Projected Impact of Deepwater Horizon Oil Spill on U.S. Gulf Coast Wetlands

The Deepwater Horizon spill oiled coastal wetland ecosystems along the northern Gulf of Mexico. We present data on probable impacts and recovery of these impacted wetlands. Based on numerous greenhouse and field studies conducted primarily in coastal Louisiana, we suggest that marsh vegetation will recover naturally without need for intensive remediation. Oiled marshes may reduce the availability of habitat for mobile fish species, resulting in their translocation to unimpacted areas. Impacts on benthic organisms may result in shifts in microbial community structure, but they will probably recover in lightly oil-impacted areas. The degradation rate or length of time oil remains in impacted wetlands depends on environmental conditions. Oil-impacted soils already contain adequate indigenous microorganisms capable of degradation under suitable environmental conditions. Nutrient addition, especially N, may increase the rate of oil biodegradation when sediment nutrient levels are low, but O2 availability appears to be the most important variable controlling oil degradation in marsh soils. Oil impacts on sediment O2 demand and restriction in O2 exchange at the sediment–water interface can alter biogeochemical processes and gaseous exchange (CO2 and CH4) with the atmosphere. Even though there were harmful impacts resulting from the Deepwater Horizon oil spill, prior research has demonstrated that Gulf Coast marshes are resilient and can recover. This view is supported by field observations of new shoots appearing in heavily oiled marshes 1 yr following the spill. Even though this review shows that Gulf Coast marshes have a high natural recovery potential, many ecological processes have not been adequately quantified or identified.