The Baltic Sea has been under pressure for decades: Although phosphorus and nitrogen river loads, the main cause for its eutrophication, have been significantly reduced, adverse effects such as algal blooms and oxygen depletion still massively occur, leading to further ecological problems. Scientists at the IOW have now published a comprehensive review showing how nutrient pollution, internal matter cycles and global warming interact, thereby delaying the impact of protective measures. They also identify potential approaches for effective Baltic Sea management. The study was recently published in the Annual Review of Marine Science.
Press Release Archive
Underestimated wake: Shipping traffic causes more turmoil in the Baltic Sea than expected
Commercial shipping not only affects the Baltic Sea on the surface, but also has a significant impact on the water column and the seabed. A study by the IOW and Kiel University (CAU) now shows for the first time that wake turbulence from large ships in heavily trafficked areas of the western Baltic Sea significantly alters water stratification and leads to marked sea floor erosion.
Since the beginning of January, an unusually long period of easterly winds has caused the average water level in the Baltic Sea to fall to a historic low. Measurements at the Swedish Landsort-Norra gauge show values that are the lowest since records began in 1886. Researchers at the IOW are currently monitoring this development very closely, as it represents a rare oceanographic situation that could lead to a large inflow of saltwater from the North Sea into the Baltic Sea.
Greenland’s coastal macroalgal forests may be a far more significant contributor to global carbon storage than previously thought. That is the outcome of a new study co-led by the IOW and the Helmholtz-Zentrum Hereon. By combining satellite imagery, ocean drifter trajectories, and high-resolution ocean turbulence models, the international research team demonstrated, how ocean currents and intense mixing events act to push seaweeds – and thus the carbon in their tissues – into the deep ocean.
Fungi Infect Nitrogen-Fixing Cyanobacteria
Under the lead of the Leibniz Institute for Baltic Sea Research Warnemünde (IOW) the influence of parasitic fungi on the physiology and survival of cyanobacteria in the Baltic Sea was investigated. Such infections are known from lakes. Due to the high nutrient load in the Baltic Sea, there are high levels of cyanobacteria, some of which are toxic (algal blooms). In addition, the decomposition of algal blooms leads to oxygen depletion. Cyanobacteria are important for the nitrogen cycle, as some fix nitrogen and thus further increase nutrient concentrations in the Baltic Sea. The findings were recently published in the journal Nature Communications.
How can eelgrass beds in the Baltic Sea be efficiently restored with the help of artificial intelligence (AI) in the most climate-resilient way possible? This is the core question of the new SEAGUARD research project, which is coordinated by the IOW. The project combines marine research, data science and environmental management and is funded with about 1.8 million euros until November 2027 as part of the German federal environment ministry's AI flagship initiative.
The Baltic Sea coast in the Anthropocene: a model for the consequences of climate change
Under the lead of the IOW, a review article outlined the state of the Baltic Sea coast and its expected development as a result of climate change. The article shows that the Baltic Sea can serve as a model for the consequences of climate change and that interdisciplinary research is needed to investigate changes in its shallow coastal zones.
Climate change promotes the spreading of vibrios: IOW study reveals global distribution patterns
Vibrio vulnificus, a bacterium that is potentially very dangerous to humans, is a natural component of marine plankton. The IOW has now presented the first comprehensive analysis of its global distribution. It shows that the pathogen occurs in almost all coastal regions of the world, but is more prevalent at comparatively high water temperatures, moderate salinity levels, and in decaying algal blooms. The study also provides a predictive model that can be used to estimate future climate change-induced changes in the distribution of vibrios.
Under the lead of the IOW, a sediment core from the Southeast Pacific was examined that reflects the last 8 million years of Earth's history. The study shows that the intensity of the Antarctic Circumpolar Current, which connects the world’s three major oceans, is particularly sensitive to temperature changes, which in turn significantly influences the exchange of CO2 between the ocean and the atmosphere.
Today, the two-day kick-off meeting for the international “Joint Action on Changing Marine Lightscapes” launched by JPI Oceans started in Hamburg with more than 50 participating researchers. The initiative aims at a better understanding of changing light conditions in the ocean and how this impacts marine ecosystems. Two projects are taking up work under the umbrella of a joint knowledge hub. The ISOLUME project coordinated by the IOW focuses primarily on ocean darkening; the ALANIS project, led by the Helmholtz-Zentrum Hereon, mainly addresses nocturnal light pollution.