Marine life under threat as oxygen levels fall

James Marshall
December 9, 2019

Climate change and nutrient pollution are driving the oxygen from our oceans, and threatening many species of fish. The scientists estimate that between 1960 and 2010, the amount of the gas dissolved in the oceans declined by 2%.

"Deoxygenation will have an impact on biodiversity, on biomass of commercially important species and on vulnerable rare species". "The habitats are shrinking as species are fleeing these oxygen-deprived areas, but it's also altering the energy and the biochemical cycling". "We are seeing species [relocating] because of this", Epps added.

Species like jellyfish want low-oxygen areas, but low-oxygen sensitive ones, including most fish, don't.

The sea gets about a portion of all fossil fuel emissions; however, there are fears that the world's seas will eventually reach a saturation point as global energy demand continues to grow.

According to the report by the year 2100, the oceans will lose 3-4% of its oxygen inventory in a business as usual situation.

Grethel Aguilar, the IUCN's acting director, told Al Jazeera that the scale of damage climate change is "wreaking" upon the ocean comes into stark focus.

Any changes to the ocean's oxygen concentration run the risk of collapsing food chains and causing widespread disruption throughout the marine ecosystem.

The loss of oxygen from the ocean due to climate change risks "dire effects" on sea life, fisheries and coastal communities, a global conservation body said Saturday. The biomes that support about one fifth of the current catch of fish in the world are formed by ocean currents that carry oxygen-poor water to the coast.

The threat to oceans from nutrient run-off of chemicals such as nitrogen and phosphorus from farms and industry has always been known to impact the levels of oxygen in the sea waters and still remains the primary factor, especially closer to coasts.

The report claims that impacts in those areas can ripple out to affect hundreds of millions of people.

This week, the World Meteorological Organization said that because of the growth of human-made emissions, the ocean was now 26% more acidic than before the revolution industrial. "This is perhaps the ultimate wake-up call from the uncontrolled experiment humanity is unleashing on the world's ocean as carbon emissions continue to increase", said report co-editor Dan Laffoley, the principal advisor on Marine Science and Conservation for IUCN's Global Marine and Polar Program.

The report pinpoints nutrient pollution and climate change as the major culprits in the depletion, which threatens several species of tuna, marlins and sharks - larger species that have greater oxygen needs.

The IUCN report also found that pollution around coastlines was having a significant effect on oxygen levels, with fertiliser and agricultural runoff promoting more algae growth, which in turn depletes oxygen as it decomposes.

World leaders will meet in Marseille in June for the IUCN World Conservation Congress.

Policymakers are now in negotiations at the COP25 climate summit in Madrid charged with ratifying a comprehensive rulebook for the 2015 Paris accord.

Other reports by Click Lancashire

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