Figure 1.
Histograms of grain size distributions for representative sampling sites at Grand Isle.
(A) Sites include dune, open beach, and swash zone locations, separated by sampling times. Results from all sample depths for each sample were averaged. (B) Average grain size cumulative frequency distributions for each sample, shown as percent of finer grains.
Figure 2.
Histograms of grain size distributions for representative sampling sites at Dauphin Island.
(A) Sites include dune, backshore beach area, foreshore beach area, and swash zone locations, separated by sampling times. Results from all sample depths for each sample were averaged. (B) Average grain size cumulative frequency distributions for each sample, shown as percent of finer grains.
Figure 3.
Oceanographic data for Grand Isle and Dauphin Island.
Mean hourly tide heights are reported according to mean sea level (MSL) from NOAA’s National Ocean Service station for (A) Grande Isle and (C) Dauphin Island. (B) Ocean salinity and temperature data from the USGS National Water Information System station #07380251 near Grand Isle, and (D) from the Dauphin Island Sea lab, Coastal Marine Station DPHA1. Shaded gray boxes represent the period of time the Macondo Canyon 252 well leaked. Arrows indicate sampling times at each beach. Long bars and shorter bars indicate hurricane or tropical storms (TS), respectively, during the study.
Figure 4.
General locations of each sampling site and taxonomic representation along the beach profile.
(A) Grand Isle and (B) Dauphin Island. Summaries include only taxa with more than 2% relative abundances (all taxonomic data are included in Tables S3 and S4). Because there were multiple sampling times in May and June at Dauphin Island, composite samples are shown for each month. Remediation activities are schematically included for relevant sampling locations. Photographs from each beach are provided on Figures S2 and S3.
Figure 5.
Order-level taxonomic results for Grand Isle and Dauphin Island.
Summaries are organized as (A) Gammaproteobacteria, (B) Alphaproteobacteria, and (C) Firmicutes, by beach, sample location, and sampling time. Numbers included to right of each bar represent the percentages that the class or phylum represented in the complete dataset for that sample, at that specific sampling time and location.
Figure 6.
Bray-Curtis similarity distances among groups of samples for sampling times and beach locations.
For Grand Isle, comparisons are (A) between different sampling times and (B) between different locations along the beach profile, and for Dauphin Island comparisons are (C) between different sampling times and (D) between different locations along the beach profile. N.S. = comparisons were not significant. *weakly significant, between p-values 0.051 to 0.1; **significant, between 0.0001 to 0.05; ***highly significant, <0.0001.
Figure 7.
Non-metric multidimensional scaling (NMDS) plots based on microbial community compositions for all beach sand.
(A) Grand Isle and (B) Dauphin Island community compositions from 16S rRNA gene pyrosequences that correspond to environmental variables and the extent of physical remediation at the beaches, shown as vectors. For (A), stress = 0.11, axis 1 R2 = 0.61 and axis 2 = 0.35. For (B), stress = 0.16, axis 1 R2 = 064 and axis 2 = 0.23. Colored arrows indicate the temporal shifts in community ordination for the dune, open beach areas, and swash zone.
Figure 8.
Changes in the percent contribution of different grain sizes compared to Shannon Diversity (H’) index values.
Diversity was calculated from OTUs for (A) and (B) Grand Isle, and (C) and (D) Dauphin Island. (A) and (C) compare the coarser grain size contribution, and (B) and (D) compare the finer grain size contribution.