Today, oysters are considered a delicacy. But the shellfish were once so common in New York City that even street carts served them. Over time, pollution, overharvesting, and habitat loss decimated the oyster population. Oysters around the world are facing a similar fate. According to The Nature Conservancy, 85 percent of the world’s oyster reefs have disappeared. “That makes them one of the most imperiled habitats on our planet,” says Peter Kingsley-Smith. He’s a marine scientist at the South Carolina Department of Natural Resources.
The loss of oysters is bad news for other animals as well. “The diversity of other organisms that call oyster reefs home is truly remarkable,” says Kingsley-Smith. “All of the nooks and crannies in an oyster reef provide potential habitats for fish, crabs, sponges, and all sorts of other fascinating creatures.”
Oyster reefs help people, too. They protect shorelines by acting as a buffer against storm surges, which occur when rising water is pushed onto land, causing flooding. The reefs help reduce erosion by blocking waves that can wash away sand and soil. Oysters also help keep harbors clean. These filter feeders pump water through their bodies, filtering out algae and bacteria to eat (see Inside an Oyster, below). In the process, they remove pollution from the water. “A single adult oyster can filter up to [190 liters] 50 gallons of water in a day,” says MS 50 sixth-grader Rose Beidel.