Post-Deepwater Horizon oil spill erosion data, Bay Batiste, LA, 2010 to 2012.

We established 30 closely-located Spartina alterniflora dominated salt marsh sites on 12-13 November 2010 along the northern edge of Bay Batiste in the southeast Louisiana estuary of Barataria Bay. There are a total of 10 groups of 3 sites each. The three sites within each group of 3 were 10 m apart. We collected a surface oil sample within the top 5 cm of soil, one meter from the marsh edge, from each site in February 2011, August 2012, and September 2012. The sites were divided into high and low oiled sites. The 13 sites where the PAH concentration was < 1000 ug kg-1 were considered ‘low’ or ‘background’ oil sites and used as the control or reference sites. The 17 sites where the PAH concentration was >1000 ug kg-1 were placed in the high oiled category. The horizontal shoreline erosion, soil strength, percent cover of S. alterniflora, and marsh edge overhang were sampled at each site. We placed permanent PVC poles 1.5 m and 4.5 m in a straight line into the marsh from the shoreline edge. Edge erosion and gain were measured five times using these poles as reference points. Soil strength and percent cover of S. alterniflora were measured at the 1.5 m pole until the edge eroded past this location; after this occurred, the readings were taken 1.5 m into the marsh from the marsh edge.