The Quaternary Pontocaspian mollusc fauna underwent multiple radiations and extinctions events. The faunas are essential in stratigraphic subdivision, palaeoenvironmental reconstructions as well as the documentation of lake basin isolation and connection phases. Environmental drivers of Pontocaspian molluscan biotic change are reconstructed from key sections in three episodes of turnover in the Black Sea and Caspian Sea basins, viz. the Early‐Middle Pleistocene, the Late Pleistocene and within Holocene successions. For each period, the composition and diversity of faunas will be assessed in near shore open lacustrine settings. Sedimentological and isotope geochemical analyses from project B5 will constrain palaeoenvironmental dynamics. The study will elucidate drivers of community change and faunal resilience.