentation) as well as how the dispersant Corexit affects these processes.
We aim to accomplish this mission by examining the microbial response to oil contamination at three levels:
- This level (Tier 1) consists of small scale (no more than 1 L) laboratory experiments on individual bacterial and phytoplankton species to test the impact of oil and/or Corexit and other pertinent stressors on the microbial growth rate and their EPS production.
- The second tier consists of medium sized (6 L) roller table experiments with individual species as well as mixed microbial populations from the Gulf of Mexico to study the interaction of EPS produced by different oil degrading bacterial and phytoplankton with oil and/or Corexit under a few selected conditions (following findings in Tier1)
- The third tier of experiments will consist of large (100 L) mesocosm experiments to study the interactions between natural microbial communities, EPS and oil/and or Corexit. Naturally produced particles from the Gulf of Mexico will be collected to seed experiments in Tier 2 & 3.
Small scale lab microchip and batch culture experiments conducted in Tier 1 will allow us to test a large number of concentrations and factors driving the oil-microbe interactions, which then determine which combinations are used at the roller table and mesocosm tiers. In turn, the interpretation of complex interactions at the higher tiers (mesocosms) will be guided by the outcomes of the simpler microchip, batch culture, and roller table experiments.
Our researchers hypothesize that microbes in the marine environment, such as bacteria and phytoplankton, respond to oil and dispersant (Corexit), by producing exopolymeric substances which interact with minerals, organic particles and organisms. This capability is believed to play a major role in determining the fate, distribution and potential effects of oil and other hydrocarbon pollutants. The most important and unique impact of the proposed research is to establish the interactive mechanisms of oil/dispersants, marine microbes, EPS and various environmental factors that could critically determine the fate of oil pollutants and the associated ecological impact. This information can serve as the basis to establish improved predictive models for the risk assessment, to develop potential interventions to reduce the environmental impact and to formulate better responding/management plans for future oil spill incidents.