Conservation on the Half Shell: Oysters Help Clean New York’s Dirty Harbor

How do you keep New York’s harbor clean? At a high school on Governor’s Island just south of Manhattan, the answer has been tested: oysters. Marine biologists have used oysters for centuries for the efficient way they filter dirt out of water, as much as 50 gallons a day per oyster. In fact, there used to be trillions of oysters in the New York Harbor about 400 years ago before the water became too polluted for them to survive.

Thanks to the Clean Water Act, oysters can now populate the river and start slurping dirt once again. The only problem is how to get them back there. This week Change Reaction visited the New York Harbor School, a small public high school on Governor’s Island, just south of Manhattan. The school’s goal is to return 1 billion oysters into the river over the next twenty years. It’s a small fraction of the number there once was, but it’s a start. And the school is using the project as a teachable moment, instructing students how to nurture the oyster larvae, build artificial reefs for the oysters to live on, and how to dive in order to put them at the bottom of the river.

Can it be done? Since 2011, the school has introduced about 2.5 million oysters. That number is expected to rise dramatically as students get faster at the process, says Murray Fisher, the founder of the Harbor School and the brains behind the Billion Oyster Project. They also hope outside funding from the city may allow them to build new equipment. “What I’m most excited about is having this type of environmental restoration become a good model for engaging students,” Fisher said, while volunteers counted oyster larvae nearby. The only thing definitely out of the question: At the end of their lives, the oysters are filled with so much bacteria and pathogens from a lifetime of filtering, they’re unsafe to eat.

Scroll down for photos.

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Oyster larvae—known as spat—are placed shells and then put into the river to grow and mature. Photo by Spencer Millsap / NGM Staff
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The process involves a lot of shuttling, taking boxes in and out of the river to monitor oyster growth. Photo by Spencer Millsap / NGM Staff
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One of the most tedious yet crucial steps is to count the number of oysters growing on shells. Putting a billion oysters into the harbor requires growing them first. Photo by Spencer Millsap / NGM Staff