Antonio Manaytay – Fourth Estate Contributor
San Diego, CA, United States (4E) – The rising level of seawater due to global warming has left the oceans gasping for breath. A new study revealed that the volume of water in the ocean with zero oxygen had increased more than four times in the past 50 years.
The same is happening for the bodies of water along the coasts where sites of low oxygen have increased more than 10 times over the same period.
To stop the drop of the level of oxygen is to mitigate climate change and address the issue of water nutrient pollution, an international team of scientists collaborating on the new paper published on January 4 in the journal Science said.
“Oxygen is fundamental to life in the oceans,” lead author Denise Breitburg, a marine ecologist with the Smithsonian Environmental Research Center said.
“The decline in ocean oxygen ranks among the most serious effects of human activities on the Earth’s environment,” she added.
Lisa Levin, a biological oceanographer at Scripps Institution of Oceanography at the University of Carolina San Diego, the condition spells disaster for support services that rely on recreation and tourism.
“It’s a tremendous loss to all the support services that rely on recreation and tourism, hotels and restaurants and taxi drivers and everything else,” she said, adding that “the reverberations of unhealthy ecosystems in the ocean can be extensive.”
The study, a product of a group of scientists from Global Ocean Oxygen Network (GO2NE), was the first to have explored the causes, implications, and solutions to low-oxygen water worldwide. GO2NE is a working group created by the United Nation’s Intergovernmental Oceanographic Commission in 2016.
GO2NE executive secretary Vladimir Ryabinin said almost half of the Earth’s oxygen “comes from the ocean.”
“However, combined effects of nutrient loading and climate change are greatly increasing the number and size of ‘dead zones’ in the open ocean and coastal waters, where oxygen is too low to support most marine life,” he stressed.
Oxygen is low in “dead zones” such as those in the Chesapeake Bay and the Gulf of Mexico causing so many animals to suffocate and die. As a result, the habitat for fish shrank because they avoid these low-oxygen sites making them more vulnerable to predators and fishing.
The problem, however, is not limited in the so-called “dead zones.” A very slight drop of oxygen, the authors said, could affect the growth in animals, causing infertility and disease and even death.
The drop of oxygen in water would also cause the release of nitrous oxide from the water, a greenhouse gas that is 300 times more harmful than carbon dioxide. It could also trigger the release of another harmful chemical – hydrogen sulfide.
It is possible that some fish may still thrive in “dead zones” but the overall diversity is compromised.
Climate change, the study said, is the major cause of low-oxygen water as warmer surface prevents the oxygen to penetrate the interior of the ocean.
GO2NE scientists said the situation should be addressed to mitigate low-oxygen water in the open ocean and coastal waters.
Some of the solutions proposed by GO2NE include the following: mitigate climate change and address water nutrient pollution; provision to protect marine life, which include the setting up of marine protected areas and no-catch zones; and enhance the monitoring of low-oxygen worldwide.
“This is a problem we can solve. Halting climate change requires a global effort, but even local actions can help with nutrient-driven oxygen decline,” Breitburg said.
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