PANAJI: Depleting oxygenlevels in the oceans and coastal waters have worried scientists, who are looking at addressing the causes and arresting its decline.
A team of scientists from GO2NE (Global Ocean Oxygen Network) in a study, ‘Declining oxygen in the global ocean and coastal waters’, have proposed various measures to tackle the falling oxygen levels.
“Approximately half of the oxygen on Earth 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,” said Vladimir Ryabinin, executive secretary of the International Oceanographic Commission that formed GO2NE.
The aim of the study is to keep oxygen levels in check, protect vulnerable marine life and improve low oxygen in water in an attempt to counter the spread of dead zones in the ocean.
Former director of the Goa-based National Institute of Oceanography (NIO) S W A Naqvi, who is the co-author of this paper, said although the rate of deoxygenation appears to be lower in the seas around India than in the Atlantic and Pacific oceans, India’s seas, especially the Bay of Bengal, are extremely vulnerable to even minor oxygen declines.
“Moreover, the western shelf of India houses the world’s largest shallow water low-oxygen zone that could intensify, and more such zones could develop in the Indian Ocean due to high population pressure. If this happens, it will have far reaching economic and socio-economic ramifications,” he said.
The scientists want people to start by adopting better sanitation systems that can protect human health and keep pollution out of the water. Also, curbing fossil fuel emissions will help cut greenhouse gases and slash dangerous air pollutants such as mercury, they said.
Further, the scientists want to create marine-protected areas or no-catch zones in locations that are used by animals to escape low oxygen.
The experts said enhanced monitoring of low oxygen zones, especially in developing countries, and numerical models that will help in pinpointing the places that are most at risk, would also help.
“Halting climate change requires a global effort, but even local actions can help with nutrient-driven oxygen decline,” said Denise Breitburg, lead author and marine ecologist with the Smithsonian Environmental Research Center.
The scientists also said livelihoods of people may be affected as smaller, artisanal fisheries may be unable to relocate when low oxygen destroys their harvests or forces fish to move elsewhere. It may make it easier for fishing, but it could result in overfishing and damage the economy, they said.
“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,” said Lisa Levin, marine biologist with the University of California. “The reverberations of unhealthy ecosystems in the ocean can be extensive,” she added.