Mývatn (Icelandic pronunciation: [ˈmiːˌvahtn̥] ) is a shallow lake situated in an area of active volcanism in the north of Iceland, near Krafla volcano. It has a high amount of biological activity. The lake and the surrounding wetlands provide a habitat for a number of waterbirds, especially ducks. The lake was created by a large basaltic lava eruption 2300 years ago, and the surrounding landscape is dominated by volcanic landforms, including lava pillars and rootless vents (pseudocraters). The effluent river Laxá [ˈlaksˌauː] is known for its rich fishing for brown trout and Atlantic salmon. The name of the lake (Icelandic mý ("midge") and vatn ("lake"); "the lake of midges") comes from the large numbers of midges present in the summer. The name Mývatn is sometimes used not only for the lake but the whole surrounding inhabited area. The river Laxá, the lake Mývatn and the surrounding wetlands are protected as a nature reserve (the Mývatn–Laxá Nature Conservation Area), which occupies 4,400 km2 (440,000 ha). Since 2000, a marathon around the lake has taken place in the summer.
Geography The lake has an average depth of 2.5 metres and a maximum depth of 4.5 metres.
Climate The Mývatn area features a tundra climate (Köppen climate classification ET), bordering on a subarctic climate (Köppen climate classification Dfc). Summers are typically cool with crisp nights while winters are very long and cold.
Flora and fauna
Birds
The lake is fed by nutrient-rich springwater and has a high abundance of aquatic insects (Chironomidae) and Cladocera that form an attractive food supply for ducks. Fifteen species of ducks breed at the site, the largest such number in Europe. The duck species composition has a mixture of European and North American species, and also of boreal and arctic species. Most of the ducks are migratory, arriving in late April to early May from north-western Europe. The commonest species at the lake is the tufted duck with 6,000 pairs present, whilst the second most abundant species is the greater scaup with 1,500 pairs. Other common species include the Barrow's goldeneye, 700 pairs of red-breasted merganser, 1000 pairs of Eurasian wigeon, around 300 pairs of gadwall, 200 pairs of mallard, around 350 pairs of common scoter, 150 pairs of long-tailed duck and 75 pairs of Eurasian teal. The northern shoveler and northern pintail also regularly breed at the lake, albeit in smaller numbers, whilst common pochard used to breed regularly, but they have not done so regularly since the 1950s. The outflowing Laxá river contains around 250 pairs of harlequin duck and there is a large colony of eider at the river mouth some 50 km away from Mývatn. The Barrow's goldeneye and the harlequin duck are both nearctic duck species. The population of the Barrow's goldeneye (of about 2000 individuals) relies entirely on the habitat provided by the Mývatn Laxá water system and its surrounding lava fields. Most of the Barrow's goldeneyes overwinter there, using ice-free areas kept open by emerging spring water (both warm and cold) and in the strong river current. This species is a hole-nester, in North America using tree-holes, but at Mývatn the birds use cavities in the lava for nesting. The other duck species nest abundantly in the numerous islands of the lake and the surrounding marshlands. Other common waterbirds include the Slavonian grebe, red-necked phalarope, great northern diver, red-throated diver and whooper swan. The lake is included in an important bird area. Bird populations have been monitored annually since 1975 by the Mývatn Research Station. There is a long tradition of harvesting duck eggs for home use on the local farms. To ensure sustainability, the harvesting follows strict age-old rules of leaving at least four eggs in a nest for the duck to incubate. The lava flows and moorlands surrounding the lake are home to rock ptarmigans and occasionally gyr falcons may be present.
Plants Mývatn is one of the few places in the world where marimo grows naturally. Also known as Cladophora ball it is a species of filamentous green algae. Due to environmental factors their population has rapidly declined and the algae appeared to have become extinct in 2013. The ecosystem is now improving and small marimo balls are forming again.
Volcanism
… excerpt ends here. Continue reading the full article.
