Lake, its characteristics
The lake — a reservoir formed on the land surface in the natural depression. As the lake has no direct connection with the ocean, it is — the pond to slow water exchange.
The total area of lakes on earth — about 2.7 million km 3. that is 1.8 % of the land surface.
The main characteristics of the lake:
the area of the lake – water surface area;
length of coastline – length of the water’s edge;
the length of the lake – the shortest distance between the two furthest apart points of the coastline, the average width — the ratio of area to length;
lake volume – the volume of the basin filled with water;
average depth – the ratio of water mass to the area;
maximum depth is a direct measurement.
The biggest area of water surface of a lake on Earth — Caspian (376 thousand km2 when water level is 28 m) and the deepest-Baikal (1620 m).
Characteristics of the largest lakes in the world are given in table. 1.
In every lake there are three interrelated components: basin, water mass, vegetation and fauna of the reservoir.
Lakes of the world
On the status of the lake basin the lake is divided into surface and underground. The latter sometimes filled Continue reading
The most ancient element in the fauna of the lake are the Indian bryozoans Victorella bengalensis, and L. S. Berg clam which, by definition, VA Lindholm, Hydrobia venturosa. This species now common to the coast of the seas surrounding Europe, there is in the Black and Azov seas, but not in the Caspian sea. Berg L. S. (1930) believed that the presence of this mollusk among the nagor-no-Asiatic fauna is the mystery.
The bottom of the bays and backwaters of the Issyk-Kul lake are covered with dense thickets of pondweed, reed, and charophytes. ‘hara thickets on the slopes of the basin of the lake drops to a depth of 30-40 m.
Phytoplankton counts 309 forms. He is poor in the open part of the lake, and significantly richer and more diverse in the coastal zone, where conditions are more varied. Zooplankton of the open lake is also monotonous.
Basically, he presents two types veslonogih Rachkov. It is characteristic of brackish waters Diaptomus salinus and cosmopolitan Cyclops viridis. V. M. Rylov, in the summer of 1928, studied the zooplankton of lake Issyk-Kul, notes that it is similar to the one in lake Baikal and Tanganyika: in the open waters of pet cladocerans.
For Issyk-Kul is characterized by the following representatives of the brackish-water zooplankton: Continue reading