Urban Planning & Policy

Photo by: Sergio Ruiz (CC BY-NC 2.0)

We are at an important crossroads in our Bay's history. As every city and agency scrambles to plan for the onslaught of the effects of climate change, we know now that it's all happening much faster than we thought it would. But there are alternatives to building higher seawalls and riprap! The San Francisco Bay is a shallow water system that once had significant intertidal habitat. However, industrial activities such as dredging and channelization have resulted in a loss of these habitats since the late 1800s. In addition, sea levels in the San Francisco Bay are expected to rise 16 inches by the year 2050 and 55 inches by 2100. This adds to losses in wetland areas. Native oyster reefs serve as natural levees, attenuating wind wave and boat wake energy along shorelines while also helping to restore ecological functions to the estuary.

Native Olympia oysters (Ostrea lurida, or Olys, as we like to call them) are well suited to provide biologically rich, native oyster reefs in the San Francisco Bay because they were once a dominant species. Olys lost important habitat due to over harvesting, sedimentation from mining during the Gold Rush, pollution, and dredging. There are still enough Olys in the San Francisco Bay to repopulate reefs, but the oysters are suffering from a lack of substrate to latch on to. Native oysters prefer to grow on other oyster shell and providing substrate is critical to their success. They just need a place to hang their hat!

Natural resource managers and scientists understand the threats of continuing shoreline erosion, sea level rise, and climate change. Urban projects that aim to prevent large scale armoring of shorelines through placement of engineered riprap, seawalls, and bulkheads are increasingly considered as alternatives. Natural shoreline protection such as oyster reefs and eelgrass beds utilize natural habitat elements to protect shorelines from erosion while providing important habitat for wetlands and aquatic plants, fish, and wildlife.

Photo by: Tyler Ingram (CC BY-NC-ND 2.0)

Natural shoreline projects provide many benefits:

• Improve water quality by settling sediments and filtering pollution. 
• Provide shoreline access and functional habitat for ecologically and commercially important wildlife.
• Increase connectivity of wetlands and deeper intertidal and subtidal lands.

To learn more about rising seas in San Francisco Bay and a list of resources, see  Rising Tides.