Seed-filled buoys may help restore diverse sea meadows in San Francisco Bay
A pearl net filled with seedpods, tethered by a rope anchored in the coastal mud but swaying with the tide, could be an especially effective way to restore disappearing marine meadows of eelgrass, according to a new study.
The resulting crop of eelgrass grown by SF State researchers is as genetically diverse as the natural eelgrass beds from which the seeds were harvested, said Sarah Cohen, an associate professor of biology at the Romberg Tiburon Center. As eelgrass meadows are threatened by a number of human activities, restoration plans that maintain diversity are more likely to succeed, she noted.
The emphasis on genetic diversity is a relatively new concern in ecosystem restoration projects, where there has been an understandable urgency to move plants and animals back into an area as quickly as possible. “It’s taken a little longer for people to say, ‘we need to know who we’re moving,'” Cohen said, “and to explore how successful different genotypes are in different settings, so we can more strategically design the movement of individuals for restoration.”
Eelgrass restoration projects are challenging because it’s not easy to plant seedlings under the water, and seeds scattered over a large area could be washed away from the restoration site. Instead, RTC researchers tested the Buoy Deployed Seeding (BuDS) restoration technique. They first harvested eelgrass seedpods from several eelgrass beds in San Francisco Bay, then suspended the pods within floating nets over experimental tanks (called mesocosms) supplied with Bay water and with or without sediment from the original eelgrass areas. As the seeds inside each pod ripened, a few at a time, they dropped out of the nets and began to grow within the tanks.
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