The Pontocaspian region is a unique system of connected and independent basins constantly transformed by major geo-climatic events. The intermittent connections of basins with different water salinity drove the evolution of an atypical brackish water biodiversity, best represented by fish, crustaceans and mollusks. During the Anthropocene, human activities started to exert strong pressure on the Pontocaspian region biota, becoming a relevant threat to its biodiversity. In this context, in my PhD I used the endemic mollusks of the Caspian Sea to evaluate the current anthropogenic threats to the Pontocaspian region. I used geospatial modeling to map nine anthropogenic pressures, finding that chemical pollution, invasive species, poaching and streamflow regulations have the highest impact score on the Caspian Sea mollusks. However, the intensity and the relative contribution of these anthropogenic pressures varied along vertical and horizontal dimensions. For example, poaching and streamflow regulation resulted in a higher pressure score in the northern part of the Caspian Sea, whereas pressure from chemical pollution and invasive species increases in the middle and southern parts of the basin. To evaluate how endemic species are affected by the anthropogenic threats, I used ecological and morphological data to review the taxonomy of the Pontocaspian endemic mollusks and to estimate hotspots of endemic mollusk diversity in the Caspian Sea. Subsequently, I evaluated the spatial overlap between anthropogenic pressures and mollusk hotspots, finding that invasive species and chemical pollution are the major anthropogenic threats to likely impact mollusks. Finally, I generated 28 spatially explicit environmental variables to facilitate the development of ecological models to investigate the combined influence of anthropogenic and environmental factors in driving spatial patterns of biodiversity. As the new variables match the world ocean data set Bio-ORACLE, they can be used to extend marine ecological models to the Caspian Sea. This allows for the first time the inclusion of the Caspian in cross- system models relevant for conservation management and planning.
