Heavily oiled salt marsh following the Deepwater Horizon oil spill, ecological comparisons of shoreline cleanup treatments and recovery

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doi: 10.1371/journal.pone.0132324
Authors:Zengel, Scott; Bernik, Brittany M.; Rutherford, Nicolle; Nixon, Zachary; Michel, Jacqueline
Author Affiliations:Primary:
NOAA, Emergency Response Division, Office of Response and Restoration, Seattle, WA, United States
Other:
Tulane University, United States
Volume Title:PLoS One
Source:PLoS One, 2015(e0132324). Publisher: Public Library of Science, San Francisco, CA, United States. ISSN: 1932-6203
Publication Date:2015
Note:In English. 74 refs.; illus., incl. sketch map
Summary:The Deepwater Horizon oil spill affected hundreds of kilometers of coastal wetland shorelines, including salt marshes with persistent heavy oiling that required intensive shoreline "cleanup" treatment. Oiled marsh treatment involves a delicate balance among: removing oil, speeding the degradation of remaining oil, protecting wildlife, fostering habitat recovery, and not causing further ecological damage with treatment. To examine the effectiveness and ecological effects of treatment during the emergency response, oiling characteristics and ecological parameters were compared over two years among heavily oiled test plots subject to: manual treatment, mechanical treatment, natural recovery (no treatment, oiled control), as well as adjacent reference conditions. An additional experiment compared areas with and without vegetation planting following treatment. Negative effects of persistent heavy oiling on marsh vegetation, intertidal invertebrates, and shoreline erosion were observed. In areas without treatment, oiling conditions and negative effects for most marsh parameters did not considerably improve over two years. Both manual and mechanical treatment were effective at improving oiling conditions and vegetation characteristics, beginning the recovery process, though recovery was not complete by two years. Mechanical treatment had additional negative effects of mixing oil into the marsh soils and further accelerating erosion. Manual treatment appeared to strike the right balance between improving oiling and habitat conditions while not causing additional detrimental effects. However, even with these improvements, marsh periwinkle snails showed minimal signs of recovery through two years, suggesting that some ecosystem components may lag vegetation recovery. Planting following treatment quickened vegetation recovery and reduced shoreline erosion. Faced with comparable marsh oiling in the future, we would recommend manual treatment followed by planting. We caution against the use of intensive treatment methods with lesser marsh oiling. Oiled controls (no treatment "set-asides") are essential for judging marsh treatment effectiveness and ecological effects; we recommend their use when applying intensive treatment methods.
Subjects:Aromatic hydrocarbons; Coastal environment; Deepwater Horizon oil spill; Ecology; Environmental analysis; Erosion; Hydrocarbons; Littoral erosion; Marshes; Methods; Mires; Oil spills; Organic compounds; Pollution; Polycyclic aromatic hydrocarbons; Remediation; Salt marshes; Soil pollution; Vegetation; Barataria Bay; Louisiana; Plaquemines Parish Louisiana; United States
Coordinates:N292700 N292700 W0895300 W0895300
Record ID:2016082060
Copyright Information:GeoRef, Copyright 2020 American Geosciences Institute.
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