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Shell Survivors

Restoring Southern California’s Ecosystem Engineer, the Olympia Oyster

oysters covered by netting SOURCE: NOAA Pollution in coastal waters around the country has damaged shellfish habitats for decades, but promising restoration programs can preserve the tiny bivalves that are crucial to healthy waters along our shorelines.

Despite a continuously expanding oil slick, the Gulf Coast isn’t the only spot in the United States where marine life is in harm’s way. Pollution in coastal waters around the country has damaged shellfish habitats for decades, but promising restoration programs can preserve the tiny bivalves that are crucial to healthy waters along our shorelines.

Native Olympia oysters were once ecologically and economically dominant along the Western Coast of North America. These bivalve shellfish were the ecosystem engineers of bays and estuaries, enabling prosperous habitats for other species and considered commercially important as a delectable food source. But a combination of over-harvesting, dredging, pollution, and wetlands destruction in the 1930s depleted natural populations.

Oysters are a keystone species: if they thrive, others will too.

Could Olympia oysters once again become a nutritional food source while also improving the water quality in Southern California bays and estuaries? Successful programs in Oregon, Washington, and the Chesapeake Bay have already set positive precedents. In Northern California, municipalities, local stakeholders, and nonprofit organizations have initiated native oyster restoration projects in San Francisco, Tiburon, and Tomales Bays.

The Puget Sound Restoration Fund, a Washington-based nonprofit organization, planted 10 million native oysters at 80 sites with the volunteer help of over 100 community partners. This organization also launched 3 community oyster farms to improve water quality, restore productive oyster growing areas and reconnect people to healthy marine resources.

A single adult oyster can filter up to 50 gallons of water a day, allowing sunlight to penetrate so that foundations of the food chain can thrive: once water clarity increases, bottom vegetation, such as eelgrass, flourishes. Ecologically, oysters serve as indicators of overall health of the environment and oyster beds provide habitat for attracting fish, crustaceans, and other marine life. Moreover, oysters are environmentally sustainable on their own since they do not require fish feeds, compete with wild species for food, or consume more protein than they produce. Oysters are a keystone species: if they thrive, others will too.

Oyster beds are essential to the health of marine ecosystems, yet in the past, they have been solely managed for harvest, not habitat. Nutritional oysters are the number one farmed aquatic species in the $90 billion global aquaculture market, the fastest growing form of food production in the world. Oysters pack huge amounts of protein; are loaded with vitamins; stocked with omega-3 fatty acids; and, replete with minerals: calcium, iodine, iron, potassium, copper, sodium, zinc, phosphorous, manganese, and sulfur.

Oyster gardening is a community-based program for growing baby oysters in bags under docks, piers, and other structures until the “spat,” or cluster of molluscs, reaches a size making them safe from predators. The spat is then released onto nearby oyster beds where their density promotes propagation. Citizen scientists get hands-on harvesting experience while learning the economic and ecological benefits of the marine habitat. According to the Chesapeake Bay Foundation, oysters in that body of water “could once filter a volume of water equal to that of the entire Bay (about 19 trillion gallons) in a week. Today, it would take the remaining Bay oysters more than a year.”

Awareness of the pollutants that oysters remove from the water could help coastal residents understand the impacts of pollution flowing into bays and estuaries as stormwater. More and more, those citizens are paying for the removal of contaminants from wastewater through utility bills and other fees for maintaining or upgrading sewage treatment facilities. Those contaminants include nutrients, especially nitrogen and phosphorus, which have “consistently ranked as one of the top causes of degradation in some U.S. waters for more than a decade,” according to the U.S. Environmental Protection Agency. “Excess nitrogen and phosphorus lead to significant water quality problems including harmful algal blooms, hypoxia and declines in wildlife and wildlife habitat. Excesses have also been linked to higher amounts of chemicals that make people sick.”

Legislators and policymakers are beginning to recognize that oyster “ecosystem services” have real economic value. Some states are providing incentives for amateur oyster gardeners and restoration programs based upon economic and environmental benefits. For instance, Maryland taxpayers are entitled to a $500 state tax credit for the purchase of a float to grow oysters under their docks. As well, next year Virginia is slated to begin a mandatory nutrient trading system that will limit nitrogen and phosphorus output from point sources such as wastewater treatment plants and municipal stormwater systems. Treatment plants exceeding the limit can buy “nutrient credits” from those that have outputs falling below the regulatory nutrient load limit.

It is unlikely that restoration projects in Southern California would result in the commercialization of the delectable Olympia oyster, but they could enable recreational harvesting once the water quality in bays and estuaries improves. If the oysters did flourish, a contamination-imposed moratorium on community harvesting would give the shellfish populations time to reproduce before mitigating the ultimate source of the pollution. While high bacteria counts and trace metals can make oyster-eaters sick, they don’t harm the oysters themselves, so the restoration programs can proceed while oysters themselves remediate some pollution that might linger in coastal waters.

We pay for polluted waters in the form of remediation costs, fewer fish, and a lower quality of life for coastal communities. Restoring the Olympia oyster as the cornerstone species for cleansing estuaries and coastal embayments, and perhaps as a future food delicacy for the community, is a promising proposition for Southern California.

Phil Cruver is president of KZO Education, where he develops media-rich platforms for social networking and online training and collaboration.


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