An unusually high level of cyanobacteria (blue-green algae) in lake Mývatn in the past two summers is a clear sign of eutrophication in the lake, caused by human activity, according to Árni Einarsson, director of the Mývatn Nature Research Center. Last summer’s measurements showed a level twelve times what is considered excessive in the guidelines of the World Health Organization.
Eutrophication is the abundant accumulation of nutrients that support a dense growth of algae and other organisms, the decay of which depletes the shallow waters of oxygen in summer.
Árni told Vísir that cyano bacteria literally overtook the biosphere of the lake at times last summer. He said there is no doubt that human activity has increased the level of bacteria excessively by releasing nutrients into the lake, originating from sewer, fertilizers and industry. A large increase in the number of tourists in the area has also put a strain on the lake. Furthermore, the effects of the Mývatn silicon factory, which closed in 2004, might still be evident.
Árni stated, “I think it’s obvious that this is caused by human activity. Everything that’s happening in Mývatn has the classical symptoms of eutrophication.” He added, “We’re witnessing great changes in the biosphere of Mývatn. Plants are disappearing.”
There is only one solution, in Árni’s opinion, and that’s to ensure that as little as possible of nutrients from populated areas goes into groundwater and from there into the lake.