Benjamin Von Wong

Oysters to the Rescue!

How students are using oysters to help protect New York City’s coastlines

By Alessandra Potenza

From the March 2020 Issue

Key Focus Area: Earth's Materials and Systems,

Cathy Crawford/Getty Images

A live oyster

The Urban Assembly New York Harbor School sits on Governors Island, a tiny island south of Manhattan, in New York City. Students at this public high school do what most students do: read novels, practice math, and learn about history. But they also have some unusual classes. These classes involve diving underwater, driving boats, and growing oysters, soft-bodied creatures that live inside shells.

Oysters live along coastlines around the world. The mollusks grow on top of each other, forming jagged structures called oyster reefs. These reefs were once common in the waters surrounding New York City. But now they have all but disappeared.

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

“I never thought something so small could have such a big impact,” says Quincy Lonnie Maloney, an 18-year-old student at the school.

Oyster City

In the 1600s, the waterways of what is now New York City were teeming with oysters—about 1 million per acre! But over time, the oysters were overharvested. Pollution from industry and sewage also killed off many oysters.

That’s a problem because oysters benefit oceans in many ways. As they pump water through their bodies, oysters absorb algae and nutrients that help them grow. That process cleans the water. An adult oyster can filter up to 189 liters (50 gallons) of water a day!

Oyster reefs provide habitat for many animals, like fish and crabs. The reefs also protect shorelines against erosion (see Shoreline Protectors). When waves hit a beach, they drag sand back to the sea. Over time, the beach can wear away. Strong waves hitting structures on the shore can also do damage. In New York City, where many homes, offices, and airports are near the water, waves can create big problems.

Oyster reefs can slow down and weaken waves heading to the shore. “They act as a buffer,” says Michael Spina, an architect who helps build artificial reefs.

Oyster Reef Spots

Here’s where the BOP oyster reefs are located in New York Harbor.

Oyster Reef Spots

Here’s where the BOP oyster reefs are located in New York Harbor.

Reef Builders

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, 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.

Shoreline Protectors

By acting as a buffer, oyster reefs slow down and weaken waves. That helps keep beaches from wearing away. Here’s how it works.

Without Oyster Reefs

When strong waves hit the shore at full force, they stir up a lot of sand and drag it out to the sea. Over time, that process wears away the beach.

With Oyster Reefs

When waves hit an oyster reef, they weaken. The water between the reef and the shore is calmer. That lessens the amount of sand leaving the beach.

Think: How might an eroded beach be a problem for people and wildlife?

Shoreline Protectors

By acting as a buffer, oyster reefs slow down and weaken waves. That helps keep beaches from wearing away. Here’s how it works.

Without Oyster Reefs

When strong waves hit the shore at full force, they stir up a lot of sand and drag it out to the sea. Over time, that process wears away the beach.

With Oyster Reefs

When waves hit an oyster reef, they weaken. The water between the reef and the shore is calmer. That lessens the amount of sand leaving the beach.

Think: How might an eroded beach be a problem for people and wildlife?

BOP collects 3,630 kilograms (8,000 pounds) of empty oyster shells from restaurants every week. Workers leave the shells in the sun for a year to rid them of potentially harmful organisms. The students fill mesh bags with those shells. Then they lower the bags into water tanks that hold the baby oysters. Up to 20 larvae can attach to one recycled shell.

Finally, it’s time to build the reefs! Students and volunteers place up to 500 mesh bags on the seafloor near the shore. They position the reefs so that they’re always underwater. That way passersby aren’t tempted to take the oysters home to eat.

Restaurant to Reef

The Billion Oyster Project collects empty oyster shells from 70 restaurants in New York City. The shells would otherwise end up in landfills.

Students place the shells in mesh bags and lower them into tanks containing oyster larvae. The larvae attach to the shells and grow into adults.

Students and volunteers place the bags filled with the oysters on the seafloor near the coast. Some reefs are made of hundreds of these bags.

Reefs can be built with different materials, like the steel cages above. Students regularly dive to monitor the health of the oyster reefs.

Restaurant to Reef

The Billion Oyster Project collects empty oyster shells from 70 restaurants in New York City. The shells would otherwise end up in landfills.

Students place the shells in mesh bags and lower them into tanks containing oyster larvae. The larvae attach to the shells and grow into adults.

Students and volunteers place the bags filled with the oysters on the seafloor near the coast. Some reefs are made of hundreds of these bags.

Reefs can be built with different materials, like the steel cages above. Students regularly dive to monitor the health of the oyster reefs.

Storm Shields

Scientists are building oyster reefs along the coasts of other states too, like Maryland and Alabama. The reefs could help these places cope with climate change. As the world’s average temperature increases, storms are getting stronger. Oyster reefs could help protect shores from powerful storm waves. “Coastal protection is more important than ever,” says Spina.

Since 2014, BOP has installed more than 30 million oysters. The students dive regularly to check how the reefs are doing. So far, the reefs are thriving. And that makes the students happy.

“The future belongs to us,” says 17-year-old Deanna Souchetsoto. “It’s time to change what previous generations did.”

Model a Reef

Observe

Waves can slowly erode, or wear away, beaches.

Make a Prediction

How will an oyster reef change the way waves affect sand?

Materials

• rectangular baking pan
• 3 centimeter (1 inch)-thick book
• bowl
• 4-5 cups of sand
• water
• measuring cup
• ruler
• 1-2 cups of small rocks

Procedure

STEP 1: Place the book under one side of the pan to raise it.

STEP 2: Wet the sand in a bowl so it sticks together. Pack the sand into the pan’s raised end to build a beach that stops about halfway down. Measure its length.

STEP 3: Slowly pour water into the lower end of the pan until it just reaches the sand.

STEP 4: Gently raise and lower the pan 10 times to make waves. What happens to the beach? Measure the beach’s length.

STEP 5: Empty the water from the pan, making sure to keep the sand inside. Rebuild your beach so it’s as long as your beach in Step 2. Slowly pour water into the pan again.

STEP 6: Use the rocks to build a model oyster reef along the shore. Then repeat Step 4.

Results

Compare how waves affected your beach with and without the reef. Record any differences you observed.

Conclusions

1. Using the word erosion, explain what caused the differences in your beaches.

2. Were the rocks a good model, or representation, of an oyster reef? Explain your thinking.

3. How might stronger waves have changed your results?