The problem of introduction of alien species in ecology is not new. In recent years, interest in this problem has increased dramatically, especially in the ecology of freshwater reservoirs and coastal zones of the seas, which is caused by the gigantic costs of combating the consequences of invasions of new species.
The purpose of the work is to consider the situation with invasive species in the Black and Azov Seas. This is important because these seas have repeatedly served as transit water bodies during the spread of new species to the Caspian and Aral Seas.
A number of environmental explosions associated with invaders have already occurred in the Black Sea. The last and best known example is Mnemiopsisleidyi (Ctenophora). The successful development of the Black and Azov Seas by the settlers is not accidental. Like most non-saline seas, the Black Sea is characterized by reduced biodiversity and therefore less resistance to invasion by alien species. The huge specific catchment of the Black Sea (it is almost 5 times the area of the sea), the high population density in the catchment, together with the intensive use of natural resources, lead to accelerated destabilization of the sea ecosystem, which also, in turn, contributes to the success of the invaders. The intensity of navigation in the Black Sea is growing: for example, in 1938, 4,500 ships passed through the Bosphorus Strait (the average tonnage of a vessel is 7,500 tons), in 1985 - 24,100 (105,500 tons), in 1996 - 49,952 (156,057 tons).
Today, the study of invasive species of the Azov-Black Sea basin is important for scientists, because only by thoroughly studying this phenomenon can one stabilize the situation, preserve native species and acclimatize fish species of commercial importance.
The Black and Azov Seas play an important role in the economic life of the Crimea. The Black Sea is the warmest in our country. The temperature of sea water (on the surface) near the South Coast is the lowest in February - March, from 6 to 8 °; in July - September it is on average above 20 °. The water temperature in summer, especially in the coastal zone, fluctuates depending on the winds due to the warm surface layer being driven away by the wind and the deep, colder layers of water rising.
The salinity of the Black Sea, desalinated by powerful rivers (Danube, Dnieper and other, less significant), is relatively low: in the upper layers - 17--18‰. The water of the Mediterranean Sea has a salinity of up to 39‰. The lighter (due to lower salinity) upper layers of the Black Sea through narrow straits - the Bosporus and the Dardanelles merge into the Mediterranean Sea. The deeper, heavier waters of the Sea of Marmara are moving back.
The Black Sea is the deepest of the seas in the European part of our country. In the central part of the basin, the depths reach more than 2200 meters. At a depth of 200 m and below, oxygen almost does not penetrate, and there the water is highly saturated with hydrogen sulfide.
The presence in the Black Sea (deeper than 200 m) of a huge thickness of water that is denser and more saline, saturated with hydrogen sulfide, until recently led to “the idea of the poverty of organic life in the Black Sea and, as a result, the low value of even the surface layer in terms of commercial use. Hydrological studies by Soviet scientists refuted this misconception about the Black Sea1. It turned out that it is not only not poor in nutrients and plankton, but even much richer than the Mediterranean Sea. Studying the marine fauna, Soviet biologists showed that some fish that were considered rare for the Black Sea are widespread here. These include sprat (small herring fish), bonito (from the mackerel family) and huge tuna fish. Although bonito and tuna migrate to the Mediterranean for the winter, they also breed profusely in the Black Sea. Sprat is common in the open waters of the Black Sea and serves as the main food for dolphins.
The fish resources of the open waters of the Black Sea are extremely large, but they are still far from sufficiently developed.
Commercial fish include beluga, sturgeon, stellate sturgeon, herring, gobies, sprat, anchovy (Black Sea anchovy), Azov anchovy, mullet, horse mackerel, red mullet, flounder, mackerel, bonito, garfish, sea bass, stingray, atherina, crucian carp, etc. In addition, there are some species of fish that have no commercial value.
Anchovy, Azov anchovy, mullet, horse mackerel, beluga, flounder, mackerel, herring, and bonito play the main role in the fisheries of the Crimea.
Compared to the Sea of Azov, the Black Sea is poorer in food, so fish come here mainly in winter to warm themselves in its warm waters. In the spring, huge shoals of fish - anchovies, herring, slats, red mullets, mullets, mackerels, etc. - quickly move to spawn through the Kerch Strait into the Sea of \u200b\u200bAzov. Here on the rich "fish pasture" they remain until autumn, and for the winter they return to the Black Sea waters again. The fish goes through the Kerch Strait from September to November. The autumn fishing season is longer than the spring season, as the fish do not quickly leave the Sea of Azov, their main food base.
During the fishing season in the Kerch Strait, several times more fish are caught than in all fishing areas of Crimea taken together. The main commercial fish in the Kerch Strait are anchovy and herring.
Dolphins are also of commercial importance in the Black Sea. Of these, dolphins are especially common here - the common dolphin and bottlenose dolphin. The herd of dolphins in the Black Sea is estimated at more than half a million heads.
The Sea of \u200b\u200bAzov is the smallest and shallowest of our seas (depth does not exceed 15 m); the water in it is heavily desalinated by the Don and other rivers. In winter, the sea is covered with ice.
In summer, the water of the Sea of Azov, due to its shallowness, mixes well and warms up strongly, reaching 29--31 ° on the surface in July. These conditions favor the development of organic life. The Sea of Azov is one of the first places in the world in terms of its productivity and richness of flora and fauna. It is unusually saturated with plankton, mollusks and algae. The development of planktonic algae in the summer during the flowering period reaches such proportions that the sea literally “blooms” and the water turns greenish or greenish-brown. The amount of algae at this time is about 270 g per 1 m3 of water. The benthic fauna of the sea is also abundant, reaching an average of 400 g per 1 m2 in autumn.
The richness of organic matter (which serves as food for fish) contributes to the huge distribution of fish in the Sea of Azov. There are over 100 species of fish here. Commercial value in the Sea of Azov, the mouths of the Kuban and the Don are mainly pike perch, bream, carp, stellate sturgeon, sturgeon, herring. Marine fish are also common - mullet, flounder, anchovy and others.
The Black and Azov Seas play an important role in the economic life of the Crimea, not only due to their natural resources, but also as important communication routes with other areas of the Azov-Black Sea basin.
The answer to the question - what is the difference between the Sea of \u200b\u200bAzov and the Black Sea - is obvious. In the same way that all seas differ from each other:
But let's try to make a comparative analysis of them, because these are not some distant seas, but ours, relatives, which every Russian has visited at least once in his life.
The area of the Black Sea is 422 thousand km 2, the Azov Sea is much smaller - about 39 thousand. The maximum depth of the Black Sea is more than 2 kilometers. And Azovskoye ranks first in this indicator. Only not in the list of the deepest, but in the list of the shallowest seas of our planet, its maximum depth is only 13.5 meters. At the bottom of the Sea of Azov, you can only hide a four-story house, and even then the television antennas will stick out above the surface.
The difference between the Sea of \u200b\u200bAzov from the Black Sea and in the salinity of the water. The salinity of the Black Sea is about 18 ppm, while in the Azov this figure is only 11 (in the past, before the creation of the Tsimlyansky hydroelectric complex on the Don, this figure was even lower). Geographically, the Sea of Azov is the northeastern bay of the Black Sea. But historically it just so happened that, despite its relatively small size and depth, it bears the proud name of “sea”, while many sea or ocean bays, which have much larger “dimensions” in all respects, have not been awarded this title. For example, the Great Australian Bight.
According to the most common hypothesis, in relatively recent times (about 5.5 thousand years BC), the Black Sea in the modern sense did not exist. In its place was a huge freshwater lake that had no connection with the Mediterranean Sea, and the water level in it was about 100 meters lower than the current one. The Sea of \u200b\u200bAzov did not exist, not only in the "modern sense", it did not exist at all, and the Don River did not flow into the current Taganrog Bay, but directly into this lake approximately in the area of \u200b\u200bthe current Kerch Strait. This situation is due to the fact that during the Ice Age, gigantic masses of water were concentrated in blocks of ice that covered vast territories. Then the climate changed, the glaciers melted, and the level of the oceans rose.
Masses of salt water rushed into the freshwater lake through the formed Bosphorus Strait. The level of the newly created sea was equal to the ocean level, and in place of a shallow depression in the lower reaches of the Don, the modern Sea of Azov was formed. That is, it is not only the shallowest, but also the youngest sea in the world. Huge territories (including developed by people) were flooded. Perhaps the memory of this cataclysm has been preserved for centuries and became the basis of the legend of the "Flood".
The differences are not only in size, depth and salinity. Although these reservoirs are nearby, the Black Sea coast is interesting in that it includes zones with different climates. If the Sea of Azov lies entirely in the temperate climate, then the Black Sea, due to the presence of mountains on the coast, in some places has a subtropical climate. These are the southern coast of Crimea (sheltered from the northern winds by the Crimean mountains), the Black Sea coast of the Caucasus and northeast Turkey. It is interesting that most of the Turkish coast (this is the southern coast of the Black Sea) belongs to the region with a temperate climate, while some areas much further north belong to the subtropics.
And, finally, the main difference is the presence in the depths of the Black Sea of a hydrogen sulfide layer (sulfur and hydrogen compounds dissolved in sea water). It starts at a depth of about 150-200 meters, and the entire volume of water below this mark is not suitable for the existence of any living organisms, except for some anaerobic bacteria. According to estimates, there are about 3.1 billion tons of hydrogen sulfide in the sea. There is no consensus on the causes of the hydrogen sulfide layer. According to recent studies, the depths of the Black Sea contain not only huge reserves of hydrogen sulfide, but also methane, but nothing of the kind is observed in the Sea of \u200b\u200bAzov.
What is the difference between the Sea of Azov and the Black Sea in terms of the distribution of living organisms? Yes, almost none. However, their common animal and plant life is very different from the Mediterranean. This is due to the fact that both seas are generally located north of the Mediterranean and have lower salinity. And the presence of a hydrogen sulfide layer makes its own adjustments to the distribution of plants and fish migration.
In the basin of the Black and Azov Seas, there are significantly fewer species of marine life than in the Mediterranean Sea. In general, there are no corals, starfish, sea urchins, octopus, squid and cuttlefish. The Black Sea katran (a subspecies of a small shark) lives only in the Black Sea, only occasionally entering the southern regions of the Sea of Azov. However, the Sea of Azov, due to its shallow water (after all, the whole sea is one large shelf, which is so loved by most commercial fish), has record levels of fish productivity. The Caspian Sea, which occupies the second position in the ranking, is 6.5 times behind the Sea of Azov, the Black Sea - 40 times (the presence of a hydrogen sulfide layer affects), and the Mediterranean - 160 times!
| Black Sea | Sea of Azov | ||
| Square | 422 thousand sq. km | 39 thousand sq. km | |
| The volume of water contained in the sea | 555 thousand cubic meters km | 256 cu. km | |
| Depth | Medium | 1240 m | 7.5 m |
| Maximum | 2210 m | 13.5 m | |
| Salinity | 18 ppm | About 11 ppm, there is slight seasonal fluctuation | |
| Education time | About 7.5 thousand years ago, before that it existed as an isolated freshwater lake | About 7.5 thousand years ago, before that, in its place there was a vast shallow lowland | |
| Flora and fauna | The types of living organisms do not differ significantly, but in terms of the number of fish per square kilometer, the Sea of \u200b\u200bAzov exceeds the Black Sea by 40 times | ||
The Black, Azov and Caspian Seas are all that remains of the ancient Tethys Ocean. The Black Sea coast is the northernmost subtropics in the world, where nature is amazing in beauty, the healing climate, the warm sea and mineral water springs. The Caspian is sturgeons and oil. It was there that the film "White Sun of the Desert" was filmed.
The Black Sea is the Mediterranean Sea of the Atlantic Ocean, it is located between Europe and Asia Minor. The sea washes the shores of Russia, Ukraine, Georgia, Romania, Bulgaria and Turkey. In the northeast, the Black Sea is connected by the Kerch Strait with the Sea of Azov, in the southwest by the Bosphorus Strait - with the Sea of Marmara and further through the Dardanelles with the Aegean and Mediterranean Seas. The length of the Black Sea is 1150 km, the width at its narrowest point is 265 km, the area is 420.3 thousand km2, the volume of water is 547 thousand km3, the average depth is 1300 m. The Danube, Dniester, Southern Bug, Dnieper, Rioni rivers flow into the Black Sea and etc.
The shores of the Black Sea are scarcely indented; the only large peninsula is Krymsiy. The total length of the coastline is 3400 km. Some sections of the coast have their own names, the Southern coast of Crimea, the Black Sea coast of the Caucasus, in Turkey - the Rumeli coast, the Anatolian coast. In the west and northwest, the shores are low, in some places steep, estuary. The northern shores of the Crimean peninsula are low, the southern ones are mountainous. In the east and south, the mountains of the Greater and Lesser Caucasus and the Pontic Mountains come close to the sea: small areas of low-lying shores are formed here by river deltas protruding into the sea near Capes Pitsunda and Kodor in Georgia, Jiva and Bafra in Eastern Anatolia. The largest bays are: Karkinitsy, Kalamitsky, Dnepro-Bugasky, Dniester, Varna, Burgas near the northwestern and western shores, Sinopsky and Samsunsky - at the south. There are few islands; the most significant are Berezan and Serpentine.
The formation of the Black Sea basin is associated with the residual basin of the ancient Tethys Ocean. The contours of the modern basin were outlined in the Oligocene, when uplifts in Asia Minor gradually separated it and the Caspian Sea from the ocean. In the Upper Miocene, the Black Sea was part of a chain of desalinated sea-lakes, the so-called Sarmatian basin. After a short-term connection with the Mediterranean Sea, a desalinated Pontic Lake was formed. In the plitson, the Black Sea separated from the Caspian. During the Middle and Upper Pliocene, it was probably a desalinated flowing lake. In the middle of the Pleistocene, for a short time, the Black Sea was twice connected with the Mediterranean and had more saline waters. During the last glaciation, the strongly desalinated Novoeuxinskoye Lake-Sea was formed, which 6-7 thousand years ago connected with the Mediterranean Sea through the straits, giving rise to the modern Black Sea. Tectonic activity in this area is manifested in earthquakes, the epicenters of which are located along the edges of the depression and in adjacent areas. The coastal zone is dominated by coarse-grained deposits: jackdaws, gravel, sands; as they move away from the coast, they are replaced by fine-grained sands.
During the year, the Black Sea is under the influence of mainly continental polar and marine polar and tropical air masses. In winter, air masses carry strong northerly and northeasterly winds, lower temperatures and clear precipitation; These winds reach especially great strength in the region of Novorossiysk, where they are called bora.
The Caspian Sea is the world's largest closed body of water, located on the territory of Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran.
The Caspian is sometimes incorrectly called a lake, but in terms of its size, the nature of the processes and the history of development, it is a sea. The sea got its name from the ancient tribes of the Caspians, who lived in the eastern part of the Caucasus. Other historical names - Hyrkan, Khvalyn, Khazar - are also named after the ancient peoples who lived on its shores. The Caspian Sea is stretched from north to south for almost 1200 km, the average width is 320 km. The area is about 371 thousand km2; the level is 28.5 m below the level of the Pacific Ocean. There are about 50 islands in the sea, including Tyuleniy, Artem and Zhiloy. The Volga, Emba, Ural flow into the northern part of the sea. A small runoff is given by the rivers of the Iranian coast.
According to the nature of the relief and hydrological features, the Caspian Sea is usually divided into the North, Middle and South Caspian. The northern Caspian is the most accumulative water area with a series of banks and islands. The so-called Mangyshlak threshold separates the Northern Caspian from the Middle.
The weather over the Caspian Sea is determined by Asian (in winter) and Azores (in summer) air masses. Characteristic features of the climate are: significant continentality, the predominance of anticyclones, dry winds, severe frosty winters, sharp temperature changes throughout the year, poverty of precipitation (except for the southwest).
The Sea of Azov is a Mediterranean Sea in the Atlantic Ocean basin, connected by the Kerch Strait to the Black Sea. The ancient Greek name of the sea is Meotian Lake, the ancient Russian name is the Sourozh Sea. The area is 38 thousand km2, the average depth is 8 m, the maximum depth is 14 m. The shores are mostly low-lying, composed of sandy-shell deposits, only in the south they are steep. A characteristic feature of the shores of the Sea of Azov are alluvial sand spits (Arabatskaya Strelka, Fedotova, Berdyanskaya, Yeiskaya, etc.), which separate a number of shallow bays (Sivish, Obitochny, etc.) and estuaries from the sea.
The climate in the area of the Sea of Azov is continental. Winter is cold, relatively dry, with strong northeast and east winds. The average winter temperature is down to -6 Celsius. Summer is hot, relatively humid, with westerly winds, the average temperature in July is 24.5 degrees. Precipitation falls up to 500 mm per year. The Sea of Azov is distinguished by exceptional biological productivity.
In the XV century. The Black and Azov Seas completely came under the control of Ottoman Turkey. In the Northern Black Sea region, the vassal state of the Ottomans, the Crimean Khanate, was established. The Russian tsars repeatedly tried to “recapture” these territories. But it is interesting that these attempts found a warm response from ordinary Cossacks. One of the brightest episodes of Russian history was the Sea of Azov. In 1637, the Cossacks (formally they were not Russian subjects) took the Turkish fortress of Azov, the “key” to ancient Meotida, as the Greeks called these places.
The Cossacks did not receive support from the tsar, since Moscow did not want to quarrel with Turkey at that time, and it did not have the opportunity. In 1641, the Cossacks withstood the siege of Azov, but in the summer of 1642 they were forced to leave it, destroying the fortifications. This unprecedented event was immortalized in the form of a poetic report to Tsar Mikhail Fedorovich - "The Tale of the Azov Siege of the Don Cossacks."
Black, Caspian and Azov Seas updated: May 21, 2017 by: site
Our Russia is washed by seas and oceans on all sides, it has seventeen exits to the high water, which makes it simply a unique world power. Some seas are located in the southern part of the country and belong to the resort area, while the northern Russian waters abound in fish and other commercial species of marine life. Most often, our compatriots visit the Black Sea and the Sea of \u200b\u200bAzov, which we will compare today.
The Sea of Azov is located in the southern part of Russia, it is a semi-enclosed type of sea and is related to the Atlantic Ocean basin. The sea is connected with the ocean by a chain of straits and various seas. The salinity of the water is provided by the influx of water masses from the Black Sea, but for the most part they are diluted by river runoff. In recent years, people have been active on the coast of the sea, so the inflow of fresh water has decreased significantly. This fact affected the population of marine life.
The Black Sea is an inland sea of the Atlantic Ocean, it is connected with the Mediterranean and Aegean Seas by various straits. The water area has long been inhabited by people, now Russia, Turkey, Georgia and Bulgaria have access to the waters of the Black Sea.
One of the features of the water area is the impossibility of the existence of life at great depths. This is due to the release of hydrogen sulfide at a depth of more than one hundred and fifty meters, in addition, this feature does not allow different layers of water to mix with each other. Therefore, large temperature differences are observed in the Black Sea at shallow depths.
In ancient times, the Sea of Azov did not exist, this territory had a swampy character. Scientists believe that the water area was formed approximately five thousand six hundred years BC as a result of the Black Sea flood. This version was expressed by ancient philosophers and is supported by modern hydrologists and oceanologists.
During its existence, the Sea of \u200b\u200bAzov has changed its name many times. According to them, you can even trace the history of the development of the reservoir itself, because the ancient Greeks attributed it to lakes, and the Romans to swamps. Although the Scythians already used the word "sea" in their name of the water area.
Scientists have counted more than fifty different names. Every nation that has chosen the shores of the Sea of \u200b\u200bAzov sought to give it a new name. Only in the eighteenth century did the familiar word "Azov" become fixed in the Russian language. Although back in the first century AD, some Greek scholars mentioned a name that was close in sound to modern pronunciation.
Hydrologists believe that a fresh lake has always existed on the site of today's Black Sea. It is worth noting that at that time it was the largest in the world, the filling of the water area with sea water occurred as a result of the same Black Sea flood, due to which the Sea of \u200b\u200bAzov was formed. A large flow of salt water caused a massive death of the freshwater inhabitants of the lake, which became the source of the release of hydrogen sulfide from the depths of the sea.
I would like to note that the Black Sea almost always had names close to today. It is believed that the Scythian tribes that lived on the coast called the sea "dark". The Greeks, in turn, changed the name and began to call the water area the "Inhospitable Sea". This is associated with frequent storms and the difficulties of passing the fairway. Some hydrologists hypothesize that sailors have noticed since ancient times that anchors take on a deep black color when lifted from the depths. This was the prerequisite for the name of the sea.
The Black Sea has an area of more than four hundred thousand square kilometers, the extent of the surface between the two most distant points is approximately five hundred and eighty kilometers. The volume of water in the water area is equal to five hundred and fifty cubic kilometers. The coordinates of the Black Sea lie between forty-six degrees thirty-three minutes and forty degrees fifty-six minutes north latitude and between twenty-seven degrees twenty-seven minutes and forty-one degrees forty-two minutes east longitude.
The area of the Sea of Azov is thirty-seven square kilometers, the length between the most distant points is equal to three hundred and eighty kilometers. The sea coordinates lie between 45°12′30″ and 47°17′30″ North latitude and between 33°38′ and 39°18′ East longitude.
The Black Sea and the Sea of Azov differ significantly from each other. First of all, the ordinary person is struck by differences in depths. The fact is that the depth of the Sea of \u200b\u200bAzov is constantly changing. Scientists are seriously concerned about the tendency towards shallowing of the waters of Azov. At the moment, the sea is one of the smallest in the world, and the process of shallowing is gaining momentum every year and becoming more active. According to the latest data, the average depth of the Sea of \u200b\u200bAzov is only seven meters, the deepest place in the entire water area is thirteen and a half meters.
The Black Sea is notable for its heterogeneous bottom topography. Therefore, the depth in different areas is seriously different. The maximum depth reaches two thousand meters. In the Yalta region, the average depth is five hundred meters, and this mark is already reached a few kilometers from the coast.
It's amazing how interconnected everything in our world is. This also applies to the seas. Every schoolchild knows that the Black Sea and the Sea of Azov are interconnected. It is a narrow strip of water, not exceeding four kilometers in width. The depth of the strait averages five meters.
Those who often visited the Black Sea and the Sea of Azov in Soviet times know that there is an absolutely unique place where you can see the contact of the two seas. If you arrive at Tuslova Spit, then on one side of you there will be the Sea of \u200b\u200bAzov, and on the other - the Black Sea. Tourists claim that this spit is an unusually good place to relax. There are practically no people here, and the opportunity to swim in both seas at once cannot but please unspoiled vacationers.
It should be noted that in comparison with the Sea of Azov, the waters of the Black Sea look lighter. With what it is connected scientists find it difficult to say.
The coasts of the Black and Azov Seas differ significantly from each other. Azov is represented by flat beaches with little indented relief. Most of the beaches are covered with sand, the Russian part is two hundred and fifty kilometers of the coastal strip. A feature of the coast of the Sea of Azov are reclaimed spits, they usually protrude deeply into the water area and do not exceed five kilometers in width.
The length of the Russian part of the Black Sea coast is four hundred and fifty seven kilometers. The coastal strip is slightly indented and is represented mainly by pebble beaches, which in some places are more than three hundred meters wide. The Black Sea is distinguished by a large number of islands randomly scattered throughout the water area.
The Black Sea and the Sea of \u200b\u200bAzov have a different composition of water, which affects their color. If you look at the Black Sea on a sunny day, you will see how the water takes on a deep cobalt hue. This is due to the absorption of the sun's rays of the red and orange spectrum. The Black Sea is not one of the most transparent, but nevertheless, visibility on a fine day here reaches more than seventy meters.
The waters of the Sea of \u200b\u200bAzov in calm weather have a greenish color, but the slightest wind immediately turns the water into a dirty yellow substance. This is due to the large amount of phytoplankton that flooded the sea. The fact is that shallow water with heated water is ideal for its development, which corresponds to the indicators of the Sea of \u200b\u200bAzov. It is shallow depths that affect the transparency of water, it is almost always cloudy with low visibility.
Hydrologists and oceanologists often compare the Black Sea and the Sea of Azov in terms of the richness of flora and fauna. This indicator reveals significant differences between the two areas.
At one time, the Sea of \u200b\u200bAzov had no competitors in terms of the number of fish, several large companies were engaged in catching it. In recent years, the population of marine species has declined significantly. According to oceanologists, more than one hundred and three species of fish live in the Sea of \u200b\u200bAzov. Almost all of them are commercial:
The Black Sea is considered relatively poor in terms of marine life, because at a depth, due to emissions of hydrogen sulfide, life is simply impossible. About one hundred and sixty species of fish and five hundred species of crustaceans live in the sea. But phytoplankton is represented by six dozen species, as opposed to two species in the Sea of Azov.
Despite the fact that the Black Sea and the Sea of \u200b\u200bAzov are located nearby and even have a common border, they differ significantly from each other. Some of these differences can only be determined by scientists, and some are clearly visible even to ordinary vacationers, who often prefer the coast of these seas to foreign resorts.
Despite the relatively short coastline, the southern seas are of great importance for our country. Through the Black, Azov and Caspian Seas, Russia maintains links with both countries of the near and far abroad. From the Azov-Black Sea basin through the Bosporus and Dardanelles one can directly get to the Mediterranean Sea and further to the Atlantic and Indian Oceans.
What is the uniqueness of the Black Sea?
The Black Sea is the warmest and friendliest of our seas; it does not freeze off the coast of Russia. This inland sea occupies a vast and deep flat-bottomed basin 2,000 m deep (the greatest depth is 2245 m). A characteristic feature of the sea is a small number of bays and bays and the almost complete absence of islands.
Over the long history of its existence, the Black Sea has experienced repeated ups and downs. Therefore, it is not surprising that at the bottom of the sea, marine archaeologists discover ancient cities and villages buried under a layer of silt.
A distinctive feature of the Black Sea water column is its “two-story structure”. The upper 100-meter layer of water mixes well and, accordingly, is saturated with oxygen. Deeper mixing does not occur, the waters stagnate more and more, and from 100-200 m oxygen is displaced by poisonous hydrogen sulfide gas. At a depth of 1500 m, its content reaches such a concentration that only anaerobic bacteria live here - this is practically a dead zone.
The Black Sea is not rich in fish resources compared to other Russian seas. Apparently, the influence of the hydrogen sulfide zone affects. Of the fish, there are Mediterranean species - mullet, mackerel (these are the main commercial species), as well as anchovy, horse mackerel and freshwater - pike perch, bream, ram and others. Very few migratory species have survived - sturgeon, herring. Much of this is due to sewage pollution.
Rice. 113. Novorossiysk - the largest port of Russia on the Black Sea
Novorossiysk was founded in 1839 as a military fortification on the shore of the Tsemesskaya (Novorossiysk) bay. At the end of the last century, the richest deposits of marls, raw materials for cement production, were discovered near the city, and soon 10 cement plants were operating here. During the Great Patriotic War, the hero city of Novorossiysk became the site of fierce battles: in September 1942, the front stopped on the southeastern outskirts, the city was completely destroyed. Modern Novorossiysk is the largest port in Russia with a cargo turnover of up to 40 million tons. It is the main port for the shipment of Russian oil abroad, which comes here via an oil pipeline from Western Siberia and the Volga region. Tsemes Bay is a very convenient harbor, the largest ships can enter it; but in autumn and winter there are hurricane-force winds - bora, blowing from the northeast through mountain passes.
What are the problems of the Sea of Azov?
The Sea of \u200b\u200bAzov is one of the smallest seas in the world and the shallowest: the greatest depth does not reach even 14 m, and the prevailing depths are only 5-7 m. In the eastern part of the sea on the Russian side, hundreds of meters from the coast, the depth usually does not exceed 2-4 m. In summer, the entire water column warms up to 26-28 ° C, in winter the sea freezes.
Through the narrow (only 3 km) and shallow (up to 7 m) Kerch Strait, water is exchanged with the Black Sea. For a long time, the Sea of Azov was distinguished by extraordinary productivity, being the world record holder for fish stocks per unit area. This was facilitated by the shallowness of the sea, good warming and illumination of the entire water column, excellent mixing and saturation of water with oxygen. The main commercial species were sturgeon (beluga, sturgeon, stellate sturgeon), pike perch, bream, carp, ram and herring.
With the regulation of rivers by reservoirs and high water consumption for industrial, domestic needs and irrigation, the river flow of the Don and Kuban into the sea has sharply decreased over the past 30-40 years. This caused some drop in the sea level and increased the inflow of more saline Black Sea waters. As a result, the salinity of the sea has noticeably increased and the water area suitable for the habitat of valuable commercial fish has decreased (the supply of food for many fish species has decreased). Dams have blocked the way to spawning grounds for migratory fish, and sewage discharges have sharply increased. The result was a drop in the productivity of the sea.
When did Russian merchants begin to explore the Caspian Sea?
For many centuries, the Caspian Sea served as the southern gate of the Russian state. It is known that the Eastern Slavs penetrated here as early as the 7th century, and from the 9th-10th centuries. Russian ships have already quite firmly mastered this sea basin. Russian merchants traded with the peoples who lived in the Caspian region, and even penetrated into distant countries - India, China. Tver merchant Afanasy Nikitin in 1466-1472. traveled to Persia and India. In his travel notes “Journey beyond three seas” it is written: “Behold, I wrote my sinful journey beyond three seas: the first sea is Derbent.”
By the way, the Caspian had a huge variety of names: Hyrcanian (for the Greeks), Eastern (for the Assyrians), Western (for the Chinese), Horosan (for the Arabs). In Russian chronicles, the Caspian was called the Khvalynsk, Derbent Sea. The modern name comes from the disappeared people of the Caspians (horse breeders), who once lived on the western and southwestern coasts.
With the accession of the Astrakhan Khanate in the middle of the XVI century. permanent Russian fortified settlements and fishing villages appear on the coast of the Caspian Sea. Russia firmly established itself on the Caspian Sea and traded with Persia, India and other southern countries.
Peter I, wishing to know as much as possible about the Caspian Sea, sent several expeditions there since 1714, thanks to which the first map of the sea was compiled.
Will the Caspian Sea ever disappear?
The Caspian Sea is the world's largest enclosed body of water, stretching from north to south for almost 1200 km, with an average width of 320 km.
The climate of the Russian part of the Caspian Sea is continental, with a predominance of anticyclonic conditions, dry winds and severe, frosty winters. In summer the temperature reaches +24-25°С, and in winter it drops to -10°С. The northern part of the sea is covered with ice up to 2 m thick for 2-3 months. The salinity of the water varies from 0.5 ppm at the mouth of the Volga to 14 in the southeast.
The main problem of the Caspian Sea is long-term fluctuations in its level. In 1929, it was at around 26 m below the level of the World Ocean, and by the 1970s. dropped to -28.5 m.
Since 1976, there has been a steady rise in sea level, which by 1995 reached 2.5 m and has now led to the flooding of vast areas and the destruction of sea berths, port and industrial facilities. Such changes, associated with the retreat or advance of the sea for many tens of kilometers, lead to the need to transfer fishing villages, redevelopment of coastal parts of cities. This is also the constant concern of cartographers - new maps of the coastal part of the sea need to be compiled.
What is the reason for such behavior of the Caspian Sea? Perhaps the most reliable fact is that the level of the Caspian Sea has always changed, either rising or falling. It is believed that level fluctuations are associated with both tectonic movements and long-term climatic cycles. The largest drop in the level was 34 m, and the rise in the 17th century. reached 22 m (many buildings of the city of Derbent were flooded).
Derbent is the oldest city in Russia, in the south of Dagestan. It was founded in 438 as a fortress on the northern border of Persian possessions. Its geographical position is unique: here the Caucasus Mountains are closest to the Caspian Sea, and by blocking a narrow passage along its coast, it is possible to control communication between the steppes of the North Caucasus and Transcaucasia.
Rice. 114. Derbent
Derbent is an ancient center of carpet weaving, high-quality grape wines, cognacs, canned fruits are produced here (gardens and vineyards are located in the vicinity of the city).
What is rich in the Caspian Sea?
The fish resources of the Caspian Sea are unique. In the shallow northern part of the Caspian Sea, the world's largest herd of sturgeon feeds: beluga, sturgeon, sterlet, stellate sturgeon, thorn, white salmon. (Until recently, the Caspian provided 90% of the world catch of white fish, 95% of black caviar.) Herring, sprat, bream, pike perch, roach, carp and others are also of great value.
Rich oil deposits have been discovered both on the coast and at the bottom of the sea, mainly near Azerbaijan and Turkmenistan. The Caspian coast also includes natural gas fields.
conclusions
The southern seas of Russia, each of which is distinguished by its own characteristics, are of great importance for our country, being its southern gate, large fishing and recreational areas.
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