Diversity of Desulfobacteriaceae and Overall Activity of Sulfate-Reducing Microorganisms in and Around a Salt pan in a Southern California Coastal Wetland

Abstract

Sulfate-reducing bacteria (SRB) are key mediators of anaerobic carbon cycling in coastal salt marsh sediments and have been shown to be important decomposer communities even in hypersaline habitats. Understanding how SRB function in various salt marsh habitats (vegetated, salt pans) is crucial to advancing our knowledge of salt marsh function. We compare overall sulfate reducing activity and the diversity of a subset of SRB (Desulfobacteriaceae) in two hypersaline sediments (salt pan and nearby area with desiccated vegetation) with a regularly inundated control site within the Huntington Beach Wetlands (HBW). Biological activity was quantified using radiotracer studies to measure sulfate reduction rates (SRR) with and without carbon amendment. All sites showed enhanced SRR under carbon amendment, suggesting short-term carbon limitation. Unique communities of Desulfobacteriaceae were found in all three sites with increased incidence of halotolerant genotypes in the salt pan. These findings indicate that, despite reduced anaerobic respiratory activity, highly diverse and functional deltaproteobacterial communities exist in salt pan and surrounding hypersaline habitats in coastal salt marshes in southern California.