. 2016. Remnant freshwater mussel diversity in Rondeau Bay, Lake Erie. canadian Field-naturalist 130(1): 76-81.in 2014 and 2015, 27 sites in Rondeau Bay, ontario, canada, were surveyed for freshwater mussels. Rondeau Bay is a large coastal wetland on the north shore of Lake Erie. twenty-three species were identified from 120 live mussels, 15 fresh whole shells, 329 weathered whole shells, and 1121 weathered valves. Live individuals of the following species were collected: Eastern pondmussel (Ligumia nasuta; endangered in canada), Giant Floater (Pyganodon grandis), Round pigtoe (Pleurobema sintoxia; endangered in canada), and three-ridge (Amblema plicata). Fresh whole shells of the Mapleleaf (Quadrula quadrula; threatened in canada) were also found. Most species (78%), including 7 species at risk, were collected only as weathered shells. these results indicate a substantial decline in freshwater mussel diversity since the Zebra Mussel (Dreissena polymorpha) invasion of Lake Erie. Evidence shows that a viable population of only Giant Floater remains.