A colorful carpet spreads over the Baltic Sea like a huge watercolor: turquoise -colored streaks pull through the depth blue of the water, shapes spirals, vertebrae and flowing patterns as if an artist had dripped on a wet canvas with a relaxed hand. But the spectacle does not come from the studio, but from nature itself: to see a large -scale algae blossom, triggered by the mass increase in cyanobacteria, also known as blue -green algae.
Such flowers are not uncommon in the Baltic Sea – on the contrary: the flat, comparatively warm and nutrient -rich inland sea offers ideal conditions for mass increases of algae. The striking turquoise comes about by spreading the sunlight on the dense cyanobacterial colonies. When the weather is quiet, the microorganisms can spread over the water surface and form impressive patterns that can still be seen from space.
The picture above, which was taken just a few days ago, comes from the European Straw observation satellite Sentinel-2. As can be seen, the flower is particularly south of the Swedish island of Gotska Sandön in the lower right area of the image and east of Stockholm in the upper left bilder ceiling. There have been distinguished vertebrae wind and current.
But as beautiful as the sight may be: it has an ecological dark side. Some types of cyanobacteria can release toxic substances that harm humans and animals. In addition, the mass dying of flower can lead to lack of oxygen in deeper layers of water. The colorful appearance is therefore not only a fascinating natural spectacle, but also an indication of the sensitive balance of the Baltic Sea ecosystem.
