Long-term impact of the Deepwater Horizon oil well blowout on methane oxidation dynamics in the northern Gulf of Mexico

Abstract

The Deepwater Horizon oil well blowout discharged an unprecedented amount of methane into the water column of the northern Gulf of Mexico between April and July 2010. The methanotrophic community bloomed in response to the sustained methane release, resulting in the highest methane oxidation rates measured in the water column of an open ocean environment to date. To assess the long-term impact and recovery of the northern Gulf of Mexico methanotrophic community, we tracked methane dynamics for five years post-blowout. We determined methane concentration and methane oxidation rates at 31 different sites, resulting in ~900 discrete water column samples across the northern Gulf ecosystem, the largest compilation of methane oxidation rate measurements in an offshore ocean environment. Though methane concentrations approached pre-blowout concentrations within one year, methane oxidation rates exhibited a more gradual trend of decreasing activity. These results suggest that Gulf-wide circulation patterns dispersed and redistributed methanotrophic biomass that bloomed and accumulated in the wake of the Deepwater Horizon blowout, and that this biomass was able to perpetuate elevated methanotrophic activity for multiple years after the blowout at levels above anticipated background rates. This dataset provides a rare view of the response of an ocean ecosystem to a large pulse of methane and reveals unanticipated dynamics of microbial methanotrophy as a result of such human-induced methane releases.