Seagrass Restoration Study Shows Rapid Recovery of Ecosystem Functions

As the dominant seagrass species on the U.S. West Coast, eelgrass supports a wide range of ecosystem services and functions, making its preservation and restoration a top priority for the region. Eelgrass restoration has a spotty record of success, however, and studies of restoration sites have rarely assessed the full range of ecosystem functions.

In a new study published October 6 in Ecological Applications, researchers demonstrated that eelgrass restoration efforts can lead to rapid expansion of restored plots and recovery of ecosystem functions.

The study involved small-scale experimental seagrass restoration efforts in Elkhorn Slough on the Central Coast of California. Researchers transplanted 2,340 shoots of eelgrass from healthy meadows into 117 small plots, and evaluated their success relative to areas without vegetation and natural eelgrass meadows.

"Within a few years, most of the ecosystem functions were near or at the level seen in natural eelgrass meadows, suggesting that these habitats can recover pretty quickly if the conditions are right," said first author Kathryn Beheshti, who earned her Ph.D. in ecology and evolutionary biology at UC Santa Cruz in 2021 and is currently a California Sea Grant Fellow at the Ocean Protection Council's Climate Change Program.

The restored plots expanded dramatically, resulting in eelgrass beds covering an area 85 times larger than the initial plots. The restored beds began to resemble the natural meadows in structural features such as canopy height and shoot density, in the richness and abundance of species using the restored habitat, and in water quality. The study assessed a suite of seven ecosystem functions, and the researchers also developed a multifunctionality index to assess the overall functional performance of the restored beds.

"We found that overall the restored plots are performing higher than unvegetated plots and just slightly below the natural meadows," Beheshti said.

The benefits of eelgrass meadows range from coastal protection and sediment stabilization to providing food and shelter for many species of fish and invertebrates. Eelgrass meadows provide crucial nursery habitat for many commercially important species, such as Dungeness crab, California halibut, and Pacific herring, whose juveniles find protection within the dense canopy. By slowing water flow and attenuating waves, eelgrass can act as a storm buffer and can protect developed coastlines from storm surges. Eelgrass meadows also counteract ocean acidification by absorbing carbon dioxide from seawater.