There are various theories about the formation of blue-green algae blooms. Above all, a connection to the nutrient content of the water was suspected. However, a study in the Baltic Sea largely refutes this assumption and comes to a different theory.
Blue-green algae blooms are a recurring problem in the Baltic Sea. The study by a research team in Kiel now provides new clues as to the causes. Accordingly, the origin of the extensive blooms of the local cyanobacteria lies in the open Baltic Sea and not – as is often assumed – near the coast.
The researchers at the University of Kiel used on-site measurements, images from satellites and models of ocean currents for their study. “Using high-resolution simulated flows, we were able to analyze in detail the conditions that lead to blooms,” co-author Ulrike Löptien is quoted as saying in a statement from her university.
All of the results indicate that complex interactions between the different types of phytoplankton are important in the formation of blue-green algae blooms, according to the journal Scientific Reports. On the other hand, assumptions about very simple direct connections, for example between the nutrient composition of seawater and the cyanobacteria blooms, should be viewed with skepticism, the research team concludes. The researchers also found no evidence of a connection with temperature – apart from the fact that the flowers generally appear in summer.
The study shows the potential of interdisciplinary research at the interface between geosciences and computer science. The results could help to better predict future blue-green algae blooms. Summer blooms of blue-green algae – i.e. cyanobacteria – are a regularly recurring problem for people and the environment in the Baltic Sea in late summer.
The flowers can significantly affect the water quality by producing toxins. In addition, they release nutrients such as nitrogen in particular, thereby increasing the oxygen deficiency in the Baltic Sea.
