Tiny Bubbles

Credit: 5W Infographics

Seagrasses store a lot of carbon in their tissues, making them a potential counterweight to rising levels of atmospheric carbon dioxide. The ability to quantify how much carbon a specific seagrass bed stores over time could help governments, businesses and environmental groups better manage these natural carbon sinks.

But it’s incredibly time-and-labor intensive – it takes a lot of people lugging instruments out into the water, taking plant and sediment samples and measuring water chemistry. Then samples have to be analyzed in a lab to estimate soil carbon content.

Ken Dunton, a professor in UT’s Marine Science Institute, and Preston Wilson, a professor in the Walker Department of Mechanical Engineering, are developing innovative ways to use sound to measure carbon storage in seagrass beds.

As seagrasses turn sunlight into energy, they absorb carbon dioxide from the water, store the carbon in their roots and other tissues and release the oxygen back into the water, some in the form of bubbles. The more bubbles a seagrass plant emits during the day, the more carbon it stores.

With support from the U.S. Advanced Research Projects Agency, they’re developing an automated system that continuously records sound intensity using underwater microphones called hydrophones. Sound intensity increases as more bubbles are released into the water. They’re simultaneously measuring sound intensity and actual carbon storage in a seagrass meadow near Port Aransas, Texas. By uncovering how those two relate, they hope to replace much of the arduous field work with passive acoustic monitoring.

“Ultimately, we want to develop these tools for commercial applications, providing them for scientists, conservation managers and others to measure carbon storage in seagrasses anywhere in the world using simple, inexpensive technology,” Dunton said.