Lacustrine molluscan carbonates: An interspecific approach toward the understanding of palaeoenvironmental conditions during the Holsteinian Interglacial (MIS 11) using δ18O and δ13C

Stable isotope geochemistry is a well-known tool for the investigation of palaeoclimate. The application of this methodology to molluscan carbonate materials has increasingly receiving more attention in recent decades, stimulating the development of numerous environmental reconstructions. Among the different habitats and shell species investigated so far, the freshwater are the ones that have received least attention. The scarcity of systematic studies on lacustrine and riverine molluscan species considerably limits the use of these remains to reconstruct the environmental conditions of inland palaeontological and archaeological sequences. The present study focuses on Bithynia tentaculata, a freshwater species abundant in the European Quaternary fossil record. The aim of the research is to validate the use of oxygen (δ18O) and carbon stable isotopes (δ13C) of this species as palaeoenvironmental proxies. For this purpose, shells and opercula from stratigraphic sequences of three palaeolakes in eastern Poland, formed during the Holsteinian Interglacial (MIS 11), are analysed. The intercorrelation between B. tentaculata and two other molluscan species, together with good agreement with the pollen record, reveal that δ18O and δ13C are suitable indicators of water temperature and humidity levels for lacustrine environments. These results pave the way for using B. tentaculata in further palaeoclimatic reconstructions.