MEPS 576:175-187 (2017)  -  DOI: https://doi.org/10.3354/meps12147

Consequences of large-scale salinity alteration during the Deepwater Horizon oil spill on subtidal oyster populations

Sean P. Powers1,*, Jonathan H. Grabowski2, Henry Roman3, Amelia Geggel3,†, Shahrokh Rouhani4, Jacob Oehrig4, Mary Baker

1Department of Marine Sciences, University of South Alabama and the Dauphin Island Sea Lab, 101 Bienville Blvd., Dauphin Island, AL 36528, USA
2Marine Science Center, Northeastern University, 430 Nahant Road, Nahant, MA 01908, USA
3Industrial Economics, Inc., 2067 Massachusetts Ave., Cambridge, MA 02140, USA
4NewFields, Inc., 1349 W. Peachtree Street, Suite 2000, Atlanta, GA 30309, USA
5National Oceanic and Atmospheric Administration, Assessment and Restoration Division, 7600 Sand Point Way NE, Seattle, WA 98115, USA
*Corresponding author: Deceased
Advance View was available online June 15, 2017

ABSTRACT: Response actions associated with oil spills often have significant impacts on ecological communities. During the 87 d long Deepwater Horizon oil spill, the State of Louisiana (USA) released vast quantities of Mississippi River water into 2 estuarine basins (Barataria Bay and Black Bay/Breton Sound) in response to the approach of oil. We assessed the impact on subtidal oyster populations of this novel oil spill response action using 3 independent methods: (1) comparison of fisheries-independent post-spill densities to a pre-spill temporal baseline; (2) comparison of oyster density collected during natural resource damage assessment sampling between the area of maximal freshwater impact and reference areas in the 2 basins; and (3) estimation from a dose-response model derived from an analysis of an in situ mark and recapture study conducted in 2010 to assess the relationship between salinity and oyster mortality. A substantial portion of both basins (483 km2 of Barataria Bay and 362 km2 of Black Bay/Breton Sound) experienced prolonged periods of very low (<5 ppt) salinity in 2010 that lasted at least 1 mo longer than the average duration of low salinity between 2006 and 2009. The 3 approaches all indicate that dramatic losses occurred in the number of market-sized (>75 mm) oysters as a result of a system-wide lowering of salinities, with an estimated 1.16 to 3.29 billion market-equivalent oysters lost. The efficacy of the large-scale response action of altering hydrographic conditions during the summer oyster growth period should be examined in light of the major perturbation to oyster communities.


KEY WORDS: Estuary · Oil spill response · Natural resources damage assessment · Oyster reefs · Gulf of Mexico · Crassostrea virginica · Hydrography


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Cite this article as: Powers SP, Grabowski JH, Roman H, Geggel A, Rouhani S, Oehrig J, Baker M (2017) Consequences of large-scale salinity alteration during the Deepwater Horizon oil spill on subtidal oyster populations. Mar Ecol Prog Ser 576:175-187. https://doi.org/10.3354/meps12147

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