On the state of Unionidae (Bivalvia, Mollusca) population in some waterbodies in the European Russia

Using histological methods, the digestive gland in different species of Unionidae (Bivalvia, Mollusca) from Ivankovo, Uglich, Rybinsk, Gorky and Uvod reservoirs as well as from Ilmen lake and Neva Bay of the Gulf of Finland is examined. In the overwhelming majority of analyzed specimens this organ turns out to be pathologically changed. Apparently, in the European Russia as in other developed countries, the Unionidae population is in a depressed state caused by human activities.