An image from the European Space Agency's Envisat satellite, released 24 July 2010, shows a vast blue-green algae bloom filling the Baltic Sea. Scientists say the potentially toxic bloom could pose a risk to marine life in the region.

Gothenburg, Sweden (SPX) Dec 09, 2010 – Continued eutrophication of the Baltic Sea, combined with an ever thinner ozone layer, is favouring the toxic cyanobacterium Nodularia spumigena, reveals research from the University of Gothenburg, Sweden. “There are several species of cyanobacteria, or blue-green algae, that can form surface blooms in the Baltic Sea,” explains Malin Mohlin from the University of Gothenburg’s Department of Marine Ecology. “Which species ends up dominating a bloom depends partly on how they deal with an increased amount of UV light and a shortage of nutrients. Nodularia spumigena is most toxic when there is little nitrogen in the water but sufficient amounts of phosphorus.” As a result, wastewater treatment processes that concentrate on removing nitrogen can make cyanobacterial blooms more toxic. Wastewater therefore needs to be cleared of both nitrogen and phosphorus. … Surface blooms of cyanobacteria, which are a type of phytoplankton, have increased in both frequency and magnitude in the Baltic Sea in recent decades, and researchers are divided on the cause. Some put it down to eutrophication – an excess of nutrients in the water – caused by human emissions of nitrogen and phosphorus over the past 150 years. …

Eutrophication Makes Toxic Cyanobacteria More Toxic