Late Glacial and Holocene lacustrine molluscs from Wielkopolska (central Poland) and their environmental significance

Abstract

Late Glacial and Holocene lacustrine molluscs occurring in three sites from the Gniezno and Poznań Lake Districts in central Poland are described. The mollusc fauna present in the sites is composed mainly of aquatic species with an accessory content of terrestrial snails inhabiting damp or very damp, periodically flooded sites. Ecological preferences of species, changes in their composition and frequency together with shell dimensions are used as indicators of palaeoenvironment and palaeoclimate. Infrequent shells present in the Imiołki and Rybitwy sites are small and thin-walled in consequence of the cold climate prevailing in the Late Glacial when the sediments in question were deposited. In the Imiołki site Pisidium lilljeborgii CLESSIN, a species indicative of low temperatures, occurs. Deposits in the Niepruszewo-Cieśle site were accumulated through most of the Holocene, thus warmer conditions resulted in considerably more abundant and larger shells with thicker walls.