On the German coast, the areas around Rügen, the Bay of Lübeck and the Fehmarn Sound are particularly affected. The yellow-green flakes, some of which form a closed carpet, not only look unappetising, they can also cause skin irritation and diarrhoea. The responsible State Office for Health and Social Affairs in Rostock against the corresponding risks of contact or ingestion of contaminated water.
Strictly speaking, blue-green algae are cyanobacteria. They occur naturally both in the central Baltic Sea and in inland waters. Due to the heavy over-fertilisation of the Baltic Sea, high temperatures lead to a mass proliferation of the bacteria, resulting in the observed carpets. Even if the office does not issue a general bathing ban in the current situation, contact with the algae should be avoided.
Further information on cyanobacteria can be found at http://www.algenreport.de/. An overview of the situation in the Baltic Sea can be found in the graphics of the Swedish Meteorological Institute.
