ALKOR AL571

Although the Baltic Sea is species-poor, it provides important ecosystem services to the Baltic States. At the same time, it is one of the marginal seas most affected by global and regional anthropogenic pressures (e.g. warming, eutrophication, oxygen minimum zones, overfishing). For this reason, the Baltic Sea is also referred to as a "time machine" that provides a perspective on future changes in coastal ecosystems.

The multi-disciplinary research during cruise AL571 continues the "Baltic Sea Integrative Long-term Data Series", one of the best available long-term data series of the pelagic Baltic Sea. Since 1986, pelagic trawling, plankton sampling, oceanographic/hydrographic measurements, and hydroacoustic surveys have been conducted in the deep basins of the Baltic Sea, using consistent methodology. The resulting sample and data sets of fish and plankton communities and environmental parameters are used to investigate changes in (1) species composition, including the distribution of non-native species, (2) the status of key species such as cod and herring, (3) the phenology within fish and plankton communities, (4) biodiversity, (5) food web structure and function, and (6) environmental conditions. The coupling of these interdisciplinary data sets provides the basis to better understand impacts of environmental change and human use on species, food webs, and ecosystems, and makes the long-term data series a "finger on the pulse of the Baltic Sea."

The focus of the cruise AL571 lies on the Bornholm Basin and the western Baltic Sea. The resulting findings, in combination with the existing time series, contribute to the projects DFG RTG TransEvo "Fisheries Induced Evolution", BMBF-FONA "BaltAdapt" and DAM "SpaCeParti", support national and international collaborations, and form the basis for newly planned projects to further the much-needed understanding of biological changes in the "Baltic Sea time machine".