Baby Oysters Use Sound to Choose a Home: The Importance of Reef Noise

Oysters are best known as being the shellfish on a dinner plate. These creatures, though, are also an integral part of oceanic ecosystems. They filter nutrients and create reefs out of hundreds of their shells. Now, scientists have learned a little bit more about these creatures. It turns out that baby free-floating oysters may be attracted by the sounds of the reef as they search for their permanent homes.

Larval oysters are planktonic. This means they drift with the current, though they do have the ability to move up and down within the column of water that they're in. As these larval oysters mature, they develop a muscular "foot" that they can use to sense the terrain along the ocean floor. When they find the right spot, the oysters will attach themselves with their foot and then remain there throughout their lives. But how exactly do these oysters choose?

"When you're as small as these larvae, even if you're only 10 or 15 feet up in a water column, you wouldn't have any real sense of where you were in terms of the seafloor beneath you," said Ashlee Lillis, one of the researchers, in a news release. "But an ocean reef has very loud, distinct sounds associated with it. They're noisy enough to be heard by scuba divers and snorklers. Even though oysters don't have ears and hear like we do, they might be able to sense the vibration from the sounds of the reef."

In order to test this idea, the researchers made underwater sound recordings of oyster reefs and the open seafloor. They then tested larval oysters in the wild and in the lab to see if the settlement rates increased when the oysters were exposed to reef sounds as opposed to those from the open sea floor. In the end, they found an increased settlement rate in both the lab and the wild when the oysters "heard" reef sounds.

"This research is the first step in establishing what normal, healthy reef environments sound like," said Lillis in a news release. "If we can figure out how the noise impacts oysters it may give us strategies for establishing new oyster beds. It might also give us a noninvasive method for keeping tabs on the health of our undersea reefs."

The findings are published in the journal PLOS One.

Want to hear some of the oyster reef soundscapes? You can check them out here.