Palaeo ec ol ogy of the Holsteinian lake in vi cin ity of Wilczyn ( east ern Po land ) based on mol lus can stud ies

Malacological stud ies of two pro files of the Holsteinian (Mazovian) Inter gla cial from east ern Po land – Roskosz and Wilczyn 1/12 – are pre sented. They are con nected with the north ern part of the Wilczyn palaeolake and seems to doc u ment palaeo eco logi cal changes in the part of the cli ma tic op ti mum and the post-op ti mal pe riod. Mol lusc com mu ni ties are typ i cal of lake en vi rons. The lat ter is sup ported by biometry of Pisidium moitessierianum. Higher en ergy con di tions are ev i denced by rheophile spe cies P. henslowanum and P. nitidum in the low er most part of the Roskosz sec tion. Mol lusc as sem blages with Lithoglyphus jahni, with Valvata piscinalis and Bithynia tentaculata as well as with Valvata piscinalis are dis tin guished at Roskosz. They re cord changes in aquatic veg e ta tion and depth con di tions. Malacofauna from Wilczyn 1/12 is dom i nated by V. piscinalis, V. piscinalis f. antiqua and B. tentaculata. Lim ited con tri bu tion of tem per ate gas tro pods Viviparus diluvianus and L. jahni as well as the oc cur rence of some cold-lov ing forms in di cate a de te ri o ra tion of ther mal con di tions. Shal low-wa ter hab i tats and ex pan sion of reed zones are in ferred from pro por tions of Bithynia shells and opercula.