Salt Marsh Bacterial Community Response to the Deepwater Horizon Oil Spill

Abstract

The Deepwater Horizon (DWH) Oil Spill, which occurred on April 20, 2010, remains the largest offshore oil spill in U.S. history, causing catastrophic impacts on the ecosystems in the Gulf of Mexico coastal regions. The objective of this study was to investigate if there was any long-term ecological impact of oil contamination on the leaf, soil, and root bacterial communities at Bay Jimmy and Fort Fourchon in Louisiana nine years after the DWH blowout occurred. Statistical analysis of alpha diversity, beta diversity, and differential abundance was performed according to each sample type (Leaf, Root, Soil) in response to oil history and sites (Bay Jimmy and Fort Fourchon) to analyze the bacterial 16S rRNA genes and characterize changes in the community abundance, diversity, and composition. The results revealed that none of the bacterial communities within each sample type had a significant difference in the abundance and diversity between sites and oil history. However, the soil and root community compositions differed significantly between Bay Jimmy and Fort Fourchon, as well as between oiled environment and non-oiled environment. The leaf community composition only varied significantly between sites. Sample type and site accounted for a larger variance in the community composition changes than oil contamination. The results of this study provide an analysis of the long-term impacts of the oil spill on the studied bacterial communities, which might provide some support for future investigations of the interactions between plant-associated bacteria and the biodegradation of oil spill at other places with a similar ecosystem.