Life in the Baltic Sea. Curonian Bay of the Baltic Sea: description, water temperature and underwater world Who lives in the Baltic Sea
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Baltic Sea
The sea is located in the center of glaciations that took place during the last ice age, when this area was completely covered with enormous masses of ice. There was practically no life here then. The formation of the reservoir and its fauna occurred 1213 thousand years ago, when it was finally freed from continental ice. Periodically, the sea either became saltier or fresher, depending on changes in its connection with the ocean. Later, melted glaciers formed a lake above ocean level. Even later, the sea waters of the North Sea, as well as its flora and fauna, penetrated here. The climate of the sea at that time was of an arctic nature; the fauna included many representatives of the Arctic, for example, harp seal, mollusk ioldia. At that time, apparently, the Baltic Sea was connected to the White Sea through Lakes Ladoga and Onega, as evidenced by some similarities between their faunas. The so-called “yoldium” phase existed for approximately 500-700 years. Then there was a strong warming and separation Baltic Sea from Northern and, as a result, new strong desalination. This phase lasted about 2200 years, but later the land subsided in the area of the straits connecting the Baltic Sea with the North Sea and the ocean, and new salinization began. The salinity of the sea then was 5-6 ppm higher than now, and the water temperature was 2-3 degrees higher than today. About three thousand years ago, the exchange of waters with the North Sea decreased again, the Baltic became somewhat desalinated, cooled and came to its modern state.
The water area of the Baltic Sea is 419 thousand km2. The sea is connected to the North Sea by the Danish Straits. It is located inside the mainland shallows, has a predominant depth of 10-40 m, a maximum depth of 470 m. The average depth of the sea is 86 m, in the Danish Straits - 7-80 m. There are four deep-sea depressions: Bornholm (maximum depth 105 m), Gdansk ( 114 m), Gotland (249 m) and Landsort (459 m). The volume of water in the Baltic Sea is 22.3 thousand km3. The main bays are: Bothnian, Finnish, Riga, Curonian and Vistula. 250 rivers flow into the Baltic Sea, the largest of which are the Neva, Daugava, Neman, Vistula and Oder. Rivers annually contribute about 500-600 km3 of continental water, so the salinity of water here ranges from 4 to 22 ppm. Heavier salty and cold waters with a salinity of 10-20 ppm accumulate in the depressions; in the upper horizon of the sea, the salinity is 6-8 ppm, in the bays - 4-5 ppm. On average, salinity is slightly higher in the western part of the sea than in the central or eastern part.
The Baltic Sea is characterized by sharp stratification of water masses, especially over great depths in summer, and this prevents vertical mixing and enrichment of deep layers with oxygen. The water temperature at the sea surface in winter is 1-3 °C away from the coast, and below zero near the coast. In summer, the temperature of the surface layers can rise to 18-20°. Ice usually forms in winter in bays and off the coast, lasting 16-45 days in the western part of the sea and up to 210 days in the east. The Volga-Baltic and White Sea-Baltic canals connect the Baltic Sea with the basins of the Caspian, Black, Azov and White Seas.
The Baltic Sea is home to 116 species of fish, of which the most commercially important are: sprat (sprat), herring, cod, flounder, bream, pike, whitefish, smelt, raw fish, lamprey, eel, salmon. In the mid-80s, the USSR fish catch here annually reached about 330 thousand tons.
Currently, the fishery resources of the Baltic Sea are distributed among all coastal countries. Russia's quota is only 50-60 thousand tons per year, including 12-15 thousand tons of herring, 30-40 thousand tons of Baltic sprat (sprat) and 3-5 thousand tons of Baltic cod.
It is very different from all its world brethren. First of all, the water salinity level in it does not exceed 7-8 percent. Moreover, we are talking about these indicators only in the southwestern part of the Baltic. In the central water area this level drops to 6 percent, and in the Gulf of Finland, Bothnia and Riga - even to 2-3 percent.
Of course, the Baltic Sea cannot be called fresh. But it is quite obvious that it differs from the salty waters of other seas and oceans (the average salinity on the planet is about 35 percent) as day and night. This factor left its mark not only on the nature of coastal areas, but also on the composition of the inhabitants of the Baltic depths.
The very low degree of salinity (especially in the northern and northwestern parts of the Baltic) has led to the fact that, along with marine fish, river fish also thrive in the Baltic Sea. The most common species are perch, bream, whitefish and grayling. But in general, freshwater inhabitants of the Baltic do not go far into the sea, preferring to stay close to water that is not at all salty. Therefore, gudgeons, roach, pike, pike perch or ruffe can be found mainly in the immediate vicinity of rivers where they flow into the Baltic Sea.
By the way, fishermen from countries with access to the Baltic (and this includes, in addition to Russia, Germany, Finland, Sweden, Poland, Lithuania, Latvia and Estonia) use this fact very competently and in certain seasons, seiners do not even have to go far to sea to return with a rich catch traditionally river fish.
However, in deep areas with saltier water, the composition of the inhabitants of the Baltic changes significantly. Here you can find cod, mackerel, many types of herring (along with sprat, it is the main fishing interest) and even flounder, gobies, eelpout and sea trout.
Back in the middle of the last century, it was believed that seals had completely disappeared from the Baltic Sea, which had been mercilessly exterminated for many years. But in last years(especially in the summer) they began to be noticed again.
This mainly happens off the coast of Sweden, Finland and Russia.
The appearance of seals in the Baltic Sea again became possible only thanks to a complete ban on hunting them and a significantly improved environmental situation.
The ringed seal lives in the Baltic. This seal got its name from the pattern on its fur - light rings with a dark frame.
Interestingly, ringed seals do not form colonies, preferring to live alone. So it’s unlikely that anyone will be able to see a whole herd of these cute animals, although occasionally they gather in small flocks. However, even in this case, Baltic seals behave separately.
By the way, Baltic seals are considered the largest of this species in the world. They can reach a size of 140 centimeters, and adult males weigh up to a hundredweight! Often, lately, they go to the beaches to take a break from being in the water for a long time.
In 2000, according to experts, about 10 thousand ringed seals lived in the Baltic. Now their number (due to the fact that seals have no natural enemies in this region) is constantly increasing and has already reached 25-30 thousand. But compared to data from a hundred years ago, this is sheer nonsense. At that time, more than 100 thousand of these cute animals lived in the Baltic Sea.
But in addition to commercial fish and harmless animals, the Baltic Sea is also home to much more dangerous creatures. The sea dragon, a small but very poisonous fish, is found here (albeit quite rarely). Her injection causes, at best, itchy skin, and at worst, paralysis, interruptions in heart function, and even death. One thing is good - it can be found much less often in the Baltic Sea than in the Black or Atlantic. Another dangerous inhabitant of the depths is the sea cat (it looks like a stingray and also has a sharp spike at the end of its tail), a poisonous snake fish.
Few people know that there are also sharks in the Baltic. Moreover, there are as many as 31 species of them, together with related cartilaginous fish! But do not be afraid - these are small sharks that are more afraid of humans than they are of them. At least that's what environmental activists say. And in Sweden they even officially banned shark fishing.
I really wanted to get acquainted with German architecture, but I decided to start in Kaliningrad so that there would be no language barrier. During the trip, it became clear that after half a century this city had lost its German appearance and became average Russian city. During our month of stay in the Kaliningrad region, we managed to visit a large number of historical places and cultural institutions. Our apartment was located next to Cathedral XIII century, where Immanuel Kant is buried. It was from this cathedral that our acquaintance with the city and region began.
Also in Kaliningrad there is an old German zoo from the late 19th century. There we were amazed by the incredibly large area, the huge number of animal species that live in good conditions. We visited the Museum of the World Ocean, the Art Gallery, and an amusement park. As for architecture, one thing really surprised me: going to a hardcore concert, where both local teams and groups from France and Canada performed, we could not imagine that the concert would take place within the walls of the Sackheim Gate. This is an architectural monument of the mid-19th century; inside it there is an art space for various informal events, exhibitions and parties. It is felt that people value the history and culture of the former city, but at the same time they are not afraid to experiment, to combine the ancient and the modern. I don’t know if it’s a coincidence, but we met extremely kind, responsive people who wanted to help. Nothing makes a city more beautiful than its people.
Small towns around Kaliningrad have retained their European flair - clean narrow streets, paving stones, small German houses. Walking around Zelenogradsk ( former city Kranz), which is located 40 minutes from Kaliningrad, we could not pass by the old water tower. It now serves as an observation tower, and inside there is the Murarium cat museum. On the promenade we were greeted by a large number of seagulls circling over the Baltic Sea. Walking along the Curonian Spit, every now and then we met wild swans and ducks. At first we walked around them very carefully, and then got used to this phenomenon.
Thousands, and maybe even more, years ago, seabirds separated from the total huge number of birds living on land. Their names are very diverse and depend on belonging to a particular order or family.
Classification
There is the following classification of seabirds:
Seabird family: description
These birds, in comparison with their other brothers belonging to other groups, are considered long-lived. In general, their life cycle has a slightly shifted time frame. For example, representatives of the marine group pair and reproduce much later than their comrades. Over the entire cycle, they have fewer chicks, but they devote relatively more time to their offspring. Life expectancy is also significantly increased. Seabirds usually nest in large colonies. Some of them live permanently in one area, others can migrate over significant distances every year, and some even travel by air around the entire Earth.
There are varieties that spend almost their entire life cycle away from the shores, in the endless waters of the oceans. And their brothers settle only on land, going to drift on the waves only for the sake of prey. However, in addition to these two opposing types, there is also a third. Its representatives spend part of their time in the coastal zone, and the rest in the waters of the seas and oceans.
As one might expect, the world of birds has not been without human intervention. People often used birds as a food source. And for experienced fishermen and experienced sailors, they served as a guide. Of course, human activity does not go unnoticed, and now many species are on the verge of extinction. Unfortunately, some exist only on the pages of the Red Book.
Birds and their structure
Specialists who have a wealth of knowledge about the characteristic features of a particular species can easily determine how its representatives feed, how they hunt, and in what area they live. The shape and length of the wings are of great importance. Thus, representatives of birds with a small scope are classified as diving species. Whereas birds with long wings most often live in deep ocean areas. For example, the wandering albatross is a bird that travels countless kilometers in the hope of a meal. However, representatives of this species over time waste their ability to make long-distance flights. Many of them have already chosen the bays or piers where fishing boats often moor.
Everything in nature tends to adapt to convenience. Why fly into the vast expanses of water if food is so available on the shore? The albatross is a bird that, in the process of evolution, even slightly changed the structure of its wings. Now these beauties often do not use active flight techniques, but have switched to dynamic or inclined soaring. That is, albatrosses simply catch the flow of air masses and maneuver.
Webbed feet and sense of smell
Almost all seabirds have webbed feet, which makes it much easier for them to move in the water. But this is not all the advantages of the building. For example, many petrels have a highly developed sense of smell. Thanks to this, they can accurately determine the location of prey in the vast expanses of the ocean.
Cormorant is a bird with a special feather structure
All representatives marine species, except for cormorants and certain varieties of terns, have plumage impregnated with a layer of fat. This water-repellent property serves as reliable protection against getting wet, and dense down ensures a constant body temperature even in cold water. The cormorant is a bird that has an advantage over its other relatives in the special structure of its feathers. This allows him not to freeze even if he has to dive a lot and for a long time. More specific gravity provides this representative of birds with the opportunity to stay under water for a long time.
Penguin
Almost all representatives of the seabird family have plumage colors of black, gray or white. However, there are birds that have brighter and more variegated colors. For example, a penguin is a bird, some species of which have multi-colored plumage in the neck and chest. Color is very important in the wild. Its main function is camouflage, that is, the ability to blend in with the colors of a certain area. This allows not only birds, but all animals to hide from a predator’s attack or not give themselves away while hunting for prey.
Description
The penguin is the bird that scientists believe is the most socialized. Their colonies consist of a huge number of individuals. They spend most of their life cycle in water. Penguins come to land only to conceive and raise offspring. The peculiarities of their structure allow these representatives of the bird family to survive in extremely low temperatures. Dense straight plumage creates a powerful barrier to the cold.
Heavy bones and wings that function as fins make penguins fast swimmers capable of diving very deep. The streamlined shape of the body helps them to excellently cut through the expanses of water, and in case of danger, to deftly escape from a predator. Their feathers do not get wet and effectively retain heat thanks to constant processing with fat secreted by the gland in the tail area. All species except the emperor penguin breed. They settle in the rocks, preparing a place for future offspring from stones and earthy breasts. Those who do not need nests place the eggs under the skin pouch. The chick is also located there for the first time after birth. In a pair, the female and male take turns incubating the egg.
Seagull and other interesting birds
Another waterfowl seabird is the gull. It feeds mainly on small fish. It obtains food in different ways: catching on the surface, diving from the air to a certain depth, hunting under water with pursuit, and does not disdain representatives of higher vertebrates.
The first principle is explained by the presence of different water currents, which often contribute to pushing small inhabitants of the seas and oceans to shallow depths. This is what birds expect when they are on the surface. They just need to dip their head into the water, and the prey ends up in the beak. The second type of food production is used by typhoon birds, frigate birds and storm petrels. They deftly soar over the surface of the sea, making an instant dive into the water and picking up food as they go. Most of them have a hard time taking off if they land on the water surface. Some gulls, including petrels, on the contrary, hunt afloat. Although the previous type of hunting is by no means alien to them. Sooty albatrosses, slender-billed petrels and many other seabirds are capable of diving to depths of up to 70 m in pursuit of prey. The structure of the beak is of particular importance. Thus, many albatrosses have plate-like growths along the perimeter, which allows them to filter and retain plankton from the water. Phaetons, gannets, terns and pelicans dive into the waves directly from above. They often work in tandem with other ocean inhabitants.
Since for effective aerial viewing the water must have a maximum degree of transparency, hunting in the wild does not always occur according to the intended principle. When visibility is limited, representatives of this species look for concentrations of dolphins, as well as tuna. By swimming, they help push schools of fish to a shallow depth from the surface, where they are caught by pelicans and the like.
Bird colony settlements are found at tropical latitudes, for example, on the Pacific Island. Christmas, outside the Arctic Circle - in Antarctica. Albatrosses nest in small numbers, while guillemots and guillemots hold the record for colony density.
Hatchets and guillemots
The northern seabird is a regular at numerous traditional bird markets. Puffins and guillemots are considered record holders among those that are able to gather in such a densely populated area. Thanks to their short wings, they dive perfectly into the water, providing themselves with food. These representatives can be called the most adapted to sea waters. Their chicks, which do not yet know how to fly, fall from their nests in rocky terrain directly into the waves.
Here they are fed and further grow. Many, of course, die, crashing on the rocky terrain. When cold weather approaches, all the inhabitants of the colonies fly away into the endless expanses of water. Some of the seabirds are migratory. They wait out the cold in warmer regions, then return home. Others are nomadic. Many seabirds fly long distances, sometimes changing latitude, and can only return to their place of birth in a circle. Sometimes the entire life cycle is not enough for such a route.
Conclusion
Seabirds, like many other water inhabitants, often become victims of environmental disasters or poaching. The number of birds largely depends on human actions.
If all of the above-mentioned inhabitants of the Baltic have poisonous body parts that they need for life - defense from enemies or hunting, then the algae microorganisms Alexandrium ostenfeldii, no less dangerous to humans, according to Finnish oceanologists, have become so due to a radically changed environmental situation.
The news that the Baltic Sea is rapidly filling with toxic glowing algae Alexandrium ostenfeldii (also called sea fire) was disseminated by Finnish scientists from the Institute of National Resources at the end of last autumn. According to the Finns, sea fire, saturated with saxytocin and neurotoxin, destroys not only the inhabitants of the depths of the Baltic, but also seabirds, as well as people. These toxins contribute to the numbness of the organisms of all living things with which they come into contact.
Scientists noticed blue-green microalgae in the Baltic Sea 40 years ago, and with climate change they began to spread more and more actively in this basin. In 2015, sea fire bloomed in the coastal waters of the Baltic due to the heat. Experts associate the cyclical flowering of Alexandrium ostenfeldii with climate change and the influx of water from the Atlantic.
Domestic oceanologists from the Moscow Institute of Oceanology named after P. P. Shirshov RAS confirmed that certain highly concentrated toxins are actually able to paralyze the respiratory muscles, cause allergic reactions, and damage the kidneys and liver. Meanwhile, neither Finnish nor domestic oceanologists provided statistics on the impact of sea fire on human health. Only deaths from eating toxic fish caught in the Baltic bays of East Prussia were mentioned. But they date back to the 20-30s of the twentieth century.
