Super Shells!

Governor’s Island is a tiny island south of Manhattan in New York City. There is a school there called the Urban Assembly New York Harbor School. Students at this public high school do what most students do: read, practice math, and learn about history. But they also have some unusual classes. These classes involve diving underwater and driving boats. They are also growing oysters.

Oysters live along coastlines around the world. These soft-bodied creatures live inside shells. They grow on top of each other. This forms jagged structures called oyster reefs close to the shore. These reefs were once common in the waters surrounding New York City. But they have disappeared.

The students at the Harbor School are trying to change that. They’re working with an organization called the Billion Oyster Project (BOP). The organization wants to reintroduce 1 billion oysters to the city’s coastlines by 2035 to rebuild the reefs. The oysters could help clean the water, increase biodiversity, and protect shorelines against powerful storms.

“I never thought something so small could have such a big impact,” says Quincy Lonnie Maloney, a former student at the school.

In the 1600s, the waterways around New York City were filled with oysters. But over time, the oysters were overharvested. Pollution also killed them.

That’s a problem because oysters benefit oceans in many ways. They pump water through their bodies. This allows oysters to absorb algae and nutrients that help them grow. That process also cleans water.

Oyster reefs provide habitat for many animals, like fish and crabs. The reefs also protect shorelines against erosion. They protect coastlines from big waves that can damage beaches. “They act as a buffer,” says Michael Spina, an architect who helps build artificial reefs.

To begin building the reefs, students grow baby oysters in a lab at the Harbor School. First, they put adult oysters in tanks filled with warm water. That tricks the oysters into thinking it’s spring. That’s when they naturally produce larvae.

These baby oysters have shells smaller than the period at the end of this sentence. After a few weeks, the larvae sprout an appendage called a foot. They use it to latch onto hard surfaces, like rocks. “But one of the best places for an oyster to set is on another oyster,” says Spina.

BOP collects empty oyster shells from restaurants every week. The students fill mesh bags with those shells. Then they lower the bags into tanks that hold the baby oysters. The baby oysters latch onto the shells.

Finally, it’s time to build the reefs! Students and volunteers place hundreds of bags or cages filled with oysters on the seafloor nearby the shore.

Since 2014, BOP has installed more than 100 million oysters in New York and other states like Maryland and Alabama. The students dive regularly to check how the reefs are doing. So far, the reefs are thriving. And that makes the students happy.