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

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 Export citation Share:    Facebook - - linkedIn