Проект "Lake Baikal" на английском языке
презентация к уроку (8 класс) на тему

« Lake Baikal »

Content

1.    Introductory part_____________3
2. History of Lake Baikal

1. History and formation_____________4
2. Legends of Baikal origin__________ 6
3. First maps of Lake Baikal_________ 7

3.  Landscapes____________________8
4. Climate

1. Average temperature_____________10
2. Fogs__________________________12
3. Winds and waves________________12
4. Ice conditions___________________15

5. Fauna and vegetation

1. Mammals______________________16
2. Lake Baikal seals________________19
3. Ichthyofauna___________________ 21
4. Invertebrates___________________ 24
5. Vegetation ____________________ 26

VI CONCLUSION________________ 27

Literature_________________________29

I. Introductory part

       Our planet Earth is our home. It is big and nice. There are a lot of forests, mountains, rivers, lakes, seas and oceans. The forests are full of animals. The oceans are full of fishes. We live because we breathe air, drink water and eat food, growing on our planet. For hundreds of years nature has been serving people. They did not think about it. Industrial progress has caused certain ecological problem. Factories and plants put waste into the atmosphere and water. Air in big cities is awful because of transport. Forests are burnt by fires caused by careless people. A lot of animals and birds are killed or died without them. Chemical wastes kill fish in the rivers, lakes, seas and oceans. Can we solve the problem of pollution? Yes, we can. We can plant trees. They clean air in our cities. We must not make fires in the forests. We must help animals, birds and not disturb wildlife. Nature riches will not last forever. It is our duty to do our best to protect the environment.

        The deepest lake in the world is Lake Baikal. It is 636 km long and 48 km wide. The Baikal is 1620 meters deep. More than 300 rivers run into the Baikal, and only one, the Angara, drains it.

        The largest inland water area is Lake Baikal. It is the deepest and the most beautiful. lake in the world. Its water is so clear, that you can see the stones on the bottom, if you look down. It contains one sixth of all the fresh water in the world. Lake Baikal is also the word’s oldest lake. Experts are still arguing about its origin and about how seals and sea cows ever came to be in it – not to mention the omul, a wnite fish of the salmon family. They have identified 1200 different creatures which are unique to Lake Baikal, many of them reputed to be survivals, which have become extinct – ever in the hottest summers. Thousands of tourists like to visit it and see picturesque scenery around if.

        Lake Baikal is the treasure of our country and we must save it for the next generations. I have chosen the subject of my project, because I would like to describe how beautiful Lake Baikal is and our task is to protect it and save for our children. I have never been to Lake Baikal, but I have read a lot about this lake and I hope I will have an opportunity to visit this natural beauty of our country this summer.

II. History of Lake Baikal

2.1 History and formation

       Geologists believe that the Baikal has already, been in existence in late Palaeogene. Its origination started not less than 25-30 millions years ago.
       In the prebaikalian period the relief was not nearly so contrasting as at present, yet it was a mountain relief. Height probably did not exceed 300-500 m above the bottom of the basins, which surrounded these mountains. Originally the Baikal basin was certainly

shallower and narrower. Probably it was a river bed, which accepted waters from uplands of Zabaikalia and Mongolia.
      Individual parts of the Baikal basin, which is currently united, were considered by geologists and geographers as being developed at different times. Some basins subsided more, some less. But this process took place in one and the same geological period, the Tertiary.
      Even in the initial stages of formation, the basins of  baikalian type represented beds of more or less large lakes, connected by rivers, and could constitute a gigantic united system, like the present lakes of the Laurenty system in North America.
    The Baikal became united late in Pliocene - early in Quaternary.
    Opinions on mechanisms and history of the Baikal basin formation differ. Investigators of the XVIII century regarded it to be a sink. Chersky believed that the Baikal basin is a result of slow and progressive transformation of folds in Laurentian rocks. Then the assumptions of the XVIII century have undergone a change and the Baikal was considered to be a large graben, and according to Zuss, a combination of two grabens, originally divided by mountains, which extend from Olkhon island to Svyatoy Nos peninsula.

      V.A.Obruchev: "It is deep, wide and its slopes are too steep and abrupt. Such a depression could be formed solely by disjunctive crustal movements and is comparatively recent in age, otherwise its steep slopes would have been smoothed out owing to washout, and the lake would have been filled with the slope products".

         Ivanov V.D. believed that the uplift of the land in the form of a wide and flat arch, in which faults and individual block structures developed in places, was responsible for formation of the recent topography of Pribaikalia and Transbaikal. The Baikal and the basins resulted from subsidence of high part of the arch. Such basins are known in geology as the rift basins.
      Block tectonics appears to be the main mechanism of formation of the topography of the Baikal mountain region. But geologists are of the opinion that phenomena of earth curve, which form its folding, should be taken into account. Consequently, curve deformations are also responsible for the formation of the Baikal basin. Pavlovsky E.V., Florensov N.A. consider the Baikal basin to be a deep syncline, complicated by normal faults.
GEOLOGICAL & Geophysical Data

Geological age of Lake Baikal:
Pre-rift (pre-baikalian) period (Cretaceous-Late Eocene): 70 - 35 million years
Rift period: 30 - 0 million years
a) protobaikalian (early baikalian) stage (Oligocene - Early Pliocene): 30 - 3.5 million years
b) neobaikalian (proper baikalian) stage (Pliocene - Holocene): 3.5 - 0 million years
The age of deposits on the Baikal shores:
Tompuda River moraine: 39000 years
Rel River moraine: 25580 years +/- 350 years
Chernozems silts on the first baikalian terraces (Holocene optimum) approximately: 7000 years
Peat bogs of Chivirkuy Bay: 10000 - 12000 years.

2.2  Legends of Baikal origin

         1: "It is said that a huge stone fell from the sky like they do now, sometimes. While it was falling it became red hot. When it hit the earth there was a great rainfall. Earth, stone, and water came to a boil and in that turmoil Lake Baikal was born."
        2: The insufficiently known Arabian Cosmography "Creation Wonders" (the 12th century) reads about Baikal: "It is a sea of  remarkably transparent and tasty water. It lies behind the Diamond Sea. The Most High has made it in the form of two joined horns. It has sprung up from an underground crevice. And it has been and it will be moaning till the Last Judgement. And the sea is always rough and enraging...".
"And God saw: "The land has appeared cold, I am afraid it may feel hurt!" And not to offend the land, gave God the Lord not just a bedding but a bountiful measure of his, the measure by which he measured everything he had. And the measure fell down and turned into Lake Baikal..."
      3: In ancient times the place where Lake Baikal now is, was covered a dense forest. There was so much game that it was difficult for man to pass through it. And among birds there was one, as big as a sturgeon. Its wings were huge and strong, and if it touched a tree, the tree would fall down with its roots up, and if it touched a rock the rock would fly to bits. The people were afraid of the bird, but they could not kill it as when it flew by, hot rays it eradiated, made hunters fall in a dead faint.
But a man was born. He grew before the people's eyes. Soon he grew up as strong as Hercules and feared nothing. The people came and asked him to save them and kill that monstrous fiery bird. The hero listened to them. From 100 trees he made a bow, from 200 stems he cut out an arrow and set off hunting. Shortly after the Earth shuddered. And the bird fell down and a fire broke out, and it was hot in the skies. The people left the taiga for the mountains and saw water columns through the flames. And a sea appeared on that place. While the Earth and the taiga were burning, the people "were crying out: "Baikal, Baikal". Since that time the place has been called Baikal. Nobody knows for sure what the people meant by that word, either that bird, or the big fire, or the word meant "much water"... All the people remember that the place is called Baikal.

2.3 First maps of Lake Baikal

    The Russian explorers were accurate at making up the "skaski", the first descriptions of a new place. These data had served as invaluable material for the initial Russian and European investigations of Siberia.
     The Russian pioneers' service is even the more remarkable, as not so many of them were among the literate part of the population.
     Innumerable "otpiski" (replies, reports), "skaski" (the first description of a new place) and "chertezhi" (drafts) of the Russian explorers were detailed and priceless since at that time there was only limited information on the main Siberian rivers, mountain ranges and previously unknown people inhabiting this area, on peculiarities of nature and never heard of before riches of the lands.

The first drafts brought by the explorers from their expeditions did not meet the standards of European cartography. However, they fully satisfied the practical goals that were planned for the exploration of Siberia in the XVII th century, moreover, these maps were made thoroughly and conscientiously.

III. Landscapes

      There are four different natural landscapes prevalent on the territory of Pribaikalye: high-elevation, mid-elevation, low-elevation and plain.

     The high-elevation landscape is dominated by mountain tundra, Alpine and, rarely, low density trailing cedar forests located on the elevation of 1600-2000 m. The severe climate, the near inaccessibility of the region and its low recreational capacity (less than 1 man per 1 hectare/day) seriously limit the use of these territories for recreational purposes. Some areas can be used for mountain tourism and mountaineering. But one should bear in mind that throughout the greater part of the year there is a danger of frost bite and trauma.
      The mid-elevation landscape is located at heights of 1200-1800 m. In some places its lower boundary goes down to 800 m and sometimes the dark-coniferous forests and trailing cedar reach the shore of Baikal, e. g. in North Baikal.
     Mid-elevation territories are covered mainly with dark-coniferous cedar or cedar/fir forests. Due to their steep slopes and near inaccessibility the forest complexes have preserved their virginal and aesthetic attraction.
    Their recreational capacity is estimated at 1-2 men per hectare/day. These areas can be used for the development of winter vacation (tourism, hunting, ice fishing, etc). In summer the recreational facilities expand due to foot and horse-paths, water and other tourist routes along with the picking of berries, mushrooms and other gifts of nature. It should be noted that from May till July there is a danger of encephalitis.
   The low-mountain landscape is on the elevation of 600-1200 m. It is dominated mostly by sloping dark-coniferous, cedar/larch, pine and mixed taiga. This landscape is rich in berries, herbs, mushrooms and cedar nuts.
    Along the plain are forest, steppe and marsh landscapes. The first two landscapes are the most frequently explored and are under a considerable human influence. They are comfortable enough for various kinds of recreation, including tourism and therapeutic treatment.
    To preserve these natural landscapes man must use caution.

 EXOGENOUS Relief Forming Processes of Baikal Basin
Bald Alpine Mountain Zone (1100 - 2800 m):
Destruction of the intensively weathering rocks surface: 2 mm/year
Identical by form and size rocks move along a 30╟ slope: 0.3 - 34 cm/year
Snow avalanches (size: length 70 - 80 m; width 50 - 55 m; thickness 2 - 2.5 m) carry out sandy loams, grasses of rock debris and blocks (aprox.) to 30m3
Expenditure of temporary torrents: 3 - 4 m3/s
Mass movement on 1 m thick layer of soils: 0.9 - 4.5 cm/year

The area of semi-covering glaciers of Middle Pleistocene > 10,000 km2
Thickness of mountain-valley glaciers > 1000 m
Forrest Zone (from the shoreline to 1100 - 1700 m):
Rocky, heavily weathered outcrops of crystalline rocks are destroyed at 0 - 26 mm/year
in zones of tectonic cracks up to 57 - 87,6 mm/years
Chemical denudation: 0,002 - 0,025 mm/year
Velocity of soil movement along the slopes of 30-45╟ at the depths of 17 - 31 cm: 1.4 - 32 mm/year
The movement of rock-streams along the slops of 35╟: 53 cm/year
When the mudflow, lateral erosion of rivers reaches 7 - 8 m per 4 - 5 days
Abrasion velocity of Baikal's shores: 0,88 m/year
Movement of the sand to the sand to the forest on the shores: 2 - 15 cm/year
Speed of sand replacement on the glades up to 10 m/year
Sand blowing on Olkhon Island: 8.8 cm/year
Steppes and forest-steppes:
Soil replacement on the slopes of 20╟: up to 0.8 mm/year
Blocks laying on the surface of the slopes of 30╟ move: up to 105 cm/year

IV. Climate

4.1 Average temperature.

      As other natural phenomena on Lake Baikal, the weather here has a range of peculiarities that one can hardly call comfortable. The main feature of the Baikal weather is its changeability and contrast created by the combination of orographic, hydrological, atmospheric characteristics and topography of the basin. The lake being located in the centre of Eastern Siberia with its continental climate characterized by sharp contrasts between summer and winter temperatures, has some signs of a maritime climate. Seasonal temperature variations of this climate are smoothed over. Thus, there is a comparatively mild winter and cool summer. The difference between the Baikal climate and the climate of Eastern Siberia becomes quite obvious when for instance, comparing the temperatures in Irkutsk and on the lake. Though the distance between them is only 70 km, in December, while it is - 25-30╟ C in Irkutsk, it is only -15-20╟ C in Listvenichnyi Bay. But in July, when it is +25 + 30╟C in Irkutsk, it is only +15 +20╟ C ashore Baikal.
Average annual air temperature:
- Southern part -0.7╟C    

 - Central part -1.6╟C
- Northern part -3.6╟C
- Average annual air temperature in Peschanaya (Sandy) Bay (the warmest place in East Siberia) +0.4╟C
Average air temperature above the open surface of Baikal:
- winter -25╟C
- summer +17╟C

      Though the annual range of temperature on the lake is not so wide and there are only a few hot summer days, one cannot complain of the shortage of sunshine. The annual sunshine exceeds 2 300 hours which is more than in Mineralnye Vody (the Caucasus) where it is estimated at 2000 hours.
    By rights, Lake Baikal can be called a sunny region. The sun shines brightly above the lake till late autumn.

     A comparatively mild winter, cool summer and abundance of sunny days are true merits of the Baikal climate considered in view of the average annual temperature and hours of sunshine. One should also bear in mind a singular characteristic of the Baikal weather - its changeability. Lake Baikal combines climatic features of the Crimea and the Okhotsky Sea coast (Far East). As the Baikal climatologist N.P. Ladyeishchikov emphasizes, even neighbouring points may differ in weather as much as if they were separated by hundreds of kilometers.
Duration of sun radiance:
In northern part of Baikal = 1900 - 2200 h/year
In southern and central parts of the lake = 2000-2400 h/year
To compare:
The Riga sea coast = 1839 h/year
Abastumani, the Caucas = 1994 h/year
Direct sun radiation inflow:
- in summer up to 9.9 kcal/cm2 per month
- during a year up to 60 kcal/cm2
- central part of the western shore and southern Baikal per year up to 110 kcal/cm2
Evaporation heat expenditure (different parts of the lake) from 30% to 70%

4.2 Fogs on lake Baikal

      A considerable discrepancy in the temperature of the water and the air is a serious reason for fog formation. In summer the warm air from the dry land descends over the cold surface of the water, in late autumn and in winter the water evaporates from the surface. It is explained by the fact that cooled air masses from the dry land blanket the lake hollow. The fog stays mostly on the shoreline bends, coves, bays and at the open inlets of the rivers. And then one can see "a wonderful fairy-tale: now, a sailer with a flowing snow-white sail is sliding at full speed to meet you; now, a handsome castle of the Middle Ages hangs poised in the air, smoothly descending as if adapting itself where to land better; now, swans, their proud heads high, are flowing close up to you..." Quite a number of legends and beliefs are connected with the Baikal mirages. From the scientific point of view there is nothing unique about the fogs on lake Baikal. Baikal fogs are just Baikal fogs.
    Mists are often frequent in June when they appear while moisture condensation which is brought to cold Baikal with heated air. Usually they are observed while the little wind weather. Average number of misty days in June is 13-20 days in the northern part and 6-12 days in the southern part of the lake.

4.3 Winds and Waves                                    

       Especially remarkable about the Lake Baikal region are shifting winds, monsoons and breezes. It is a certain sign of a maritime climate. And as such, the huge mass of water exerts a serious influence on the surrounding environment and gives rise to a complex local wind system. The exceptional variety of the Baikal winds is reflected in the great number of names for them. Many local signs are connected with the winds. It should be noted that each wind brings along a definite type of weather.

     "Verkhovik" is a dry wind starting in the Verkhnyaya (Superior) Angara River valley, and is one of the mightiest and durable winds on Baikal. Verkhovik is a north and north-east wind, blows over the whole lake, usually in spring and summer. Its speed can reach 18 - 20 m/sec. Far from immediately do the waves calm down after this wind and a strong gentle swell persists for a long time.
    "Gorny" (Gora, Gornaya, Gornyak, Kharakhaikha) - these are the names for the strongest mountain wind that is the most dangerous for navigation. It blows along the western shores of the lake, from the west and north west, and from the mountainous peaks of the Primorsky and Baikalsky ranges. They are momentary winds reaching hurricane power and speed of more than 40 m/sec. Suddenness, insidiousness, unpredictability of force and powerful roughness are characteristics of these winds.
   "Sarma", in the Olkhon region, is particularly strong. Its gusts are so strong that they can lift roofs off houses, and turn boats and launches over. In these gusts the wind speed can reach 40 m/sec. Waves whipped up by this wind can be as high as 2 - 3 metres and in the centre of the lake up to 5.5 metres.
  "Shelonnik" (Selenga) comes from the south east. In summer its speed is moderate, up to 10 m/sec., and stronger in autumn, up to 20 m/sec. It reaches its maximum speed at the mouth of the Selenga and quickly weakens in Baikal's southern basin. Only seldom does it raise storms in this southern part with waves of more than 2 metres. Shelonnik brings air from Mongolia over the Khamar-Daban Range. It is followed by thaw and clear weather.
   "Barguzin" blows from the north east down the valley of the Barguzin. Typically this is an autumn and winter wind. In the open sea, it reaches a speed of 18 - 20 m/sec. Storms brought about by the Barguzin whip up waves of 3.5 - 4 metres along the western coast of the lake in the region of Olkhon and Goloustnaya.
   "Kultuk" (nizovik) blows from the south west along the entire length of the lake. The speed of this wind can get up to 18 - 20 m/sec. When this wind is blowing, the whole lake is disturbed, the height of the waves is usually not less than two metres. In the zone where the wind's speed is the highest, the waves can be more than 3 metres height. The waves caused by the Kultuk take a long time to settle down.
   The most well known winds on Baikal are Barguzin, Kultuk and Sarma. In no time, they come impetuously from the river valleys and can make much turmoil on the lake. The Baikal fisherman will hardly say: "Hey, Barguzin, do stir up the billow", as the folksong sings.

WAVE CHARACTERISTICS
June - July: calm (the waves are less than 0,5 m) - 80%
From August 15 to September: summer storms, waves are up to 1.5 m high - 80% of all summer storms
The waves higher than 2 m - 17%
The waves higher than 3 m - 3%
In autumn the waves can reach - 5 m high (rare)

 Winds' activity:
The cross-lake winds are of NW, ESE (up to 40 m/sec.) direction (estimated wave height - 5.5 m, period 6.5 sec.) = 50 - 90 km
Along-lake winds (NE, SW direction) = 400 - 600 km

Wind effected phenomena
3 wind effected ebbs and 3 - 4 wind induced surges per month, 24 and 37 for a year respectively

Tides (Kultuk village region)
period: 12 hours
height: 1 - 2 cm

Currents
Wind current velocity near the surface - up to 1.4 m/s
Velocity of circulating currents at the depths of
50 m - 56 cm/s
250 m - 30 cm/s
675 m - 12 cm/s
1000 m - 8 cm/s
1200 m - 6 cm/s

4.4 Ice conditions

      For almost five months a year Lake Baikal is covered with ice. This period of ice plays a very significant role in its life. The most considerable peculiarity of the ice regime of Lake Baikal is its late freezing that takes place only in the middle of winter (usually, 1 January), long after the beginning of severe Siberian frosts. When other rivers and lakes froze long before in the year, Baikal still resists ice fetters. Its cold waves break against the shore and decorate the seaboard rocks with icy patterns.
The lake is freed of its ice imprisonment around May - June when its shores turn rosy due to blossoming of rhododendrons. The late ice phenomena (freezing and melting) are caused by the small range of temperature change of a huge water mass. The lake's ice attire, its beauty and majestic symphony of "ice music" make it very attractive for every onlooker.
Duration of ice covered period: 4 - 5 months
Freezing of the bays before the freeze-up: 10 - 30 days before
Ice thickness in a freeze-up day: 5 - 20 cm
Ice thickness in hummock areas: from 40 - 70 cm to 2 m and more
Speed of the ice growing: from 1 to 5 cm/day
Thickness of the ice: from 40 cm to 1.2 m
In Maloe More / Small Sea area: thickness of ice is up to 1.5 m

Width of multiyear constant cracks: 40 cm up to several metres
The size of ice fields divided with cracks: 10 - 30 km
Ice height in strain cracks: up to 10 - 12 m
Duration of drift ice: 10 - 20 days (in the South up to 30 days)

V. Fauna and vegetation

5.1 Mammals

     On the boundary of the two elements - land and water, on the narrow Baikal shore, fascinating and peculiar life forms are found. The Baikal shore is a unique ecological niche the inhabitants of which are connected with both dryland and water. Some of them live on land but feed in water, others spend the greater part of the time in water but breed and end their lifetime ashore. Due to its unique location, the land animals of the Baikal region contain specimens of the fauna found in Central Asia, Europe - Siberia and East Asia. Furthermore, the taiga near-lake backwoods are inhabited by rare animals which have become extinct in other places.
    Among the upland high ridges, the mammals most widespread are mountain goat, snow sheep, Alpine field-vole, marmots, and in some places - lemmings. In summer on the slope and valley zones one can come across big ungulate animals and their predators, brown bear in particular.

    Bears generally weight 200-300 kilos. A bear entering hibernation weights 60% more than it did a few months earlier. In late autumn they retire to their winter den. It is often just a space under or over a hanging rock, or a fallen tree. Bears are not true hibernators and may be aroused easily without too much difficulty. However, their heart beat, breathing rate, and temperature are depressed. This slowdown of body functions will help to conserve the stores of fat. Local bears leave their den by mid April or early May. A female bear may give birth to cubs in late January. The cubs are tiny - about the size of chipmunks. The cubs stay with their mother through the summer and then share the den in the following winter. Mother and father have full charge of the young. The bear is territorial by nature and each bear has its own area that it uses and protects. In the water, it is a strong swimmer.

  Rein deer, white tailed deer, elk, moose, musk deer, Siberian roe, wild boar, are typical fauna between the Alpine belt and the sparse growth of trees and the coniferous taiga zone.
    The moose is about 800-900 pounds. Females are someone smaller. One or 3 calves are born after mating season.

     Water rats and musk rats are characteristic of the river banks. Among predators besides bear there are lynx and wolverine. The Lynx is relatively lightweight. Each lynx has a large home range. Furs are highly valued at international auctions. The taiga also shelters and feeds a great number of little mouse - like rodents and insectivorous animals. 

    Roe deer, polecats, ground squirrels, field-voles, insectivorous animals and wolves mainly inhabit the partially - wooded steppes.
   The Wolf is a member of the dog family. These animals are divided into packs which are believed to be a family group. Each mated pair produces a litter of about 5-6 pups in May. Wolves are highly social by nature. Each pack is well-organized and has its most dominant and submissive family member. Research has shown that a wolf is not a reckless killer of wild life and therefore it is prey is mostly old and sick animals. Wolves are stimulated to chase any animals that will run from them.

       Siberian forests are famous for 69 species of fur bearing animals. 29 of them are found in Baikal region.  Squirrel is one of the most common members of our forest land. It prefers forest with a lot of conifers trees. The primary food is the seed of conifers. In Autumn, squirrels store cones around the base of a tree. They eat natural fruit, berries, and mushrooms. When food is abundant birth and survival are high.
     American Mink was imported here from Canada. Most of its life is spent close to the water. It is short and durable fur has always been a favorite of fashion designers. Most of the demand for fur is mink and it raised at mink-farms.
     Red fox is a member of a dog family. During the day it remains hidden. The number of pups in a litter is from 2 to 10.  Ermine. In winter they are white except for a black tip on the tail. They are capable of killing nestling birds, chipmunks and mice.
  Muskrat is one of the most numerous fur-bearing animals in Siberia. The fur is thick and smooth used in making coats and hats. They live mostly on plants of various kinds.
   Kolinsky, Alpine hare, chipmunk are also among the Baikal fur-bearers.

At the most inspired hour, Nature presented the world with sable - the most typical and valuable inhabitant of the south Siberian mountain taiga.

 What does this little animal mean to Russia? Russians followed the sable trail throughout Asia to the Pacific Ocean. In the XVII th century fur-trade made up half of the national income of Russia. Salaries were paid in sable skins, debts were also repaid in sable; Russian tsars presented the nobility of Europe and East with sable.
   Sable fur is valued not only for its beauty, but because Sable fur is valued not only for its beauty, but because it is rather practical and durable. Nowadays, there is a great demand for sable at international fur auctions. Sable, or the "fur-king" as it is sometimes called, was awarded several gold medals.
   It is not very easy to see a sable in the taiga. The sable is a very careful and extremely secretive predator. Sable hunting requires special hunting skills, endurance and also good knowledge of the animal's habits and habitat.

5.2 Lake Baikal seals – nerpa

      Baikal is one of the few continental reservoirs inhabited by "nerpa" (the Baikal seal). It is still a great mystery how nerpa appeared in the centre of the Asian continent, if its relatives live in the northern arctic regions. Some scientists consider that it was pushed southward from the Arctic Ocean by advancing polar ice during the Ice Age when oceanic waters carved out the Yenisey valley up to the mouth of the Tunguska River. Baikal seals are known to go up rivers and rise rather high up with their streams, and sometimes they may even take an overland trip from one river to another. Add to this fact, the chromosomic analyses and other data are in favour of the nerpa being an arctic-sea seal. Anyway, there are many differences that the nerpa has to other seals. First, Baikal seals are more graceful, especially females. Second, they differ from others by the silver-grey colour of the skin. And, finally, they have 2 more litres of blood which enables the nerpa to do without fresh air for almost 70 minutes. According to the observations of workers of the Limnological Institute, nerpa is able to dive at a depth of almost 300 m.
   Lake Baikal forms an ideal habitat for nerpa - plentiful food, mainly golomyanka fish and bullheads; an ice regime that creates the optimum conditions for nerpa's breeding and moult cycle, and rather large and deep water body.
   Since ancient times nerpa has been an important resource for man. It valued for its wonderful fur, median fat and soft meat. According to the archaeologists' data, since time immemorial nerpa has been attracting people to the Baikal shores. Once nerpa was used as an object of barter and was also regarded as a totem.
   Nerpa is a big animal, it grows about 120-150 cm long and can weigh as much as 100-120 kg; it has a long life span. Specimens that appear to at the age of 50 and even older have been found.

    In the lifetime of a female, after a gestation period of 11 months, it can give birth to about twenty young ones. In winter time, when the lake is covered by the thick layer of ice, the seal makes holes in the ice by its sharp claws. Nearby, in a snowy den, it gives birth to one or, rarely, to two seal-calves. At first, they are of yellow-green colour. Two weeks later they turn white, and later they acquire a noble silver-grey tint of colour. As usual seal calves are born at the end of winter or the beginning of spring. The seal-mother suckles her young ones for one and a half months to two months. Seals live throughout Baikal but mostly in the northern section. In summer time the seals are dispersed all over the lake. In late autumn and at the end of spring the animals keep themselves to ice floes.

The seals usually spend the winter under ice. Each animal keeps open some air-holes. Often they are well hidden by snow-drifts or ice hummocks. Thus, it is an out of sight lair ("logovo"), where nerpa rests.
   Nerpa feeds mainly at night-time, as golomyanka fish, its favourite food, only concentrate after dark in the upper layer, 100 m deep, which is accessible for nerpa. At daytime the fish submerge to great depths.
  The average daily intake of a grown-up nerpa is about 3-4 kg of fish. So, throughout the year the nerpa eats up more than a ton of fish, mainly golomyanka. Man has often accused nerpa of aiding the extinction of omul. But the pursuit of omul requires considerable energy on the part of the seal. And nerpa prefers when available, the rather immobile golomyanka fish an bullheads.
   Nerpa is the only mammal endemic to Lake Baikal. At present the number of seals is estimated at around 60 000 heads (according to information gained by researchers E. Petrov and M. Ivanov, nerpa's population is no less than 100,000 animals.)

5.3 Ichthyofauna

    The Baikal ichthyofauna has formed as a result of freshwater fish getting into the lake at different times. All the fish according to its origin and habitat conditions can be subdivided into several groups:
1. The fish characteristic of Siberian valley reservoirs such as sturgeon, pike, eel-pout, ide, roach, dace, perch, minnow occupy mostly coastal shallow waters, half closed bays ("sory") and river mouths;
2. Siberian mountain rivers fish: grayling, taimen, lenok inhabit small inflowing streams of the lake and its coastal area;
3. To estuaryarctic fish belong omul and sig (white fish), the former of which lives both in open and coastal parts of the lake while the latter is spread only in the coastal area. Omul, sig, as well as grayling are members of the salmonidae family.

     Omul has been the symbol of Lake Baikal, in addition to bread that has been a symbol of Russia since time immemorial. There are five types of omul: Selenginsky, Chivyrkuisky, Severobaikalsky, Barguzinsky and Posolsky. They differ morphologically and by their spawning areas - 5 tributaries of Baikal. The instinct of continuation of generation forces the omul to overcome turbulent rapids and river shoals. The caviar is left on the sandy and pebbly bottoms with moderate flows, and the development of its larvae lasts 6-7 months. For different reasons, a greater part of the caviar perishes: it is either buried under sand and silt or eaten up by predators. Omul lives 18-20 years.
    It is assumed that the ancestors of omul got into Baikal from the polar regions - Arctic ocean. One theory is that there was a time when a group of omul, going with the stream up Arctic rivers to spawn, came to Baikal and favoured these conditions for breeding and development. Probably the rout of infiltration of this fish drove on Yenisei and Angara rivers. The omul's colonization of Baikal and its adaptation to new living conditions appeared to be Nature's tremendous experiment, revealing flexibility and adaptability of aquatic organisms to changes of the environment. Omul biomass in Lake Baikal by data of the survey made on May 25 - June 5, 1999 = 26000 ton (300 000 000)

      Grayling. Local name for grayling - harius. A sappy fat fish can weigh up to 12 pounds and more. Splendid sporting items of fishery are the black and the white Baikal graylings. In spring, after the ice breaks up, the black Baikal grayling, a surprisingly graceful fish with a high spinal fin, sparkling with all rainbow colours, move up into the rivers falling into Baikal. It overcomes the rapids and zaloms (wood-piles stuck in a river) up to one metre high, and 17 days later the caviar gives life to the larvae that roll backwards into Baikal. The black grayling lives both in the lake's quiet waters and swift mountain rivers.
    Sturgeon. Special place in the lake's ichthyofauna is taken by the Baikal sturgeon which largely inhabit the areas of the Baikal's major tributaries: the delta zone of the Selenga River, Proval Bay, Chivyrkuy and Barguzin Buys. The sturgeons migrate widely throughout the whole lake alongside the coastal line of Baikal, swimming into bays and coves. In former times, the sturgeons caught used to weigh about 250 pounds, yet, they grow slowly and mature late.

       Bullheads. Born in Baikal from an ancient form, a kin to the Anadyr and Michigan bullheads, they are represented in Baikal by 20 species, 20 of which are endemic. There is a variety of deep sea bottom bullheads - the shirokolobka ('wide forehead', as called locally). Largely, the bullheads are typical inhabitants of the bottom, occupying all water depths. Also, Baikal homes the world's most abyssal fish living in fresh water. These fish have preserved eyesight even at the greatest depths, though it is black-and-white there, in fact. Two species of the bullheads: the yellow-fin and the black-crest - inhabit the water depths. These pelagic forms live in the upper 100 metre thick layer, feeding on the epischura and the yur. The pelagic bullheads' fries, especially those of the yellow-fin bullheads, the so called poyed (glad meal), is one of the food components for the omul.

     Golomyanka (fat fish). The most interesting of bullheads are these fishes. The Lake wonder! Golomyanka can be found nowhere else on the earth. It is unusually beautiful, sparkles blue and pink in sunshine. However, the sunshine causes it to melt! Only bones and a fat spot will be left there. It contains about 30% of oil, rich in vitamin ╚A╩. There was a time when Tibetian monks came to Baikal and gathered golomyanka along the shores. Its fat was used as a remedy for many diseases. Native Siberians used it as the fuel for their lamps, and also medicinally. Old residents said that long time ago, after the storms, golomyankas were picked alongside the shores, the fat was melted and used in treatments for rheumatism, atherosclerosis and for healing wounds.
    Golomyanka is the main and the most numerous inhabitant of Baikal, but it very seldom gets into fishermen's nets. Its resources amount for about 150 thousand tons, but on neither of its life stages does it swim in great gatherings or schools, and, that's why, it's not entered in the food-fish list. Its predator is nerpa (the Baikal seal), for which golomyanka is the staple diet.
   Golomyanka is a very independent fish and quite different from its relatives who tend to shoal. It prefers a solitary existence. Golomyanka fish lives down in the depth of Lake between 700-1600 feet where the water temperature is low. It is noted that the golomyanka is very sensitive to the temperature of water. The temperature of up to +5╟C is optimal for it, it avoids higher temperatures, and +10╟C is mortal for it.
   This fish is small in size, 15-20 cm long. It's designed to live in extreme pressures. Interesting are vertical migrations of Golomyanka from small depth to bottoms of very deep depressions, where even a cannon cannot shoot (because of the enormous pressure). Golomyanka moves up and down obeying the waves. This is probably due to the absence of swimming bladder and strong fins. During migrations the change of pressure leads to forced stops necessary for the adaptation to existing conditions. At night Golomyanka rises to the water surface, and at daytime it swims down to great depths.
  Each autumn the females being viviparous instead of laying eggs produce 2000-3000 of larvae ready to swim progeny and after that they are generally died.

5.4 Invertebrates

      Recently about 2635 animal species have been registered in the open part of Baikal. Most abundant of them are invertebrates: infusoria (about 400 species), sponges (10 species), flat worms (over 100 species), free-living nematodes (about 80 species), arthropods (about 700 species) molluscs (over 170 species) etc. Due to some of these organisms the ability of Lake Baikal for self-purification is one of the greatest. They purify water.

The systematic composition of invertebrate fauna of Baikal can not be considered finally defined. Annually tens of new species are described by experts in zoology (mainly - from the laboratory of hydrobiology and systematics of fresh-water invertebrates of Limnological Institute), unknown so far animals are discovered.
    Three groups of organisms are distinguished according to their inhabitation in Baikal as in any other reservoir: benthos - bottom inhabitants; bentho-pelagic, occupying near-bottom water layers and pelagic, inhabiting water body (pelagial). Benthos organisms reach greatest diversity in the Lake (over 1000 species).
    Infusoria - most variable one-celled organisms of Baikal. They are generally divided into 2 groups; free-living (benthic and pelagic), and also symbiotic infusoria. In contrast to other fresh-water reservoirs, Baikal produced several endemic communities of free-living infusoria both in waterbody, and in the bottom. L. A. Obolkina found amazing infusoria fauna inhabiting microscopic space between sand particles (cyliopsammon). One of them is a new species and new genus Aleksandrina baicalensis Obolkina, n. gen., n. sp. Similar organisms, as a rule, inhabit only seas. Baikal is an exclusion to this. Symbiotic infusorians are unusual and diverse in form. They live on other bigger animals, for example, crustaceans, molluscs. All Baikal infusoria - symbionts (about 30 genera and 200 species) are endemic.
   Flat worms - planarians. Looking like a baby-bear with many eyes, Papilloplana sp., which is only 2 cm long; largest fresh-water planaria of the World-Baikaloplana valida, which is 40 cm long, when moving. Giants, common at the depth over 100 m, are predators and therefore are provided with suckers - Baikaloplana has over 100 ones on both sides of the body; another giant - Rimacephalus arecepta having two ventral ones on the frontal end of the body - is often taken out the deep-water nets, when it eating a fish there.

    Lubomirskia. Crust and branched forms of endemic sponge Lubomirskia baicalensis are real submarine forests at the depths of 2 to 40 m. Externally the sponges resemble fantastic plants. But they are real animals, ones of the first many-celled organisms (Metazoa), inhabiting the Earth. Their green colour is due to small symbiotic algae - zoochlorella. 

    Epishura - one of the most well-known invertebrates of Baikal. This small, 1.5 mm long crustacean plays an important role in the pelagic ecosystem. It consumes the majority of Baikal algae and serves an essential feeding object of famous omul. The epischura plays an exceptional part in Baikal's life circle. Without any exaggeration, one can say that the epischura is the major filter of Baikal. According to academician G. Galazy, a well-known scientist (Lake Baikal, 1979),  throughout the year all crustaceans of this species filter from 500 to 1,000 cubic kilometres of the Baikal water or more, which is 10-15 times more the annual inflow of water from all tributaries╩. The epischura lives only in cold clean water with constant chemical composition and high saturation with oxygen. Biomass of Epishura and cyclop (aprox.) = 1800000 ton.
   One-celled and small invertebrate animals, inhabiting the Lake pelagic zone are joined into zooplankton group. They posess such apparatus, that support them in water body. They are free-moving together with Lake waters and occur up to great depths. Total biomass of zooplancton = 4600000 ton.

5.5 Vegetation

     Nature is very generous to Lake Baikal. A necklace of coniferous forests, decorating the shore mountain chains, creates a unique beauty of landscapes, shelters animals and birds, and enlivens the surroundings. The pride of Pribaikalye is the taiga forest. The light green of larch, birch, poplar and alder trees growing in the lower belt, covers the slopes. Higher up it is replaced by a belt of a dark coniferous forest - cedar, fir and spruce. Up this belt the slopes are covered with impassable brushwoods of trailing cedar, through which only bear trails run. Above them on the gentle sloping terrace there are Alpine grasslands with parterres and finally, snowcovered peaks.
   In contrast to European new woods the Baikal taiga has preserved trees of all ages - from young ones to 500-600 and even 800 year old giants. It is the only place where pine forests, with the world famous Angara pine tree, extend. Its timber has no match. In the undergrowth of pine forests, on the former burnings and clearings, one can come across rich red bilberries and on the hillsides, fern thickets.
  Mixed pine-birch and birch-aspen forests have rather a wide spreading, as it is a stage of indigenous pine reforestation.

   The most precious woods in Pribaikalye are cedar groves. The major forestry areas are located in the east of the Central Siberian Upland.
  Spruce and firewoods are the least in Pribaikalye. They grow mostly alongside cedar, larch and sometimes, pine trees.
  Among non-forest types, most widely spread are steppe, Apline meadowland and marsh vegetation. The Alpine flora is rich in colourful, ornamental plants, e.g. vodosbor, Aquilegia (Lat.); gorechavka Gentiana (Lat.), cyclamens, herbs and "zharky" (endemic flowers of bright yellow colour).
  Meadowland vegetation is firstly water meadows along the valleys of big and small rivers, located mostly near hamlets and villages.
  Marshes in Pribaikalye dominate in cold areas. The taiga swamps are rich in cranberries and fragrant currants.

VI. CONCLUSION

      Our planet Earth is only a tiny part of the universe, but nowadays it's the only place where we can live.

People always polluted their surroundings. But until now pollution was not such a serious problem.

Today our planet is in serious danger. Acid rains, global warming, air and water pollution, and overpopulation are the problems that threaten human lives on the Earth.

The pollutants that harm our respiratory system are known as particulates. Particulates are the small solid particles that you can see through rays of sunlight. They are products of incomplete combustion in engines, for example: internal-combustion engines, road dust and wood smoke. While such pollutants as particulates we can see, other harmful ones are not visible. Among the most dangerous to our health are carbon monoxide, nitrogen oxides, sulfur dioxide and ozone or active oxygen.

Seas and lakes are also in danger. Water pollution occurs mostly, when people overload the water environment such as streams, lakes, underground water, bays or seas with wastes or substances harmful to living beings.

Water is necessary for life. All organisms contain it, some drink it and some live in it. Plants and animals require water that is moderately pure, and they cannot survive, if water contains toxic chemicals or harmful microorganisms. Water pollution kills large quantity of fish, birds, and other animals, in some cases killing everything in an affected area.

Pollution makes streams, lakes, and coastal waters unpleasant to swim in or to have a rest. Fish and shellfish harvested from polluted waters may be unsafe to eat. People who polluted water can become ill, if they drink polluted water for a long time, it may develop cancer or hurt their future children.

The major water pollutants are chemical, biological, and physical materials that lessen the water quality. Pollutants can be separated into several different classes:

1.  petroleum products: oil, fuel, lubrication, plastics. The petroleum products get into water by accidental spills from ships, tanker trucks and when there are leaks from underground storage tanks. Many petroleum products are poisonous for animals. Spilled oil damages the feathers of birds and the fur of animals, often it causes death.
2.  pesticides and herbicides. There are chemicals used to kill harmful animals and plants. If they penetrate into streams, rivers, lakes, these chemicals can be very dangerous. The chemicals can remain dangerous for a long time. When an animal eats a plant that's been treated with it, the poisons are absorbed into the tissues and organs of the animals. When other animals feed on a contaminated animal, the chemicals are passed up to them. As it goes up through the food chain, the chemical becomes more harmful, so animals at the top of the food chains may suffer cancers, reproductive problems, and death.

Nitrates can cause a lethal form of anemia in infants.

3.  heavy metals, such as, mercury, selenium, uranium, radium, cesium, etc. They get into the water from industries, automobile exhausts, mines, and natural soil. Heavy metals also become more harmful as they follow the food chain. They accumulate in living being's cells and when they reach high levels of concentration in the organism, they can be extremely poisonous, or can result in long-term health problems. They can sometimes cause liver and kidney damage.
4.  fertilizers and other nutrients used to promote plant growth on farms and in gardens.
5. infectious organisms and pathogens. They enter water through sewage, storm drains, runoff from farms, etc.
6.  thermal pollution. Water is often taken from rivers, lakes or seas to be used in factories and power plants. The water is usually returned to the source warmer than when it was taken. Even a small temperature change in a body of water can drive away the fish and other species that were originally there, and attract other species in place of them. It breaks a balance and can cause serious circumstances in future.

Our task is to protect the most beautiful lake in the world. Together we will be able to save our beautiful planet for future generations.

    LITERATURE:

1. Brusova N.G., Lebedeva N.A. “English topics for improving on Conversational Skills”. Forms 6-9. Drofa Publisher, Moscow, 2000.
2. Боярская Ю.А. «Дополнительные упражнения по английскому языку» к учебнику В.П. Кузовлева и др. «English-8».

INTERNET SITES:

3. http://www.bww.irk.ru/baikalhistory/baikalexplorations.html
4. http://en.wikipedia.org/wiki/Lake_Baikal
5. http://www.baikalnature.com/guides/86611
6. http://www.greenpeace.org/russia/en/campaigns/world-natural-heritage/lake-baikal/
7. http://www.irkutsk.org/baikal/animals.htm
8. http://www1.american.edu/ted/baikal.htm
9. http://www.bww.irk.ru/baikalwater/pollution.html