Lake Bästeträsk 2.19

Lake Bästeträsk is a freshwater lake located in the northern part of the Swedish island of Gotland. It is the largest lake on the island.GeographyThe lake is located at the north end of Gotland only 0.4km from the Baltic Sea. It has three islands: Falholmen, Storholmen and Lillholmen. The lake represents 681ha of the 1494ha Bästeträsk nature reserve, one of the largest on Gotland. With an area of 6.52sqkm it is the largest lake on the island. Despite its size, the maximum depth is only 4.5m and most of it is considerably shallower.GeologyMost of the lake is surrounded by a so called "beach barricade", a 0.5to high wall of gravel and larger blocks of stone, that has been displaced or pushed out by the expanding ice during the winter.The bottom of the lake is made up of blocks of stone, especially in the shallower parts, and sediments.It is connected to the Baltic Sea through the stream Arån, which is a breeding ground for sea trout.BiologyBästeträsk is a freshwater reserve with very clean inflows, a number of them has the same aspects as drinking water. The water has a greenish tint with low content of nutrients, making the lake almost void of vegetation save for stands of Chara aspera, Chara tomentosa, Chara globularis and the only occurrence in Sweden of Nitella tenuissima. It inhabits species such as northern pike, perch, roach, rudd, tench, european bullhead and whitefish. The lake was stocked with crayfish during the 1920s. A number of rare lichens and polyporales can be found in the nature reserve surrounding the lake, along with the Cochlicopa nitens land snail. The islands in the lake have a large colony of eiders.