Marine Life Threatened as Ocean Oxygen Levels Fall

The world’s oceans are currently losing oxygen, a nature conservation organization reported. According to the International Union for Conservation of Nature (IUCN), around 700 areas in oceans around the world have low oxygen levels. This is a stark increase from only 45 sites back in the 1960s. The organization also found that the volume of anoxic waters, or areas completely devoid of oxygen, has quadrupled and that the oceans’ oxygen levels have declined by 2% since the 1950s. Furthermore, the organization predicts that oceans are expected to lose 3%-4% of their oxygen levels by the year 2100. The scientists found two major causes of deoxygenation or oxygen loss: climate change and eutrophication [yoo-tra-fuh-KEI-shuhn], or excessive algae [AL-jee] growth. Climate change has caused a global increase in temperature. Because of this, oceans have become warmer, lowering their oxygen levels. This affects marine life since metabolic and respiration rates increase as the temperature does. Additionally, warmer waters make it difficult for oxygen to travel to colder, deeper waters. Meanwhile, eutrophication occurs when agricultural wastes, like artificial fertilizers, sewage, and animal waste, accumulate into large bodies of water and feed algae. The algae grow then decompose, causing deoxygenation. According to the scientists, deoxygenation is threatening fish species, especially the large ones with high energy demand. These include marlin, tuna, and sharks. These marine animals are swimming closer to the surface, where there is more oxygen available, to survive. This leaves them prone to overfishing and puts them at risk from mass extinction. To solve this, the scientists advised people to slow down deoxygenation by reducing greenhouse gas emissions and limiting agricultural waste through legislation.