San Rafael Oyster Reef Probed

Scientists are wading into bay waters in the San Rafael area this afternoon to monitor the progress of an underwater oyster reef where scientists say more than 2 million native oysters have settled since last year.

The activity is part of the San Francisco Bay Living Shorelines project, which aims to test various methods of restoring oyster populations and to explore whether such reefs can help prevent erosion related to rising sea levels, organizers said.

The project is a partnership between the California Coastal Conservancy and The Nature Conservancy, which owns the parcel in San Rafael where the reef is located, Project Manager Marilyn Latta said.

The project started in two Bay Area locations last summer -- the site off of Baypoint Village Drive in San Rafael, and an area near the Eden Landing Ecological Reserve in Hayward.

The 1-acre oyster reef in San Rafael was constructed last year when about 10,000 clean Pacific oyster half shells were placed into the water there, Latta said.

In the past year, plankton have attached themselves to the shells, and now 2 million native Olympia oysters have populated the habitat, which has also attracted other wildlife including juvenile Dungeness crabs and bay shrimp, she said.

Many different types of birds have also appeared at the site, which Latta said shows that the habitat is becoming a growing food source.

The birds include the Black Oystercatcher, which specifically feeds on oysters, she said.

The project has also constructed an eelgrass bed that forms meadows with deep roots that stabilize the sediment, she said.

Scientists hope that using this "nature-based solution" will protect the shoreline by stabilizing sediment as erosion increases because of rising tides.     

Latta said data collected so far have shown a 30 percent decrease in wave action, which she said can be attributed to the reef's  three-dimensional structure.

The site will be monitored through 2017 to make sure the habitat can meet the goals of the San Francisco Bay Subtidal Habitat Goals project, she said.

Scientists will be on the shoreline through Saturday, counting and measuring the oysters to monitor their growth rates, Latta said.

About 25 percent of the oysters are reproductive, which "gives us a good indication that (the habitat) is self-sustaining," she said.

The scientists will also be counting other invertebrates on the reef structures that have naturally come into the habitat, she said.

More information on the project is available at www.sfbaylivingshorelines.org.