RAPID: Impact of Nutrient Limitation on Microbial Degradation of Deepwater Horizon Oil in the Gulf of Mexico

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Natural microbial degradation plays an important role in the remediation of crude oil released to the marine environment. One important characteristic of the Deepwater Horizon oil release that could limit microbial degradation rates is that the oil is surfacing in waters that are highly depleted in available nutrients; microbes need these nutrients in order to grow and degrade oil. Although there have been comparatively few studies on N and P limitation of oil degradation since the 1980s, in the intervening time there have been major advances in our ability to assess the identity, activity and nutrient-limitation status of microbes in seawater; most of the early work centered on simply tracking the disappearance of oil over time, but now we have the ability to monitor the behavior of the microbial community in parallel. With funding through this Grant for Rapid Response Research (RAPID), a team of microbial biogeochemists at the Woods Hole Oceanographic Institution will examine how microbial heterotrophy, nutrients, and petroleum compounds in the oil spill interact. They posit that the obvious potential for nutrient limitation to impact the degradation of oil from the Deepwater Horizon release warrants an immediate, targeted assessment of this issue in the Gulf of Mexico using up-to-date microbial and molecular methods. The study will achieve three objectives: 1) assess the degree to which microbes in the Gulf of Mexico are stressed by the unavailability of nutrients both inside and outside of areas contaminated by Deepwater Horizon oil; 2) examine the relationship between nutrient stress and the microbial degradation rate of Deepwater Horizon oil; 3) specifically determine whether oil degradation rates are stimulated by lecithin, a plant-derived, non-toxic, hydrophobic N- and P-containing organic nutrient. Broader impacts The Deepwater Horizon oil release is an event of historic significance that has the potential to severely negatively impact the environmental quality and economic competitiveness of our nation. The primary benefit of the proposed work will be to reveal potential biogeochemical barriers to microbial oil degradation that might be overcome through novel remediation efforts. In addition, by conducting measurements collected by the lead investigator in 2002, the project will have the secondary benefit of identifying perturbations in the phosphorous field that will be propagated throughout the food web, including Gulf of Mexico fisheries.