The Black Sea has tides

The Black Sea is running out of air

Scientists repeatedly come across spectacular wrecks and remains of settlements from the Bronze Age in the Black Sea. Just recently, underwater archaeologists found the oldest known intact shipwreck off the coast of Bulgaria at a depth of 2000 meters. The extremely well-preserved finds provide detailed archaeological information about ancient shipbuilding and the old trade routes. For centuries the inland sea was an important trade route for the Greeks and Romans as well as for the Byzantines and Ottomans.

Ideal preservation conditions

However, some of the merchant ships did not reach their destination, as the numerous wrecks that have already been found show. They were found by remote-controlled diving robots on the bottom of the 2,212-meter-deep Black Sea, which has an area of ​​around 436,400 km², i.e. about the size of Morocco or Sweden.

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Sensational find in oxygen-free depths: the 2400 year old wreck is surprisingly well preserved

Not only is it complete darkness on the sea floor, there is also no oxygen. This anoxic, i.e. completely oxygen-free, seabed means that organic material, like ancient ships, is preserved for thousands of years. Since the low-salt surface water of the sea lies like a lid on the denser, more salty deep water, there is no exchange of oxygen. All organisms that need oxygen cannot exist on the seabed of the Black Sea. The archaeologists are pleased, but the habitat for aquatic organisms is shrinking dramatically.

Hardly any movement in the Black Sea

This is due to the nutrients introduced from agriculture, such as nitrogen and phosphorus, as well as an unusually stable water stratification. The Black Sea is only connected to the Mediterranean by the narrow Bosphorus. Only a small amount of fresh salt water reaches the inland sea via this strait. Instead, large freshwater rivers like the Danube flow in.

The oxygen-rich fresh water swims above, the denser, salty deep water lies below. Nor is there enough wind, waves, or cooler surface temperatures to mix the zones. With the exception of a few adapted species, most of the organisms lived in the more oxygen-rich surface water. In 1955 this zone reached a depth of 140 meters; today the death zone begins at 90 meters.

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Climate change exacerbates the lack of oxygen in the oceans

In the course of advancing climate change, the seas and oceans around the world are becoming measurably warmer. The warmer the water, the less oxygen it can absorb. At the same time, sea creatures in warmer water need more energy and oxygen to move, to eat, or to reproduce. Many species therefore try to leave their original habitat, for example in greater water depths. The ecosystems are being radically upset and biodiversity is shrinking rapidly. In the past few years, oxygen-free zones in open oceans have grown fourfold, in coastal waters even tenfold, reported experts from the Global Ocean Oxygen Network (GO2NE) in the journal "Science" at the beginning of the year. And in the Black Sea, too, the available habitat for aquatic organisms has shrunk by more than 40 percent in just 60 years.

Archaeologists will probably come across numerous sunken treasures in the Black Sea in the future, whereas marine biologists will find fewer and fewer marine organisms there.

  • The inventions of Jacques-Yves Cousteau

    Diving is also much easier

    The underwater pioneer Jacques-Yves Cousteau stands here in 1973 next to a historic helmet diving suit. On the occasion of the founding of his Society for Exploration and Protection of the Seas, he is awarded a medal. Cousteau has done a lot to ensure that divers today can move about in the water with almost the ease of fish - and not like knights in steel armor.

  • The inventions of Jacques-Yves Cousteau

    Still without swim bladder but with funk

    Cousteau with a compressed air device in 1963 on the bottom of the Red Sea. He accompanies his research submarine. Even then he had a radiotelephone connection in the boat. But something crucial is missing: a diving jacket or a bladder that can be filled with air in order to be optimally balanced in the water. Without this, a diver cannot avoid churning up sediment or damaging corals.

  • The inventions of Jacques-Yves Cousteau

    Inventor of the regulator

    The regulator that the engineer Emile Gagnan developed for Cousteau had only one pressure reduction stage. The disadvantage: the pressure of the breathing air corresponded to the ambient pressure at the cylinder valve. If you dived upside down, the diver had to actively suck in air. If you emerged vertically, you had to blow against it while breathing. The advantage: The air escaped behind the head - good for filming.

  • The inventions of Jacques-Yves Cousteau

    The diving saucer

    In her time she looked like she was out of a science fiction film. In 1959, Cousteau presented his research submarine at the International Oceanographic Congress in New York. In particular, Cousteau developed the technology for his film recordings himself: underwater housing, lighting and much more.

  • The inventions of Jacques-Yves Cousteau

    From minesweeper to dream of the Caribbean

    The calypso was a gift from the Irish Guinness Brewery to the underwater explorer. He equipped them with a helicopter landing pad and used the crane systems for his submarines, diving chambers, shark cages and dinghies. Inside there was some space for laboratory work. Above all, the ship was a constant film set, because Cousteau conveyed the dream of the South Seas in over 100 films.

  • The inventions of Jacques-Yves Cousteau

    A trimaran for underwater

    This peculiar underwater vehicle bears the name of his son Philippe. Cousteau launched it in 1980 in the port of Le Cap d'Agde in southern France. The submarine could carry eight people and was intended as a kind of underwater sightseeing bus - to bring the beauty of the sea to many people.

  • The inventions of Jacques-Yves Cousteau

    Living under water

    Cousteau presents the Precontinent III underwater station. Divers can also stay overnight in it. Behind this is a principle that is particularly important nowadays for professional divers or construction workers in tunnel construction: They also have to work for long periods of time under increased ambient pressure.

  • The inventions of Jacques-Yves Cousteau

    Nitrogen saturation as a permanent condition

    If people are under an increased ambient pressure, more nitrogen saturates in the blood. If it rose too quickly to the surface of the sea, it would bubble out, like carbon dioxide in sparkling water. Therefore, divers who have been down for a long time also have to come up extremely slowly. It is often more practical to stay down there and rest in this capsule.

  • The inventions of Jacques-Yves Cousteau

    A diving bell on the ocean floor

    This diving bell is the previous model, but without overnight accommodation. Divers who come from greater depths can dive in from below. It is not very deep on the seabed. But that is enough to spend a few hours there and wait until the nitrogen content in the blood has dropped so far that the further ascent can take place safely.

  • The inventions of Jacques-Yves Cousteau

    A holdover from early research

    This tubular frame was Cousteau's shark cage, which he had experimented with in the Red Sea. Today it is still lying around on the sea floor as an archaeological asset and diving attraction.

  • The inventions of Jacques-Yves Cousteau

    Shark diving for everyone

    On coasts, where there are many dangerous sharks like this bull shark, companies are now offering tourists the special thrill in such shark cages. Some use bait to attract the animals. However, this is frowned upon and illegal among recreational divers.

  • The inventions of Jacques-Yves Cousteau

    Be close to the animals

    But you can also approach animals in a completely different way - for example by camouflaging yourself well. The Cousteau team developed this walk-in hippopotamus for film recordings.

  • The inventions of Jacques-Yves Cousteau

    When the muscle strength is not enough

    Underwater scooters have not only existed since James Bond. Cousteau experimented with this model as early as 1956. The photo was not taken before a dive, however, but on the occasion of a film screening on board the Calypso during the Cannes film festival. Also pictured: Actresses Edith Zetline, Isabelle Corey and Bella Darvi.

  • The inventions of Jacques-Yves Cousteau

    Today with more ease

    Unlike the early underwater scooters, the devices today have more powerful batteries and motors. This allows divers to enjoy the beauties of the seas in a more relaxed manner.

  • The inventions of Jacques-Yves Cousteau

    The unfinished dream

    This is what the successor to the Calypso should have looked like: With an innovative sail as an additional drive. It never came to that. The original Calypso sank in an accident in Singapore in January 1996. Jacques-Yves Cousteau died on June 25, 1997 at the age of 87. His first ship is currently being restored in Turkey. It will later sail the oceans as an environmental protection ambassador.

    Author: Fabian Schmidt