Caspian Sea - the largest lake on Earth, an endless lake, located at the junction of Europe and Asia, called the sea because of its size, and also because its bed is composed of an oceanic crust. The water in the Caspian is salty, - from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data was 27.16 m below sea level. The area of \u200b\u200bthe Caspian Sea is currently about 371,000 km², the maximum depth is 1025 m.
Geographical position
The Caspian Sea is located at the junction of two parts of the Eurasian continent - Europe and Asia. The length of the Caspian Sea from north to south is about 1200 kilometers (36 ° 34 "-47 ° 13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46 ° -56 ° c. d.). The Caspian Sea is conventionally divided by physical and geographical conditions into 3 parts - the North Caspian, the Middle Caspian and the South Caspian. The conditional border between the North and Middle Caspian runs along the line about. Chechnya - Cape Tyub-Karagan, between the Middle and South Caspian - along the line about. Residential - Cape Gan-Gulu. The area of \u200b\u200bthe North, Middle and South Caspian Sea is 25, 36, 39 percent, respectively.
The length of the coastline of the Caspian Sea is estimated at about 6500-6700 kilometers, with islands up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low and smooth. In the northern part, the coastline is cut by water channels and islands of the Volga and Ural deltas, the banks are low and swampy, and the water surface is covered with thickets in many places. The eastern coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding shores are on the western coast in the area of \u200b\u200bthe Apsheron Peninsula and on the eastern coast in the area of \u200b\u200bthe Kazakh Bay and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian region.
Peninsulas of the Caspian Sea
Major peninsulas of the Caspian Sea:
- Agrakhan Peninsula
- Absheron Peninsula, located on the western coast of the Caspian Sea on the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory are the cities of Baku and Sumgait
- Buzachi
- Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory is the city of Aktau
- Miancale
- Tyub-Karagan
Islands of the Caspian Sea
There are about 50 large and medium-sized islands in the Caspian Sea with a total area of \u200b\u200babout 350 square kilometers. The largest islands:
- Ashur-Ada
- Garasu
- Boyuk-Zira
- Zyanbil
- Kur Dashi
- Hara-Zira
- Ogurchinsky
- Sengi-Mugan
- Seal
- Seal Islands
- Chechen
- Chygyl
Bays of the Caspian Sea
Large bays of the Caspian Sea:
- Agrakhan Gulf
- Kizlyar Bay
- Dead Kultuk (former Komsomolets, former Gulf of Tsarevich)
- Kaydak
- Mangyshlak
- Kazakh
- Kenderli
- Turkmenbashi (bay) (former Krasnovodsk)
- Turkmen (bay)
- Gizilagach (former Kirov Bay)
- Astrakhan (bay)
- Hasan-kuli
- Gyzlar
- Hyrcanus (formerly Astarabad)
- Anzali (formerly Pahlavi)
- Kara-Bogaz-Gol
Rivers flowing into the Caspian Sea- 130 rivers flow into the Caspian Sea, of which 9 rivers have delta-shaped estuaries. The large rivers flowing into the Caspian Sea are Volga, Terek, Sulak, Samur (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Atrek (Turkmenistan), Sefidrud (Iran) and others. The largest river flowing into the Caspian Sea is the Volga, its average annual runoff is 215-224 cubic kilometers. The Volga, Ural, Terek, Sulak and Emba provide up to 88-90% of the annual runoff into the Caspian Sea.
Physiography
Area, depth, volume of water- the area and volume of water in the Caspian Sea varies significantly depending on fluctuations in the water level. With a water level of -26.75 m, the area is approximately 371,000 square kilometers, the volume of water is 78,648 cubic kilometers, which is approximately 44% of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated using the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.
Water level fluctuations- the water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past three thousand years, the magnitude of the change in the water level of the Caspian Sea has reached 15 meters. According to archeological data and written sources, a high level of the Caspian Sea is recorded at the beginning of the XIV century. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuation have been carried out since 1837, during this time the highest water level was recorded in 1882 (-25.2 m), the lowest - in 1977 (-29.0 m), with In 1978, the water level increased and in 1995 reached the level of -26.7 m, since 1996 there has been a downward trend again. Scientists associate the reasons for the change in the water level of the Caspian Sea with climatic, geological and anthropogenic factors. But in 2001, the sea level began to rise again, and reached -26.3 m.
Water temperature- the water temperature is subject to significant latitudinal changes, most pronounced in winter, when the temperature changes from 0-0.5 ° C at the ice edge in the north of the sea to 10-11 ° C in the south, that is, the difference in water temperature is about 10 ° C. For shallow water areas with depths less than 25 m, the annual amplitude can reach 25-26 ° C. On average, the water temperature near the western coast is 1-2 ° C higher than that of the eastern one, and in the open sea the water temperature is 2-4 ° C higher than near the coasts.
Water composition- the salt composition of the waters of the enclosed Caspian Sea differs from the ocean. There are significant differences in the ratios of the concentrations of salt-forming ions, especially for the waters of areas under the direct influence of continental runoff. The process of metamorphization of sea waters under the influence of continental runoff leads to a decrease in the relative content of chlorides in the total amount of salts of sea waters, an increase in the relative amount of carbonates, sulfates, calcium, which are the main components in the chemical composition of river waters. The most conserved ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ions. In the Caspian, the content of calcium and magnesium cations is almost twice as high as in the Sea of \u200b\u200bAzov, and the content of sulfate anions is three times higher.
Bottom relief- the relief of the northern part of the Caspian is a shallow undulating plain with banks and accumulative islands, the average depth of the North Caspian is 4-8 meters, the maximum depth does not exceed 25 meters. The Mangyshlak sill separates the North Caspian from the Middle. The Middle Caspian is quite deep, the depth of water in the Derbent depression reaches 788 meters. The Absheron sill separates the Middle and South Caspian. The South Caspian Sea is considered deep-water, the depth of water in the South Caspian depression reaches 1025 meters from the surface of the Caspian Sea. Shell sands are widespread on the Caspian shelf, deep-water areas are covered with silty sediments, in some areas there is an outcrop of bedrocks.
Climate- The climate of the Caspian Sea is continental in the northern part, temperate in the middle and subtropical in the southern part. In winter, the average monthly air temperature varies from -8 ... -10 in the northern part to + 8 ... + 10 in the southern part, in summer - from + 24 ... + 25 in the northern part to + 26 ... + 27 in the southern part. The maximum temperature of +44 degrees was recorded on the east coast. The average annual rainfall is 200 millimeters, ranging from 90-100 millimeters in the arid eastern part to 1,700 millimeters off the southwestern subtropical coast. Evaporation of water from the surface of the Caspian Sea is about 1000 millimeters per year, the most intense evaporation is in the area of \u200b\u200bthe Absheron Peninsula and in the eastern part of the South Caspian - up to 1400 millimeters per year. The average annual wind speed is 3-7 meters per second, northern winds prevail in the wind rose. In the autumn and winter months, the winds increase, the speed of the winds often reaches 35-40 meters per second. The windiest areas are the Apsheron Peninsula, the vicinity of Makhachkala and Derbent, where the highest wave of 11 meters was recorded.
Currents- water circulation in the Caspian Sea is associated with runoff and winds. Since most of the runoff is in the North Caspian, northern currents prevail. The intense northern current carries water from the North Caspian along the western coast to the Absheron Peninsula, where the current divides into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.
Economic development of the Caspian Sea
Mining of oil and gas- Many oil and gas fields are being developed in the Caspian Sea. The proven oil resources in the Caspian Sea are about 10 billion tons, the total oil and gas condensate resources are estimated at 18-20 billion tons. Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf near Baku. In the second half of the 19th century, oil production began in industrial volumes on the Absheron Peninsula, and then in other territories. In 1949, oil production from the bottom of the Caspian Sea began for the first time at Oil Rocks. So, on August 24 this year, Mikhail Kaverochkin's team began drilling a well, which gave the long-awaited oil on November 7 of the same year. In addition to oil and gas production, salt, limestone, stone, sand and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.
Shipping- shipping is developed in the Caspian Sea. On the Caspian Sea ferry crossings, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a navigable connection with the Azov Sea through the Volga, Don and Volga-Don Canal.
Fishing and seafood production-fishing (sturgeon, bream, carp, pike perch, sprat), caviar production, as well as seal hunting. More than 90 percent of the world's sturgeon catch is carried out in the Caspian Sea. In addition to industrial production, illegal production of sturgeon and their caviar is flourishing in the Caspian Sea.
Legal status of the Caspian Sea- after the collapse of the USSR, the division of the Caspian Sea has long been and still remains the subject of unresolved disagreements related to the division of the Caspian shelf resources - oil and gas, as well as biological resources. For a long time, negotiations were going on between the Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran on dividing the Caspian by one fifth of the Caspian states. The current legal regime of the Caspian was established by the Soviet-Iranian treaties of 1921 and 1940 These treaties provide for freedom of navigation throughout the sea, freedom of fishing except for ten-mile national fishing zones and a ban on ships flying the flag of non-Caspian states in its waters. Negotiations on the legal status of the Caspian are currently ongoing.
The Caspian Sea is the largest enclosed body of water. And although the water in it is salty, and the bed is lined with rocks of the oceanic type, it is located far from the world's oceans and is a giant closed lake.
The Caspian Sea is located in two parts of the world at once. Its western coast washes the European part of the mainland, and the eastern one is part of Asia. Its length from north to south is 1030 km, and from west to east 435 km at the maximum point. Sea coordinates: 36 ° 34'-47 ° 13 ′ north latitude and 46 ° -56 ° east longitude.
You can get to the Caspian from anywhere in Russia. One of the main destinations for Russians will be Astrakhan and the region, from which the capital and others major cities all year round there is both air traffic and railway flights. It is not so easy to get from remote cities, as often stations do not make direct flights to Astrakhan.
Another popular route runs through Dagestan and leads to Makhachkala, Kaspiysk or Derbent - the main cities for tourists. Planes fly to the capital of the republic all year round from Moscow, St. Petersburg, Yekaterinburg and Krasnoyarsk. It is possible to get there by train, but in summer they are usually packed with people.
Historical facts
The lake was formed from the Sarmatian Sea tens of millions of years ago, when the Caucasus Mountains did not divide it into the Black and Caspian Seas. The Sarmatian Sea itself finally lost its direct access to the ocean more than 70 million years ago.
Some of the first written records of the Caspian Sea were found on clay tablets dating from the 9th century. BC e. They were found during excavations in Assyria, the territory of which mainly belongs to modern Iraq and Syria. Later, Herodotus, Aristotle and the "father of geography" Hecateus of Miletus mention the Caspian. Their knowledge was generalized and expanded by Arab scholars in the 9th-10th centuries.
How the Caspian Sea was formed
With the development of medieval trade relations, information about the Caspian Sea spread to Europe and Turkey. The famous seafarer and traveler Marco Polo described it in the 13th century. With the subsequent passage of time, knowledge about the lake only increased, more detailed and truthful maps were created.
As for the name, over the thousands of years of its existence on it, people have given the lake more than 70 names. So, the ancient peoples called it Hyrcanian, and the Arabs called it Khazar. The Chinese gave it the name Sihai, the Iranians - Kolzum, the Turks - Kuchuk-Deniz.
The Russians called it "Blue Sea", Khvalynsky or Khozemsky. The name also changed depending on the adjacent states. At one time it was called Sarai, Turkmen, Avar, Persian and many other names. It took its modern name from the ancient nomadic pastoralist tribes - the Caspians, who lived on its right bank around the 2nd millennium BC.
Characteristic
Of all the characteristics of the Caspian, the greatest interest is its unique flora and fauna, which have collected many rare species of plants and animals, the determination of its origin and problems associated with the ecology and pollution of the reservoir.
Bottom relief and depth
The Caspian Sea is subdivided into three geographic zones: North, Middle and South. The North is a sea plume with an average depth of no more than 5 m. It accounts for the smallest amount of lake water - about 1%. The second largest is the Middle Caspian, where the bottom reaches 780 m at its maximum point. It contains more than 30% of water reserves. 
The southern part is equal to the Average in area, but it is deeper and has more than 60% of the water mass.
It is here that the deepest point of the lake to date is located - 1025 meters under water.
The boundaries between the parts are rather arbitrary, but they are.
Between the North and the Middle, the Chechen Island and Cape Tyub-Karagansky became the border, and between the Middle and the South - the Zhiloy Island and Cape Gan-Gulu.
The bottom relief of the lake is fairly uniform, but it differs in different zones.
In Severnaya, it is a flat shallow water with small alluvial areas. The middle one goes deep and is covered with silt or shells. The southern one, being the deepest, is also covered with silt, and in some places and ledges of bedrock.
Area and length
The surface area of \u200b\u200bthe lake is approximately 370,000 square meters. km. The water level is subject to cyclical changes: it goes down, then it rises. Scientists have found that over the past millennium, the water level in the lake has fluctuated within ten meters. This is a very big indicator.
It is associated primarily with the activity of people, as well as geological factors that constantly affect the reservoir. According to confirmed data, the water level is only increasing. The South, the Middle and the North account for 40, 35, 25% of the area, respectively.
The length of the coastline is 6700 km, and taking into account the island territories - about 7000. The shores themselves are quite smooth, without large elevations. In the north, the lowland of the coast is represented by channels and islands formed by the Volga.
The terrain is swampy and covered with dense reeds. The eastern coastal areas are adjacent to deserts and are composed of limestone or shells. The most "mountainous" were the coasts of the Absheron Peninsula and the Kazakh Gulf. 
The Caspian Sea is located in an area with many islands and peninsulas. The largest and most significant peninsulas are: Agrakhan Peninsula, Apsheron Peninsula, on which Baku is located, Mangyshlak Peninsula, which has the Kazakh city of Aktau, Buzachi Peninsula, Miankale and Tyub-Karagan.
There are about 50 large and medium islands in the lake. Their total area is 350 sq. km. The most famous of them are: Chechen, Gum, Dash, Zyanbil, Seal Islands, Chygyl, Garasu and Ashur-Ada.
Water composition
The composition of the water is different from that observed in the seas and oceans. This is due not only to the fact that the Caspian Sea is closed, but also subject to a significant influence of continental runoff waters. This significantly reduces the content of chlorides and salts in the water, but increases the amount of calcium, carbonates and sulfates inherent in river water.
In the Azov Sea, for example, there are two times less calcium cations than in the Caspian. Despite this, the water in the lake is salty, from 0.05 ppm at the confluence of the Volga to 11-13 ppm in the southern part.
| Carbonates (CaCO3) | Sulfates CaSO4, MgSO4 | Chlorides NaCl, KCl, MgCl2 | Average salinity of waters ‰ | |
| Ocean | 0,21 | 10,34 | 89,45 | 35 |
| Caspian Sea | 1,24 | 30,54 | 67,90 | 12,9 |
Sea basin and its relationship with the World Ocean
The Caspian Sea basin is 3.1 million square meters. km. It includes such rivers as the Volga, Kuma, Uluchay, Samug, Sudak, Terek. The Volga is the largest and deepest river that flows into the lake. More than two hundred large rivers flow into it, and the number of its tributaries is more than 5000.
Its delta begins from the Astrakhan region, which is the largest in Europe. The Volga receives most of its water from melting snows, rains and springs. In addition to these rivers, more than 100 rivers flow into the Caspian.
To date, the Caspian Sea has no direct connection with the ocean, but an indirect one is provided through the Volga-Don canal. Through it, ships and fleet can get from the Caspian and Volga to the Don, Azov and Black Sea.
Climate
The Caspian Sea is located in several climatic zones and the climate depends on its parts. In the northern part, it is continental with temperatures ranging from -10 ° C in winter to +25 ° C in summer. In the southern part, the climate becomes subtropical. The temperature there ranges from + 8 ° C in winter to +27 ° C in summer. 
The middle part of the Caspian Sea is located in a temperate climate with average temperatures. The highest temperature recorded on the east coast was + 44 ° C.
Water temperature is also subject to significant changes and depends on latitude. During the cold season, in the northern part, the water can freeze or cool down to 0 - 1 ° C, and in the south the temperature does not drop below 10 ° C. In summer, the water warms up from +20 ° C to +27 ° C, depending on the region.
As for precipitation, their average annual rate is 200 mm. Again, everything depends on the climate and varies from 100 mm in the eastern part to 1700 mm in the southern subtropics. It is best to visit the Caspian Sea in the summer at the end of July or in August. The ideal resorts will be Baku, Makhachkala and Astrakhan.
Flora and fauna
The fauna of the Caspian is diverse and rich. He somehow repeats other reservoirs, but in his own way it is original. Ancient sturgeon and salmon fish species, as well as several types of herring, carp, pike perch, carp, sprat, mullet, bream, pike, roach live here. There are about 100 species of fish in total. 
The volume of sturgeon is 90% of all reserves in the world. The only and unique view The mammal living in this area is the Caspian seal, which is the smallest of all seals. Many of the species are protected by three reserves: Astrakhan, Caspian and Gyzylagaj.
The vegetation numbers over 700 species. The most important for maintaining favorable conditions for animals are blue-green, red, brown and diatoms. Flora mostly represents the Neogene period of the ancient Caspian, however, some species were introduced into the sea on purpose or accidentally due to shipping.
Ecological situation
The current ecological situation in the Caspian Sea is not the best. The main polluting factor was oil and its processing. As you know, it began to be mined here 150 years ago in Azerbaijan.
In this regard, the suppression of the development of finoplankton and blue-green algae began, the concentration of oxygen in the water decreased, which affected the reproduction of sturgeon fish, waterfowl and other living organisms. 
The mass reproduction of the ctenophore Mnemiopsis, which entered the Caspian Sea from the Black and Azov Sea through the Volga-Don Canal, also brought a lot of troubles. The comb jelly feeds on the same plankton as the Caspian fish.
This has reduced their food supply and put sturgeon on the brink of extinction. The number of valuable sturgeon fish has also declined due to poaching, which, according to unofficial data, accounts for more than half of the catch.
The unique biological and hydrocarbon resources of the Caspian are also destroyed by phenols and heavy metals that enter it with wastewater from industrial enterprises located near the reservoir.
Countries washed by the Caspian Sea
The waters of the sea are washed by the territories of modern:
The main cities on the coast are Astrakhan, Baku, Aktau, Bender-Anzeli, Makhachkala and Turkmenbashi.
Tourist infrastructure on the Caspian Sea
The Caspian Sea is located around developed countries and its tourist infrastructure is represented by a large number of coastal resort towns with many recreation centers and hotels. At the disposal of tourists not only active recreation in the form of fishing or water parks, but also beaches, where for little money you can relax from morning until late at night, renting sun loungers, hammocks or gazebos.
Resorts on the Caspian Sea
One of the most prestigious resorts became Baku. The capital of Azerbaijan with a population of 2.5 million people provides an opportunity not only to relax on the beach, but also to visit many sights, some of which are included in the UNESCO World Heritage List.
It is still better to go to the beaches in the suburbs of Baku, where Shikhovo, Mardakan or Zagulba are located. The resort infrastructure of the Caspian Sea is at a high level. The beaches are clean and well maintained, and hotel complexes provide a wide range of accommodation close to the coast. IN
all this is in 30 minutes drive from Baku. Sumgait should not be written off as well. It is located 30 km from Baku, but has more extensive shell-type beaches. It has less bustle of the city, but service and maintenance is not inferior to the capital. 
Kazakhstan also has several resorts in large cities. The most popular were Aktau and Atyrau. Despite the fact that Aktau is located in the desert and began to recreate the tourism infrastructure relatively recently, it has new hotel complexes with a decent quality of service.
Atyrau has ceased to be in demand, since the Caspian Sea in these places has become shallow and the beaches have ceased to exist. In general, Kazakh resorts are in low demand among foreign and Russian tourists.
The Caspian Sea washes several large Turkmen cities, including Turkmenbashi and Avaza. The second city is in demand for tourists. Here, the construction of hotels and complexes also began relatively recently, but the resort has already managed to find its adherents.
One of its features are sandy and shell beaches, stretching for kilometers. The resorts of Turkmenistan cannot be called popular among foreigners either, since there is a rather complicated visa system when entering the country.
In Russia, two resorts of Astrakhan and Dagestan are the most popular, represented by Astrakhan itself, Makhachkala, Derbent, Caspian and a couple of other small cities. Derbent is one of the most picturesque. Thanks to its landscapes and ancient buildings included in the UNESCO heritage, the city has become popular not only among tourists from Russia, but also foreigners.
Beaches on the Caspian Sea
The most interesting beaches of the Russian resorts are Jami, Goryanka, Laguna and the beach of the Caspian sanatorium, located in Dagestan. Unfortunately, according to tourists, there are few good beaches in Astrakhan, and most of the coastal areas are in thickets of reeds. 
Jami Beach, like the Caspian Sea, belongs to hotel and sanatorium apartments located on the coast. That is why they are well equipped in terms of recreation and service. Goryanka beach differs in that only women and boys under 6 years old can enter its territory.
Among the beaches of Kazakhstan, the beaches of Manila, Nur Plaza, Dostar, and Marakesh deserve the greatest attention. The beaches of Manila and New Marrakech are very popular, since the entrance to them is free, and they work until late at night.
Nur Plaza and Dostar are paid. The entrance costs from 35 to 80 rubles. This price already includes umbrellas, sun beds and other benefits. There is an opportunity to rent gazebos, barbecues and park cars cheaply.
The beaches of the Turkmen Avaza stretch for 30 km and have good infrastructure and huge hotel complexes... But not everything is so good. Many people point out many disadvantages of hotels and service for rather high ticket prices. Among them: cold sea water, low population, odors from oil refineries, which are located near the Caspian Sea. 
The beaches of Azerbaijan are rightfully considered the most developed. There are a lot of them here for every taste and budget. Almost the entire coastal zone of Baku is built up with hotel complexes, recreation centers and beaches.
The most famous is the beach of the Shikhovo water park... It has everything for active recreation not only for adults, but also for children. The water slides and attractions will not make you bored, and the large number of sun loungers will fit everyone who wants to just lie in the sun. But do not forget about such beaches as Nabran, Sumgaiti, Novkhani and other places.
Attractions of the Caspian Sea
On the territory of Russia there are many attractions that are worth visiting when arriving at the resort. In Astrakhan they were the Astrakhan Kremlin, the Bridge of Lovers, the Wedding Waltz fountain. In Makhachkala, you can visit the Juma Mosque, many museums and theaters, and in Derbent, the ancient Naryn-Kala fortress and the 150 year old Derbent lighthouse are often visited. 
Azerbaijan possesses unique architectural objects of its kind. In the suburbs of Baku there is the Maiden Tower and a whole complex of walls with the palace of the Shirvanshahs, the Gobustan landscape with ancient rock paintings. There is also much to see in the city center. It houses modern hotels, galleries and museums. For example, the Carpet Museum, TV Tower, Heydar Aliyev Cultural Center.
There are not so many attractions in the Turkmen Avaza. Among them are several yacht clubs, a park, a congress center and an aqua park with attractions. There are no special sights in the Kazakh Aktau, as well as streets. The whole city is divided into districts.
Entertainment and active recreation on the Caspian Sea
For people who love active rest, there are special fishing tours to Astrakhan. Prices start at 20,000 rubles. and includes accommodation, boat rental, fish freezing and cooking facilities.
In Kazakhstan, for those who like active recreation, there are bases with fitness centers, shady courts and much more. The Kenderli base stands out among them. Its only drawback: it is located 300 km from the coast. 
The Azerbaijani coast has everything for a good pastime. Water parks Shikhov and Resort will not let children and adults who love active entertainment get bored. Just like the Turkmen water park in Avaza.
Prices for hotels in the Caspian Sea
The prices for a resort in Russia are the cheapest. Accommodation in apartments in Astrakhan will cost 600-700 rubles, and in hotels from 1200 to 3600 rubles. per day. The most popular hotels are Corvette, Bonotel, Novomoskovsky. In Dagestan, the average price for a hotel will be 1,500 rubles. Coastal hotels: Argo, Pegasus, Assorti, Sharhistan, Versailles.
In Kazakh Aktau there are hotels Rakhat, Aktau, Victoria. Prices depend on the quality of services, but on average start at 2,000 thousand rubles. Renting an apartment starts from 600 rubles.
Baku hotels provide the best conditions and service, however, the prices here are by no means the highest. The average price is 2,000 rubles. Hotels Consul, Bosfor, Safran are popular. It is also possible to rent apartments and separate rooms.
But Turkmen hotels are the most expensive. Prices here start at $ 70. Despite this, many complain that the service leaves much to be desired for the money.
The Caspian Sea is a unique reservoir with its own distinctive flora and fauna. On its shores there are 5 states, most of which provide good tourist infrastructure and services at affordable prices. Coastal cities have ancient landmarks that are world heritage UNESCO.
Article design: Mila Friedan
Video about the Caspian Sea
Caspian Sea Vacation Review:
Caspian Sea - the largest lake on Earth, located at the junction of Europe and Asia, called the sea because of its size. Caspian Sea is a closed lake, and its water is salty, from 0.05% near the mouth of the Volga to 11-13% in the southeast.
The water level is subject to fluctuations, currently - about 28 m below the level of the World Ocean.
Square Caspian Sea at present, it is about 371,000 sq km, the maximum depth is 1025 m.
Coastline length Caspian Sea estimated at about 6500 - 6700 kilometers, with islands up to 7000 kilometers. Shores Caspian Sea most of its territory is low and smooth. In the northern part, the coastline is cut by water channels and islands of the Volga and Ural deltas, the banks are low and swampy, and the water surface is covered with thickets in many places. The east coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding shores are on the western coast in the area of \u200b\u200bthe Apsheron Peninsula and on the eastern coast in the area of \u200b\u200bthe Kazakh Bay and Kara-Bogaz-Gol.
IN Caspian Sea 130 rivers flow into the river, 9 of them have delta-shaped estuaries. Large rivers flowing into the Caspian Sea are the Volga, Terek (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Samur (Russian border with Azerbaijan), Atrek (Turkmenistan) and others.
Caspian Sea Map
The Caspian Sea washes the shores of five coastal states:
Russia (Dagestan, Kalmykia and Astrakhan region) - in the west and north-west, the length of the coastline is 695 kilometers
Kazakhstan - in the north, north-east and east, the length of the coastline is 2320 kilometers
Turkmenistan - in the southeast, the length of the coastline is 1200 kilometers
Iran - in the south, the length of the coastline is 724 kilometers
Azerbaijan - in the southwest, the length of the coastline is 955 kilometers
Water temperature
subject to significant latitudinal changes, most pronounced in winter, when the temperature varies from 0 - 0.5 ° C at the ice edge in the north of the sea to 10 - 11 ° C in the south, that is, the difference in water temperature is about 10 ° C. For shallow areas with depths of less than 25 m, the annual amplitude can reach 25 - 26 ° C. On average, the water temperature near the western coast is 1 - 2 ° C higher than that of the eastern one, and in the open sea the water temperature is 2 - 4 ° C higher than that of the coasts.
Climate of the Caspian Sea - continental in the northern part, temperate in the middle and subtropical in the southern part. In winter, the average monthly temperature of the Caspian Sea varies from −8-10 in the northern part to +8 - +10 in the southern part, in summer - from +24 - +25 in the northern part to +26 - +27 in the southern part. The highest temperature recorded on the east coast is 44 degrees.
Animal world
The fauna of the Caspian is represented by 1809 species, of which 415 are vertebrates. IN Caspian Sea 101 species of fish have been registered, and most of the world's stocks of sturgeon, as well as freshwater fish such as roach, carp, and pike perch, are concentrated there. Caspian Sea - habitat of such fish as carp, mullet, sprat, kutum, bream, salmon, perch, pike. IN Caspian Sea there is also a marine mammal - the Caspian seal.
Vegetable world
Vegetable world Caspian Sea and its coastline is represented by 728 species. From plants to Caspian Sea predominantly algae - blue-green, diatomaceous, red, brown, charovy and others, from flowering - zostera and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into Caspian Sea a person knowingly or on the bottoms of ships.
Mining of oil and gas
IN Caspian Sea many oil and gas fields are being developed. Proven oil resources in Caspian Sea are about 10 billion tons, the total resources of oil and gas condensate are estimated at 18 - 20 billion tons.
Oil production in Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf. In the second half of the 19th century, oil production began in industrial volumes on the Absheron Peninsula, then in other territories.
Besides oil and gas production, on the coast Caspian Sea and the Caspian shelf is also mining salt, limestone, stone, sand, clay.
Environmental problems
Environmental problems Caspian Sea associated with water pollution as a result of oil production and transportation on the continental shelf, the influx of pollutants from the Volga and other rivers flowing into Caspian Sea, the vital activity of coastal cities, as well as the flooding of certain objects due to an increase in the level Caspian Sea... Predatory hunting of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeon and to forced restrictions on their production and export.
The Caspian Sea is rightfully the largest lake on the entire planet and this sea-lake is located at the junction of two significant parts of the world: Asia and Europe.
There are still disagreements in the name of the Caspian: it is a sea or a lake. And it is called the sea due to the large size of the reservoir.
Origin of the sea
The Caspian Sea is of oceanic origin. It was formed about 10 million years ago as a result of the division of the Sarmatian Sea.
According to one of the legends, the Caspian reservoir received its modern name in honor of the Caspian tribes living on the southwestern shores. For all the time, the Caspian Sea has changed its names about 70 times.
Currents
The Caspian Sea area can be divided into the following three parts:
- southern (39% of the area)
- medium (36% of the total area)
- the northern part (25% of the area).
The currents of the reservoir are formed as a result of the following influences: the general influence of the wind regime, the differences in density in certain regions and the runoff of the inflowing rivers.
On the western coast of the middle part of the Caspian, the southern and southeastern currents prevail. For the middle and southern parts of the Caspian Sea, depending on the direction of the winds, the currents of the northern, northwestern, southern and southeastern directions are characteristic. Eastern currents prevail in the eastern part of the Caspian.
The following currents also play an important role in the circulation of the Caspian waters:
- seiche;
- gradient;
- inertial.
What rivers flow into the Caspian Sea
The main part of river waters into the Caspian Sea flows through the Volga River. In addition to the Volga, the following rivers flow into this reservoir:
- Samur, flowing on the border of Azerbaijan and Russia;
- Astarachay, flowing on the border of Iran and Azerbaijan;
- Kura, located in Azerbaijan;
- Heraz, Sefudrud, Tejen, Polerud, Chalus, Babol and Gorgan flowing in Iran;
- Sulak, Kuma, located on the territory of the Russian Federation;
- Emba and Ural, flowing in Kazakhstan;
- Atrek, located in Turkmenistan.
sulak river photo
Where does the Caspian Sea flow
The Caspian reservoir has no connection with the ocean, since it is a closed body of water. The Caspian Sea has dozens of bays. The largest of them can be distinguished: Komsomolets, Gyzlar, Kara-Bogaz-Gol, Mangyshlak, Kazakh, Krasnovodsky and others. Also in the waters of the Caspian Sea there are about 50 islands of different sizes, with a total area of \u200b\u200bmore than 350 km2. Some of the islands are combined into archipelagos.
Relief
The following forms can be distinguished in the relief of the bottom of the Caspian Sea: in the south of the reservoir there are deep-water depressions; continental slope, starting just below the shelf boundary and descending into the southern part of the Caspian Sea up to 750m, and in the middle part of the Caspian Sea - up to 600m. the shelf, the length of which from depth to the coastline is 100 m and is covered with shell sands, and in deep water - with silty sediments.
Derbent photo
The coastline of the northern region of the sea is low-lying, rather indented, in some areas gently sloping. The western shore of the reservoir is rugged and mountainous. In the east, the shores are distinguished by elevations. The southern coastline is mostly mountainous. The Caspian Sea is located in a zone of high seismicity. Also, mud volcanoes often erupt here, most of which are located in the southern part of the reservoir.
Cities
The following states have access to the waters of the Caspian Sea:
- Russia. Makhachkala, the capital of Dagestan, is a large city. Also in Dagestan are the cities of Kaspiysk and Izberbash. In addition to the above cities in the Russian Federation on the Caspian Sea, Derbent should be noted, the most southern City Russia located on the western coast of the Caspian Sea, Olya in the Astrakhan region.
- Azerbaijan: the port city of Baku, the capital of Azerbaijan, is located in the southern part of the Absheron Peninsula. Another big city is Sugmait, located in the northern part of the peninsula. The resorts of Nabran and Lankaran should also be noted. The latter is located near the southern border of Azerbaijan.
- Turkmenistan with the port city of Turkmenbashi.
- Iran: Bender-Torkemen, Anzali, Noushehr.
Makhachkala photo
Flora and fauna
The whole animal world the waters of the Caspian Sea can be conditionally divided into the following groups:
- The first group consists of the descendants of ancient organisms: representatives of herring (pusanok, Volga, Kessler and Brazhnikovskaya herring); representatives of the Caspian gobies (golovach, pugolovka, Berga, Ber, Knipovich and bubyr); sprat; a large number of crustaceans; some types of molluscs.
- The second group includes representatives of the fauna that entered the sea from the north in the post-glacial era of desalination of the reservoir: seal; fish species: perch, carp, nelma, white fish and brown trout; some representatives of crustaceans: sea cockroaches, mysida crustaceans and others.
- The third group includes the species that got into the Caspian from the Mediterranean Sea: the following fish species: singil, flounder and needle fish; representatives of molluscs; representatives of crustaceans: shrimps, amphipods, crabs.
- The fourth group includes representatives of freshwater fish that entered the Caspian Sea from fresh rivers: stellate sturgeon, beluga, sturgeon, Caspian vimba, red-lipped asp, barbel, pike perch, catfish.
sturgeon photo
The water area of \u200b\u200bthe Caspian Sea is the main and main habitat of sturgeon representatives on the entire planet. Almost 80% of all sturgeon in the world live in the sea. Sharks and various predatory fish, which carry any danger to humans, do not live in this reservoir.
Flora of the Caspian Sea is represented by more than 700 species of lower plants (phytoplankton), as well as 5 species of higher ones (spiral and sea ruppies, crested pondweed, zostera, sea naiad). Various water birds can be found here. Some of them come here for wintering from the north (sandpipers, loons, gulls, geese, swans, ducks, geese), some come from the south for nesting (eagles).
Characteristic
Let's get acquainted with the main characteristics of the Caspian Sea:
- The length from north to south was approximately 1200 km;
- The width of the basin from west to east is approximately 200- 435 km;
- The total area of \u200b\u200bthe Caspian Sea is approximately 390000 km2;
- The volume of sea water is 78000 km3.
- The maximum sea depth is about 1025m.
- Salinity of water is up to 13.2% on average.
Sea level is below the level of the World Ocean. The North of the Caspian Sea is characterized by a continental climate. The middle Caspian Sea is characterized by a temperate climate. The southern part of the sea is characterized by a subtropical climate. In winter, the average temperature in the north varies from 8 to 10 degrees below zero, and in the south from 8 to 10 degrees of heat. In summer, the average temperature in the north is 24-25 degrees above zero, and in the south it is 26-27 degrees.
Caspian Sea. birds photo
- To this day, scientists are arguing: what status to give the Caspian Sea or lake? After all, this reservoir is closed and endless. At the same time, this reservoir predominates in size over some other seas.
- The bottom at the deepest point is separated from the water surface of the Caspian Sea by a distance of more than a kilometer. In the Caspian, the water level is unstable and tends to decrease.
- This reservoir had about 70 names that were given to it by different tribes and peoples living on the banks.
- There is a scientific theory that the Caspian and Black Seas were combined into one sea in ancient times.
- The Volga River supplies the Caspian with most of the river water.
- Since the Caspian is the main habitat of the sturgeon fish on the planet, most of the black caviar is produced here worldwide.
- The waters of the Caspian reservoir are constantly renewed every 250 years. The name of the reservoir, according to legends, comes from the name of the tribe that lived on its shores.
- The Caspian Sea area exceeds the area of \u200b\u200bJapan and slightly less than the area of \u200b\u200bGermany.
- If this reservoir is considered a lake: it will take the third deepest in the world, after Lake Baikal and Tanganyika. Also, the Caspian is the largest lake on the planet.
- The Caspian Sea is very rich in natural resources... Oil, gas, limestone, salt, clay, stones and sand are mined here.
- The Caspian Sea has recently faced the following environmental problems: Sea pollution. Oil is the main pollutant of the sea, suppressing the development of phytoplankton and phytobenthos. In addition to oil, phenols and heavy metals enter the Caspian. All this leads to a decrease in oxygen production, as a result, a large number of fish and other organisms die. Also pollution leads to disease of living organisms in the sea. Poaching is one of the main reasons for the sharp decline in the sturgeon catch. Changes in natural biogeochemical cycles. Construction on the Volga deprives fish of their natural habitats.
- The Caspian Sea is a very important site in the field of shipping and economics. This reservoir is completely closed and isolated from the world's oceans. This is the distinctive uniqueness of the Caspian.
The Caspian Sea is inland and is located in an extensive continental depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows us to call it a lake, but it has all the features of the sea, since in past geological eras it had connections with the ocean.
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 \u200b\u200babout 3.5 million km2. The nature of the landscapes, climatic conditions and types of rivers are different. Despite its vastness, only 62.6% of its area falls on waste areas; about 26.1% - for closed drainage. The area of \u200b\u200bthe 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 bank does not have a single river reaching the sea at all). 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 Russia's economy is located in the basin of this river, and this undoubtedly determines many other features of the Caspian Sea waters), as well as the Kura River , Zhaiyk (Ural), Terek, Sulak, Samur.
Physically and geographically and by nature, the sea is divided into three parts: northern, middle and southern. The conventional boundary between the northern and middle parts runs along the line of the Chechen island - Cape Tyub-Karagan, between the middle and southern - along the line of Zhiloy Island - Cape Kuuli.
The shelf of the Caspian Sea is, on average, limited to a depth of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at about 500–600 m depth, 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, maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom relief is complicated by the presence of banks, islands, grooves.
The middle part of the sea is a separate basin, the area of \u200b\u200bthe maximum depths of which - Derbent - is shifted to the western coast. 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 Absheron threshold, which is a continuation. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum depth of 1025 m for the sea is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.
The shores of the Caspian Sea are 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 - Tyuleniy, Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islets and channels, which often change their position. Many small islands and banks 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, the Absheron Peninsula is located. To the east of it are the islands and banks of the Apsheron archipelago, of which the largest is Zhiloy Island. The eastern coast of the Middle Caspian is more indented; the Kazakh Gulf with the Kenderli Bay and several capes stand out here. The largest bay on this coast is.
The islands of the Baku archipelago are located to the south of the Absheron Peninsula. The origin of these islands, as well as some banks off the eastern coast of the southern part of the sea, is associated with the activity of underwater mud volcanoes lying on the bottom of the sea. On the eastern coast there are large bays Turkmenbashy and Turkmensky, and near the island of Ogurchinsky.
One of the most striking phenomena in the Caspian 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) over the sea level, the amplitude of its fluctuations was almost 4 m, from –25.3 m in the eighties of the XIX 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 was close to this mark for almost a century, this level position was considered as a mean annual or secular level. In 1930, the level began to decline rapidly. Already by 1941, it dropped by almost 2 m. This led to the drying up of vast coastal bottom areas. A decrease in the level, with its small fluctuations (short-term insignificant level rises in 1946-1948 and 1956-1958), continued until 1977 and reached -29.02 m, that is, the level took the lowest position in the last 200 years.
In 1978, contrary to all forecasts, the sea level began to rise. As of 1994, the level of the Caspian Sea was at -26.5 m, that is, in 16 years the level rose by more than 2 m. The rate of this rise is 15 cm per year. The increase in the level in some years was higher, and in 1991 it reached 39 cm.
The general fluctuations in the level of the Caspian Sea are superimposed on its seasonal changes, the average long-term of which reaches 40 cm, as well as surges. The latter are especially pronounced in the North Caspian. The northwestern coast is characterized by large surges created by the prevailing storms of the eastern and southeastern directions, especially during the cold season. A number of large (more than 1.5-3 m) surges have been observed here over the past decades. An especially 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 water area.
Climate... The Caspian Sea is located in the temperate and subtropical. Climatic conditions change in the meridional direction, since the sea stretches for almost 1200 km from north to south.
In the Caspian region, various circulation systems interact, however, during the year, the winds of the eastern points prevail (the influence of the Asian maximum). The position in rather low latitudes provides a positive balance of heat inflow, therefore the Caspian Sea serves as a source of heat and moisture for most of the year for those passing by. The average annual in the northern part of the sea is 8–10 ° С, in the middle - 11–14 ° С, in the southern part - 15–17 ° С. However, in the northernmost regions of the sea, the average January temperature is from –7 to –10 ° С, and the minimum during invasions is up to –30 ° С, which determines the formation of the ice cover. In summer, the entire region under consideration is dominated by rather high temperatures - 24–26 ° С. Thus, the North Caspian is subject to the most drastic temperature fluctuations.
The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, and most of it falls on the cold season of the year (from October to March). However, the North Caspian Sea differs in this respect from the rest of the basin: here the average annual precipitation is less (for the western part, only 137 mm), and the seasonal distribution is more even (10–18 mm per month). In general, we can talk about proximity to arid.
Water temperature... Distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, nature, isolation) have a certain impact on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be regarded as homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and South Caspian, surface and deep masses can be distinguished, separated by a transitional layer. In the North Caspian and in the surface layers of the Middle and South Caspian, the water temperature varies over a wide range. In winter, temperatures change from north to south from less than 2 to 10 ° С, the water temperature near the western coast is 1–2 ° С higher than that of the east, in the open sea the temperature is higher than at the coasts: by 2–3 ° С in the middle part and by 3-4 ° С in the southern part of the sea. In winter, the temperature distribution is more uniform with depth, which is facilitated by the winter vertical circulation. In moderate and severe winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing point.
In summer, the temperature changes 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 North Caspian. The zone of distribution of the lowest temperatures is adjacent to the eastern coast. This is due to the rise to the surface of cold deep waters. Temperatures are also relatively low in the poorly warmed deep-water central part. In the open areas of the sea in late May – early June, a layer of temperature jump begins, which is most pronounced in August. Most often it is located between 20 and 30 m in the middle part of the sea and 30 and 40 m in the south. In the middle part of the sea, as a result of the drive off the east 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 and 5.8–5.9 ° C in the southern part.
Salinity... Salinity values \u200b\u200bare determined by such factors as river runoff, water dynamics, which mainly includes wind and gradient currents, the resulting water exchange between the western and eastern parts of the North Caspian and between the North and Middle Caspian, bottom topography, which determines the location of waters with different, mainly along isobaths, evaporation, providing a shortage of fresh water and the inflow of more saline water. These factors collectively affect seasonal differences in salinity.
The North Caspian can be seen as a 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. In this case, the horizontal salinity gradients can reach 1 ‰ per 1 km.
The eastern part of the North Caspian is characterized by a more homogeneous salinity field, since most of the river and sea (Middle Caspian) waters enter this sea area in a transformed form.
According to the values \u200b\u200bof the horizontal salinity gradients, it is possible to distinguish in the western part of the North Caspian a 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, with runoff playing a decisive role. The intensification of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated water arriving in summer from the seaside is 10–15 ° C higher than that of the bottom water.
In the deep-water basins of the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5 ‰. The largest difference between the maximum and minimum salinity was noted in the Apsheron sill area, where it is 1.6 ‰ in the surface layer and 2.1 ‰ at the 5 m horizon.
The decrease in salinity along the western coast of the South Caspian in the 0–20 m layer is caused by the Kura river runoff. The influence of the Kura runoff decreases with depth, at the horizons of 40–70 m the range of salinity fluctuations is not more than 1.1 ‰. Along the entire western coast to the Apsheron Peninsula, there is a strip of desalinated waters with a salinity of 10–12.5 ‰ coming from the North Caspian.
In addition, in the South Caspian, an increase in salinity occurs when saline waters are carried out from bays and bays on the eastern shelf under the influence of southeastern winds. Later, these waters are transferred to the Middle Caspian.
In the deep layers of the Middle and South Caspian, 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 South Caspian, the upper boundary of waters with increased salinity drops to 250 m. It is obvious that in these parts of the sea vertical mixing water is difficult.
Surface water circulation... The currents in the sea are mainly wind-driven. In the western part of the North Caspian, the currents of the western and eastern quarters are most often observed, in the eastern part, southwestern and southern ones. The currents caused by the runoff of the Volga and Ural rivers are traced only within the estuarine seashore. The prevailing current velocities are 10–15 cm / s, in the open regions of the North Caspian the maximum velocities are about 30 cm / s.
In the coastal areas of the middle and southern parts of the sea, in accordance with the directions of the wind, currents of the north-west, north, south-east and south directions are observed, along the east coast currents of the east direction often take place. Along the western coast of the middle part of the sea, the most stable currents are southeastern and southern. The velocities of the currents on average are about 20–40 cm / s, the maximum ones reach 50–80 cm / s. Other types of currents also play a significant role in the circulation of sea waters: gradient, seiche, inertial.
Ice formation... The North Caspian is covered with ice annually in November, the area of \u200b\u200bthe freezing part of the water area depends on the severity of winter: in severe winters, the entire North Caspian is covered with ice, in soft ice it is kept within the 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, ice is of local origin, on the western coast, it is most often brought from the northern part of the sea. In severe winters near the eastern coast of the middle part of the sea, shallow bays freeze, near the coast, banks and fast ice form, and near the western coast, drifting ice in abnormally cold winters extends to the Absheron Peninsula. The disappearance of the 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 regularities.
The central part of the North Caspian is characterized by a fairly uniform oxygen distribution. An increased oxygen content is found in the areas of the pre-estuarine seaside of the Volga River, and a decreased one in the southwestern part of the North Caspian.
In the Middle and South Caspian, the highest oxygen concentrations are confined to coastal shallow areas and pre-estuarine 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 regularity remains in all seasons - a decrease in oxygen concentration with depth.
Due to the autumn-winter cooling, the density of the waters of the North Caspian increases to a value at which it becomes possible for the 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 course and the seasonal ratio of production and destruction processes taking place in the sea.
In spring, the production of oxygen in the process of photosynthesis very significantly overlaps the decrease in oxygen caused by a decrease in its solubility with an increase in water temperature in spring.
In the areas of estuarine seaside rivers feeding the Caspian Sea, in 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 zones of mixing of sea and river waters.
In summer, due to significant warming up and activation of photosynthesis processes, the leading factors in the formation of oxygen regime in surface waters are photosynthetic processes, in bottom waters - biochemical oxygen consumption by bottom sediments.
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 rapidly consumed with a minimum supply of it to the lower layers of the sea, as a result of which an oxygen deficiency zone forms in the North Caspian. Intensive photosynthesis in open waters of deep-water areas of the Middle and South Caspian Sea covers the upper 25-meter layer, where oxygen saturation is more than 120%.
In autumn, in the well-aerated shallow-water regions of the Northern, Middle and Southern Caspian, 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 regularities:
- high concentrations of biogenic substances are characteristic of the areas of the estuarine seasides of rivers feeding the sea and shallow areas of the sea, subject to active anthropogenic influence (Baku Bay, Turkmenbashy Bay, waters adjacent to Makhachkala, Fort-Shevchenko, etc.);
- The North 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 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 areas of the Middle and South Caspian, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.
The dynamics of nutrient concentrations throughout the year in the Caspian Sea is influenced by such factors as seasonal fluctuations in nutrient runoff in the sea, seasonal ratio of production and destruction processes, the intensity of exchange between soil and water mass, ice conditions in the North Caspian in winter, winter processes. vertical circulation in deep sea areas.
In winter, a significant water area of \u200b\u200bthe Northern Caspian is covered with ice, but biochemical processes are actively developing in sub-ice water and in ice. The ice of the Northern Caspian, being a kind of accumulator of nutrients, transforms these substances entering the sea from and from the atmosphere.
As a result of the winter vertical circulation of waters in the deep-water areas of the Middle and South Caspian in the cold season, the active layer of the sea is enriched with nutrients due to their supply from the underlying layers.
For the waters of the Northern Caspian, spring is characterized by the 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 significant water area of \u200b\u200bthe Northern Caspian during floods, are due to intensive washing by river waters.
In the spring season, in the area of \u200b\u200bwater exchange between the North and Middle Caspian in the subsurface layer, with the maximum oxygen content, the phosphate content is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.
In the South Caspian, the distribution of nutrients in spring is basically similar to their distribution in the Middle Caspian.
In the summertime, redistribution of various forms of biogenic compounds is found in the waters of the Northern Caspian. Here, the content of ammonium nitrogen and nitrates significantly decreases, at the same time there is a slight increase in the concentration of phosphates and nitrites and a rather significant increase in the concentration of silicon. In the Middle and South Caspian, the concentration of phosphates decreased due to their consumption during photosynthesis and the difficulty of water exchange with the deep-water accumulation zone.
In autumn in the Caspian Sea, due to the cessation of the 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 produced on the shelf of the Caspian Sea.
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 of oil equivalent (of which 132 million tons of oil and 78 billion cubic meters of gas), on the shelf of the North Caspian - 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 products of its processing during extraction, transportation and use reach 2% of the total volume.
The main sources of pollutants, including oil products, into the Caspian Sea are the outflow with river runoff, discharge of untreated industrial and agricultural wastewater, municipal wastewater from cities and villages 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. Places of entry of pollutants with river runoff are 90% concentrated in the North Caspian, industrial ones are mainly confined to the area of \u200b\u200bthe Absheron Peninsula, and increased oil pollution of the South Caspian is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud) in the zone oil and gas structures.
From the territory of Russia, about 55 thousand tons of oil products are annually supplied to the North Caspian, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.
Thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange, threatens the death of the hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg / l, for phytoplankton - 0.1 mg / l.
The development of oil and gas resources of the bottom of the Caspian Sea, the projected reserves of which are estimated at 12-15 billion tons of standard fuel, in the coming decades will become the main factor of anthropogenic pressure on the ecosystem of the sea.
Caspian autochthonous fauna... The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, molluscs, etc.
Arctic species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire fauna of the Caspian Sea (mysids, sea cockroach, white fish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna is made up of crustaceans (71.4%), which easily tolerate desalination and live at great depths of the Middle and South Caspian (from 200 to 700 m), since the lowest water temperatures are kept 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 mithielastr mollusk penetrated here, later 2 types of shrimp (with mullets, upon acclimatization), 2 types of mullets and flounder. Some species entered the Caspian after the opening of the Volga-Don channel. Mediterranean species play an essential role in the food supply for fish in the Caspian Sea.
Freshwater fauna (228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, carp, as well as rotifers).
Marine species... These are ciliates (386 forms), 2 types of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalve molluscs (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most original brackish water bodies of the planet.
The Caspian Sea provides more than 80% of the world's sturgeon catches, the bulk of which is in the North Caspian.
To increase catches of sturgeon, which sharply decreased during the years of falling sea level, a set of measures is being implemented. Among them - a complete ban on fishing for sturgeon in the sea and its regulation in rivers, an increase in the industrial breeding of sturgeon.
