Eelgrass: Ecosystem extraordinaire and keeper of carbon

Eelgrass at low tide


If Puget Sound were a grumpy old man, it would rightly say, “Get off my lawn!” But what lawn? What kind of grass grows in the water? If you guessed eelgrass, you’d be right.

A swath of eelgrass might even remind you of your own backyard, except underwater (and more overgrown than your lawn); using photosynthesis to grow, it can produce strands up to three feet long that look like green ribbons, anchored by roots in the ground below. Eelgrass is very responsive to changes in water quality, so it’s a useful ecosystem indicator: its presence, or lack thereof, affects many animal species.

Puget Sound and the Strait of Juan de Fuca are home to two species of eelgrass. Both the eelgrass blades and the roots play important roles for their ecosystem. Animals like pipefish and juvenile salmon can hide in the swaying greenery, while some organisms are attached directly to the strands, like herring eggs. Crabs, scallops and wading birds also rely on eelgrass meadows to find food, shelter or a place to raise young. Just like with trees on land, the roots of the eelgrass help prevent erosion from the surf, and they even help filter polluted runoff as it enters the ocean.


Herring eggs on eelgrass
Fish eggs attached to eelgrass


Eelgrass beds are also great for slowing global warming. They’re able to store huge amounts of carbon (keeping it from entering our atmosphere as carbon dioxide), making them one of the most efficient “carbon sinks” on our planet.

So when you come across eelgrass—whether you’re checking out Puget Sound’s beaches during low tide or find yourself in another temperate or subtropical climate—you’ll want to keep this incredible resource healthy and its occupants happy. How? It’s easy: Don’t step on it. Instead, you can crouch or kneel close by and observe this fascinating green marine habitat without putting any weight on it.

Interested in learning more about eelgrass on location? Our beach naturalists will be stationed on local shorelines during summer low-tide days, and they’d love to share their knowledge and enthusiasm with you. Check out our Beach Naturalist program page for dates and locations.

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