How oysters are cleaning New York's polluted harbor

50 gallons of water. That’s more than a bathtub full.

It’s also the volume that a single adult oyster can purify in a day, removing pollutants including sediment and nitrogen as it sifts for food.

And it’s this natural superpower that nonprofit group The Billion Oyster Project seeks to harness to clean up New York Harbor while also engaging the local community to help out.

“New York Harbor is a massively degraded natural system,” says Pete Malinowski, Executive Director and Murray Fisher, Chairman of the project. “Oyster reefs have the power to transform NY Harbor. They provide habitat for thousands of marine species, filter water, and can help shield shorelines from storm damage.”

Bringing life back to the water is no small task. Every time it rains in the city, untreated household wastewater enters the harbor, making the water so murky that visibility can be less than a foot. That’s where oysters come in, acting as “ecosystem engineers”, removing excessive nitrogen that would otherwise trigger algal blooms that deplete the water of oxygen and overwhelm other marine life.

Making headway

Since it started in 2014, the project has placed around 28 million oysters in the harbor, recycled 1 million pounds of shell, and engaged 75 restaurants and 70 schools in its initiative. The aim is to distribute one billion live oysters by 2035.

Variations of the idea are also being used in other locations, for example to clean up rivers in North Carolina and waterways in Cape Cod.

For The Billion Oyster Project it’s about more than just clean water. It’s also about restoring history and engaging the local community.

Thriving habitat

It harks back to the 1600s, when, according to the project, there were around 220,000 acres of oyster reefs in New York Harbor and the environment was one of the most biologically productive, diverse, and dynamic on the planet. By 1906, New Yorkers had eaten every last oyster, reefs were dredged up or covered in silt, and the water quality was poor.

“When we go out to our reef sites, we always see an abundance of all these different types of encrusting invertebrates,” says Liz Burmester, a restoration ecologist who works on the project. “We’re also seeing a bunch of small specialist fish and crabs that thrive in an oyster habitat, a reef habitat. They might not necessarily have that habitat without oysters being there.”

The New York City restaurants donate used oyster shells, which are cleaned by volunteers and used to grow baby oysters for release into the harbour. By engaging local volunteers and school children, the project’s founders hope to increase awareness of the natural world and engage more people in looking after it.

And the restoration is taking hold. The small oysters introduced are growing, surviving and forming reefs.

Conservation and biodiversity are key themes at this year’s World Economic Forum Annual Meeting in Davos. Between 1970 and 2020, the world will have experienced a two-thirds decline in wildlife populations.

Protecting the future

Sir David Attenborough warned delegates that more must be done to arrest the decline.

"The future of the natural world is in our hands,” he said. “In our daily lives, the thing I really care for ... is not to waste the riches of the natural world on which we depend. It's not just energy, but it's also dealing with the natural world with a degree of respect. Don't throw away food, or throw away power, just care for the natural world, of which we are a part.”