The Baltic Sea is suffocating. Oxygen concentrations in waters lowest since 1,500. years
The coastal waters of the Baltic Sea have been largely deprived of oxygen, Finnish and German scientists say. Its content is the lowest in 1,500. years and is related to human activities. This is primarily agriculture and municipal wastewater.
Dead zones are areas of the sea, usually near the bottom, that are too low in oxygen for oxygen-breathing organisms to survive in them. They are formed as a result of entering the wod huge amounts of phosphateow and nitrateow – componentoin nutrients, from whichowhich algae readily use. When these organisms die, they sink to the bottom and are broken down by bacteria that use oxygen to do so. As a result, the concentration of oxygen in the water is falling.
The resulting lack of oxygen not only reduces habitat for creatures living on the seabed, but also affects fish stocks and can lead to bloomsoof toxic cyanobacteria. But it’s not just a Baltic problem.
At the beginning of the year, a study was published, from whichoThe study shows that dead zones in the seas and oceans have quadrupled over the past 50 years. The problem is affecting the areaoin coastal areas around the world, where large human populations live – From Europe, to the Americas PoThe analysis takes us back to medieval Europe, long before the Industrial Revolution and the. For more on this topic, see Declining oxygen content in the oceans. Dead zones inod getting larger.
Currently, the dead zone of the Baltic Sea extends over an area of 70,000 kilometersoin square. That’s an area almost twice the size of Denmark.
While previous studies have revealed that the central Baltic Sea has experienced oxygen depletion in rotions over the past few thousand years, the latest research analyzes changes in the level ofow of oxygen in coastal waters.
Researchers from Finland and Germany took two sediment coresow from the seafloor from the shallow region between the coasts of Finland and Sweden. Each of them had a length of four metersow. This has made it possible to learn about conditions in the Baltic Sea over hundreds of years. This research was published in the journal „Biogeosciences”.
Scientists have performed a number of rotive analyses of the cores taken. They studied m.in. grain size in sediment layersoin and the proportions of roThe number of elementsoin them. Scientists were able to reconstruct the changes in the level ofow of oxygen in the seafloor over the past 1,500 years, revealing that while the degree of oxygen loss in coastal areas has fluctuated throughout this period – largely due to climate change – This has clearly accelerated over the past 100 years.
Scientistsow was surprised to learn that the sharp decline in oxygen levels began even before the postwar peak of urbanization and intensive agricultural development in the region in the 1950s. 1990s.
– Our evidence of oxygen depletion inod the Baltic Sea at the beginning of the 20th century suggest that human impact was felt earlier. In other words, that the system is more vulnerable than we previously thought – admitted Sami Jokinen of the University of Turku and Tom Jilbert of the University of Helsinki, whooers are wspohe authors of the study.
Since 2007, the coastal states wokoł Baltic Sea prob are improving the situation through an action plan to reduce the inflow of componentoin nutrients to wod. However, as the researchers point out, improvements in the situation are not in sight. This may be related to climate change. – Global warming likely opoIt makes the whole process of oxygen recovery easier, the scientists admitted.
– The great advantage of this study is the precise scheduling of changes in conditionsow. These analyses take us back to medieval Europe, long before the Industrial Revolution and the cooThe rapid growth of the population. In this wayob scientists can separate human activity from the environmental forces shaping the Baltic Sea to show that those responsible for the Baltic dead zones are those whooers live along its edgesow – said in an interview with „The Guardian” Callum Roberts, a professor of marine conservation at York University, whoory was not involved in the study.