Mercury methylation in periphyton of the Florida Everglades

Trophic accumulation of mercury (Hg) in aquatic ecosystems is of global con cern due to health effects associated with eating fish with elevated Hg lev els. The methylated form of Hg bioaccumulates so it is important to underst and how inorganic Hg is transformed to methylmercury in the environment. He re, a new site for Hg methylation, the periphyton communities that are prev alent in the Florida Everglades, is described. It is hypothesized that peri phyton communities that support an active microbial sulfur cycle support Hg methylation. This new methylation site has implications for trophic transf er of methylmercury since periphyton can be the base of the food web in aqu atic ecosystems.