Climate oscillations of the Holsteinian (Mazovian) Interglacial recorded in shell morphometry of Viviparus diluvianus (Kunth, 1865) from eastern Poland

Lake deposits of the Holsteinian (Mazovian) Interglacial from eastern Poland are characterised by a rich occurrence of mollusc shells. Mollusc assemblages from five sites: Ortel Królewski, Szymanowo, Ossówka, Hrud II and Roskosz are presented. Populations of the snail Viviparus diluvianus (Kunth) are subjected to biometric analysis to verify how climatic changes in the Holsteinian Interglacial influenced the shell morphology. The pollen analysis allows assignment of sediments from different sites to the certain parts of the interglacial, characterised by influences of maritime or continental climates. A combination of palaeobotanical and mollusc data shows that variability in shell morphometry of V. diluvianus is strongly connected with climate conditions. The strongest correlation with the climate shows slimness of the shell. It appears that during the periods with predominating oceanic climate the mean slimness of the shell increases, smaller and wider individuals are typical of the climate with continental features and lake shallowing. Thus V. diluvianus shells from eastern Poland are used to reconstruct climate from Taxus zone up to the end of the climatic optimum of the Holsteinian (Mazovian) Interglacial = MIS 11 (Carpinus-Abies zone).