San Diego Port Installing 'Reef Balls' To Protect From Sea Rise

SAN DIEGO -- The Port of San Diego, in partnership with the California State Coastal Conservancy and U.S. Fish & Wildlife Service, has begun installation of the South Bay Native Oyster Living Shoreline Project adjacent to the Chula Vista Wildlife Refuge.

The project, which has been years in the making, is the latest of several POSD projects to protect the shoreline from impacts related to rising sea levels and to increase the biodiversity of San Diego Bay by creating new marine habitats.

The project’s total cost is about $960,000 and is fully funded via grants from the U.S. Fish and Wildlife Service and Builders Initiative. The cost covers the fabrication, installation, and long-term monitoring of the project.

“The Port of San Diego is proactively and continuously planning for and implementing various strategies to reduce the impacts of future sea level rise,” Port of San Diego Board of Port Commissioners Chair Michael Zucchet said.

“The State of California is investing in the health and resilience of its shorelines to protect our communities and economies, while supporting the biodiversity of our coastal habitats,” California State Coastal Conservancy Executive Officer Amy Hutzel said. “This project demonstrates the potential of nature-based solutions to help one of California’s most iconic and vibrant waterfronts keep pace with rising seas.”

This project is utilizing a modular approach under which constructed reef ball elements are being placed in a series of six arrays. Each reef array includes 15 reef groups composed of four reef ball elements made of baycrete (concrete mixed with local sand and oyster shell aggregate) placed in a square pattern for a total of 360 reef ball elements and 90 reef groups. The elements will be placed at specific elevations to optimize recruitment of native oysters.

Each reef array is roughly 88 feet long by 45 feet wide to accommodate the 15 reef groups with 14-20 feet of spacing between each reef group. While the total area of the project spans about 29,700 sf (0.68 acre) of intertidal shoreline, the total "footprint" of the reef ball elements would be substantially lower at 5,760 sq ft (0.13 acre).

The project’s objective is to demonstrate the ability to attract and establish native oyster populations that create structurally complex "reef" habitats for fish, birds, invertebrates, and aquatic plants. The project is also expected to improve local water quality via oyster water filtration and settling of sediments, as well as increase wetland connectivity to intertidal and subtidal lands.

After installation is complete, the pilot project and the adjacent shoreline will be monitored and assessed for five years to study the amount of growth of native oysters on the reef elements; learn about the presence and/or absence of non-native species on the reef elements; learn how the reef impacts or enhances local species richness of fish, birds and mobile invertebrates within the project footprint; and determine the ability of the reef elements to catalyze sediment accretion or reduce erosion of sediment shoreward of the project.

If successful, the reef will be permanent.