Geomicrobiology

Open water in post-Katrina marsh, Louisiana. Photo credit: J. Holloway, USGS Image Gallery

The combined effects of Hurricanes Katrina (August 29, 2005) and Rita (September 24, 2005) resulted in a catastrophic destruction of wetlands. A study was initiated in March 2006 to characterize storm impacts on coastal marsh soils in areas directly impacted by storm surge. Soil pore water chemistry and soil microbial community characterization using phospholipid fatty acids (PLFA) were used to assess marsh soil health and recovery. The post-hurricane recovery of coastal marsh soils is indicated b: 1) increased PLFA biomass, 2) decreased chloride for salt marshes and 3) decreased PLFA stress indicators. Coastal marshes are dynamic ecosystems that have adapted to endure regular hurricane-force winds and storm surges. However, modern coastal marshes are destabilized by pipeline and canal networks and periodic fresh water subsidies to some marsh areas. The physical damage to the soils likely represents a permanent loss of wetlands in spite of the biogeochemical indicators of recovery in remnant brackish marshes.

For more information contact JoAnn M. Holloway, Crustal Imaging & Characterization Team; Christopher M. Swarzenski , Louisiana Water Science Center; Ken W. Krauss, National Wetlands Research Center; and Thomas Doyle, National Wetlands Research Center.

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