Lake Baikal

Article excerpt

The world's deepest lake holds one-fifth of the fresh water on the surface of the Earth

LAKE Baikal, the world's deepest lake, contains in its basin more than 23,000 cubic kilometres of fresh water. This represents about 20 per cent of the world's fresh water reserves and 80 per cent of the total surface fresh water reserves of the USSR. This is about the same amount as is contained in all the five North American Great Lakes put together.

The lake, into which 336 rivers and streams flow, is home to some 2,600 species of plants and animals. Three-quarters of these species-as well as eleven families and sub-families and ninety-six genera-are endemic to the lake.

Scientists at the Siberian branch of the USSR Academy of Sciences, based at the Limnological Institute at Irkutsk, have been studying Lake Baikal for many years and have obtained a wealth of data on such aspects as water inputs, nutrient flows, sedimentation rates, trophic relationships, benthic and littoral fish communities, productivity of phytoplankton and zooplankton, and the effect of vertical stratification of the water column on the distribution of organisms of all trophic groups. Quantitative measures of biomass and productivity include an estimated average total net weight biomass of invertebrates of 750.000 tons, of which 40 per cent is comprised of 300 benthos.

Research has highlighted the dynamic nature of the Baikal ecosystem and the intricacy of the interactions between the lake and its surroundings. Pollution through water recycled by industrial (particularly cellulose) plants is a major threat to water quality, which in turn is crucial to the plant and animal communities living in the lake. One cubic metre of re-circulated water from a cellulose plant, normally diluted in more than 1,000 cubic metres of lake water, is not capable of supporting life. When it is considered that some of the larger cellulose plants are re-circulating more than 300,000 cubic metres of water per day (water containing highly toxic components which, even at low concentrations, may affect the life and behaviour of living organisms), the importance of the threat to the Lake Baikal ecosystem can readily be appreciated. …