Trophic accumulation of mercury (Hg) in aquatic ecosystems is of global concern due to health effects associated with eating fish with elevated Hg levels. The methylated form of Hg bioaccumulates so it is important to understand how inorganic Hg is transformed to methylmercury in the environment. Here, a new site for Hg methylation, the periphyton communities that are prevalent in the Florida Everglades, is described. It is hy...