Can Eelgrass Help in the Fight Against Climate Change?

Ben Levenson

When showing visitors around the Great Bay estuary in CLF’s Great Bay–Piscataqua Waterkeeper vessel, it can be challenging to drum up enthusiasm for eelgrass. This unique type of seagrass resides beneath the surface of the water and is hard to see. But this amazing organism plays a major role in the health of the estuary’s ecosystem – as well as the fight against climate change.

As our climate continues to change and the effects become more obvious, the benefits of healthy and productive eelgrass beds are becoming better understood – and more important. Besides providing needed oxygen and anchoring sediments, a unique quality of eelgrass is its ability to sequester carbon at an extremely high rate. In an article for the Boston Globe, Derrick Jackson wrote that one acre of healthy eelgrass can sequester as much carbon as forty acres of forest.

On a global scale, this means that, despite covering less than 0.2 percent of the world’s oceans, eelgrass accounts for nearly 12 to 20 percent of the ocean’s carbon sequestration. According to Phillip Colarusso, an EPA biologist, eelgrass is able to store carbon in a more effective way than terrestrial plant systems by storing the carbon in the sediments and deposits beneath the root mass. In the low oxygen area beneath roots, the carbon can be buried for the entire lifetime of the meadow and will only be released if the meadow is disturbed or the eelgrass dies off. This is an amazing feat!

This sounds like great news for addressing the threat of climate change. But, the reality is that seagrass meadows are at risk – nearly 29 percent of all seagrass meadows have been destroyed. In the Great Bay estuary, that rate of loss is even higher, with eelgrass decreasing by 41 percent since 1996. In addition to losing sequestration capacity, the loss of eelgrass meadows results in the slow release of stored carbon back into the environment – the opposite of what we need.

In light of the rapid decline of eelgrass, it is important that the quality of the water in Great Bay is restored. Local activists are optimistic that with improvements such as reductions in inorganic fertilizer use and upgrades to local sewage treatment plants, eelgrass will have a chance to recover – improving water quality, anchoring sediments, providing oxygen, and sequestering carbon.

CLF and the Great Bay–Piscataqua Waterkeeper are working to rally and educate the public about the threats to eelgrass – and support local action to restrict fertilizer use and fund much-needed updates to sewage plants. Find out how you can get involved in our work to protect Great Bay..

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