How Filter Feeding Restores the Environment

In this lesson, students will learn how oysters filter water and help restore coastal environments. Oysters feed by filtering plankton and other particles from the water, which also removes excess nutrients like nitrogen from pollution. This process helps keep rivers, bays, and estuaries cleaner and healthier for other animals. Students will explore the environmental benefits of oyster reefs and how a single oyster can make a big difference in water quality.

How Water Pollution Connects to the Ocean

 Did you know that your backyard, sidewalk, or street is connected to the ocean—even if you don’t live near one? Rainwater runs downhill through a watershed, picking up anything on the ground: pet waste, lawn fertilizer, soap, and oil from cars. These pollutants carry extra nutrients, like nitrogen, into rivers and bays, where they can harm water quality and the animals that live there.

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Oysters: Nature’s Water Cleaners

 Oysters are champions of nitrogen removal. They feed by sucking in water to find tiny food like phytoplankton, and while doing so, they filter out pollutants. Some of the nitrogen gets absorbed into their bodies, and some is expelled in slimy bundles called pseudofeces that sink to the ocean floor, cleaning the water as they go.

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The Power of an Oyster Reef

 One oyster can filter up to 50 gallons of water a day—almost a full bathtub! When oysters grow together in reefs, their combined filtering power can dramatically improve water quality, reduce harmful algae, and create habitats for other marine life. Oyster reefs are a natural way to restore and protect coastal ecosystems.