By Charlotte Pitt
Sprawled across the San Francisco Bay in habitats known as shellfish beds reside a multitude of species sensitive to the quality of water, such as oysters, mussels, and clams. These shellfish were once a popular food source for the residents of the San Francisco Bay area, however in modern times pollution runoff from industry and agriculture is too high to consume any shellfish from the bay.
The most abundant of these species, the native Olympia oyster (Ostrea lurida), has been a primary focus of restoration efforts, as pollution and loss of habitat have caused the population size to greatly decline. In an effort to help sustain a healthy population of Olympia oysters, known as Olys to oyster lovers, The Watershed Project created an artificial reef habitat by placing 100 reef balls at Point Pinole in Richmond, CA. The reef balls provide a hard surface for the oysters to attach to and grow on, providing crucial habitat for these impressive creatures that can filter 50 gallons of water a day!
Another type of shellfish in the San Francisco Bay is the California mussel (Mytilus californianus). The California mussel ranges along the coast of the eastern Pacific Ocean from southern Baja California to southeastern Alaska, and can be found throughout the San Francisco bay but are more abundant in the areas with higher salinity and more rocky substrate around the Central Bay. California mussels attach themselves to hard substrates by producing protein fibers called byssal threads and can be found in the tidal zones up to 24 meters in depth, but tend to favor surf zones where the waves are breaking. The exterior of the dark blue-black shells are often eroded from wave action, while the interior of the shell is protected and is a light blue-grey with an iridescent shine.
California mussels form extensive shellfish beds and often attach on top of each other, and these multi-layered beds serve as important habitat for a wide variety of other living beings. The California mussel shellfish beds trap water and sediments which then act as shelter and food for a wide diversity of plants and animals. As a filter-feeder, meaning they strain matter and food particles from the surrounding water, the California mussel is very sensitive to the quality of the water as toxins accumulate in the tissues of the mussel. This is unfortunate for the many organisms that prey on California mussels, such as crabs, shore birds, sea stars, sea otters, and humans.
Unfortunately the San Francisco Bay is inundated with pollutants spilling into the water from surrounding industry, agriculture, and everyday life. In order to improve the quality of the bay not only for the shellfish that live in it but for the many organisms that depend on them, more habitat for California mussels and other filter-feeders is crucial. These shellfish can filter pollution out of the bay and provide cleaner water and food for all life in the San Francisco Bay area. But until conditions in the San Francisco Bay improve it is best to not be selfish, and don’t eat the shellfish!
Neal, Elizabeth A. “Mytilus Californianus.” Animal Diversity Web, University of Michigan, animaldiversity.org/accounts/Mytilus_californianus/.
“Shellfish Beds.” San Francisco Bay Subtidal Habitat Goals Project: Conservation Planning for the Submerged Areas of the Bay, San Francisco Bay Subtidal Habitat Goals Project, www.sfbaysubtidal.org/shellfish.html.
Veltman, Chloe. “The San Francisco Bay Once Teemed with Oysters. What Happened?” KQED, www.kqed.org/news/11857703/san-francisco-bay-once-teemed-with-oysters-what-happened.