According to the estimate made by scientists, 50 – 80% of the Planet’s oxygen production is from Ocean. Oceanic phytoplankton contributes the majority of oxygen production. Phytoplankton is tiny plants that live on the surface of oceans and lakes, which are mainly drifting plants, algae and some bacteria that can photosynthesize.
Phytoplankton blooms during spring when lights and nutrients are more available. By this phenomenon, the density of phytoplankton varies. Sometimes, they float just at the surface. They can be a hundred meters – around 100 yards thick.
Scientists say, by about 400 million years ago, necessary oxygen accumulated in Earth’s atmosphere for the living of oxygen-breathing land beings. Then, in that particular place, three atoms of oxygen bonded together and the ozone layer formed. At the top of Earth’s atmosphere, this formed layer of ozone shields land organisms from harmful ultraviolet radiation from the sun.
Oceans have lost around 2% of dissolved oxygen since the 1950s globally. Since then, it is expected to lose about 3- 4 % by the year 2100 a business–as–usual scenario. The scale of effect varies regionally. In the upper 1000 m, much of the oxygen loss takes place. This is so because richness and abundance will be the highest. A slight overall reduction in the level of oxygen dissolved in the ocean can induce oxygen. Stress in marine organisms by depriving them of an adequate oxygen supply at the tissue level. This is known as hypoxia.
Two major causes of the loss of oxygen in the ocean
- Algae’s excessive growth: Animal waste, aquaculture, sewage, fertilizer run-off and nitrogen deposition from the burning of fossil fuels are helping excessive growth of plants – eutrophication process, which coastal areas will be most affected. Studies say that the warming of ocean water is expected to cause further oxygen loss in nutrient-rich coastal areas, exacerbating the situation.
- Ocean warming – driven deoxygenation: Ocean water that is warmer holds less oxygen and is more buoyant than cooler water. This will lead to reduced water which is oxygenated near the surface with deeper waters, which naturally contain less oxygen. The oxygen demand is also been raised by warmer water from living organisms. As a result, less oxygen is available for marine life.
As a result of these processes, regions with very low oxygen concentrations are expanding and new regions are exhibiting low oxygen conditions. In 2011, there were around 700 reported sites worldwide affected by low oxygen conditions. Reports and shreds of evidence suggest that temperature increases explain about 50% of oxygen loss in the upper 1000m of the oxygen.
The oxygen loss at a depth of between 100 – 300 m is said to be the largest oxygen loss. It is observed in the Tropical and North pacific ocean, the Southern and Arctic Ocean and South Atlantic Ocean.
Oxygen loss was driven by excessive organic matter and the growth of algae and the threats it poses to ecosystem services are documented in many regions but likely under-reported in others. Oxygen loss due to ocean warming, on the other hand, was only recognized more recently and is not as fully understood. The causes can also interact-warming-induced oxygen loss is tipping coastal areas into hypoxia and may contribute to the dramatic increase in reports of coastal hypoxia.
One of the multi-human-induced stress factor affecting the marine ecosystem is Deoxygenation. It Is so because respiration consumes oxygen and releases carbon dioxide. By deoxygenation of the ocean, it is often accompanied by Ocean Acidification, making it necessary to mitigate these stressors together. Warming to the ocean decreases oxygen supply but on the other hand, it increases oxygen requirements of marine organisms, making it critical to understand the combined effects of these stressors.
Why is The Ocean “So Important”?
The Ocean plays a major role in sustaining life on Earth. 97% of the physical habitable space on the planet is represented by the Ocean. Oxygen loss from the Ocean will have severe impacts on marine biodiversity and the functioning of Oceanic ecosystems. Much more facts remain unknown as to the long-term human health, Social and Economic consequences of Ocean oxygen loss.
The Ocean’s food provisioning ecosystem services for human require oxygen to support Organism production and growth. To sustain the life of all the fishes and invertebrates, oxygen is necessary. Deoxygenation is already casing measurable declines of fish species. Some of the Ocean’s most productive biomes, supporting one-fifth of the world’s wild marine fish harvest, are formed by ocean currents that bring nutrient-rich but oxygen-poor water to coasts that live the eastern edges of the world’s ocean basins. Oxygen–poor systems as naturally, these areas are particularly vulnerable to ocean deoxygenation, and such effects may ripple out and affect hundreds of millions of people. Degradation of habitats due to climate-change-driven hypoxia and an increase of algal blooms may lead to the reduction of fisheries and collapse of regional stocks are possible.
What can be done right now?
To prevent and reverse the loss of oxygen, people, industry and government must urgently cut carbon dioxide emissions and reduce ocean nutrient pollution. Deoxygenation is driven by warming cannot be easily reversed, but it can considerably be slowed down by mitigating greenhouse gas emissions. Without a reduction in greenhouse gas emissions, it is nearly impossible to recover from warming projected under business-as-usual emissions scenarios. To prevent widespread ocean oxygen loss by reducing human-driven warming (by cutting climate-changing emissions by fossil fuel combustion) can prevent widespread ocean loss. That helps to recover to some degree.
Protect marine ecosystems to conserve marine genetic biodiversity and to allow ocean life to recover. It will also help to cut carbon dioxide emissions.