BALTIC SEA

Belongs to the Atlantic Ocean. Square water surface is 386 thousand km2, the prevailing depths are 40-100, the maximum - 459 m. The territory of Russia is washed by the waters of the southeastern part of the sea (in the Kaliningrad region) and the waters of the southern part of the Gulf of Finland with the Neva Bay. The Neva flows into the Baltic Sea. Zapadnaya Dvina and other smaller rivers, bringing on average over 100 km2 of fresh water per year. Industrial fishing of cod, perch, sprat is developed.

SEA OF AZOV

It is located in the south of the European part of Russia, deeply cut into the land. It belongs to the inland seas, but is also connected with the World Ocean: the Kerch Strait of Azov Sea connects with the Black Sea. The area of ​​the water area is 38 thousand km2, the depth is up to 14 m. The territory of Russia includes East End sea ​​adjacent to the Rostov Region 11 Krasnodar Territory. The water quality of the shallow Sea of ​​Azov in more than other seas, is determined by the ratio of the volumes of continental runoff and sea water, equal and on average 1:8. Under the influence of winds, the current in the Kerch Strait is variable, therefore, on average, 41 km3 / year of water flows from the Black Sea to the Azov Sea, and 66.6 km2 / year from the Azov Sea to the Black Sea. The salt regime and mineralization of the water of the Sea of ​​Azov is the result of mixing fresh river, atmospheric and salty Black Sea waters. In the catchment area, intensive economic activity. Here are concentrated coal and metallurgical industry, placed about 2 million hectares of irrigated agricultural land, high population density. AT recent decades due to economic development In the region, the amount of river runoff has significantly decreased, irrevocable water consumption has increased, and the flow of salty Black Sea waters has increased. As a result, the average mineralization of water increased to 12-13 g/l, while biological productivity decreased at the same time.

BLACK SEA

It is also deeply incised on land. The area of ​​the water surface is 422 thousand km3, the average depth is 1315, the greatest is -2210 m, the volume of sea water is 555 thousand km3. A distinctive feature of the Black Sea is a pronounced vertical stratification. The upper layer of water 10-15 m thick is saturated with oxygen, salinity is about 1.8%. A powerful benthic elephant with a thickness of 1500-1800 m has a salinity of 2.1-2.2%, is characterized by a complete absence of oxygen and high concentration hydrogen sulfide. Between these layers there is a water column with large differences in temperature and salinity, the vertical exchange between the upper and deep layers of water is insignificant. The length of the coastline adjacent to Russia (coast Krasnodar Territory), is 400 km. sea ​​waters belong to the class of "moderately polluted", there are processes of eutrophication and the formation of zones of oxygen deficiency. The main sources of pollution in the Black Sea are wastewater industrial enterprises and housing and communal services.

The territory of the Russian Federation is washed by three oceans. All the seas of Russia, a list of which is given in the text of the article, are interesting and special in their own way. All of them are unique and original.

Seas of Russia: list

The largest country on the planet is connected to three oceans through 12 seas, both inland and marginal. One sea of ​​Russia does not have a direct connection with the World Ocean (except for the connection through - this is the Caspian Sea, which is drainless.

Alphabetical list of seas surrounding Russia

Sea	Belonging to the ocean
Azov	to the atlantic ocean
Barents	to the Arctic Ocean
Baltic	to the atlantic ocean
White	to the Arctic Ocean
Beringovo	to the Pacific Ocean
East Siberian	to the Arctic Ocean
Caspian	drainless
Kara	to the Arctic Ocean
Laptev	to the Arctic Ocean
Okhotsk	to the Pacific Ocean
Black	to the atlantic ocean
Chukchi	to the Arctic Ocean
Japanese	to the Pacific Ocean

Total - 13 seas.

Seas of the Atlantic

The seas from the Atlantic basin beat against western shores Russia. From the north it is the Baltic Sea, in the south - the Sea of ​​Azov and the Black Sea.

They are united by such features:

• they are all inland, that is, deeply continental;
• all of them are the final seas of the Atlantic, that is, to the east of them, either the waters of another ocean, or land.

The coastline of Russia along the seas of the Atlantic is about 900 km. Baltic Sea concern the Leningrad and Kaliningrad regions. The Black and Azov Seas are washed by the shores of the Rostov Region, the Krasnodar Territory and the Crimea.

Seas of the Arctic Ocean

Some seas of Russia (the list is given above) belong to the Arctic Ocean basin. There are six of them: five of them are marginal (Chukotskoye, Kara, Laptev, East Siberian, Barents) and one is internal (Beloye).

Almost all of them all year round covered with ice. Thanks to Atlantic current southwest Barents Sea. The waters of the Arctic Ocean reach the territory of such subjects of Russia as Murmansk region, Arkhangelsk region, Yamal-Nenets Autonomous Okrug, Taimyr Autonomous Okrug, Republic of Sakha, Chukotka Autonomous Okrug.

Seas of the Pacific Ocean

The list of seas washing the shores of Russia from the east and belonging to the Pacific Ocean is given below:

• Beringovo;
• Japanese;
• Okhotsk.

These seas adjoin the territories of the Chukotka Autonomous Okrug, the Magadan Region, the Kamchatka Region, Khabarovsk Territory, Sakhalin Region, Primorsky Territory.

warm seas

Half Russian seas covered with ice all year round. There are seas that are partially covered with an ice crust for a certain period of time. The warm seas of Russia, the list of which is given below, do not freeze during the year. So, the warm seas of Russia include:

Seas of Russia: a list of unique seas

All geographic features The lands are special and interesting in their own way. There are objects that are unique and unrepeatable. Of course, this is Lake Baikal, the Volga, Kamchatka geysers, the Kuril Islands and much more. The seas of Russia are also exceptional, a list of which is given below. The table shows the characteristics of some of the seas of Russia in terms of their uniqueness.

List of seas washing Russia

Sea	Characteristic in terms of uniqueness
Azov	It is considered the most inland sea of ​​the planet. Communication with the waters of the oceans occurs through four straits and four seas. With a depth of no more than 13.5 m, it is recognized as the shallowest sea on the planet.
Baltic	It is one of the most "unsalted" seas in the world. Approximately 80% of the world's amber is mined here, which is why the sea was called Amber in ancient times.
Barents	This is the westernmost sea of ​​Russia from those that are beyond the Arctic Circle. It is considered the cleanest sea of ​​all that wash the shores of Europe.
White	The sea, which has a small area, is the second small sea in Russia after the Sea of ​​\u200b\u200bAzov. Washes the lands of the historical and cultural monument of Russia -
Beringovo
Japanese	The southernmost, but not the hottest sea in Russia. Of all the seas of Russia, this one has the richest underwater world.

We hope that the article was interesting and useful.

Russia, with an area of ​​17.12 million km², is washed by the waters of one inland Caspian Sea and 14 external seas, of which 7 seas belong to the Arctic basin, 4 - to the sea Pacific Ocean, and 3 - Atlantic.

Seas surrounding Russia

The Caspian Sea (area - 371 thousand km²) is located at the junction of Europe and Asia, the Middle and Northern Caspian are included in the water area of ​​the Russian Federation, the coastline stretches for 695 km. Most of the river flow (up to 80%) belongs to the Volga, and the Ural, Terek, Sulak, Samur rivers also flow here. The inland closed sea-Lake Caspian is the world's largest closed body of water; on the Russian coast there are Lagan, Makhachkala, Kaspiysk, Izberbash, Dagestan Lights and the most Southern City Russia Derbent...

Seas of the Atlantic Ocean

The seas of the Atlantic Ocean basin, washing the territory of Russia, include the Baltic Sea, the Black Sea and the Sea of ​​Azov.

The Baltic Sea is an inland sea, deeply incised into the northwestern part of the Eurasian continent and washing the northwestern part of Russia, its area is 415 thousand km². The Russian waters of the Baltic Sea are some areas in its eastern part: the Kaliningrad Bay, separated from the sea by the Baltic Spit, part of the Curonian Lagoon (Kaliningrad Region of the Russian Federation), the eastern part of the Gulf of Finland on the territory of the Leningrad Region and its capital St. Petersburg. The Neva River flows into the sea, flowing from Lake Ladoga, bringing in a year most runoff. The largest port is Kronstadt on the island of Kotlin in the Gulf of Finland...

The Black Sea, with an area of ​​422 thousand km², is an inland sea located in the depths of the Eurasian continent, washes the coast of the Krasnodar Territory of the Russian Federation, located in the south of the European part of Russia (the coastline from Kerch Strait between the Black and Azov Seas to the mouth of the Psou River - 400 km) and the Crimean Peninsula (the length of the coastline is 750 km). Krasnodar line Black Sea coast is divided into the Kerechensk-Taman and West Caucasian regions. In the northwestern part of the Black Sea on the territory of Crimea there are large bays - Karkinitsky, Kalamitsky, Feodosia. One of the major rivers flowing into the Black Sea is the Dnieper, major seaports are Novorossiysk, Sevastopol, Anapa, Tuapse...

The Sea of ​​Azov is the shallowest and smallest inland sea in the world with an area of ​​37.8 thousand km², located in the southern part of the Russian Plain, washes the southeastern part of the Rostov Region and the Krasnodar Territory. Such large rivers as the Don and Kuban flow into it, small ones - the Mius, Eya. Large bays - Taganrog, Miusky in the northeast, in the east - Yasensky Bay, Beisugsky estuary, Akhtarsky estuary, in the south - Temryuksky. Major seaports - Taganrog ( Rostov region, Taganrog Bay), Yeysk (Krasnodar Territory). coasts southern seas- important areas of recreation, industrial fishing and sea routes of communication ...

Seas of the Arctic Ocean

Seas of the Arctic Ocean - Barents, Pechora, White, Kara, Laptev Sea, East Siberian and Chukchi.

The Barents Sea (S - 1405 thousand km²), washes the northern coast of the Russian Federation, the Svalbard archipelago, the islands of Frank Josef Land and Novaya Zemlya. A port city of great strategic importance for Russia is Murmansk. The largest bays are Varyazhsky, Motovsky and Kola, smaller ones are Cheshskaya Bay, Pechora Bay, Khaipudyrskaya Bay. The Pechora and Indiga rivers flow...

The Pechora Sea - the southwestern part of the Barents Sea with an area of ​​81.2 thousand km² is located between the islands of Kolguev and Vaigach (Nenets Autonomous Okrug). Its borders run along the line from Cape Kostin Nos on the Novaya Zemlya archipelago, further along the eastern part of Kolguev Island, further along Cape Svyatoy Nos along the Timan coast of continental Russia to the Yugorsky Peninsula and Vaigaya Island. The sea is named after Pechora, the deep river falling into it. The largest bays (in other words, lips) on its area are Pechora and Khaipudyrskaya ...

The White Sea washes the north of the Russian Federation, its area is small - 90 thousand km² (this is 1/16 of the area of ​​the Barents Sea), it stretches from west to east at a distance of 600 km. Rivers flow into the sea: Onega, Kem, Northern Dvina, port cities White Sea- Arkhangelsk, Belomorsk, Onega, Severodvinsk...

The marginal Kara Sea, with an area of ​​880 thousand km², lies between the islands of Franz Josef Land, Novaya Zemlya, Vaigach and Geiberg, an archipelago Severnaya Zemlya. This is the coldest sea in Russia, positive indicators are only at the mouths of the inflowing rivers (these are the Yenisei, Ob), most of the year the surface of the sea is under ice cover. The largest bays are the Gulf of Ob, the Yenisei Gulf ...

The Laptev Sea, a marginal sea of ​​the Arctic Ocean, from the south it is bounded by the northern coast of Siberia and the Taimyr Peninsula, from the west by the island of Novaya Zemlya, from the east by the New Siberian Islands. The area is 700 thousand km², the sea is covered with ice, the largest flowing rivers are the Lena, Yana, Khatanga, Anabar, Olenyok. Many bays and bays, a large port city - Tiksi ...

The East Siberian Sea is located between the New Siberian Islands and Wrangel Island, it is mainly covered with ice, the area is 944.6 thousand km², the flowing rivers are the Indigirka, Kolyma, Alazeya. Chaunskaya Bay, Omulyakhskaya Bay, Khromskaya Bay, Kolyma Bay, Kolyma Bay crash into the mainland. The largest port is Pevek, a city in the Chukotka Autonomous Okrug of the Russian Federation ...

The marginal Chukchi Sea is located between Chukotka and Alaska, the Long Strait is connected to the East Siberian Sea, Cape Barrow - to the Beaufort Sea, Bering Strait - to the Pacific Ocean. The area is 585 thousand km², almost always covered with ice. Very few rivers flow in, the largest are Amguema and Noatak. The largest islands are Wrangel, Kolyuchin and Gerald, the largest settlement is Uelen, 632 people live here, engaged in reindeer herding, fishing and sea hunting...

Seas of the Pacific Ocean

The seas of the Pacific Ocean, washing the north-east of Russia, include Bering, Okhotsk, Shantar and Japan.

The northern part of the Pacific Ocean is occupied by the Bering Sea (an area of ​​2292 thousand km 2), separated from it by the Aleutian and Commander Islands. In its northwest lie the shores of Northern Kamchatka, the Koryak Highlands and the Chukotka Peninsula, in the northeast - the shores of Western Alaska. The coast is heavily indented, there are many bays and bays: Anadyrsky, Karaginsky, Korfa, Cross. The Russian island territories washed by the Bering Sea are the Diomede Islands (Chukotka Autonomous Okrug), the Commander Islands and the Karaginsky Island (Kamchatka). largest river flowing into this sea - Anadyr ...

The Inland Sea of ​​Okhotsk (its area is 1603 thousand km²) is located in the northwestern part of the Pacific Ocean, its borders are delineated by the Kuril Islands and the Kamchatka Peninsula. The largest flowing rivers are the Amur, Okhota and Kukhtui, most of the year the sea is jammed with ice. The western part of the Sea of ​​Okhotsk washes the shores of the Russian Far East(Khabarovsk Territory, Magadan Region), the coast of Sakhalin Island, the northern coast of Koryaksky autonomous region, eastern - the shores of the Kamchatka region and the chain of the Kuril Islands. The main port is Magadan, the mainland coast is Okhotsk, the Sakhalin Islands are Korsakov, the Kuril Islands are Severo-Kurilsk...

The Shantar Sea is the inland sea of ​​the eastern coast of Russia, it represents the northwestern water area of ​​the Sea of ​​Okhotsk. The north and east of the sea are separated from the main waters of Okhotsk by the Shantar Islands (Big and Small), the south - by the Tugur Bay, the west - by the Uda Bay ...

The Sea of ​​Japan (S - 1062 thousand km²) is the marginal sea of ​​the Pacific Ocean, located between Eurasia and the Korean Peninsula, it is limited by the Japanese Islands and Sakhalin. The Russian coast of the Sea of ​​Japan is Primorsky Krai, the southeast of the Khabarovsk Territory and the southwest of Sakhalin. The coastline stretches from west to east at a distance of 3900 m. Major Russian ports are Vladivostok, Nakhodka, Vostochny, Aleksandrovsk-Sakhalinsky, Sovetskaya Gavan, Vanino ...

The Black Sea lies in a depression within two zones of Alpine folding and separates Eastern Europe from Asia Minor. The area of ​​the Black Sea is 423 thousand km2. Together with the Sea of ​​Azov (38 thousand km2), which is a large bay or lagoon, the Black Sea covers an area of ​​461 thousand km2. The average depth of the Black Sea is 1197 m, the Sea of ​​Azov is 8 m. The volume of water in the Black Sea reaches 537 thousand km3, and in the Sea of ​​Azov 300 km3. The narrow and shallow Bosporus Strait ( maximum depth 27.5 m) connects the Black Sea with the Sea of ​​Marmara and further through the Dardanelles with the Mediterranean Sea. The even shallower Kerch Strait, which is only 5 m deep, connects the Black Sea with the Sea of ​​Azov. The wide geosynclinal area of ​​the Black Sea is a deep-water part of the sea bed (maximum depth 2245 m), which has a flat bottom, bordered by a very steep continental slope (in some places up to 20°). In the eastern part of the Black Sea, the slope is dissected by numerous underwater canyons. The northwestern part of the Black Sea and the Sea of ​​Azov are located within a shallow continental shelf. The maximum depth of the Sea of ​​Azov is only 13.5 m.

Bottom relief

The western part of the Black Sea is a wide continental shelf, which, gradually narrowing to the south, stretches to the Bosporus. The continental shelf passes into the continental slope at a depth of 100-150 m. In other coastal areas of the Black Sea continental shelf or very narrow (width does not exceed 10-15 km), or completely absent, since it is replaced by a narrow abrasion terrace.

Geological history

The Black Sea basin initially, in the early Tertiary period, was formed as a median ("intermountain") zeugeosyncline, which sagged between mountain systems Crimea and the Caucasus on the one hand and the Pontic Mountains of Anatolia on the other. During the Cretaceous period, this massif was a mountainous region, from which precipitation was carried both to the north and to the south. Tectonic movements, which caused the formation of depression, occurred in the Tertiary and Quaternary periods and continue to this day. Geophysical studies made it possible to determine that the earth's crust under the bed of the central part of the Black Sea basin is oceanic. There is no granite layer here. Black Sea - classic example"oceanization" of the original mainland earth's crust. However, unlike the oceans, sedimentary layer The Black Sea reaches 10-15 km. On the continental slope, at a depth of up to 1500 m, there are terraces of fault origin with young shallow-water sediments. The continental slope zone, especially along the Crimean and Anatolian coasts, is highly seismic.

In the Quaternary period, there was also a significant uplift of mountain belts on the Black Sea coast, as evidenced by the different heights of the sea terraces formed at that time. In the Neogene, the outlines, area and salinity of the Black Sea again underwent changes. In Pontic times, it joined the Caspian Sea and turned into a vast closed lake. The Pliocene period and the evolution of the Black Sea fauna were first studied and systematized by N. I. Andrusov (1918).

The Quaternary period was also characterized by numerous changes in the level of the Black Sea associated with eustatic fluctuations in the level of the World Ocean. The latter are closely connected with the change of glacial epochs. Repeatedly, when the level of the Black Sea fell below the level of the Bosphorus, it turned into a lake and its waters were desalinated. On the other hand, at a high level of the Black Sea, the water exchange with the Mediterranean Sea became more and more active, the waters of the Black Sea became saline and it was populated by organisms requiring relatively high salinity.

Changes in the species composition of mollusks make it possible to very accurately date the sediments of the bottom of the Black Sea and its shores: the remains of mollusks found in sediments belong to different eras quaternary period. Based on organic remains in sediments, the New Euxinian desalinated phase of the development of the Black Sea was also studied, which, as it turned out, dates back to the time of the last ice age (Wurm glaciation).

Deposits of this phase have been exposed in many places, both in shallow and deep waters, but they are rarely or never found on land. The level of the Black Sea (from -40 to -60 m) during this period was significantly lower than the Bosphorus Threshold. This was followed by a relatively fast Holocene transgression and salinization of the sea waters. close to modern level established about 5000 years ago.

Terraces

The most common on land are the two Karangat terraces. It has been established that their coastlines are elevated by 12–14 m in the Caucasus and by 22–25 m in Bulgaria. This was the period of a more complete connection between the Black Sea and the Sea of ​​Marmara and the formation of the ancient Euxinian basin. During this period, many large stenohaline forms (such as mollusks, sea ​​urchins etc.). Many researchers compare this period of the Black Sea with the monastic period mediterranean sea.

In the same areas, there are ancient Euxinian (55-60 m) and Uzunlar (35-40 m) terraces. They correspond to the Tyrrhenian terraces. The ancient Euxinian basin became desalinated and was dominated by Caspian relics and endemic forms.

At the turn of the Pliocene and the Quaternary, the Chaudinskaya terrace was formed. In the Crimea, its deposits are found at a height of up to 30 m, in the Caucasus up to 95-100 m, but there they are deformed under the influence of the movement of the earth's crust.

In the Sea of ​​Azov, the terraces are poorly preserved, as the area has recently experienced intense subsidence. During the low-level periods of the Black Sea, the Sea of ​​Azov turned into a swampy alluvial plain.

Hydrological regime

The Black Sea is typical example inland "Euxine" sea, which affects its hydrological conditions. It was found that in the lower layers salty water(36 ind.) of the Sea of ​​Marmara penetrates into the Black Sea, and desalinated water of the surface layer of the Black Sea enters the Sea of ​​Marmara. According to recent studies, the inflow of Mediterranean waters is 202 km3 per year, and surface runoff carries 348 km3 of water from the Black Sea. Over 400 km3 of water is brought to the Black Sea by numerous rivers. (The inflow and outflow of water into the Black Sea are subject to slight annual fluctuations.)

Average salinity surface water layer in the central part 16~18%. At depths greater than 150–200 m, salinity increases to 21–22.5 ppm. Surface waters warm up to 25°C in summer (up to 28°C near the coast). In winter, in the open sea, they cool down to 6-8 ° C. The Sea of ​​\u200b\u200bAzov and the northwestern part of the Black Sea are covered with ice in winter. Deep waters have a temperature of 8-9 ° C all year round.

Since surface and deep waters differ in density, their mixing is difficult. Only the upper 50-meter layer is saturated with oxygen. In the lower layers, the oxygen content decreases, and hydrogen sulfide appears at a depth of 150-200 m,
the amount of which in the bottom layers can reach 6 cm3/l. The origin of hydrogen sulfide is explained by the activity of both anaerobic bacteria, which decompose the protein substance, and desulfuric bacteria.

An analysis of the balance of fresh and salt water in the Black Sea shows that, despite the difficulty of exchange between the upper and lower layers, such an exchange still exists. Every year up to 3000 km3 of deep water rises to the surface. The mechanism of this phenomenon is still not entirely clear.

The weak connection of the Black Sea with the ocean, abundant river flow, difficult water exchange between the upper and lower layers lead to some change chemical composition water compared to the World Ocean, namely, it contains slightly less sulfates and much more carbonates.

The movement of surface water is determined by both winds and river runoff. Generally surface water The Black Sea circulate along the coast counterclockwise.
Apart from general circulation There are two circular currents - east and west. On the border between them, the water moves both to the south and to the north. The speed of these currents ranges from 0.1 to 0.3 m/s. Drift currents develop in coastal areas and have a speed of up to 0.5 cm/s.

The water level in the Black Sea is subject to seasonal fluctuations up to 20 cm on average. In coastal regions, especially in the northwest, significant amplitudes of level changes are observed under the influence of wind. Tidal fluctuations in the water level (up to 8-9 cm) are completely imperceptible in comparison with fluctuations in the level under the influence of winds. AT western region, surges up to 7 m high are formed.

Biology

The bottom vegetation of the Black Sea includes 285 species of brown, red and green algae. It is mostly depleted Mediterranean flora. It should be noted the numerous flora along the rocky shores, as well as the huge banks of the Phylophora and the northwestern part of the sea. Philophora is used in Industry.

Phytoplankton is represented by 350 Mediterranean species. It is widely distributed in the open sea to depths of 100–125 m. Phytoplankton occurs off the coast to a depth of 200 m. Phytoplankton biomass in the open sea averages 0.1 g/m3 with a sharp increase near the coast: diatoms make up to 79% of plankton. In spring, the number of phytoplankton reaches 20 million cells per liter. In summer, the number of dinoflagellates rises to 48,000 per liter.

Zooplankton includes over 70 species; its biomass in the open sea averages 0.3 g/m3. The most numerous benthic and nekton organisms are the "immigrants" of the Mediterranean Sea, which have adapted to the more "fresh" water of the Black Sea. The bays of the northwestern part of the Black Sea are inhabited by Pontic relics (Pliocene), close to the Caspian. In the Black Sea, there are also river forms that have adapted to brackish water.

Due to the low salinity of the Black Sea, its fauna and flora, and especially the fauna and flora of the Sea of ​​Azov, are much poorer than the fauna and flora of the Mediterranean Sea. If the latter is inhabited by up to 7000 various kinds of plant and animal organisms, then only 1200 species are found in the Black Sea and about 100 in the Sea of ​​\u200b\u200bAzov. Many classes of animals living in the Mediterranean Sea are not represented at all in the Black Sea (coral polyps, cephalopods and pteropods). Of the echinoderms, only small forms of holothurians and brittle stars are found. All representatives of the Black Sea benthic fauna are smaller in size than the Mediterranean ones.

The benthos biomass in the Black Sea is relatively rich near the coast. But the biomass and number of species gradually decrease starting from a depth of 5–70 m. Below 50 m, benthos is represented by the most common mollusk

At a depth of 13-180 m, benthic organisms are not found at all (except for bacteria).
The fauna of the Sea of ​​Azov is even poorer in terms of the number of species, but in the Sea of ​​Azov there is an intensive development of three species of mollusks, which make up the bulk of the biomass (up to 400 g/m2).

About 180 species of fish are found in the Azov-Black Sea basin. Many of them migrate from the Black Sea to the Sea of ​​Azov and back. Fishing is highly developed, especially in the Sea of ​​Azov. There are many dolphins in the Black Sea; seals are found.

Bottom sediments

Shell sediments are common on a wide shelf, as well as along the coasts of the northwestern part of the Black Sea and south of the Kerch Strait. The shell also composes large accumulative coastal forms (bars, bay bars and spits). Terrigenous (mussel) silt along the mountainous shores of the Black Sea occurs starting from a depth of about 20 m. Large areas of the continental slope are devoid of modern sediments. Tubes for taking soil cores bring Neo-Euxinian and Karangatian sediments or run into bedrock outcrops. Extensive areas of the bottom near the inflection of the shelf are exposed as a result of gravitational displacements of sediments. Below, mixed sediments of underwater landslides occur in many places.

In the deep-water part of the Black Sea basin, there are thick layers of clayey-calcareous silt with different composition and structure. Ribbon stratification of organic matter is associated with the death of planktonic organisms in summer and autumn. A layer of fine-grained calcite is deposited in winter, a thin layer of clay in spring. The thickness of the layers is hundredths or tenths of a millimeter in different areas. Microlayering makes it possible to calculate the rate of silt deposition. For 5000 years, the average accumulation of clayey silt is 1 m, and calcareous silt is only 10-20 cm. All types of deep-sea silt contain a large amount of diagenetic iron sulfide (pyrite, hydrotroilite), indicating a reducing environment.

Based on the changes in the lithological composition at the bottom of the deep-water depression, it is possible to distinguish the sediments of several phases of the development of the Black Sea up to the New Euxinian deposits. Relic water, in the thickness of sediments, has retained an exceptionally low salinity: 4 ppm. in a layer or at a depth of 6 m below the bottom surface. Layers and lenses of sand, which are obviously the result of turbidity flows, are found in the thickness of deep-water silts along the edges of the deep-sea basin.

The coast of the Black Sea almost everywhere have simple outlines. An exception is the western Crimea, where long braids are developed. big islands no. Limans and lagoons of the western part of the Black Sea have a special character. They are flooded estuaries, cut off from the sea by embankments. Along the straight coasts of the western part of the Black Sea and the Caucasian coast, several powerful alongshore streams of sand and pebbles have been established.

In the Sea of ​​Azov, the rate of abrasion of clay shores is very high - up to 4 m per year. On the northern coast of the Sea of ​​Azov, as a result of the action of waves coming from the northeast, a series of long streamers was formed, protruding into the sea at an angle of about 45°.

With all the differences that exist between the Baltic, Black and Azov Seas, which belong to the Atlantic Ocean basin, they also have some common features. These common features consist primarily in the fact that the Baltic, Black and Azov seas are inland, Mediterranean seas, and as a result weak connection with the Atlantic Ocean have a peculiar hydrological regime. These three seas have relatively warm waters and in winter they freeze far from everywhere and only on a short time. The warmest of them - the Black Sea - is covered with ice only in the very north within a narrow coastal strip.

The Caspian is in close genetic connection with the Black Sea. And although the Caspian is a closed drainless lake, however, given its size, history of development and hydrobiological features, there is every reason to consider it a marine reservoir.

Through the seas of the Atlantic Ocean; the shortest waterways to the countries of Western Europe, to the Atlantic Ocean. The vast majority of our exports and imports pass through the port cities located on their coasts. The Baltic and Black Seas are connected by large coastal routes with all other seas surrounding the USSR.

Baltic Sea. The Baltic Sea is one of the youngest seas Soviet Union. It was formed in the Quaternary time as a result of a tectonic trough at the junction of the Baltic crystalline shield with the sedimentary cover of the Russian Platform. During the epoch of glaciation, the territory now occupied by the waters of the Baltic Sea was covered by continental ice. After the retreat of the glacier, the Yoldian Sea arose, which, like a giant strait, connected the North Sea with the White Sea. Then there are uplifts, the connection of the newly formed reservoir with the seas is terminated and it turns into a closed lake Ancylus. He soon forms a connection with North Sea and the Litorin Sea is formed, which is the direct predecessor of the modern Baltic Sea.

The depths in the Baltic Sea are shallow. Its maximum depth south of Stockholm is 459 m. In the Gulf of Finland and Riga, the deepest places do not reach 100 m. The straits connecting the Baltic Sea with the North Sea (Great and Small Belts, Øresund) are even shallower. As a result, the water exchange of the Baltic Sea with the North Sea and the Atlantic Ocean is very difficult and the Baltic waters are desalinated due to river runoff. The salinity of the water even in the west of the Baltic Sea does not exceed 7-8°/00, and in the Gulf of Finland it drops to 2-3°/oo. Salinity increases with depth, and this circumstance makes it difficult to vertically mix water, which at depths of more than 50 m all year round has low temperature. The upper layers of water warm up well in summer (up to 15-17 ° off the coast of the USSR), in winter they are very cold, up to the formation of ice in the Gulf of Finland and Riga. At the western borders of the USSR, the sea is free of ice all year round. Here is a large non-freezing port of the USSR - Kaliningrad.

Animal world The Baltic Sea is not rich. It is dominated by arctic forms, which are replaced by boreal ones in warmed shallow waters. In commercial terms, Baltic herring and Baltic sprat, small representatives of herring fish, are of great importance.

Black, Azov and Caspian Seas" Like our quietoceanic seas, the Black and Caspian Seas were formed as a result of deep subsidence of the earth's crust in the zone of young alpine folding. Therefore, they have significant depths, in the Black Sea up to 2245 m, in the Caspian - 980 m.

Even in the Miocene, on the site of the Black and Caspian Seas, there was one sea basin - the Sarmatian, isolated from the ocean. By the end of the Miocene, it passes into the Maeotic Basin, which has already received a connection with open ocean. At the very beginning of the Pliocene, this connection is broken and a desalinated Pontic lake-sea is formed on the site of the Maeotic basin. In the Pliocene, the Pontic lake-sea splits into two separate reservoirs, and from that time begins independent life Black and Caspian Seas, which have changed their shape many times and between which repeatedly established a connection through the Kuma-Manych depression.

The Black Sea is connected to the Mediterranean by narrow straits - the Bosphorus and the Dardanelles, formed in the Quaternary. At its narrowest point, the Bosphorus is only 750 meters wide.

Being almost closed or completely closed water bodies, the Black and Caspian Seas are heavily desalinated, despite their southern position. In the Black Sea, salinity ranges from 18 to 22.5 ° / 00, in the Caspian Sea it is 12-13 0 / 00. Such a strong desalination is caused by the bringing into the seas of large masses fresh water rivers.

The desalinization of the upper water horizons, as well as their significant warming up in summer, greatly complicates the vertical circulation in the Black and Caspian Seas. The weakening of the vertical circulation is also facilitated by the relief of the bottom of these seas - the presence of more or less closed depressions. All this leads to the depletion of deep layers of water with oxygen and the accumulation of hydrogen sulfide and organic matter in bottom sediments. The process of hydrogen sulfide contamination is especially pronounced in the Black Sea; the hydrogen sulfide zone begins in it from a depth of 180-200 m.

The rivers bring many nutrient salts to the southern seas of the USSR. This circumstance, combined with high temperatures water creates conditions for high biological productivity of these seas. In terms of biological productivity, the shallow Sea of ​​Azov ranks first, and the Caspian Sea ranks second. There are cases when in the Sea of ​​Azov the biological mass of phytoplankton during the flowering period reached a huge value - up to 200 g/m 3 .

The fauna of the southern seas, not distinguished by the diversity of species, is rich in the number of individuals. Genetically, it is composed of three elements: Pontian relics, Mediterranean immigrants and freshwater species. The main commercial fish in the Black Sea are anchovy, sprat, ram, mullet, gobies, carp, bream, sturgeon; in Azov - sprat, pike perch, anchovy, bream; in the Caspian - herring, pike perch, bream, carp, roach, sturgeon.

The Sea of ​​Azov ranks first in terms of fish catch per unit area, and the Caspian Sea ranks second.

However, in terms of the total catch of fish, the first place belongs not to the Sea of ​​\u200b\u200bAzov, but to the Caspian Sea, which is larger in area, which is second only to all our Far Eastern seas taken together.