Coastal marsh (Louisiana) microcosm experiments Targeted Locus (Loci)

This study was done to evaluate natural organic matter degradation rates by microbes from Louisiana marsh soil and sediments that were impacted by the Deepwater Horizon oil spill in 2010. Native soil and sediments with differing oiling histories have been characterized from these marshes since 2010 as part of the Coastal Waters Consortium research agenda (http://cwc.lumcon.edu/). Push-core samples from both 0-1 cm and 9-10 cm depths were used for laboratory microcosm experiments; samples were acquired in 2013. Spartina alterniflora leachate was used to represent fresh natural organic matter. Soil and sediments were amended with plant leachate and the fastest organic matter degradation rates were from more heavily oiled soils. Compositional changes in the bacterial communities were assessed from the native material and experimental microcosms based on amplicon pyrosequences libraries of single-direction reads generated from multiplexed, bar-coded primers targeting the V1-V3 region of the 16S rRNA gene. The findings are being used to evaluate large-scale changes in microbial communities from the marshes as part of the CWC longitudinal studies since the DWH oil spill.