Ocean dead zones - terrible consequences of human activity


Posted on Jan 12, 2021      154


 

The most popular environmental problem of our time is global warming. But despite the fact that every year the climate is really getting warmer, not all experts are ready to directly link this with the human influence: it may be just a normal warming-cold cycle for our planet.

A much more serious problem remains poorly lit. We are talking about the so-called dead zones of the ocean - vast areas of water with extremely low oxygen levels, where large living creatures can not live.

For the first time divers working at depths noticed such zones in the second half of the 20th century. The sea bottom, dotted with bodies of thousands of animals - shellfish, crabs and fish - made an oppressive impression. Subsequently, such areas were called “dead”. On their borders, living creatures, feeling a lack of oxygen, are forced to migrate in a hurry, affecting other eco-zones.

Studies show that since the 1970s, because of the appearance of dead zones, the world ocean has lost about 2% of all oxygen, which has already led to the disappearance of large marine animals in the affected regions. Sometimes, there has been a significant reduction in the size of living organisms that have been oxygen-deprived for generations. This has had a negative impact on both general biodiversity and fisheries, leading to a decline in the welfare of nearby regions. At present, the largest number of dead zones are in the Baltic Sea and the Gulf of Mexico, but recently they are being recorded in other parts of the world.

Why do dead zones appear in the seas and oceans? It is the fertilizers used by humans that are almost uncontrollable. Together with rainwater, they get into rivers that carry these substances to the seas and oceans. Once in water, nitrogen fertilisers cause rapid algae growth, which promotes explosive growth of microorganisms that feed on these algae. And the more microorganisms, the less oxygen is in the water.

According to scientists, it is the fight against dead zones that should become one of humanity’s top priorities in the 21st century. Over the past 10 years, their number has increased by 10 times. To stop oxygen loss by the ocean, it is necessary to modernize water supply system of coastal agricultural areas as soon as possible and reduce the amount of waste discharged into rivers. In those few countries where this has already been done, there is a gradual recovery of oxygen levels in coastal waters.


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