Friday, May 9, 2014

Lake Baikal: A World's Treasure

Lake Baikal is a rift lake in the south of the Russian region of Siberia, between the Irkutsk Oblast to the northwest and the Buryat Republic to the southeast.

Lake Baikal is the freshwater lake with greatest volume in the world, containing roughly 20% of the world's unfrozen surface fresh water, and at 1,642 m (5,387 ft), the deepest.  It is also among the clearest of all lakes, and thought to be the world's oldest lake at 25 million years. It is the 7th largest lake in the world by surface area.

Like Lake Tanganyika, Lake Baikal was formed as an ancient rift valley, having the typical long crescent shape with a surface area of 31,722 km2 (12,248 sq mi). Baikal is home to more than 1,700 species of plants and animals, two thirds of which can be found nowhere else in the world and was declared a UNESCO World Heritage Site in 1996.  It is also home to Buryat tribes who reside on the eastern side of Lake Baikal, rearing goats, camels, cattle and sheep, where the regional average temperatures vary from a minimum of −19 °C (−2 °F) in winter to maximum of 14 °C (57 °F) in summer.

Baikal's age is estimated at 25–30 million years, making it one of the most ancient lakes in geological history.  It is unique among large, high-latitude lakes, in that its sediments have not been scoured by overriding continental ice sheets. U.S. and Russian studies of core sediment in the 1990s provide a detailed record of climatic variation over the past 250,000 years. Longer and deeper sediment cores are expected in the near future. Lake Baikal is furthermore the only confined fresh water lake in which direct and indirect evidence of gas hydrates exists.

The lake is completely surrounded by mountains. The Baikal Mountains on the north shore and the taig are technically protected as a national park. It contains 27 islands; the largest, Olkhon, is 72 km (45 mi) long and is the third-largest lake-bound island in the world. The lake is fed by as many as 330 inflowing rivers.  The main ones draining directly into Baikal are the Selenga River, the Barguzin River, the Upper Angara River, the Turka River, the Sarma Rier an the Snezhnaya River.  It is drained through a single outlet, the Angara River.

Despite its great depth, the lake's waters are well-mixed and well-oxygenated throughout the water column, compared to the stratification that occurs in such bodies of water as Lake Tanganyika and the Black Sea.

Wildlife and Vegetation

 Lake Baikal is rich in biodiversity.  It hosts 1,085 species of plants and 1,550 species and varieties of animals.  More than 80% of the animals are enemic (found only at Lake Baikal). Epischura baikalensis is endemic to Lake Baikal and the dominating zoooplankton species there, making up 80 to 90 percent of total biomass.  The Baikal Seal or nerpa (Pusa sibirica) is found throughout Lake Baikal.  It is one of only three entirely freshwater seal populations in the world, the other two being subspecies ofj Ringed Seal.  Perhaps the most important local species is the omul (Coregonus autumnalis migratorius), a smallish endemic salmonid.  It is caught, smoked and then sold widely in markets around the lake.

Of particular note are the two species of golomyanka or Baikal oil fish (Comephorus baicalensis and C. dybowskii). These long-finned, translucent fish normally live in depths of 200–500 m (650–1,600 ft) and are the primary prey of the Baikal seal, representing the largest fish biomass in the lake. The Baikal grayling (Thymallus arcticus baicalensis), a fast swimming salmonid, popular among anglers and the Baikal sturgeon (Acipenser baerri baicalensis), are both important endemic species with commercial value. The lake also hosts rich endemic fauna of invertebrates. Among them turbellarian worms, snails and amphipod crustaceans are particularly diverse.

The watershed of Lake Baikal has numerous flora species represented. The marsh thistle, Cirsium palustre, is found here at the eastern limit of its geographic range.

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