45 minutesThe Baltic Sea is the sea that is closest to our hearts. It is located on the coast of northern Poland, so many of us had the opportunity to get to know it during our vacations. Not only Poles spend their vacations on the Baltic. After all, we share it with other countries: Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Germany and Denmark.
45 minutes
45 minutesNot everyone knows that the Baltic Sea is THE in many ways. It is THE youngest, THE sweetest, THE shallowest in the world and THE coldest in Europe.
45 minutesMore than 900,000 years ago, an ice age began in the world. Ice sheets - huge areas of land covered with thick ice - were forming on land. 100,000 years ago, the Scandinavian ice sheet formed. It began to melt 12,000 years ago, giving rise to the Baltic Sea. Worldwide, only Hudson Bay is equally "young".
45 minutesAfter the Ice Age, the Scandinavian ice sheet began to melt, forming two lakes. As this process proceeded, the water in the two lakes increased enough that in time it overcame the obstacles separating the lakes, merging them into the Baltic Ice Lake. At that time, the Baltic Sea was completely fresh and frozen for most of the year. This lasted about three thousand years, during which the glacier continued to melt and the reservoir of the Baltic Ice Sea grew larger.
45 minutesAt one point there was so much water in the Baltic Ice Lake that it began to overflow through a small strip of land separating the lake from the ocean. For the first few years, water from the lake poured into the ocean very heavily. The water level in the Baltic Sea dropped by 25 metres in the first few years, as much as a skyscraper measures. When the water level in the lake became equal to that in the ocean, salty water from the Atlantic began to flow into the lake. The Baltic Sea ceased to be a freshwater lake and went into a second phase of development. It was now called the Yoldia Sea.
45 minutesThe water level in the ocean and the connected Yoldia Sea was rising. The global air temperature was also rising, as a result of which the heavy Scandinavian glacier was melting. When the glacier receded, the earth's crust, freed from its weight, rose at the point where it had previously connected the Baltic Ice Lake with the ocean. The sea once again ceased to ahve access to the ocean and was cut off from the inflow of saltwater. Instead, fresh river water continuously flowed into it, making the Baltic Sea a fresh lake for the second time, called the Ancylus Lake.
45 minutesWhen the ocean water rose again, Lake Ancylus through the Danish Straits connected to the North Sea, through which it connected to the ocean. Salt water began to seep into the reservoir of Ancylus Lake, changing its taste and chemical composition. Once again it became a salty sea, twice as salty as the Baltic Sea today and slightly warmer. It was called the Littorina Sea.
45 minutesWhen the crust of the earth in the area of the Danish Straits raised the bottom again, the supply of very salty ocean water decreased again, therefore the salinity of the Baltic Sea, i.e. the amount of salt dissolved in seawater, also decreased. The further away you are from the North Sea and the Atlantic Ocean, the lower its salinity. The average salinity is 7 per mille. The Baltic has become the sweetest sea in the world. This, however, has its consequences.
.
45 minutesThe Baltic Sea is sweet because more fresh than salty water flows into it. This water comes primarly from the 250 rivers that end up feeding the Baltic reservoir. You can see the largest of these in the illustration. The rest of the freshwater is the result of precipitation (rain, snow).
45 minutesThe higher the salinity, the greater the number of animals and plants living in it. So if the Baltic is a relatively sweet sea, it unfortunately has little biodiversity compared to the other seas. At its current stage of development, the Baltic Sea is almost completely surrounded by land, thus having little water exchange between it and the North Sea, which is caused shallowness of the bottom around the Danish straits that limits the free flow of water. This is important information. When we combine it with the information that the saltier the water, the greater the capacity of the reservoir to regenerate, we discover that the structure of the Baltic Sea indicates its sensitive nature.
45 minutesThe higher the salinity, the greater the number of animals and plants living in it. So if the Baltic is a relatively sweet sea, it unfortunately has little biodiversity compared to the other seas. At its current stage of development, the Baltic Sea is almost completely surrounded by land, thus having little water exchange between it and the North Sea, which is caused shallowness of the bottom around the Danish straits that limits the free flow of water. This is important information. When we combine it with the information that the saltier the water, the greater the capacity of the reservoir to regenerate, we discover that the structure of the Baltic Sea indicates its sensitive nature.
45 minutesThe higher the salinity, the greater the number of animals and plants living in it. So if the Baltic is a relatively sweet sea, it unfortunately has little biodiversity compared to the other seas. At its current stage of development, the Baltic Sea is almost completely surrounded by land, thus having little water exchange between it and the North Sea, which is caused shallowness of the bottom around the Danish straits that limits the free flow of water. This is important information. When we combine it with the information that the saltier the water, the greater the capacity of the reservoir to regenerate, we discover that the structure of the Baltic Sea indicates its sensitive nature.
45 minutesWhen there is too much water in the Baltic Sea, it gives away the excess by pouring it into the North Sea. Sometimes, however, it is the North Sea that pours salt water into the Baltic Sea during a storm, thus oxygenating it. These are crucial and at the same time beneficial moments for the ecosystem of the Baltic Sea, which in recent years have been extremely rare. This is a result of ongoing climate change.
45 minutes
The Baltic Sea is extremely sensitive. Although it seems huge when we look at it from the beach, which may give us the impression that we have little influence on its waters, its shape, depth, coastline and low salinity make it easy to harm it. We can take care of the sea not only when we are on vacation, by being careful not to let garbage get into it, or by choosing natural creams with filters that will not harm its chemical composition when we swim.
We also take care of the Baltic Sea by protecting the purity of the rivers. We can go a step further, by making sure that the land we cultivate is not saturated with artificial fertilizers. They seep into the groundwater and end up in rivers, which then flow into the Baltic Sea. Sometimes even the fact that you spill floor cleaner in your yard and it soaks into your lawn can harm the Baltic Sea. Literally everything in the world is interconnected and affects each other. Please keep this in mind. So let's take care of the Baltic Sea, if we want to continue taking refreshing, although not too warm baths in it.
45 minutesThe temperature of the Baltic Sea is not very high. It is the coldest sea in Europe. Anyone who has ever bathed in a warmer sea knows that the Baltic Sea is really cold. The maximum average surface water temperature in summer reaches 18 degrees Celsius. The low temperature causes the decomposition processes of organic molecules to take longer in the Baltic Sea than in other seas.
45 minutes
Sometimes in summer we hear that swimming is not allowed because of cyanobacteria. This is when there is a large increase in microscopically visible plant organisms and the water turns green as a result. Cyanobacteria are just one of 700 species of microorganisms, the sum of which constitutes what is known as phytoplankton.
Usually these organisms float in the layer of water that receives sunlight. They belong to the underwater world of plants and thanks to them not only in the Baltic Sea, but also in the oceans, life can exist. They are at the very beginning of the food chain.
45 minutesThe bottom of the Baltic Sea is covered with plants. The clearer the water and the more sunshine reaches the sea bottom, the more plants can be found. On the other hand, the less sun, the fewer plants. As a result, they grow at depths of up to three meters. The main plant species that we meet at shallower depths are green algae and flowering plants, followed by brown algae - living at medium depths - and kelp, which grows the deepest. We call them all phytobenthos.
45 minutesIt is also the shallowest sea in the world and although in the deepest spot (Landsort Deep - off the coast of Sweden) by submarine you can dive to 459 meters, the average depth is 55 meters. If you're wondering if 55 meters is a lot, it's the same as two Palaces of Science and Culture placed on top of each other.
45 minutesMany tourists come to the Baltic Sea for their health. Some of them come to the seaside spas and sanatoriums to inhale iodine. It is an important element for the proper functioning of the human body. When it is missing, the thyroid stops functioning well, which makes us feel slightly tired and sluggish. The skin becomes slightly dry, hair falls out more intensively and nails break more easily. Such deficiencies can be replenished by breathing in the sea air. Iodine is released from the sea into the air and falls on land - most of it can be found up to 300 meters from the sea. So it is recommended to take a walk on the beach to replenish the deficiency.
45 minutesWhile walking down the beach, we hear the sound of the sea, feel the wind on our face and the sand under our feet. Looking around, we notice dunes, often protected by fences and warning signs. Why do you think it is so important to protect the dunes? We mentioned that the world is undergoing climate change and water levels in the seas and oceans are rising. As a result the sea is consuming more and more land, which can be seen especially in Trzęsacz, where the Baltic Sea has swallowed almost the whole church; only one wall remains. The only barrier for the sea are the dunes. However, due to the strong storms and winds they are being washed and blown away. Human activity does not help either, with them destroying dunes and cutting down trees growing on them to build houses or hotels.
45 minutesAt the seaside, it is worth taking care not only for the state of the dunes, but also for your own safety. That’s why it’s good to be acquainted with basic signs that can be found near the guarded bathing beaches. The Baltic currents and waves can be unpredictable, so it is worth knowing what the signals on the bathing flags mean:
White buoy – paddling pool for children (water depth up to 40 cm).
Red buoy – end of the zone for unskilled swimmers (water depth up to 1,2 meters).
Yellow buoy – end of the zone for skilled swimmers.
45 minutesLifeguard may reprove a person that will not comply to commands given through sound signals.
Short whistle – reprimand.
Multiple long whistles or a siren/gong – order for one to leave the water.
White flag – it’s safe to bathe.
Red flag – bathing prohibited.
No flag – no lifeguards are present.
That is the end of the lesson about the Baltic Sea.
45 minutesThe Baltic Sea is the sea that is closest to our hearts. It is located on the coast of northern Poland, so many of us had the opportunity to get to know it during our vacations. Not only Poles spend their vacations on the Baltic. After all, we share it with other countries: Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Germany and Denmark.
45 minutes45 minutesNot everyone knows that the Baltic Sea is THE in many ways. It is THE youngest, THE sweetest, THE shallowest in the world and THE coldest in Europe.
45 minutesMore than 900,000 years ago, an ice age began in the world. Ice sheets - huge areas of land covered with thick ice - were forming on land. 100,000 years ago, the Scandinavian ice sheet formed. It began to melt 12,000 years ago, giving rise to the Baltic Sea. Worldwide, only Hudson Bay is equally "young".
45 minutesAfter the Ice Age, the Scandinavian ice sheet began to melt, forming two lakes. As this process proceeded, the water in the two lakes increased enough that in time it overcame the obstacles separating the lakes, merging them into the Baltic Ice Lake. At that time, the Baltic Sea was completely fresh and frozen for most of the year. This lasted about three thousand years, during which the glacier continued to melt and the reservoir of the Baltic Ice Sea grew larger.
45 minutesAt one point there was so much water in the Baltic Ice Lake that it began to overflow through a small strip of land separating the lake from the ocean. For the first few years, water from the lake poured into the ocean very heavily. The water level in the Baltic Sea dropped by 25 metres in the first few years, as much as a skyscraper measures. When the water level in the lake became equal to that in the ocean, salty water from the Atlantic began to flow into the lake. The Baltic Sea ceased to be a freshwater lake and went into a second phase of development. It was now called the Yoldia Sea.
45 minutesThe water level in the ocean and the connected Yoldia Sea was rising. The global air temperature was also rising, as a result of which the heavy Scandinavian glacier was melting. When the glacier receded, the earth's crust, freed from its weight, rose at the point where it had previously connected the Baltic Ice Lake with the ocean. The sea once again ceased to ahve access to the ocean and was cut off from the inflow of saltwater. Instead, fresh river water continuously flowed into it, making the Baltic Sea a fresh lake for the second time, called the Ancylus Lake.
45 minutesWhen the ocean water rose again, Lake Ancylus through the Danish Straits connected to the North Sea, through which it connected to the ocean. Salt water began to seep into the reservoir of Ancylus Lake, changing its taste and chemical composition. Once again it became a salty sea, twice as salty as the Baltic Sea today and slightly warmer. It was called the Littorina Sea.
45 minutesWhen the crust of the earth in the area of the Danish Straits raised the bottom again, the supply of very salty ocean water decreased again, therefore the salinity of the Baltic Sea, i.e. the amount of salt dissolved in seawater, also decreased. The further away you are from the North Sea and the Atlantic Ocean, the lower its salinity. The average salinity is 7 per mille. The Baltic has become the sweetest sea in the world. This, however, has its consequences.
.
45 minutesThe Baltic Sea is sweet because more fresh than salty water flows into it. This water comes primarly from the 250 rivers that end up feeding the Baltic reservoir. You can see the largest of these in the illustration. The rest of the freshwater is the result of precipitation (rain, snow).
45 minutesThe higher the salinity, the greater the number of animals and plants living in it. So if the Baltic is a relatively sweet sea, it unfortunately has little biodiversity compared to the other seas. At its current stage of development, the Baltic Sea is almost completely surrounded by land, thus having little water exchange between it and the North Sea, which is caused shallowness of the bottom around the Danish straits that limits the free flow of water. This is important information. When we combine it with the information that the saltier the water, the greater the capacity of the reservoir to regenerate, we discover that the structure of the Baltic Sea indicates its sensitive nature.
45 minutesThe higher the salinity, the greater the number of animals and plants living in it. So if the Baltic is a relatively sweet sea, it unfortunately has little biodiversity compared to the other seas. At its current stage of development, the Baltic Sea is almost completely surrounded by land, thus having little water exchange between it and the North Sea, which is caused shallowness of the bottom around the Danish straits that limits the free flow of water. This is important information. When we combine it with the information that the saltier the water, the greater the capacity of the reservoir to regenerate, we discover that the structure of the Baltic Sea indicates its sensitive nature.
45 minutesThe higher the salinity, the greater the number of animals and plants living in it. So if the Baltic is a relatively sweet sea, it unfortunately has little biodiversity compared to the other seas. At its current stage of development, the Baltic Sea is almost completely surrounded by land, thus having little water exchange between it and the North Sea, which is caused shallowness of the bottom around the Danish straits that limits the free flow of water. This is important information. When we combine it with the information that the saltier the water, the greater the capacity of the reservoir to regenerate, we discover that the structure of the Baltic Sea indicates its sensitive nature.
45 minutesWhen there is too much water in the Baltic Sea, it gives away the excess by pouring it into the North Sea. Sometimes, however, it is the North Sea that pours salt water into the Baltic Sea during a storm, thus oxygenating it. These are crucial and at the same time beneficial moments for the ecosystem of the Baltic Sea, which in recent years have been extremely rare. This is a result of ongoing climate change.
45 minutes
The Baltic Sea is extremely sensitive. Although it seems huge when we look at it from the beach, which may give us the impression that we have little influence on its waters, its shape, depth, coastline and low salinity make it easy to harm it. We can take care of the sea not only when we are on vacation, by being careful not to let garbage get into it, or by choosing natural creams with filters that will not harm its chemical composition when we swim.
We also take care of the Baltic Sea by protecting the purity of the rivers. We can go a step further, by making sure that the land we cultivate is not saturated with artificial fertilizers. They seep into the groundwater and end up in rivers, which then flow into the Baltic Sea. Sometimes even the fact that you spill floor cleaner in your yard and it soaks into your lawn can harm the Baltic Sea. Literally everything in the world is interconnected and affects each other. Please keep this in mind. So let's take care of the Baltic Sea, if we want to continue taking refreshing, although not too warm baths in it.
45 minutesThe temperature of the Baltic Sea is not very high. It is the coldest sea in Europe. Anyone who has ever bathed in a warmer sea knows that the Baltic Sea is really cold. The maximum average surface water temperature in summer reaches 18 degrees Celsius. The low temperature causes the decomposition processes of organic molecules to take longer in the Baltic Sea than in other seas.
45 minutes
Sometimes in summer we hear that swimming is not allowed because of cyanobacteria. This is when there is a large increase in microscopically visible plant organisms and the water turns green as a result. Cyanobacteria are just one of 700 species of microorganisms, the sum of which constitutes what is known as phytoplankton.
Usually these organisms float in the layer of water that receives sunlight. They belong to the underwater world of plants and thanks to them not only in the Baltic Sea, but also in the oceans, life can exist. They are at the very beginning of the food chain.
45 minutesThe bottom of the Baltic Sea is covered with plants. The clearer the water and the more sunshine reaches the sea bottom, the more plants can be found. On the other hand, the less sun, the fewer plants. As a result, they grow at depths of up to three meters. The main plant species that we meet at shallower depths are green algae and flowering plants, followed by brown algae - living at medium depths - and kelp, which grows the deepest. We call them all phytobenthos.
45 minutesIt is also the shallowest sea in the world and although in the deepest spot (Landsort Deep - off the coast of Sweden) by submarine you can dive to 459 meters, the average depth is 55 meters. If you're wondering if 55 meters is a lot, it's the same as two Palaces of Science and Culture placed on top of each other.
45 minutesMany tourists come to the Baltic Sea for their health. Some of them come to the seaside spas and sanatoriums to inhale iodine. It is an important element for the proper functioning of the human body. When it is missing, the thyroid stops functioning well, which makes us feel slightly tired and sluggish. The skin becomes slightly dry, hair falls out more intensively and nails break more easily. Such deficiencies can be replenished by breathing in the sea air. Iodine is released from the sea into the air and falls on land - most of it can be found up to 300 meters from the sea. So it is recommended to take a walk on the beach to replenish the deficiency.
45 minutesWhile walking down the beach, we hear the sound of the sea, feel the wind on our face and the sand under our feet. Looking around, we notice dunes, often protected by fences and warning signs. Why do you think it is so important to protect the dunes? We mentioned that the world is undergoing climate change and water levels in the seas and oceans are rising. As a result the sea is consuming more and more land, which can be seen especially in Trzęsacz, where the Baltic Sea has swallowed almost the whole church; only one wall remains. The only barrier for the sea are the dunes. However, due to the strong storms and winds they are being washed and blown away. Human activity does not help either, with them destroying dunes and cutting down trees growing on them to build houses or hotels.
45 minutesAt the seaside, it is worth taking care not only for the state of the dunes, but also for your own safety. That’s why it’s good to be acquainted with basic signs that can be found near the guarded bathing beaches. The Baltic currents and waves can be unpredictable, so it is worth knowing what the signals on the bathing flags mean:
White buoy – paddling pool for children (water depth up to 40 cm).
Red buoy – end of the zone for unskilled swimmers (water depth up to 1,2 meters).
Yellow buoy – end of the zone for skilled swimmers.
45 minutesLifeguard may reprove a person that will not comply to commands given through sound signals.
Short whistle – reprimand.
Multiple long whistles or a siren/gong – order for one to leave the water.
White flag – it’s safe to bathe.
Red flag – bathing prohibited.
No flag – no lifeguards are present.
That is the end of the lesson about the Baltic Sea.
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