Coastkeeper Seeks To Replenish Oyster Reefs

November 23rd, 2015

Parimal M. Rohit
The Log

Oysters and eelgrass go together like peanut butter and jelly or cookies and milk. Such a connection is being made by Orange County Coastkeeper, which seeks to replenish Southern California’s oyster reefs to help maintain eelgrass populations and generally benefit marine life.

Replenishing oyster populations could play a significant role in eelgrass management. Southern California has an eelgrass mitigation policy in effect dictating dredging projects and limiting the placement of boat docks, gangways and ramps. Eelgrass mitigation measures often require dock owners, marina managers or harbor operators to ensure the submerged plant receives sufficient sunlight.

“The depth in which eelgrass is able to grow is solely dependent on how much light can reach them. By filtering the water of its particles, oysters have the ability to make the water clearer and allow eelgrass to receive more sunlight,” Sara Briley wrote in a blog for OC Coastkeeper. “Oysters may drastically improve water quality. They filter large amounts of water by feeding and thus removing nutrients, sediments and other pollutants out of the water. Filtering up to 50 gallons of water per day, oysters may be able to improve the amount of light reaching nearby eelgrass.”

OC Coastkeeper reported earlier this month about 85 percent of the world’s oyster reefs have disappeared since the 1990s. The nonprofit clean water organization, in conjunction with Cal State Fullerton, Cal State Long Beach and KZO Education, launched an effort to restore an oyster habitat at Jack Dunster Marine Reserve in Long Beach’s Alamitos Bay. Oysters help sunlight penetrate ocean water by filtering sediments or other pollutants. The increased water quality provides clarity, allowing sunlight to penetrate into deeper waters. Eelgrass requires at least 18 percent (and as much as 30 percent) sunlight exposure for eelgrass to properly grow.

Briley said oysters play a significant role in the ecosystem.

“Oysters are a foundation species, meaning that they play a large role in modifying their environment and a critical role in maintaining structure in the community,” she said. “A group of oysters forms a bed or reef because they themselves provide habitat for a number of marine species. The nooks and crannies in the oyster shells provide a place where other small organisms may live.”

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Categories: Waterkeepers at Work