Which country is located on the shores of the Caspian Sea. Temperature and salinity

I was resting somehow in the camp. It's no secret that almost every day competitions are held there to entertain children and youth. So here it is. Was we have quiz. Question: “Which lake is the largest?” One guy of about fifteen was the first to raise his hand and answer: “Baikal.” The strangest thing was that his answer was counted as correct! How so? Isn't the Caspian Sea the most big lake? Now I will explain to you.

How to distinguish a sea from a lake

I'll list several signs by which a body of water is defined as a sea.

1. Rivers can flow into the sea.

2. The outer sea has direct access to the ocean.

3. If the sea is internal, then it is connected by straits with other seas or directly with the ocean.

Does the Caspian Sea fit sea parameters?

Need to check, does the Caspian Sea have signs of a sea. into it really rivers flow in, but they flow into many bodies of water: seas, lakes, oceans, and other rivers. The Caspian Sea is surrounded from all sides by land. Is this really inland sea? Then it must connect to the Black or Azov Seas somehow strait. Strait Same No. Exactly due to the lack of access to the World Ocean, the Caspian Sea is considered a lake.

“But why was it called the sea then, if it is a lake?”- you ask. Answer very simple: because of his large size and salinity. Indeed, The Caspian Sea is several times larger than the Azov Sea and almost equal in size to the Baltic Sea.

Great! The problem with the quiz has been resolved. Judge to hell!!!

Well then, I told, that the Caspian Sea In fact - lake. Now I want to you provide small selection interesting facts about this lake.

1. The Caspian Sea is below sea level (-28 m), which once again proves that this is a lake.

2. BC near the lake area lived nomadic Caspian tribes,in honor of which he was nicknamed Caspian.

3. This the deepest enclosed body of water on the planet.

4. Many people think that the name of the group “Caspian Cargo” is related to the Caspian Sea. In some ways they are right ( No). In fact the expression “Caspian cargo” can mean any illegal cargo.

5.Caspian Sea Fine suitable for tourism. During the USSR, a large number of sanatoriums were built here. Today same here you can see many hotels, water parks and beaches.

The Caspian Sea is the largest lake on planet Earth. It is called the sea because of its size and bed, which is built like an ocean basin. The area is 371,000 square meters, the depth is 1025 m. The list of rivers flowing into the Caspian Sea includes 130 names. The largest of them are: Volga, Terek, Samur, Sulak, Ural and others.

Caspian Sea

It took 10 million years before the Caspian Sea was formed. The reason for its formation is that the Sarmatian Sea, having lost contact with the World Ocean, was divided into two bodies of water, which were called the Black and Caspian Seas. Between the latter and the World Ocean there are thousands of kilometers of waterless route. It is located at the junction of two continents - Asia and Europe. Its length in the north-south direction is 1200 km, west-east - 195-435 km. The Caspian Sea is an internal endorheic basin of Eurasia.

Near the Caspian Sea, the water level is below the level of the World Ocean, and it is also subject to fluctuations. According to scientists, this is due to many factors: anthropogenic, geological, climatic. Currently, the average water level reaches 28 m.

The river network and wastewater are unevenly distributed along the coast. A few rivers flow into part of the sea from the northern side: Volga, Terek, Ural. From the west - Samur, Sulak, Kura. The east coast is characterized by the absence of permanent watercourses. Differences in space in the flow of water that rivers bring to the Caspian Sea are important geographical feature of this reservoir.

Volga

This river is one of the largest in Europe. In Russia it ranks sixth in size. In terms of drainage area, it is second only to Siberian rivers flowing into the Caspian Sea, such as the Ob, Lena, Yenisei, and Irtysh. The source from which the Volga begins is taken to be a spring near the village of Volgoverkhovye, Tver Region, on the Valdai Hills. Now at the source there is a chapel that attracts the attention of tourists who are proud to step over the very beginning of the mighty Volga.

A small fast stream gradually gains strength and becomes a huge river. Its length is 3690 km. The source is 225 m above sea level. Among the rivers flowing into the Caspian Sea, the largest is the Volga. Its path runs through many regions of our country: Tver, Moscow, Nizhny Novgorod, Volgograd and others. The territories through which it flows are Tatarstan, Chuvashia, Kalmykia and Mari El. The Volga is the location of millionaire cities - Nizhny Novgorod, Samara, Kazan, Volgograd.

Volga Delta

The main channel of the river is divided into channels. A certain shape of the mouth is formed. It's called delta. Its beginning is the place where the Buzan branch separates from the Volga river bed. The delta is located 46 km north of the city of Astrakhan. It includes channels, branches, and small rivers. There are several main branches, but only Akhtuba is navigable. Among all the rivers of Europe, the Volga has the largest delta, which is a rich fishing region in this basin.

It lies 28 m lower than ocean level. The mouth of the Volga is the location of the southernmost Volga city of Astrakhan, which in the distant past was the capital of the Tatar Khanate. Later, at the beginning of the 18th century (1717), Peter 1 gave the city the status of “capital of the Astrakhan province.” During his reign, the city's main attraction, the Assumption Cathedral, was built. Its Kremlin is made of white stone brought from the capital of the Golden Horde, Saraya. The mouth is divided by branches, the largest of which are: Bolda, Bakhtemir, Buzan. Astrakhan is southern city located on 11 islands. Today it is a city of shipbuilders, sailors and fishermen.

The Volga currently needs protection. For this purpose, a reserve was established in the place where the river flows into the sea. The delta of the Volga, the largest river flowing into the Caspian Sea, is replete with unique flora and fauna: sturgeon, lotuses, pelicans, flamingos and others. Immediately after the revolution of 1917, a law was passed on their protection by the state as part of the Astrakhan Nature Reserve.

Sulak River

It is located in Dagestan and flows through its territory. It is fed by the waters of melted snow that flow from the mountains, as well as by tributaries: Maly Sulak, Chvakhun-bak, Akh-su. Water also enters Sulak through a canal from the Aksai and Aktash rivers.

The source is formed by the confluence of two rivers that originate in the basins: Didoiskaya and Tushinskaya. The length of the Sulak River is 144 km. Its pool has a fairly large area - 15,200 square meters. It flows through a canyon with the same name as a river, then through the Akhetlinsky gorge and finally reaches the plane. Rounding the Agrakhan Bay from the south, Sulak flows into the sea.

The river provides Kaspiysk and Makhachkala with drinking water, and is home to hydroelectric power stations, the urban-type settlements of Sulak and Dubki, and the small town of Kizilyurt.

Samur

The river received this name not by chance. The name translated from the Caucasian language (one of them) means “middle”. Indeed, the waterway along the Samur River marks the border between the states of Russia and Azerbaijan.

The sources of the river are glaciers and springs originating in the spurs of the Caucasus Range on the northeastern side, not far from Guton Mountain. The height above sea level is 3200 m. Samur has a length of 213 km. The height at the headwaters and the mouth differs by three kilometers. The drainage basin has an area of ​​almost five thousand square meters.

The places where the river flows are narrow gorges located between the mountains high altitude, composed of clayey shale and sandstone, which is why the water here is cloudy. The Samur basin has 65 rivers. Their length reaches 10 km or more.

Samur: valley and its description

The valley of this river in Dagestan is the most densely populated area. Derbent is located near the mouth - ancient city peace. The banks of the Samur River are home to twenty or more species of relict flora. Endemic, endangered and rare species listed in the Red Book grow here.

In the river delta there is a relict forest, which is the only one in Russia. The liana forest is a fairy tale. Huge trees of the rarest and most common species grow here, intertwined with vines. The river is rich in valuable fish species: mullet, pike perch, pike, catfish and others.

Terek

The river received its name from the Karachay-Balkar peoples who lived along its banks. They called it “Terk Suu”, which means “swift water”. The Ingush and Chechens called it Lomeki - “mountain water”.

The beginning of the river is the territory of Georgia, the Zigla-Khokh glacier is a mountain located on the slope of the Caucasus ridge. It is located under glaciers all year round. One of them melts when sliding down. A small stream is formed, which is the source of the Terek. It is located at an altitude of 2713 m above sea level. The length of the river flowing into the Caspian Sea is 600 km. When it flows into the Caspian Sea, the Terek is divided into many branches, resulting in the formation of a vast delta, its area is 4000 square meters. In some places it is very swampy.

The riverbed in this place changed several times. The old branches have now been converted into canals. The middle of the last century (1957) was marked by the construction of the Kargaly hydroelectric complex. It is used to supply water to the canals.

How is the Terek replenished?

The river has a mixed supply, but for the upper reaches, water from melting glaciers plays an important role; they fill the river. In this regard, 70% of the flow occurs in spring and summer, that is, at this time the water level in the Terek is highest, and the lowest is in February. The river freezes if the winters are characterized by a harsh climate, but the ice cover is unstable.

The river is not clean and transparent. The turbidity of the water is high: 400-500 g/m3. Every year the Terek and its tributaries pollute the Caspian Sea, pouring into it from 9 to 26 million tons of various suspended matter. This is explained by the rocks that make up the shores, which are clayey.

Estuary Terek

The Sunzha is the largest tributary flowing into the Terek, the lower reaches of which are measured from this river. By this time, the Terek flows for a long time through the flat terrain, leaving the mountains located behind the Elkhotov Gate. The bottom here is made of sand and pebbles, the current slows down, and in some places stops altogether.

The mouth of the Terek River has an unusual appearance: the channel here is raised above the valley, in appearance it resembles a canal, which is fenced by a high embankment. The water level becomes higher than the land level. This phenomenon is due to natural causes. Since the Terek is a turbulent river, it brings sand and stones in large quantities from the Caucasus Range. Considering that the current in the lower reaches is weak, some of them settle here and do not reach the sea. For residents of this area, sediment is both a threat and a blessing. When they are washed away by water, floods of great destructive power occur, this is very bad. But in the absence of floods, the soils become fertile.

Ural River

In ancient times (until the second half of the 18th century) the river was called Yaik. It was renamed in the Russian way by decree of Catherine the Second in 1775. Just at this time, the Peasant War, the leader of which was Pugachev, was suppressed. The name has been preserved to this day in the Bashkir language, and is official in Kazakhstan. The Urals are the third longest in Europe; only the Volga and Danube are larger rivers.

The Urals originate in Russia, on the slope of the Round Hill of the Uraltau ridge. The source is a spring gushing out of the ground at an altitude of 637 m above sea level. At the beginning of its journey, the river flows in a north-south direction, but after meeting a plateau along the way it makes sharp turn and continues to flow in a northwesterly direction. However, beyond Orenburg its direction changes again to the southwest, which is considered the main one. Having overcome a winding path, the Urals flows into the Caspian Sea. The length of the river is 2428 km. The mouth is divided into branches and tends to become shallow.

The Ural is a river along which the natural water boundary between Europe and Asia passes, with the exception of the upper reaches. This is an inland European river, but its upper reaches east of the Ural Range are Asian territory.

The importance of the Caspian rivers

The rivers flowing into the Caspian Sea are of great importance. Their waters are used for human and animal consumption, domestic, agricultural and industrial needs. Hydroelectric power stations are built on rivers, the energy of which is in demand by people for various purposes. River basins full of fish, algae, shellfish. Even in ancient times, people chose river valleys for future settlements. And now cities and towns are being built on their banks. The rivers are plied by passenger and transport ships, performing important tasks for transporting passengers and cargo.

The Caspian Sea is the largest enclosed body of water on planet Earth, located on the continent of Eurasia - in border area states Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. In fact, it is a giant lake left after the disappearance of the ancient Tethys Ocean. Nevertheless, there is every reason to consider it as an independent sea (this is indicated by the salinity, big square and a decent depth, a bottom made of oceanic crust and other signs). In terms of maximum depth, it is the third among closed reservoirs - after lakes Baikal and Tanganyika. In the northern part of the Caspian Sea (a few kilometers from northern shore- parallel to it) runs the geographical border between Europe and Asia.

Toponymy

• Other names: throughout the history of mankind, the Caspian Sea has had about 70 different names among different peoples. The most famous of them: Khvalynskoye or Khvalisskoye (took place during the Ancient Rus', arose from the name of the people praises, who lived in the Northern Caspian region and traded with the Russians), Girkanskoe or Djurdzhanskoe (derived from alternative names for the city of Gorgan, located in Iran), Khazarskoe, Abeskunskoe (after the name of the island and city in the Kura delta - now flooded), Saraiskoe, Derbentskoe, Sikhai .
• Origin of name: according to one hypothesis, its modern and most ancient name, The Caspian Sea received from a tribe of nomadic horse breeders Caspian Sea, who lived in the 1st millennium BC on the southwestern coast.

Morphometry

• Catchment area: 3,626,000 km².
• Mirror area: 371,000 km².
• Coastline length: 7,000 km.
• Volume: 78,200 km³.
• Average depth: 208 m.
• Maximum depth: 1,025 m.

Hydrology

• Availability of permanent flow: no, drainless.
• Tributaries:, Ural, Emba, Atrek, Gorgan, Kheraz, Sefidrud, Astarchay, Kura, Pirsagat, Kusarchay, Samur, Rubas, Darvagchay, Ulluchay, Shuraozen, Sulak, Terek, Kuma.
• Bottom: very diverse. At shallow depths, sandy soil with an admixture of shells is common; in deep-sea areas, it is silty. In the coastal strip there may be pebble and rocky places (especially where mountain ranges adjoin the sea). In the estuarine areas, the underwater soil consists of river sediments. The Kara-Bogaz-Gol Bay is notable for the fact that its bottom is a thick layer of mineral salts.

Chemical composition

• Water: salty.
• Salinity: 13 g/l.
• Transparency: 15 m.

Geography

Rice. 1. Map of the Caspian Sea basin.

• Coordinates: 41°59′02″ n. latitude, 51°03′52″ e. d.
• Height above sea level:-28 m.
• Coastal landscape: thanks to coastline The Caspian Sea is very long, and it itself is located in different geographical zones - the coastal landscape is diverse. In the northern part of the reservoir, the banks are low, swampy, and in the deltas of large rivers, they are cut by numerous channels. The eastern shores are mostly limestone - desert or semi-desert. Western and southern coast adjacent to mountain ranges. The greatest ruggedness of the coastline is observed in the west, in the area of ​​the Absheron Peninsula, and also in the east, in the area of ​​the Kazakh and Kara-Bogaz-Gol bays.
• Settlements on the banks:
  • Russia: Astrakhan, Derbent, Kaspiysk, Makhachkala, Olya.
  • Kazakhstan: Aktau, Atyrau, Kuryk, Sogandyk, Bautino.
  • Turkmenistan: Ekerem, Karabogaz, Turkmenbashi, Khazar.
  • Iran: Astara, Balboser, Bender-Torkemen, Bender-Anzeli, Neka, Chalus.
  • Azerbaijan: Alyat, Astara, Baku, Dubendi, Lankaran, Sangachali, Sumgayit.

Interactive map

Ecology

The ecological situation in the Caspian Sea is far from ideal. Almost all large rivers flowing into it are polluted by wastewater from industrial enterprises located upstream. This could not but affect the presence of pollutants in the waters and bottom sediments of the Caspian Sea - over the past half century, their concentration has increased significantly, and the content of some heavy metals has already exceeded permissible standards.

In addition, the waters of the Caspian Sea are constantly polluted by domestic wastewater from coastal cities, as well as during oil production on the continental shelf, and during its transportation.

Fishing on the Caspian Sea

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• Artificial settlement: not all of the above fish species in the Caspian Sea are native. About 4 dozen species were found by chance (for example, through canals from the Black and Baltic seas), or were deliberately inhabited by humans. As an example, it is worth citing mullets. Three Black Sea species of these fish - mullet, sharpnose and singil - were released in the first half of the 20th century. The mullet did not take root, but the mullet and the singil have successfully acclimatized, and by now have settled virtually throughout the entire Caspian waters, forming several commercial herds. At the same time, the fish fatten up faster than in the Black Sea and reach larger sizes. In the second half of the last century (starting from 1962), attempts were also made to introduce such Far Eastern salmon fish as pink salmon and chum salmon into the Caspian Sea. In total, several billion fry of these fish were released into the sea over the course of 5 years. Pink salmon did not survive in the new habitat, chum salmon, on the contrary, successfully took root and even began to enter the rivers flowing into the sea to spawn. However, it was unable to reproduce in sufficient quantities and gradually disappeared. There are still no favorable conditions for its full natural reproduction (there are very few places where spawning and development of fry could successfully occur). To provide them, river reclamation is necessary, otherwise, without human help (artificial collection of eggs and their incubation), the fish will not be able to maintain their numbers.

Fishing spots

In fact, fishing is possible anywhere on the Caspian Sea coast, which can be reached by land or water. What types of fish will be caught depends on local conditions, but to a greater extent on whether the rivers flow here. As a rule, in places where estuaries and deltas are located (especially large watercourses), the water in the sea is greatly desalinated, so freshwater fish (carp, catfish, bream, etc.) usually predominate in the catches; species characteristic of the flowing rivers may also be found. rivers (usachi, shemaya). Of the marine species in desalinated areas, those for which salinity does not matter (mullet, some gobies) are caught. At certain periods of the year, semi-anadromous and anadromous species can be found here, feeding in the sea and entering rivers to spawn (sturgeon, some herrings, Caspian salmon). In places where there are no flowing rivers, freshwater species are found in slightly smaller numbers, but marine fish also appear, usually avoiding desalinated areas (for example, sea pike perch). Away from the coast, fish that prefer salt water and deep-sea species are caught.

Conventionally, we can distinguish 9 places or areas that are interesting in terms of fishing:

1. North Shore (RF)- this site is located on the northern coast of the Russian Federation (from the Volga delta to the Kizlyar Bay). Its main features are low salinity of water (the lowest in the Caspian Sea), shallow depth, the presence of multiple shoals, islands, and highly developed aquatic vegetation. In addition to the Volga delta with its numerous channels, bays and eriks, it also includes the estuary coastal area, called the Caspian Peaks. These places are popular among Russian fishermen, and for good reason: the conditions for fish here are very favorable, and there is also a good food supply. The ichthyofauna in these parts may not shine with a wealth of species, but it is distinguished by its abundance, and some of its representatives reach quite considerable sizes. Typically, the bulk of the catches are freshwater fish characteristic of the Volga basin. Most often caught: perch, pike perch, roach (more precisely, its varieties called roach and ram), rudd, asp, sabrefish, bream, silver carp, carp, catfish, pike. Somewhat less common are black bream, silver bream, white-eye, and bluegill. Representatives of sturgeons (sturgeon, stellate sturgeon, beluga, etc.) and salmonids (nelma, brown trout - Caspian salmon) are also found in these places, but their fishing is prohibited.
2. Northwestern coast (RF)- this area covers the west coast Russian Federation(from Kizlyar Bay to Makhachkala). The rivers Kuma, Terek and Sulak flow here - they carry their waters both through natural channels and artificial canals. There are bays in this area, some of which are quite large (Kizlyarsky, Agrakhansky). The sea in these places is shallow. Freshwater fish predominate in the catches: pike, perch, carp, catfish, rudd, bream, barbel, etc., and marine species are also caught here, for example, herring (blackback, bellyfish).
3. West Bank (RF)- from Makhachkala to the border of the Russian Federation with Azerbaijan. An area where mountain ranges adjoin the sea. The salinity of the water here is slightly higher than in previous places, so marine species are more common in fishermen's catches (sea pike perch, mullet, herring). However, freshwater fish are by no means uncommon.
4. West Bank (Azerbaijan)- from the border of the Russian Federation with Azerbaijan along the Absheron Peninsula. Continuation of the area where mountain ranges adjoin the sea. Fishing here is even more similar to typical offshore fishing, with fish such as razorback and mullet and several species of gobies also caught here. In addition to them, there are kutum, herring, and some typically freshwater species, for example, carp.
5. Southwestern coast (Azerbaijan)- from the Absheron Peninsula to the border of Azerbaijan with Iran. Most of this area is occupied by the Kura River delta. The same types of fish that were listed in the previous paragraph are caught here, but freshwater ones are somewhat more common.
6. Northern coast (Kazakhstan)- this area covers north coast Kazakhstan. The Ural delta and the Akzhaiyk state reserve are located here, so fishing directly in the river delta and in some adjacent water areas is prohibited. Fishing can only be done outside the reserve - upstream from the delta, or in the sea - at some distance from it. Fishing near the Ural delta has much in common with fishing at the confluence of the Volga - almost the same species of fish are found here.
7. Northeast coast (Kazakhstan)- from the mouth of the Emba to Cape Tyub-Karagan. Unlike the northern part of the sea, where the water is greatly diluted by large rivers flowing in, its salinity here increases slightly, so those species of fish appear that avoid desalinated areas, for example, sea pike perch, which is fished in Dead Kultuk Bay. Also, other representatives of marine fauna are often found in the catches.
8. Eastern coast (Kazakhstan, Turkmenistan)- from Cape Tyub-Karagan to the border of Turkmenistan and Iran. It is distinguished by the almost complete absence of flowing rivers. The salinity of the water here is at its maximum. Of the fish in these places, marine species predominate; the bulk of the catches are mullet, sea pike perch and gobies.
9. South Bank (Iran)- covers South coast Caspian Sea. Throughout this section, the Elborz mountain range adjoins the sea. Many rivers flow here, most of which are small streams, there are also several medium-sized and one large river. Of the fish, in addition to marine species, there are also some freshwater, as well as semi-anadromous and anadromous species, for example, sturgeon.

Fishing Features

The most popular and catchy amateur tackle used on the Caspian coast is a heavy spinning rod, converted into a “sea bottom”. It is usually equipped with a durable reel on which a fairly thick fishing line (0.3 mm or more) is wound. The thickness of the fishing line is determined not so much by the size of the fish, but by the mass of a fairly heavy sinker, which is necessary for ultra-long casting (in the Caspian Sea it is widely believed that the farther from the shore the casting point is, the better). After the sinker comes a thinner line - with several leashes. The bait used is shrimp and amphipods that live in coastal algae thickets - if you plan to catch sea fish, or ordinary bait like a worm, chafer larvae and others - if there are freshwater species in the fishing area.

At the mouths of inflowing rivers, other gear can be used, such as a float rod, feeder and traditional spinning rod.

kasparova2 majorov2006 g2gg2g-61 .

Photo 8. Sunset in Aktau.

The Caspian Sea is located in different geographical zones. It plays a large role in world history and is an important economic region and source of resources. The Caspian Sea is a unique body of water.

Short description

This sea is large. The bottom is covered with oceanic crust. These factors allow us to classify it as a sea.

It is a closed body of water, has no drains and is not connected to the waters of the World Ocean. Therefore, it can also be classified as a lake. In this case, it will be the largest lake on the planet.

The approximate area of ​​the Caspian Sea is about 370 thousand square kilometers. The volume of the sea changes depending on various fluctuations in water level. The average value is 80 thousand cubic kilometers. The depth varies in its parts: the southern one has greater depth than the northern one. The average depth is 208 meters, the greatest value in the southern part exceeds 1000 meters.

The Caspian Sea plays a major role in the development of trade relations between countries. The resources mined there, as well as other trade items, were transported to different countries since the development of maritime navigation. Since the Middle Ages, merchants have brought exotic goods, spices and furs. Today, in addition to transporting resources, ferry crossings between cities are carried out by sea. The Caspian Sea is also connected by a shipping canal through rivers to the Sea of ​​Azov.

Geographical characteristics

The Caspian Sea is located between two continents - Europe and Asia. It washes the territory of several countries. These are Russia, Kazakhstan, Iran, Turkmenistan and Azerbaijan.

It has more than 50 islands, both large and small in area. For example, the islands of Ashur-Ada, Tyuleniy, Chigil, Gum, Zenbil. And also the peninsulas, the most significant - Absheronsky, Mangyshlak, Agrakhansky and others.

Main influx water resources The Caspian Sea receives its water from the rivers flowing into it. There are a total of 130 tributaries of this reservoir. The largest is the Volga River, which brings the bulk of water. The rivers Heras, Ural, Terek, Astarchay, Kura, Sulak and many others also flow into it.

The waters of this sea form many bays. Among the largest: Agrakhansky, Kizlyarsky, Turkmenbashi, Hyrkan Bay. In the eastern part there is a bay-lake called Kara-Bogaz-Gol. It communicates with the sea through a small strait.

Climate

The climate is characterized geographical location sea, therefore it has several types: from continental in the northern region to subtropical in the southern. This affects air and water temperatures, which have large contrasts depending on the part of the sea, especially in the cold season.

In winter, the average air temperature in the northern region is about -10 degrees, the water reaches -1 degree.

In the southern region, air and water temperatures in winter warm up to an average of +10 degrees.

In summer, the air temperature in the northern zone reaches +25 degrees. It's much hotter in the south. The maximum recorded value here is + 44 degrees.

Resources

The natural resources of the Caspian Sea contain large reserves of various deposits.

One of the most valuable resources of the Caspian Sea is oil. Mining has been carried out since approximately 1820. The springs opened on the territory of the seabed and its coast. Already by the beginning of the new century, the Caspian Sea occupied a leading position in obtaining this valuable product. During this time, thousands of wells were opened, which made it possible to extract oil on a huge industrial scale.

The Caspian Sea and its surrounding area also have rich deposits of natural gas, mineral salts, sand, lime, several types of natural clay and rocks.

Inhabitants and fisheries

The biological resources of the Caspian Sea are distinguished by great diversity and good productivity. It contains more than 1,500 species of inhabitants and is rich in commercial fish species. Occupancy depends on climatic conditions in different parts of the sea.

In the northern part of the sea, pike perch, bream, catfish, asp, pike and other species are more common. The western and eastern areas are inhabited by gobies, mullet, bream, and herring. Southern waters are rich in different representatives. One of the many is sturgeon. In terms of their content, this sea occupies a leading place among other bodies of water.

Among the wide variety, tuna, beluga, stellate sturgeon, sprat and many others are also caught. In addition, there are mollusks, crayfish, echinoderms and jellyfish.

The Caspian seal is a mammal that lives in the Caspian Sea, or this animal is unique and lives only in these waters.

The sea is also characterized by a high content of various algae, for example, blue-green, red, brown; sea ​​grass and phytoplankton.

Ecology

Oil production and transportation have a huge negative impact on the ecological situation of the sea. Oil products getting into water is almost inevitable. Oil stains cause irreparable damage to marine habitats.

The main influx of water resources to the Caspian Sea comes from rivers. Unfortunately, most of them have high levels of pollution, which deteriorates the quality of sea water.

Industrial and domestic wastewater from surrounding cities is discharged into the sea in huge quantities, which also causes environmental damage.

Poaching causes great damage to marine habitats. The main target for illegal fishing is sturgeon species. This significantly reduces the number of sturgeon and threatens the entire population of this type.

The information provided will help to assess the resources of the Caspian Sea and briefly study the characteristics and ecological situation of this unique body of water.

Caspian Sea is inland and located in a vast continental depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows it to be called a lake, but it has all the features of the sea, since in past geological eras it had connections with the ocean.
Today Russia has access only to the Northern Caspian Sea and the Dagestan part west coast Middle Caspian. The waters of the Caspian Sea wash the shores of countries such as Azerbaijan, Iran, Turkmenistan, and Kazakhstan.
The sea area is 386.4 thousand km2, the volume of water is 78 thousand m3.

The Caspian Sea has a vast drainage basin, with an area of ​​about 3.5 million km2. The nature of the landscapes, climatic conditions and types of rivers are different. Despite the vastness of the drainage basin, only 62.6% of its area is drainage areas; about 26.1% - for non-drainage. The area of ​​the Caspian Sea itself is 11.3%. 130 rivers flow into it, but almost all of them are located in the north and west (and the eastern coast does not have a single river reaching the sea). The largest river in the Caspian basin is the Volga, which provides 78% of the river waters entering the sea (it should be noted that more than 25% of the Russian economy is located in the basin of this river, and this undoubtedly determines many hydrochemical and other features of the waters of the Caspian Sea), as well as rivers Kura, Zhaiyk (Ural), Terek, Sulak, Samur.

Physiographically and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conventional border between the northern and middle parts runs along the line Chechen Island–Cape Tyub-Karagan, and between the middle and southern parts along the line Zhiloy Island–Cape Kuuli.
The shelf of the Caspian Sea is on average limited to depths of about 100 m. The continental slope, which begins below the shelf edge, ends in the middle part at approximately 500–600 m depths, in the southern part, where it is very steep, at 700–750 m.

The northern part of the sea is shallow, its average depth is 5–6 m, the maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom topography is complicated by the presence of banks, islands, and grooves.
The middle part of the sea is a separate basin, an area maximum depths of which - the Derbent depression - is shifted to the western shore. The average depth of this part of the sea is 190 m, the greatest is 788 m.

The southern part of the sea is separated from the middle by the Absheron threshold, which is a continuation of the Greater Caucasus. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum sea depth of 1025 m is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.

Shores The Caspian Sea is diverse. In the northern part of the sea they are quite indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy and Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islands and channels, often changing their position. A lot of small islands and cans are located on other parts of the coastline.
The middle part of the sea has a relatively flat coastline. On the western coast, on the border with the southern part of the sea, is the Absheron Peninsula. To the east of it, the islands and banks of the Absheron archipelago stand out, of which the most large island Residential. The eastern coast of the Middle Caspian is more indented; the Kazakh Gulf with Kenderli Bay and several capes stand out here. The largest bay of this coast is Kara-Bogaz-Gol.

South of the Absheron Peninsula are the islands of the Baku archipelago. The origin of these islands, as well as some of the jars east coast the southern part of the sea is associated with the activity of underwater mud volcanoes lying on the seabed. On the eastern shore there are large bays of Turkmenbashi and Turkmensky, and near it the island of Ogurchinsky.

One of the most striking phenomena of the Caspian Sea is the periodic variability of its level. IN historical time The Caspian Sea had a level lower than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) of sea level, the amplitude of its fluctuations has been almost 4 m, from –25.3 m in the eighties of the 19th century. to –29 m in 1977. In the last century, the level of the Caspian Sea changed significantly twice. In 1929 it stood at about -26 m, and since it had been close to this level for almost a century, this level position was considered to be a long-term or secular average. In 1930 the level began to decline rapidly. By 1941 it had dropped by almost 2 m. This led to the drying out of vast coastal areas of the bottom. The decrease in level, with slight fluctuations (short-term slight rises in level in 1946–1948 and 1956–1958), continued until 1977 and reached a level of –29.02 m, i.e. the level reached its lowest position in history the last 200 years.

In 1978, contrary to all forecasts, sea level began to rise. As of 1994, the level of the Caspian Sea was at –26.5 m, that is, over 16 years the level rose by more than 2 m. The rate of this rise is 15 cm per year. The level increase in some years was higher, and in 1991 it reached 39 cm.

The general fluctuations in the level of the Caspian Sea are superimposed by its seasonal changes, the long-term average of which reaches 40 cm, as well as surge phenomena. The latter are especially pronounced in the Northern Caspian Sea. The northwestern coast is characterized by large surges created by prevailing storms from the eastern and southeastern directions, especially in the cold season. A number of large (more than 1.5–3 m) surges have been observed here over the past decades. A particularly large surge with catastrophic consequences was noted in 1952. Fluctuations in the level of the Caspian Sea cause great damage to the states surrounding its waters.

Climate. The Caspian Sea is located in temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since the sea stretches from north to south for almost 1200 km.
Various atmospheric circulation systems interact in the Caspian region, however, winds from the eastern directions predominate throughout the year (the influence of the Asian High). The position at fairly low latitudes provides a positive balance of heat influx, so the Caspian Sea serves as a source of heat and moisture for passing air masses for most of the year. The average annual air temperature in the northern part of the sea is 8–10°C, in the middle part - 11–14°C, in the southern part - 15–17°C. However, in the northernmost areas of the sea, the average January temperature is from –7 to –10°C, and the minimum during intrusions of Arctic air is down to –30°C, which determines the formation of ice cover. In summer, rather high temperatures dominate over the entire region under consideration - 24–26°C. Thus, the Northern Caspian is subject to the most dramatic temperature fluctuations.

The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, with most of it falling during the cold season of the year (from October to March). However, the Northern Caspian differs in this respect from the rest of the basin: here the average annual precipitation is lower (for the western part only 137 mm), and the seasonal distribution is more uniform (10–18 mm per month). In general, we can talk about the proximity of climatic conditions to arid ones.
Water temperature. The distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, the nature of the bottom topography, isolation) have a certain influence on the formation of temperature conditions. In the shallow Northern Caspian Sea, the entire water column can be considered homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and Southern Caspian Sea, surface and deep masses can be distinguished, separated by a transition layer. In the Northern Caspian and in the surface layers of the Middle and Southern Caspian, water temperatures vary over a wide range. In winter, temperatures vary from north to south from less than 2 to 10°C, the water temperature off the west coast is 1–2°C higher than that on the east, in the open sea the temperature is higher than at the coasts: by 2–3°C in the middle part and by 3–4°С in the southern part of the sea. In winter, the distribution of temperature with depth is more uniform, which is facilitated by winter vertical circulation. During moderate and severe winters in the northern part of the sea and shallow bays of the east coast, the water temperature drops to freezing temperature.

In summer, the temperature varies in space from 20 to 28°C. The highest temperatures are observed in the southern part of the sea; temperatures are also quite high in the well-warmed shallow Northern Caspian Sea. The zone where the lowest temperatures occur is adjacent to the east coast. This is explained by the rise of cold deep waters to the surface. Temperatures are also relatively low in the poorly heated deep-sea central part. In open areas of the sea, at the end of May–beginning of June, the formation of a temperature jump layer begins, which is most clearly expressed in August. Most often it is located between horizons of 20 and 30 m in the middle part of the sea and 30 and 40 m in the southern part. In the middle part of the sea, due to the surge off the eastern coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature throughout the year is about 4.5°C in the middle part and 5.8–5.9°C in the southern part.

Salinity. Salinity values ​​are determined by such factors as river flow, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts of the Northern Caspian and between the Northern and Middle Caspian, bottom topography, which determines the location of waters with different salinities, mainly along isobaths, evaporation providing a deficit fresh water and an influx of more salty ones. These factors collectively influence seasonal differences in salinity.
The Northern Caspian Sea can be considered as a reservoir of constant mixing of river and Caspian waters. The most active mixing occurs in the western part, where both river and Central Caspian waters directly flow. Horizontal salinity gradients can reach 1‰ per 1 km.

The eastern part of the Northern Caspian Sea is characterized by a more uniform salinity field, since most of the river and sea (Middle Caspian) waters enter this area of ​​the sea in a transformed form.

Based on the values ​​of horizontal salinity gradients, it is possible to distinguish in the western part of the Northern Caspian the river-sea contact zone with water salinity from 2 to 10‰, in the eastern part from 2 to 6‰.

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea ​​waters, the determining role is played by runoff. The strengthening of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated waters coming from the seashore in summer is 10–15°C higher than the bottom waters.
In the deep-sea depressions of the Middle and Southern Caspian Sea, fluctuations in salinity in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of ​​the Absheron threshold, where it is 1.6‰ in the surface layer and 2.1‰ at a 5 m horizon.

The decrease in salinity along the western coast of the South Caspian Sea in the 0–20 m layer is caused by the flow of the Kura River. The influence of the Kura runoff decreases with depth; at horizons of 40–70 m, the range of salinity fluctuations is no more than 1.1‰. Along the entire western coast to the Absheron Peninsula there is a strip of desalinated water with a salinity of 10–12.5‰, coming from the Northern Caspian Sea.

In addition, in the Southern Caspian Sea, an increase in salinity occurs when salted waters are carried out from bays and bays on the eastern shelf under the influence of southeastern winds. Subsequently, these waters are transferred to the Middle Caspian Sea.
In the deep layers of the Middle and Southern Caspian Sea, the salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep-water part of the Southern Caspian, the upper boundary of waters with high salinity drops to 250 m. Obviously, in these parts of the sea, vertical mixing of waters is difficult.

Surface water circulation. Currents in the sea are mainly wind-driven. In the western part of the Northern Caspian, currents of the western and eastern quarters are most often observed, in the eastern part - southwestern and southern ones. Currents caused by the runoff of the Volga and Ural rivers can be traced only within the estuary coastal area. The prevailing current speeds are 10–15 cm/s; in open areas of the Northern Caspian Sea, maximum speeds are about 30 cm/s.

In the coastal areas of the middle and southern parts of the sea, in accordance with the wind directions, currents in the northwestern, northern, southeastern and southern directions are observed; currents often occur near the eastern coast east direction. Along the western coast of the middle part of the sea, the most stable currents are southeastern and southern. Current speeds are on average about 20–40 cm/s, with maximum speeds reaching 50–80 cm/s. Other types of currents also play a significant role in the circulation of sea waters: gradient, seiche, and inertial.

Ice formation. The Northern Caspian Sea is covered with ice every year in November, the area of ​​the frozen part of the water area depends on the severity of the winter: in severe winters the entire Northern Caspian Sea is covered with ice, in mild winters the ice remains within 2–3 meter isobath. The appearance of ice in the middle and southern parts of the sea occurs in December-January. On the eastern coast the ice is of local origin, on the western coast it is most often brought from the northern part of the sea. In severe winters, shallow bays freeze off the eastern coast of the middle part of the sea, shores and fast ice form off the coast, and on the western coast, drifting ice spreads to the Absheron Peninsula in abnormally cold winters. The disappearance of ice cover is observed in the second half of February–March.

Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of patterns. The central part of the waters of the Northern Caspian Sea is characterized by a fairly uniform distribution of oxygen. An increased oxygen content is found in the areas near the Volga River near the mouth, while a decreased oxygen content is found in the southwestern part of the Northern Caspian Sea. In the Middle and Southern Caspian Sea, the highest concentrations of oxygen are confined to shallow coastal areas and pre-estuary coastal areas of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.). In the deep-water areas of the Caspian Sea, the main pattern remains the same throughout all seasons - a decrease in oxygen concentration with depth. Thanks to autumn-winter cooling, the density of the North Caspian Sea waters increases to a value at which it becomes possible for North Caspian waters with a high oxygen content to flow along the continental slope to significant depths of the Caspian Sea. The seasonal distribution of oxygen is mainly associated with the annual variation of water temperature and the seasonal relationship between production and destruction processes occurring in the sea. In spring, the production of oxygen during photosynthesis very significantly covers the decrease in oxygen caused by a decrease in its solubility with increasing water temperature in spring. In the areas of the estuary coastal areas of rivers feeding the Caspian Sea, in the spring there is a sharp increase in the relative oxygen content, which in turn is an integral indicator of the intensification of the photosynthesis process and characterizes the degree of productivity of the mixing zones of sea and river waters. In summer, due to the significant warming of water masses and the activation of photosynthesis processes, the leading factors in the formation of the oxygen regime are photosynthetic processes in surface waters, and biochemical oxygen consumption by bottom sediments in bottom waters. Due to the high temperature of the waters, the stratification of the water column, the large influx of organic matter and its intense oxidation, oxygen is quickly consumed with minimal entry into the lower layers of the sea, resulting in the formation of an oxygen deficiency zone in the Northern Caspian Sea. Intensive photosynthesis in the open waters of the deep-sea regions of the Middle and Southern Caspian Sea covers the upper 25-meter layer, where oxygen saturation is more than 120%. In autumn, in the well-aerated shallow areas of the Northern, Middle and Southern Caspian Sea, the formation of oxygen fields is determined by the processes of water cooling and the less active, but still ongoing process of photosynthesis. The oxygen content is increasing. The spatial distribution of nutrients in the Caspian Sea reveals the following patterns:

– increased concentrations of nutrients are characteristic of areas near the mouth of the coastal rivers that feed the sea and shallow areas of the sea, subject to active anthropogenic influence (Baku Bay, Turkmenbashi Bay, water areas adjacent to Makhachkala, Fort Shevchenko, etc.);
– The Northern Caspian, which is a vast mixing zone of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
– in the Middle Caspian, the cyclonic nature of the circulation contributes to the rise of deep waters with a high content of nutrients into the overlying layers of the sea;
– in the deep-water regions of the Middle and Southern Caspian Sea, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.

On the dynamics of concentrations nutrients During the year, the Caspian Sea is influenced by such factors as seasonal fluctuations in nutrient runoff into the sea, the seasonal ratio of production-destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter time in the Northern Caspian, processes of winter vertical circulation in deep-water areas of the sea.
In winter, a significant area of ​​the Northern Caspian Sea is covered with ice, but biochemical processes actively develop in subglacial water and in ice. The ice of the Northern Caspian Sea, being a kind of accumulator of nutrients, transforms these substances entering the sea with river runoff and from the atmosphere.

As a result of the winter vertical circulation of water in the deep-water regions of the Middle and Southern Caspian Sea during the cold season, the active layer of the sea is enriched with nutrients due to their supply from the underlying layers.

Spring for the waters of the Northern Caspian Sea is characterized by a minimum content of phosphates, nitrites and silicon, which is explained by the spring outbreak of phytoplankton development (silicon is actively consumed by diatoms). High concentrations of ammonium and nitrate nitrogen, characteristic of the waters of a large area of ​​the Northern Caspian Sea during floods, are due to intensive washing by river waters of the Volga delta.

In the spring season, in the area of ​​water exchange between the Northern and Middle Caspian Seas in the subsurface layer, with a maximum oxygen content, the phosphate content is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.
In the Southern Caspian, the distribution of nutrients in spring is basically similar to their distribution in the Middle Caspian.

In summer, a redistribution is detected in the waters of the Northern Caspian various forms biogenic compounds. Here the content of ammonium nitrogen and nitrates decreases significantly, while at the same time there is a slight increase in the concentrations of phosphates and nitrites and a rather significant increase in the concentration of silicon. In the Middle and Southern Caspian Sea, the concentration of phosphates has decreased due to their consumption during photosynthesis and the difficulty of water exchange with the deep-sea accumulation zone.

In autumn in the Caspian Sea, due to the cessation of activity of some types of phytoplankton, the content of phosphates and nitrates increases, and the concentration of silicon decreases, as there is an autumn outbreak of the development of diatoms.

For more than 150 years, oil has been mined on the shelf of the Caspian Sea. oil.
Currently, large hydrocarbon reserves are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons in oil equivalent (of which 132 million tons of oil and 78 billion m3 of gas), on the shelf of the Northern Caspian Sea - at 1 billion tons of oil .
In total, about 2 billion tons of oil have already been produced in the Caspian Sea.
Losses of oil and its products during production, transportation and use reach 2% of the total volume.
Main sources of income pollutants, including petroleum products into the Caspian Sea - this is the removal with river runoff, the discharge of untreated industrial and agricultural wastewater, municipal wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, transportation of oil by sea. The places where pollutants enter with river runoff are 90% concentrated in the Northern Caspian Sea, industrial wastes are confined mainly to the area of ​​the Absheron Peninsula, and increased oil pollution of the Southern Caspian Sea is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud volcanism) in the zone of oil and gas bearing structures.

From the territory of Russia, about 55 thousand tons of petroleum products enter the Northern Caspian annually, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the runoff of the Terek and Sulak rivers.
Thickening of the film on the water surface to 0.01 mm disrupts gas exchange processes and threatens the death of hydrobiota. The concentration of petroleum products is toxic to fish at 0.01 mg/l and to phytoplankton at 0.1 mg/l.

The development of oil and gas resources on the bottom of the Caspian Sea, the forecast reserves of which are estimated at 12–15 billion tons of standard fuel, will become the main factor in the anthropogenic load on the sea ecosystem in the coming decades.

Caspian autochthonous fauna. The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, mollusks, etc.

Arctic species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire Caspian fauna (mysids, sea cockroach, white fish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna are crustaceans (71.4%), which easily tolerate desalination and live at great depths of the Middle and Southern Caspian Sea (from 200 to 700 m), since the lowest water temperatures are maintained here throughout the year (4.9– 5.9°C).

Mediterranean species. These are 2 types of mollusks, needle fish, etc. At the beginning of the 20s of our century, the mollusk mytileaster entered here, later 2 types of shrimp (with mullet, during their acclimatization), 2 types of mullet and flounder. Some Mediterranean species entered the Caspian Sea after the opening of the Volga-Don Canal. Mediterranean species play a significant role in the food supply of fish in the Caspian Sea.

Freshwater fauna(228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, carp, and also rotifers).

Marine species. These are ciliates (386 forms), 2 species of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalves (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most unique brackish bodies of water on the planet.

The Caspian Sea produces more than 80% of the world's sturgeon catches, the bulk of which occur in the Northern Caspian Sea.
To increase sturgeon catches, which sharply decreased during the years of falling sea levels, a set of measures is being implemented. Among them are a complete ban on sturgeon fishing in the sea and its regulation in rivers, and an increase in the scale of sturgeon factory farming.