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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