Geomorphological influence on the Holocene climate signal from a karst wetland in the Central Mediterranean

Lake sediments from the Dinaric karst region (Central Mediterranean) hold valuable paleoenvironmental records, yet remain underexplored compared to other Mediterranean areas. This study presents a multiproxy analysis of Holocene paleolake sediments from Prološko Blato karst wetland in Dalmatia (Croatia), using geochemistry, ostracods, and radiocarbon dating to reconstruct past hydroclimate variability. Proxy records indicate intermittent lake conditions during the wetter Early Holocene, contrasting with other lake level records, probably due to high surface and subsurface connectivity in the karst. The Middle to Late Holocene is characterized by lake deepening and lacustrine carbonate sedimentation, decreased run-off and increased ostracod abundances, indicating the development of permanent lake conditions. The oxygen and carbon isotope data suggest progressive aridification towards the Late Holocene, in line with other Mediterranean records. However, a pronounced shift to lower isotope values between 2100 and 500 cal yr BP indicates wetter conditions in the lake, in contrast to the lower lake levels and more arid conditions reported for the Roman and Medieval Warm Periods in other Mediterranean records. The sudden shift was linked to the opening of a sinkhole in the paleolake's marginal part, which caused hydrological disturbance and the formation of a modern, seasonally flooded wetland. This research provides a new Holocene hydroclimate record for the Dinarides, while highlighting the influence of geomorphological processes in karst on paleoclimate interpretation.