Simply blowing air bubbles in the seawater may help protect coral reefs, a new study has found.
What seems like a fun activity may protect the reef from the ocean waters, which are increasingly becoming acidic due to human interventions that stripped off carbon dioxide from marine environments and transport it into the air.
Ocean acidification pose hazards to different marine species, but the impact is much higher in those that use calcium carbonate to arrange their shells and skeletons.
In a new study by Stanford University, researchers showed how introducing air bubbles through seawater for a couple of hours in the morning can help boost the transfer rate of carbon dioxide between the air and water. The said increase amounts to 30 times faster than the natural rate, leading to a notable decrease in greenhouse gas concentrations in local marine environments.
Study co-author Rob Dunbar says the good thing about bubbling is that it involves an engineering method that brings the coral reefs close to an environment that existed for them 100 years ago.
The study started when lead author David Koweek was studying natural chemical cycles of coral reefs and other ecosystems in shallow waters. He noticed that carbon dioxide levels follow a constant pattern of highs and lows within a day. Carbon dioxide levels decline when the sun is out and photosynthesis among some marine species takes place. During the night, however, carbon dioxide levels shoot up when plants and animals respire and the process of photosynthesis takes a dip.
With this, Koweek wondered if it may be feasible to stimulate coral development by decreasing the levels of carbon dioxide in the water during predawn through bubbling - taking the gas out of the water and transport it into the air.
The team then conducted a bubbling experiment wherein they placed a sensor-laden water tank at a marine station. Every night, they would put bags of giant kelp into the tank.
The kelp is left to respire throughout the night thus, adding more carbon dioxide into the water and spurring gas buildup.
Every morning, the team would remove the kelp and bubble up the carbon dioxide-filled seawater to see if the intervention could lower the gas concentrations.
Indeed, the team observed that bubbling can boost the transfer of carbon dioxide from the water to the air 10 to 30 times faster than natural circumstances, all within the short span of two hours only.
Doing It The Right Way
Experts say bubble stripping, if timed in the right way, could have the potential of becoming an effective measure for taming down activity in coastal environments today and in the future.
Study co-author Robert Dunbar says strategic implementation of little bubbling can have vast effects, taking note of the unidirectional water flow that exists in majority of Pacific coral reefs.
"If you operate your bubbler in an area that is upstream of a large section of coral, you could reduce CO2 levels for an entire reef," he says.
Corals are not the only ones. Bubbling may also have beneficial effects on other marine ecosystems such as seagrass meadows, mangroves and salt marshes that also face varying levels of carbon dioxide from day to night.
The study was published in the journal Environmental Science & Technology on March 18.