Seawater is salty, marine life adapts to the environment in the sea, generally many marine creatures from salt water to freshwater areas will be difficult to adapt, but there is a freshwater lake in Asia but there are a large number of marine animals, the most typical marine animal is seals.
This very special freshwater lake with marine life is called Lake Baikal, which is located in the southern region of Eastern Siberia, Russia, in the territory of the Republic of Buryatia and the Irkutsk region. Because of the high transparency of Lake Baikal, it is also known as the "blue eye of Siberia".
According to data measured in 2015, Lake Baikal has a total volume of 23.6 trillion cubic meters, an average depth of 730 meters, and the lake's deepest point is 1,637 meters, covering an area of 31,500 square kilometers. It is the deepest lake in the world and the largest freshwater lake in Asia, with abundant reserves of freshwater resources. It is estimated that the freshwater resources of Lake Baikal account for about 20% of the world's total freshwater resources, account for 85% of the total water of Russian lakes, and 8 times the total freshwater resources of the mainland.
The reason why Lake Baikal has so much fresh water, in addition to the large area of the lake, the average depth of the lake, can store a large amount of fresh water resources, is also because of a large number of fresh water resources to replenish, according to statistics, about 300 large and small rivers flow into the lake, of which the Selenge River replenishes more than 50% of the lake's water. As a freshwater lake, the overflowing water of Lake Baikal flows into the Arctic Ocean via the Angara River, a tributary of the Yenisei River. The Yenisei River is the largest river in Russia by volume and one of the largest in the world.
Lake Baikal is so deep because it is a lake formed by the collapse of strata fractures caused by earthquakes, which is not difficult to see from the bathymetric map of the lake, and the section is very vertical.
When it comes to Lake Baikal, we have to mention its historical ties with China, Baikal was called the Beihai in ancient China and was one of the main areas of activity of the northern tribes in ancient China. Su Wu herded sheep in the Han Dynasty, and it is said that it was here, but Su Wu herded sheep there as a prisoner of the Xiongnu.
The Yuan and Qing dynasties controlled the place for a short time, but after the signing of the Treaty of Nebuchu between Qing and Russia, the Baikal region became part of tsarist Russia, and hundreds of years have passed, which has long become an unchangeable fact, and it is useless to think about it.
Lake Baikal is located deep in the continent, more than 2,000 kilometers from the nearest coastline, so why is this freshwater lake far from the sea home to unique marine life?
As one of the largest freshwater lakes in the world, Lake Baikal is rich in biological resources. Statistics show that the Baikal region is home to about 1,000 species of plants and 2,500 species of animals, 80% of which are unique to the Baikal region.
The origin of marine life in Lake Baikal begins with the evolutionary history of Lake Baikal.
According to Soviet scientist Vereshchin, there was a Transbaikal Sea east of Lake Baikal during the Jurassic period of the Mesozoic era, and due to changes in the earth's crust, the Transbaikal Sea completely disappeared about 20 million to 25 million years ago, leaving Lake Baikal. With the continuous infusion of fresh water resources, the salinity of the water in this lake continues to decrease, and gradually becomes a freshwater lake. According to this speculation, it is indeed a good explanation of the origin of marine life in Lake Baikal.
However, in the 90s of last century, Russian scientists found that there were no Mesozoic sedimentary layers in the sample, only cenozoic sedimentary layers. This evidence proves that Lake Baikal did not evolve from the sea, thus rejecting the claim that the marine life of Lake Baikal is a marine relic species.
It is now generally believed that the Baikal Rift Valley, where Lake Baikal is located, formed in the same way as the Great Rift Valley in East Africa, and is due to the geological fault collapse zone formed by plate movement.
It's just that how exactly did the marine life in Lake Baikal come about? There are still no entirely convincing conclusions.
As for the seals in Lake Baikal, it is believed that these seals traveled from the Arctic Ocean along the Yenisei and Angara rivers a long time ago and finally arrived in Lake Baikal and made their home here. However, the current surface of Lake Baikal is 455 meters above sea level, and it is more than 2,000 kilometers from the Arctic Ocean, and it is difficult to understand that seals have traveled all the way to Baikal to make their home.
The mystery of the origin of Baikal's marine animals requires more evidence and research to uncover the final answer.
Lake Baikal is one of the important fishing grounds in Russia due to its rich aquatic resources. However, due to overexploitation and environmental pollution, water quality and species diversity in the area have declined to some extent. According to a 2005 survey, the number of seals in Lake Baikal has plummeted from 104,000 in 1994 to 67,000.
However, Russia has formulated a series of protection policies and established a number of nature reserves and national parks, which to a certain extent curbed the deterioration of the biological resource diversity and ecological environment in the Baikal region.