There is suspicion that it could be blue-green algae, according to the Office for Fire Protection, Rescue Services and Disaster Management. On Tuesday came an update: "Investigations have confirmed the presence of toxin-producing cyanobacteria, so-called blue-green algae," the Rostock health authority announced. The health authority confirmed that blue-green algae had been detected in the Baltic Sea. Skin contact with blue-green algae can cause swelling, irritation or allergic reactions. The warning applies to the Baltic Sea coast off Warnemünde, specifically beach sections 30 to 36.