Climate change buffer
By Phil Colarusso
Particles settle in grass
Seagrass meadows rule
Seagrass meadows collect and sequester large amounts of carbon in the sediments below the meadows. The carbon accumulates through 2 different pathways. First, through photosynthesis and tissue growth, seagrasses extract carbon from the water column and incorporate it into its own tissues. The root and rhizome structures and some cast leaf material end up being incorporated into the sediments. In most cases, this provides less than half of the carbon found in those sediments. The majority of the carbon in the sediments originates from outside of the meadow. The canopy of the meadow functions as a filter, facilitating the settlement of organic particles as the tide passes over the meadow going in and out.
As long as the meadow stays intact, the carbon in the sediments remains isolated and out of the global carbon cycle. Data shows that the age of carbon in meadows can be hundreds of years old. Seagrass meadows, salt marsh and mangroves all perform the same carbon sequestration function and collectively are referred to as blue carbon habitats. This is still a relatively young field of research.
In the above photo, you can see the seafloor in the foreground, which is primarily sandy cobble. The eelgrass meadow has a dark organic layer indicating the large carbon component that has accumulated due to the presence of the plants.
Further reading on seagrass blue carbon: https://doi.org/10.1038/ngeo1477
Dr. Phil Colarusso is a marine biologist with US EPA Region I. He has been working on eelgrass restoration, conservation and research for 31 years. He and his team just recently had a paper on carbon sequestration rates in eelgrass in New England accepted for publication.
Interested in seagrass meadows? They’re also hugely important for the world’s fisheries. Find out more in the sciku Forgotten Value here. You can also check out Phil’s sciku Invasive Species and Diving for Science.
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