Euryhaline, sand-dwelling, testate rhizopods in the Great Lakes

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Journal of Great Lakes Research





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Rich and highly specialized communities of sand-dwelling testate rhizopods (amoebae, mainly of the subclass Testaceafilosia) are known from marine and brackish waters of the world's oceans, but no representatives of these communities have been reported previously from the Great Lakes. Beach sand samples were collected in September, 2002 at 37 locations in Lake Superior, Lake Huron (including the North Channel and Georgian Bay), Lake Erie, and Lake Ontario and were examined for the presence of psammobiont (obligate sand-dwelling) testate rhizopods. Four species were found, three of which belong to the genus Psammonobiotus that may have their origins in the Ponto-Caspian region of Eurasia. Psammonobiotus communis Golemansky was originally described in the late 1960s as a marine relict from Lake Ohrid, Macedonia and from the Black Sea, but has since become the most widely reported Psammonobiotus species in marine/brackish water beach sands. It was abundant and widely distributed in the Great Lakes samples, as was a presently unnamed species of Psammonobiotus known previously only from the Polish coast of the Baltic Sea. A third species, P. linearis Golemansky, also widely known from oceanic and brackish beach sands, was found at the eastern end of Lake Ontario and in Rondeau Bay, Lake Erie. The fourth psammobiont, Corythionella golemanskyi Nicholls is apparently an exclusively freshwater form that was common in many of our Great Lakes samples. Based on published accounts, the three Psammonobiotus species have wide salinity tolerances that may have facilitated their establishment in the Great Lakes, perhaps after introduction in ships' ballast water.