FRESHWATER MOLLUSCS Biodiversity and distributions of freshwater mollusks in relation to chemical and physical factors in the thermokarst lakes of the Gydan Peninsula, Russia Yulia V. Bespalaya . Olga V. Aksenova . Svetlana E. Sokolova . Alexander R. Shevchenko . Alena A. Tomilova . Natalia A. Zubrii Received: 25 October 2019 / Revised: 5 March 2020 / Accepted: 10 March 2020 Ó Springer Nature Switzerland AG 2020 Abstract Knowledge of factors affecting the diver- sity of benthic invertebrates is very important for biodiversity conservation, for monitoring, restoring and maintaining aquatic ecosystems. The purpose of this study was to investigate how the diversity and distribution of freshwater mollusks related to envi- ronmental factors. Twelve species of freshwater mollusks were identified during a survey of 15 thermokarst lakes in the Gydan Peninsula, Russia. Canonical correspondence analysis (CCA) was used to study the relationships between environmental variables and species abundance. The first CCA axis correlated with the content of macro-ions, mainly Mg 2? , Na ? , Cl - , substrate types, and plant remnants. Along the second CCA axis stations were ordered by depth and the presence of mosses. We found that the type of substrate, depth, abundance of mosses and hydrochemical parameters play an important role in the distribution of the mollusks in thermokarst lakes. These results expand our understanding of mollusks ecology in thermokarst lakes, and identify environ- mental stressors important for the performance of abiotic control. Keywords Arctic Á Freshwater mollusks Á Environmental factors Á Distribution Á Thermokarst lakes Introduction The Arctic region is currently undergoing significant and rapid environmental and socio-economic changes, which in turn have an impact on freshwater ecosys- tems and their associated habitats (Kling, 2009). Intensive development of the Gydan Peninsula, including geological exploration and the development of oil and gas infrastructure, requires more efforts to preserve the diversity of freshwater ecosystems (Gu- dovskikh et al., 2016). The territory belongs to the Arctic tundra zone and characterized by the absence of Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10750-020-04227-9) con- tains supplementary material, which is available to authorized users. Guest editors: Manuel P. M. Lopes-Lima, Nicoletta Riccardi, Maria Urbanska & Ronaldo G. Sousa / Biology and Conservation of Freshwater Molluscs Y. V. Bespalaya (&) Á O. V. Aksenova Á S. E. Sokolova Á A. R. Shevchenko Á A. A. Tomilova Á N. A. Zubrii N. Laverov Federal Center for Integrated Arctic Research, Russian Academy of Sciences, Severnaya Dvina Emb. 23, Arkhangelsk, Russian Federation 163000 e-mail: jbespalaja@yandex.ru Y. V. Bespalaya Á O. V. Aksenova Laboratory of Macroecology & Biogeography of Invertebrates, Saint Petersburg State University, Universitetskaya Emb. 7-9, Saint Petersburg, Russian Federation 199034 123 Hydrobiologia https://doi.org/10.1007/s10750-020-04227-9