The IOW, together with the interdisciplinary shallow coastal water project Shore To Basin (S2B), focuses on Baltic Sea research and is involved in numerous international fundamental research projects. One of these projects is currently being carried out. On January 24, 2026, a three-week field study with a focus on coral physiology started on Heron Island, a small island in Australia's Great Barrier Reef, led by IOW scientist Soeren Ahmerkamp.

On Heron Island, he is working with researchers Mathilde Godefroid (Max Planck Institute for Marine Microbiology, Bremen, Germany), Michael Hansen (Aarhus University, Denmark), and Emma Charlotte Clauder (Rostock University, Germany) to study the physiology of corals, with a particular focus on so-called ciliary currents. Michael Kühl and his team from the University of Copenhagen (Denmark), Lars Behrendt (Technical University of Denmark, Copenhagen) and Klaus Koren (Aarhus University, Denmark) are collaborating partners.

Corals have tiny hair (cilia) on their surface that generate ciliary currents and enable corals to cope with rapidly changing environmental conditions. These cilia play a central role in the exchange of substances at the coral surface, influence the supply of oxygen and nutrients, and thus contribute substantially to the resilience of corals to environmental stress. The researchers have built a light-sheet microscope that can be used to measure flow directly in the field. They have now used it for the first time to measure how ciliary currents along the coral surface interact with the surrounding water currents.

Soeren Ahmerkamp explains: "Marine heatwaves and oxygen depletion are exposing corals to increasingly extreme and highly fluctuating environmental conditions. As a result, large-scale coral bleaching has occurred worldwide. Our research aims to understand the physiological adaptation mechanisms that corals use to potentially cope with these stressors. These include active ciliary currents, which have a decisive influence on substance exchange and the immediate environment of the corals."

Numerous organisms in the Baltic Sea also rely on ciliary currents. These include sea anemones (which, like corals, belong to the phylum Cnidaria), mussels and other bivalves, sponges, certain algae, and many unicellular microorganisms. These currents enable them to bring in food particles, exchange gases, and efficiently remove metabolic waste products. Therefore, the results obtained by the researchers in Australia and the applied measurement methods are also important for studying organisms in the Baltic Sea.

A custom-made microscope is used for measuring the corals‘ ciliary currents directly in the field. (Photo: M. Hansen, Aarhus University)