PE-066 (JTK):

Effects of elevated CO₂ and salinity on microbial community and biogeochemical processes in a salt marsh ecosystem

Salt marshes are an ecosystem with extremely high productivity and dynamic biogeochemical reactions. Salt marshes are anticipated to be exposed to elevated atmospheric CO₂ and intrusion of sea water, of which impacts on soil microbes have not fully understood. This study aimed to reveal effects of elevated CO₂ and salinity on microbial community and various biogeochemical processes including CH₄ flux. Intact cores from salt marsh in Wales, UK were exposed to 2 levels of CO₂ and 2 levels of salinity over a growing season using FACE facility. No effects of elevated CO₂ or/and salinity were discernable for the abundances of bacteria and denitrifier, while significant increases were observed for sulfate reducers. CO₂ effects on microbial composition were not significant, but community structures of denitrifiers and sulfate reducers were changed by higher salinity. Reduction in plant biomass was found under high salinity, which disappeared under elevated CO₂. Higher CH₄ emissions were found by elevated CO₂ only under control salinity. Overall results of this study suggest that effects of elevated CO₂ on microbes in salt marshes are strongly constrained by salinity change.

keywords:Elevated carbon dioxide,Sea level rise,Wetland,Microbial community,Green house gas