Climate oscillations of the Holsteinian (Mazovian) Interglacial recorded in shell morphometry of Viviparus diluvianus (Kunth, 1865) from eastern Poland Marcin Szymanek * Faculty of Geology, University of Warsaw, Al. _ Zwirki i Wigury 93, 02 089 Warsaw, Poland article info Article history: Available online 16 April 2010 abstract 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 ¼ MIS 11 (CarpinuseAbies zone). Ó 2010 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Eastern Poland, considered as an area transitional between the influence of continental and oceanic climates, is a great field for climatic and environmental investigations, especially for the Holsteinian (Mazovian) Interglacial ¼ MIS 11, which is regarded in this area as the best known and documented period of the Polish Pleistocene. Lacustrine deposits of this age, known at about 30 locations, were the subject of palynological (e.g., Bi  nka and Nitychoruk, 1995, 1996; Krupi  nski, 1995, 2000; Bi  nka et al., 1997), isotopic (Nitychoruk et al., 1999, 2005; Nitychoruk, 2000), diatomological (e.g., Lindner et al., 1990, 1991; Lindner and Marciniak, 1998; Marciniak, 1998) and malacological research (e.g., Lindner et al., 1991; Albrycht et al., 1995; Szymanek et al., 2005), leading to recognition of climatic, floristic and ecological changes which took place during the interglacial. The papers of Nitychoruk et al. (2005, 2006) have particular meaning here. Combining isotopic and palynological data enables reconstruction of climate conditions in the Hol- steinian (Mazovian) Interglacial and in the initial part of the succeeding Saalian (Odranian) Glaciation, and correlation of the Holsteinian with Marine Isotope Stage 11 (MIS 11). This paper also focuses on palaeoclimatic investigations. It is an attempt to combine abundant mollusc data from eastern Poland with climate fluctuations which took place at this area in the Hol- steinian Interglacial. This kind of research was initiated at Ortel Królewski, where certain relation between climate, environment and shell morphometry of extinct gastropod Viviparus diluvianus was observed for the first time (Szymanek et al., 2005). This species, characteristic of the Holsteinian Interglacial in Poland (it is unknown from younger lake deposits of Poland), is also quite common in many sites from the so-called ‘Paludinen Bank’ in Germany (e.g., Schmierer, 1923; Steusloff, 1953), from Tiglian and Holsteinian in the Netherlands (e.g., Boettger, 1955; Meijer, 1989), from the Hoxnian Stage (MIS 11) in England (e.g., Keen, 2001; Roe, 2001) as well as from Early and Middle Pleistocene in Russia and Belarus (e.g., Popov, 1970; Karaszewski, 1972; Kondrashov, 2007). However, morphologically, shells of V. diluvianus can vary distinctly, even between neighbouring localities (Franz, 1932; Boettger, 1955; Meijer, 1989; Kondrashov, 2007). According to Franz (1932), this phenomenon should be connected with dissimilarity of researched populations rather than with changes after deposition, whereas Meijer (1989) considers V. diluvianus “as a complex of closely related species”. Results obtained at Ortel Królewski (Szymanek et al., 2005), where shell shape change made it possible to distin- guish two populations of this species, one characteristic of the relatively cool PiceaeAlnus pollen zone of the Holsteinian * Corresponding author. Tel.: þ48 22 554 04 86; fax: þ48 22 554 00 01. E-mail address: m.szymanek@uw.edu.pl Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint 1040-6182/$ e see front matter Ó 2010 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2010.04.003 Quaternary International 241 (2011) 143e159