Friday, 3 December, 2021

Ocean scientists for global tracking of oxygen loss

Ocean scientists for global tracking of oxygen loss

A team of ocean scientists from six continents have made an urgent call for a global system to track the loss of oxygen from parts of the ocean and coastal waters that causes dead zones, where almost nothing can live, reports The Guardian.

Ocean heating caused largely by burning fossil fuels is making the problem worse, experts say, with serious consequences for communities, fisheries and ecosystems around the world.

Fifty-seven scientists from 45 institutions in 22 countries have laid out the urgent need for the global monitoring system, which they say could help protect ecosystems such as coral reefs and fisheries around the world.

Dead zones with low or no oxygen can last from days to months in so-called hypoxic events that can kill fish, plants and crustaceans.

Coastal events are usually triggered by extra nutrients running into estuaries, and are made worse by warming waters. There are hundreds of hypoxic zones on coastlines around the world, with some evidence oxygen levels in parts of the open ocean are also falling.

Prof Karin Limburg, of State University of New York, is one of the scientists calling for a global system to monitor ocean oxygen, to be established under the UN.

“There is a pressing need to document and predict hypoxic episodes and hotspots of low oxygen in order to take protective actions for aquaculture, put in place precautionary measures for affected fisheries, and monitor the wellbeing of important fish stocks,” Limburg said.

“Without this understanding, we are in the dark about impacts that have large economic-ecological implications.”

Prof Jodie Rummer, of James Cook University, is a co-author of an article to appear on Sunday in the journal Frontiers in Marine Science laying out the case for the monitoring system.

“Everything needs oxygen in the water. Most life in the ocean is not hypoxia tolerant,” Rummer said.

“These problems are getting worse because we are not solving the problems of nutrient run-off and our waters are continuing to warm. “We still don’t know the long-term implications of these problems that affect fisheries and aquaculture that feed human populations.”

Rummer is coordinating a new project with Unesco to look at the affects of lower oxygen levels on the world’s sharks. There is emerging evidence, she said, that corals in tropical areas are also at risk from low-oxygen events.

There is already an array of equipment taking ocean oxygen measurements,      including underwater gliders, free-floating instruments and sensors. But there needs to be more and the data is not openly available or standardised, the scientists say, making global assessments and research harder at a time when the problem is becoming urgent.