Palaeoecological Conditions in the South-Eastern and Western Baltic Sea during the Last Millennium

Abstract

The paper presents the reconstruction of paleoenvironmental conditions in the Gdansk, Bornholm and Arcona Basins of the Baltic Sea over the last millennium. A complex study (including geochemical, XRF, grain size, AMS and micropalaeontological analyses) of five sediment cores, retrieved by short gravity corer of Niemistö type, was performed. The cores are mainly represented by undisturbed silty muds of olive-grey and grey colours. The age models for the cores were built based on Pb distribution along the sediment sequences as radiocarbon dating resulted in excessively old age. Despite generally very low foraminiferal amount and diversity the increased inflow activity was reconstructed during the Medieval Climate Anomaly. The strongly positive North Atlantic Oscillation (NAO) index during this period led to a prevalence of westerlies over the Baltic region and stronger saltwater intrusions. In the recent sediments, the reconstructed inflow frequency demonstrates a decadal variability rather than the reduction, although, the general decline compared to the Medieval Climate Anomaly is seen.