Periphyton, a complex mixture of eukaryotic algae, cyanobacteria, heterotrophic microbes (bacteria, fungi, protozoa and micrometazoa), and fine particulate detritus, is ubiquitous in the Florida Everglades and has a profound effect on mercury (Hg) cycling in this subtropical wetland. Periphyton can adsorb and/or take up Hg species inclcuding inorgnanic Hg and methylmercury (MeHg), release extracellular polymeric substances and low molecular organic ligands influcing Hg speciation, and act as an ecological niche for enhanced Hg methylation. The MeHg produced in periphyton matrix could be bioaccumulated into the food web as periphhyton is a food base, and/or be released into the surrounding water entering aquatic MeHg cycling. All these processes may affect the distribution of Hg in Everglades water. In order to determine the role of periphyton in water Hg distribution, surface water (away from periphyton), overlying water (on floating mat), and pore water (held within periphyton) samples were collected from the Everglades and analyzed for MeHg and total Hg (THg) for examination of Hg distribution pattern. The decreasing MeHg concentrations with the distance away from periphyton and the increasing water THg concentrations toward periphyton suggest that periphyton does have a complex effect on Hg distribution, and further studies are warranted for investigation of the role periphyton plays in Hg distribution and cycling.<br/>

Effects of periphyton presence on the distribution of mercury in water in the Florida Everglades

256th National Meeting (2018)

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