Our principal research interests focus on the documentation and better understanding of climate changes as recorded in marine sediments in different time scales. Especially interesting are the role of polar oceans and the documentation of environmental changes in high-latitude sediments. This includes the reconstruction of water-mass properties and circulation. We use foraminiferal species assemblages and the stable isotopic composition of foraminferal calcareous tests as basic proxies. To reconstruct late Pleistocene ocean circulation and deep-ocean ventilation more precisely, we for example investigate if changes in sea-ice distribution have substantially influenced the relationship between nutrients and carbon isotopes in deep and bottom water masses.