Bubbles could protect corals from ocean acidification

Blowing tiny bubbles through seawater could protect coastal ecosystems such as coral reefs and oyster farms from the harmful effects of ocean acidification by stripping CO2 from the water and transferring it to the atmosphere, say Stanford scientists.

The technique could provide a relatively inexpensive solution to ocean acidification, which threatens a variety of marine organisms such as coral, mussels and oysters, which use calcium carbonate to assemble their skeletons and shells, writes Stanford University.

Ocean acidification is particiularly harmful to coral reefs, 30 to 60 per cent of which have died since the Industrial Revolution as the oceans absorb more CO2 and become more acidic.

“The entire structure of the ecosystems is built upon the calcium carbonate skeletal remains of dead coral,” explains David Koweek at Stanford’s School of Earth, Energy & Environmental Sciences. “Ocean acidification makes it difficult for corals to calcify and makes it easier to erode these skeletal remains, threatening the integrity of the entire reef.”

In their study, the Stanford scientists showed that bubbling air through seawater for a few hours first thing in the morning can boost the transfer rate of CO2 from the ocean to the atmosphere – up to 30 times faster than natural processes. This significantly reduces CO2 concentrations in coastal marine environments.

Because the technique can only be used on a small sections of shallow coastlines at a cost, Koweek and his colleagues believe that the benefits to the marine environments from lowered ocean acidity levels would far outweigh the relatively small amount of atmospheric CO2 generated by the bubbling process and by the compressors needed to produce the bubbles.

“In the tropics, where there’s a lot of sunlight, you could charge your compressors with solar energy during the day and then bubble at night,” adds Koweek.


Image credit: Max Elman, flickr/Creative Commons

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