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  Main arrow Baikal Discovery Digest arrow Lake Baikal Ecology arrow Lake Baikal and the Human Impact  
 
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Lake Baikal and the Human Impact

 

Abstract ( From the web-site  of  Baikal Environmental Wave)
Surrounded by the steep forest-clad mountains of an enormous rift valley, Lake Baikal - the oldest and deepest lake on earth - contains 20% of the world's surface freshwater. Baikal is one of the most biologically diverse lakes on earth, some 80% of its living organisms being unique to the lake. The lake's basin covers an area of 570,000 square kilometres. Its cold waters have an unusually low mineral content, and unlike most other lakes, they are oxygenated from top to bottom.  However, the impact of human activities on Baikal has increased dramatically over the last half century. A hydroelectric dam, logging, agriculture, settlements, two pulp mills, and other highly polluting industries in its air and water basins are bringing about disturbing changes in its sensitive ecosystems.

 

Altitude:                445 metres above sea level
Length:               636 kilometres
Width:                 between 25 and 80 kilometres
Surface area:      31, 500 square kilometres
Volume:              23,000 cubic kilometres (20% of world's surface liquid freshwater)
Greatest depth:  1,637 metres -  Central basin
Age:                    25 – 30 million years
Biodiversity:        2,565 animal species & sub-species and 700 plant species are found in the Lake
As you can see from the space image, Lake Baikal,  is situated very centrally in the great Eurasian land mass, further from any ocean than other large freshwater lakes.  This area has an extreme continental climate with temperatures varying from minus 500 Centigrade and lower to + 350 C or more over the surrounding land.  Baikal itself is large enough to influence atmospheric temperature over its open waters and the surrounding land up to 25 kilometres, cooling them in summer and warming in winter.  Average temperatures over its open waters varying from - 210 C in winter to + 150 C in summer.  However, the average yearly atmospheric temperature over the lake varies from - 1 degree C in the south to - 4 degrees C in the northern basin.  Baikal's waters themselves are cold - with a summer surface temperature rarely above 12 - 140 C in the open lake.  Below a depth of 200 - 250 metres the temperature is constant at around 3.30 - 3.60 C.   These factors have naturally played a major role in determining the lake's life.
The water catchment area, watershed  or basin, occupies about 570,000 square kilometres. 300 or more rivers and streams flow into Baikal draining this area, and only one river flows out, the river Angara.  Because most of the rivers entering the lake flow over hard rock, the lake's waters have an extremely low mineral content - some 25 - 50% lower than most other freshwater lakes and are very clear.  The scientific term to describe lakes of this kind is 'oligotrophic' (low level of dissolved salts, high oxygen and low organic content).  Lake Baikal contains some 20% of the worlds total surface liquid freshwater. (Alkaline - pH 7.5-8.6)
A number of things make Lake Baikal unique. One is that it is the oldest lake on earth, having formed from a series of large lakes in a deep rift in the earth's crust over a period of some 25-30 million years, as the result of the action of tectonic forces.  Most lakes are less than 30,000 years old at most. Today, Lake Baikal is made up of three distinct basins: north, central and southern. In the place of the central and southern basins, some 6 million years ago there were lakes something more than 100 metres deep.  Baikal's northern basin was the youngest of these ancient lakes and was filled with water only about 6 million years ago.  By about 800 thousand years ago the lakes had become much deeper, and about 250-200 thousand years ago all three basins combined to form a single lake.   By comparison, the rift valley Lake Tanganyika, in Africa, took on its present form some 9-10 thousand years ago, and the Great Lakes of North America - around 5 thousand years ago. 
Baikal is the deepest lake on earth. Its greatest depth, 1,637 metres, being in the central basin next to the island of Ol'khon.  Sediment builds up very slowly on the lake floor. Over a period of 100 years only about 4 centimetres will accumulate in the central basin, from 0.8 cm in the northern, and 1.5 cm in the southern basin.  The thickness of the sediment below the lake's floor varies from place to place, the deepest being from 2 - 3.5 kilometres thick, despite the slowness of deposition.  This, of course, speaks for the age of the lake. The Baikal rift zone is seismically active, weak tremors are constantly being registered, while every 10 - 12 years tremors of 5 or 6 degrees can occur.  There can be and have been more severe earthquakes. In 1862 a quake of 10.5  degrees caused an area of 200 square kilometres to sink and form the Proval Bay just to the north of the river Selenga delta.  And in 1959, as the result of a quake in the central basin, the floor of the lake dropped by 15 - 20 metres. The sides of the lake are moving slowly apart at a rate of about 1.5 cm a year.  There are thermal (hot water) vents at two points on the lake's shores, and vents have been found on the lake's floor.  So, geological activity is still very much in evidence.
An important feature is the mixing of the lake's waters from top to bottom as a result of the vertical downward movement of cold surface waters. For this reason the waters are rich in oxygen throughout.  For comparison, in the deep African lakes, Tanganyika and Nayasa, where the surface waters are well warmed and do not sink, only the top 90 -150 metres are oxygenated. Below this, there is a high hydrogen sulphide content and therefore hardly any life.  By contrast,  because of Baikal's high oxygen content, living organisms are found even at the greatest depths. Because of the lake's depth and size, the average residence time of water molecules in Baikal is something like 400 years.  This is an important factor when considering pollution. Pollutants on the whole remain in the lake. 
The high oxygenation of Baikal's waters leads to another peculiarity of great significance to the lake's ecosystems: Baikal's phytoplankton (in the main diatomic algae) develop to their maximum in spring (March-April) under the thick layer of very transparent ice that covers the entire lake. In other cold-climate lakes, as a rule, towards the end of winter there is a lack of oxygen in water under ice, and this often results in the death of organisms, especially fish. In Baikal, the top 100 metres of water under the ice cover has a higher level of oxygen than in the open-water period. This peak in phytoplankton development takes place in water with a temperature of only one degree above zero Centigrade. In other northern lakes this usually happens when the temperature of the water reaches +50 C, and phytoplankton development peaks some one and a half to two months later. 
Lake Baikal's antiquity together with the peculiarities of its hydrology and hydrochemistry are perhaps the main reasons for its biological diversity and the high degree of endemism of its flora and fauna.  Some 2,565  species and sub-species of animal and 700 species of plant are found in the Lake, of which something like 80-85% are endemic - that is, they are found nowhere else.  New species are still being discovered. It is expected that  even as much as a third more are yet to be found.  Lake Baikal is, indeed, the most biologically diverse lake on earth. (By comparison, Lake Tanganyika, the second most biodiverse, has 1248 species and subspecies).
One of the reasons for this great variety is thought to be the occurrence of nine periods of very low temperature with the formation of glaciers in the surrounding mountains over the past million years. During these periods of freezing, fauna occupying the top 25 - 50 metres of water around the shores died out.  In the warmer periods, species that had occupied the 50 - 100 metre layer moved into the top layer with accompanying changes in shape and physiology. This brought about intensive formation of species, and is the reason why most endemic species occupy the top 100 metres in the open waters of the lake today (85% of the lake's molluscs, for example). The process of species formation is continuing. This is particularly found in certain areas of the lake (by the Selenga delta, the Ushkany shallows and Olkhon Strait, that even have their own endemic species).  Because of its great depth and oxygenated waters Baikal is the only lake in the world with deepwater freshwater fauna.
One of the endemic zooplankton, a minute shrimp-like animal (crustacean) with the Latin name of Epischura baikalensis, makes up the main bulk (90%) of zooplankton of this size (1.5 - 2 mm), and plays the main role in filtering and purifying Baikal's water.
At the top of the lake's food web is one of the world's few species of freshwater seals - the Baikal nerpa, an attractive and highly inquisitive animal. It is thought to have originally entered the lake via one of two north flowing rivers that open out into the Arctic ocean - the rivers Angara-Yenisei or the river Lena, some 500,000 years ago. The nerpas' main food is an interesting endemic viviparous fish (that is, it gives birth to live young), the golomyanka, one species of which has a fat content of between 30-40%.
All this makes Baikal a natural laboratory of invaluable interest to evolutionary science. For this reason the lake has been called the "Galapagos of Russia".
In December 1996 Lake Baikal was entered onto the list of UNESCO's World Natural Heritage Sites.  To qualify for inclusion on this list, a site has to satisfy at least one of four criteria indicating its importance to both science and conservation.  Lake Baikal satisfies all four criteria.  For its geological, biological-evolutionary significance, its natural beauty, and as a habitat of outstanding importance for conservation.
The human impact
The human impact on Lake Baikal has grown considerably since the beginning of the 20th century, but especially in the last fifty years.
At the beginning of the century, 1900 - 1904 the Trans-Siberian railway was extended along the shore of the southern basin of the lake.
From the 1930 - 1950s there was a dramatic increase in logging in the lake's basin.
The 1950s and '60s saw the intensive development of agriculture in the lands around the lake, with a considerable increase in the use of pesticides in the Baikal watershed.  As a result of poor agricultural practices and logging some 3 million tons of earth are washed into Baikal annually.  One of the results of this is that a mere 1% of the natural steppe communities has remained intact.
In addition, the development of industry in Ulan-Ude at this time caused a sharp rise in pollution in Baikal's largest tributary, the river Selenga, that brings 50% of Baikal's annual input of water via rivers (60 km3).  Today, it is considered one of the two largest sources of pollutants entering the lake.
At the beginning of the1960s the construction of the Irkutsk hydro-electric power station and dam brought about a rise in the level of Baikal's waters and consequent  large-scale erosion of  its  shores, bringing damage to vital spawning grounds. The lake's littoral zone is very narrow, before the floor drops sharply into the depths. 
In 1966, the construction of the Baikalsk pulp and paper mill was completed and the mill went into operation despite unprecedented opposition from scientists. The pulp and paper industry is one of the most polluting industries. The Baikalsk mill is still in operation today. Apart from the enormous volume of waste water that the mill has discharged into the lake since it started operating, its solid waste has been accumulated in large sludge ponds that stretch some 11 kilometres along the shores of Baikal.  These present a great potential threat to Baikal as they contain high concentrations of heavy metals, phenols and dioxins. As yet there is no satisfactory method of dealing with this accumulated waste.   At present much of the solid waste from the mill is being burnt. A method that will produce dioxins so long as chlorine bleaching is used.  The Baikalsk mill and the industries of the river Selenga basin are considered to be the two largest sources of pollution for the lake today.
In 1973, the Selenginsk Pulp and Carton Mill went into operation.  To make matters worse, both mills are situated in areas with a particularly high chance of earthquakes occurring. 
 Both mills cause considerable air pollution that has had its impact on the taiga (forest) covering the mountains of the Khamar-Daban mountain range where the drying out of trees can be observed over an area of about 5,000 square kilometres stretching along the north facing slopes. In an area of about 500 square kilometres, the process of drying out is irreversible.  The impact has had a particularly heavy toll on fir trees.  In all, some 61% of the taiga  around the southern basin has been weakened by the impact of air pollution, with a sharp decline in photosynthesis.
In the 1960s and '70s, logging,  the floating of timber down large tributaries of the lake, and their subsequent floating in rafts to feed the Baikalsk pulp mill led to the sinking of thousands of logs.  Serious damage was caused by these practices, until a decree of the Communist Party in 1987 stopped a number of damaging practices in this sphere, and brought about some improvement in the situation.
The mid-1970s saw the building of the Baikal-Amur railway, or BAM, that runs alongside the lake at its northernmost tip with large-scale disturbance of land, causing a significant increase in the input of minerals and organic substances into Baikal. This was accompanied by a sharp rise in the population of  settlements adjacent to the lake.  These settlements were not equipped with adequate waste water treatment facilities.   The '70s also saw a rise in tourism, both organised and unorganised that has had a severe impact on vegetation in certain favoured areas.  The factor of disturbance by humans has caused a dramatic reduction in the number of permanent haul-out points for the Baikal seal. In fact only one such remains today at the Ushkany islands, in the north-east.  Increased tourist disturbance could have a negative effect here too, if visits are not strictly limited.  
Polluted waste waters and atmospheric pollution increased from the railway town of Sliudyanka at the extreme south-west end of the lake.
In the 1970s and '80s the Irkutsk industrial complex with highly polluting industries, such as chemical, petrochemical, and aluminium, upwind of the lake,  increased air pollution considerably. It is believed that the chemical town of Usolye-Sibirskoe is the largest source of dioxin and PCB contamination in Irkutsk region. 
Towards the end of the '80s a series of accidents at the Baikalsk pulp mill, causing massive discharges of untreated waste into Baikal, marked a peak that most likely  played a role in the massive epidemic that caused the deaths of thousands of Baikal seal in 1987.  
Analyses of the lake's organisms, from the most minute up to the Baikal seal,  at the top of the lake's food web, have shown high levels of dioxins and PCBs. Indeed, levels that can be compared with those found in seals in the Baltic Sea at the time of the epidemic of the late 1980s that killed thousands of seal, and in ringed seal in parts of the Canadian Arctic.
As a result of inadequate or lack of treatment of municipal waste waters and human waste in the towns and settlements situated on the lake, it is now not advisable to drink water from the area close to the shore because of the marked presence of E coli bacteria.
The 1990s saw a sharp rise in building in the water protection zone around the lake. Much of it quite lawless. This period has also been marked by uncontrolled logging in the basin for shipment to the Chinese market.  Of the 200 thousand cubic metres of timber logged in the Baikal basin, 20% remains at the site causing outbreaks of disease in the remaining forest. 
The human presence at Baikal can be felt in the disappearance of about 10 species of water-linked birds. The cormorant, once a common sight at the lake, has not been seen since the '50s.
Quite recently, at the turn of the century, 1999-2000,exploratory drilling for gas and oil  was re-started in the river Selenga delta.   This was, thank goodness, stopped by the chief prosecutor of the Republic of Buryatia after NGO and public protest, and subsequently such  activities have been banned in the central zone of the Baikal World Natural Heritage Site.  However, as the boundaries of the central zone have yet to be confirmed, this remains a potential threat.
A mountain skiing resort was bulldozed into the mountains behind the Baikalsk pulp mill in the '80s, with accompanying erosion.  Now there are plans to construct yet another at the settlement of Listvyanka. Not only will this entail the cutting of the forest in the water protection zone, it is also highly unlikely that measures  for the prevention of erosion will be carried out.  More likely, this will become yet another point of degradation on the shores of this precious and unique lake. 
As a result of human activity, changes are being observed in the lake's delicate ecosystem. So far, most impact has been on  the southern basin. It is reported that the hydro-chemical character of the lake has been disturbed, and that changes have occurred in the cycles of development of endemic phytoplankton. One significant indicator is a change in the species composition of phytoplankton with a decline in native phytoplankton species and increase in more common species that are found in other Siberian freshwater bodies.  These were formerly met only in shallow bays, but seldom in Baikal's open waters.  Growth rates of fish have fallen and there has been a deterioration in their physiological characteristics.
Over the period1990-2000 by comparison with the years 1979-89, an increase of about 20 C was observed in the average surface water temperature in August. 
A factor that needs monitoring is the occurrence of biological pollution, that is, the introduction, sometimes by mishap, sometimes on purpose, of alien species to the lake. These could be a  threat to native communities. One such case is the  plant species, Elodea canadensis.  There was concern that it could press native species out of their habitat in the littoral zone, so changing the natural community.  It would appear, however, that it has not become dominant, perhaps because it requires a higher level of mineralization to flourish uninhibitedly.  This should be monitored, all the same.  Alien fish species have also been introduced in the past. Impact on native species differs from case to case and requires further study and monitoring. It is now well understood that such a practice is impermissible for Lake Baikal, and it is banned by law.
The conservation of such a vast and special lake and its natural surroundings requires the efforts all sectors of Russian society, and even the assistance of the international community.  Tomorrow, I would like to talk to you about the efforts of NGOs for the preservation of Lake Baikal

 
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