San Diego Bay might look a little different beneath the surface — this past December the California State Coastal Conservancy + U.S. Fish and Wildlife Service installed 360 reef balls as part of the South Bay Native Oyster Living Shoreline Project. The great balls of water are designed to mimic natural reefs and attract oysters who help reduce rising sea levels and promote biodiversity in San Diego Bay.

We had a chance to speak with Eileen Maher — Port of San Diego's Director of Environmental Conservation — to understand the basics of this $960,000 project + learn more about its progress and objective.

Q: In your opinion, why is the South Bay Native Oyster Living Shoreline Project important to South Bay?

A: This is a first of its kind nature-based solution that we’ve done in San Diego Bay. It’s very important for resiliency and protecting against future sea-level rise impacts — especially in South Bay because it’s so shallow down there. It’s also very important for protecting the additional species we have. We think it will attract additional bird + fish species to the area. Oysters have multiple benefits including filtering the water and making the water cleaner for everyone. It’s going to help with reducing any storm surge to an adjacent wetlands project, and help with erosion.

Q: Why are oysters so important?

A: Oysters play an essential function in the ecosystem of San Diego Bay. They filter 50 gallons a day of water, so it helps remove contaminants that are in the water, and they help sequester carbon, so they help with the reduction of greenhouse gasses and absorbing that carbon to pull it out of the atmosphere.

Q: “Reef balls” sound interesting. How did they get their name?

A: It’s a nature-based solution — we’re mimicking what nature would do by itself with this project — reefs are an important habitat.

Q: Why so many reef balls?

A: We put in 360 reef balls. They are set up in a specific formation, so there’s four reef elements in a reef array, to attract the native oyster, and they’re also designed to reduce the wave action on the adjacent shoreline.

Q: Will the presence of the reef balls impact the public?

A: Most of the public won’t be using them beyond photos unless you’re kayaking at low tide. We welcome the public to go look at them, please don’t touch them because they’re trying to form a habitat (obviously). The public benefits from the water the oysters will bring to the bay and benefits from the carbon sequestration the oysters provide. Any saltwater habitat can also help with the storm surge and help bring different species. So, it’s connected a habitat that anyone can benefit from.

Photo of Eileen Maher via Port of San Diego

Q: What plants + animals are you hoping to attract?

A: San Diego Bay has a lot of eelgrass. It has about 20% of the eelgrass in the state of California, and about 50% in Southern California. And we believe that the reef balls will accumulate sedimentation so that — behind the reef balls we set up — we will create additional habitats that don't currently exist.

We also think that because the oysters will be on the reef balls, fish will come to the reef balls. Fish can swim in and out of the reef balls so a little bit more habitat is protected, so they can hide from their predators. And we believe that because the fish are there, the eelgrass will also attract birds. We are monitoring fish and bird populations — pre-construction and post-construction, so we’ll see what the increases of the birds will be.

Q: Why is eelgrass so important to San Diego Bay?

A: Eelgrass is very important to the bay. It’s at the base of the food chain, so eelgrass is submerged aquatic vegetation — it’s a long, thin, bladed grass. Anywhere from 75-80% of the fish in San Diego bay are juvenile fish and they spend early life stages in the eelgrass beds. It’s a place to hide from predators so they can grow big and spend their adult lives in the ocean. A lot of birds feed off the eelgrass, and the turtles in San Diego Bay feed off the eelgrass.

Q: The project is being measured for five years — what has happened since the installation in December?

A: Probably getting more fish, but we haven’t actually verified that. Typically the oysters will sprout at the appropriate terms they would in the water, and they will float around and find a place to live. The oyster reefs were actually made with pieces of oyster shells — and the oysters, they’ll say, “Oh, there’s shells there, that must be a safe place for me to live,” — so they’ll attach to other oyster shells. Typically they have a big pulse of that in the March/April timeframe. So, it will probably be more summer time that we’ll start seeing the growth.

Q: What are you hoping to see in five years?

A: There would be a very healthy oyster population on all of the reef balls, that we’ve attracted more fish + birds to the area, and there’d be sediment secretion on the backside on the oyster reefs. Eelgrass would grow naturally, there'd be less erosion on the shoreline adjacent to it, and we’d have the added benefit of all those additional oysters filtering water and sequestering carbon.

Q: Why are you most excited for this project?

A: What really interests me is any project providing additional habitats or resources to San Diego Bay, and this will have so many cool benefits that help with sea level rise, help with the carbon sequestration, help to clean the water — that it’s just a fantastic project in my mind.

Q: In your opinion, what makes this project a success?

A: A very healthy oyster habitat after five years. What really would be successful in my mind is that the same project is placed — not just in San Diego Bay — but in coastal communities across the United States. That would be really successful, that other cities + municipalities can learn from this project and mimic it and also provide the same great benefits to their municipalities and their bays + waterways.