Emerald green and resplendent with glittering baby fish and tiny crabs, eelgrass meadows are among the most productive and ecologically important places in Puget Sound. Already highly valued as nurseries for sea life, researchers have discovered a new eelgrass superpower, as living urban systems that reduce human pathogens in seafood by as much as 65%. The researchers’ findings, published in an Aug.
2 paper in Nature Sustainability, point to yet another reason to protect eelgrass here. Climate change has taken a devastating toll on eelgrass, a kind of seagrass, in some areas of the Salish Sea. For example, declines of 90% and more have been documented in the San Juan Islands because of a wasting disease stoked by warming water.
To find out how much eelgrass can clean up the water it grows in, researchers employed a species with exceptional filtering and concentrating abilities: mussels. In the study, they acted as a sort of test strip, to find out what is in the water. Working with volunteers in the Washington Department of Fish and Wildlife’s Puget Sound mussel monitoring program, the researchers obtained clean mussels from Penn Cove on Whidbey Island, then placed them around urban waters of Puget Sound, in cages so predators wouldn’t get them.
Put out in late fall, the mussels were collected three months later. In 20 locations around Puget Sound, mussels placed in areas with eelgrass were 65% cleaner (of bacteria that can sicken people) than mussels placed in areas wi.