Puget Sound eelgrass beds create a ‘halo’ with fewer harmful algae, new method shows

Lead author Emily Jacobs-Palmer and Washington Department of Natural Resources intern Max Miner conduct follow-up work in a Port Gamble eelgrass bed.

Eelgrass, a species of seagrass named for its long slippery texture, is one of nature’s superheroes. It offers shade and camouflage for young fish, helps anchor shorelines, and provides food and habitat for many marine species.

A University of Washington study adds one more superpower to the list of eelgrass abilities: warding off the toxin-producing algae that regularly close beaches to shellfish harvests. Researchers found evidence that there are significantly fewer of the single-celled algae that produce harmful toxins in an area more than 45 feet, or 15 meters, around an eelgrass bed.

“We’re not in the laboratory. The effect we’re seeing is happening in nature, and it’s an effect that’s really widespread within this group of harmful algae. What we see is this halo of reduced abundance around the eelgrass beds,” said Emily Jacobs-Palmer, a research scientist at the UW. She is the lead author of the study published this spring in the open-access journal PeerJ.

Researchers sampled five coastal sites three times in the spring and summer of 2017. Four sites were within Puget Sound and one was in Willapa Bay, on Washington’s outer coast.