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The world’s oceans absorb nearly a third of global carbon dioxide emissions. Seagrass beds, in particular, are carbon-storing powerhouses. While less than 1% of the seafloor is made up of seagrass beds, those beds store about 11% of the ocean’s buried carbon, according to the National Oceanic and Atmospheric Administration.
But soaking up all that carbon can cause ocean water to become more acidic, a problem that scientists have been tracking for years.
Now, Georgia researchers are studying an approach that could counteract that effect and also encourage seagrass to store even more carbon.
Georgia Southern University professor Tyler Cyronak and a colleague at the University of California-Davis, with the help of a $250,000 grant from the National Science Foundation, are testing what’s called enhanced weathering. The idea is to add alkaline rock to seagrass beds to decrease their acidity.
“We sort of want to see if we can add on top of this enhanced weathering to sort of supercharge the seagrass as carbon removal,” Cyronak said.
It’s an approach that some companies are already trying, adding ground-up rock to beach renourishment projects and offshore berm placements.
However, altering ecosystems like this can have unintended consequences. Some of the rock in question has heavy metal components, which could leach into the seagrass and make their way into the food chain, affecting the health of other species. The alkaline rock could also harm the growth of the seagrass itself. Cyronak’s team plans to study those potential impacts.
“We want to just understand the basic science behind it and to understand whether it’s a good idea or not,” he said.
“Whether the seagrass thrives under it and it helps them grow, and we can remove carbon dioxide and everything works, or whether it actually ends up being bad for the seagrass, which then we know this is not a good idea to pursue.”
The researchers plan to measure the growth of the seagrass and test the roots and leaves for evidence of heavy metals.
Seagrass is important beyond its ability to store carbon, Cyronak noted: it provides essential habitat to many species and protects shorelines by acting as a natural barrier to erosion, stabilizing the sediment on the seafloor.
“If we can somehow make it valuable in the sense that we’re also removing carbon…I think it’s a win-win situation,” he said.
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