Ocean exhausted oxygen at record level, alarming a series of 'dead zones'

Experts warn the ocean has lost its unprecedented levels of oxygen as a result of climate change and intensive human activity.

The discovery was made by the International Union for Conservation of Nature (IUCN) at the United Nations climate conference in Madrid on December 7, according to the Guardian.

According to the organization's report, more and more "dead zones" , where oxygen deficiency is severe, form in the ocean while other areas are also depleted of oxygen.

The number of dead zones has quadrupled in the past half century and at least 700 areas have dangerously low levels of oxygen, up from 45 in comparison with the 1960s.

Sharks, tuna, marlin and other large fish face a particularly high risk of this situation. Many important ecosystems are also likely to be wiped out.

Large fishes are threatened by the oxygen depleted ocean.(Photo: Getty).

Every fish needs dissolved oxygen, but the largest species are especially vulnerable because they need more oxygen to survive. Depleted oxygen forces these species to move up to the surface and into shallow areas of the sea, where they are more easily caught.

Global warming also depletes oxygen in the ocean, because warmer water contains less oxygen. Warming sea water also causes stratification, making it difficult for oxygen-rich and oxygen-poor layers to mix.

The ocean is expected to lose about 3-4% of its oxygen by the end of the century, but the impact will be much greater in the water near the ocean, where many species are concentrated.

Intensive agriculture is also one of the main causes. When excess manure from crops or animal manure from soil flows into rivers and the sea, they cause algae to bloom and then cause oxygen depletion when decomposed.

Grethel Aguilar, acting director of IUCN, said negotiators should consider the ocean an important factor to consider.

"As the ocean heats up and loses oxygen, the equilibrium of marine life becomes chaotic. The decisions made at this conference are important because they have the potential to have a serious impact on activity." fisheries and vulnerable coastal communities , " Ms Aguilar said.

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