Contribution of different wetland plant species to the DOC exported from a mesocosm experiment in the Florida Everglades

Abstract

Carbon stable isotopes were used to investigate the contribution of different wetland plant communities commonly found in the Everglades to the dissolved organic carbon (DOC) exported from a mesocosm experiment. The species conforming the different treatments in the mesocosms were: Typha domingensis Pers, Cladium jamaicense Crantz, Nymphaea sp., Nymphaea sp./Eleocharis sp., Najas guadalupensis [Spreng] Magnus/Chara sp. and Najas guadalupensis. Results indicate that Nymphaea sp./Eleocharis sp. and Najas guadalupensis/Chara sp. treatments functioned as temporary sinks for DOC, but over the study period all treatments were net sources of DOC. A two-source carbon isotope mixing model was used to estimate the contribution from inflow water and biomass into the outflow DOC in each treatment. DOC from biomass was relatively higher in treatments with emergent and floating vegetation (24–30%) than in treatments containing submerged aquatic vegetation (≤5%). The relevance of these findings for restoration and management in the context of the Everglades region, specifically its implications for organic phosphorus exports, are discussed.