Oceans Losing Oxygen at Unprecedented Rate, Experts Warn

Oxygen in the oceans is being lost at an unprecedented rate, with "dead zones" proliferating and hundreds more areas showing oxygen dangerously depleted, as a result of the climate emergency and intensive farming, experts have warned. From a report: Sharks, tuna, marlin and other large fish species were at particular risk, scientists said, with many vital ecosystems in danger of collapse. Dead zones -- where oxygen is effectively absent -- have quadrupled in extent in the last half-century, and there are also at least 700 areas where oxygen is at dangerously low levels, up from 45 when research was undertaken in the 1960s. The International Union for the Conservation of Nature presented the findings on Saturday at the UN climate conference in Madrid, where governments are halfway through tense negotiations aimed at tackling the climate crisis.

Grethel Aguilar, the acting director general of the IUCN, said the health of the oceans should be a key consideration for the talks. "As the warming ocean loses oxygen, the delicate balance of marine life is thrown into disarray," she said. "The potentially dire effects on fisheries and vulnerable coastal communities mean that the decisions made at the conference are even more crucial." All fish need dissolved oxygen, but the biggest species are particularly vulnerable to depleted oxygen levels because they need much more to survive. Evidence shows that depleted levels are forcing them to move towards the surface and to shallow areas of sea, where they are more vulnerable to fishing.