Like anyone with rowdy neighbors, oysters may be feeling stressed thanks to the growing problem of underwater noise pollution, and are trying to filter out the racket.
(From The New York Times / by Douglas Quenqua) — New research published Wednesday in PLoS One reveals that oysters will close their shells when exposed to noises along a range of frequencies that includes the sounds emitted by known noise polluters like cargo ships and underwater oil exploration.
In oysters, closed shells are an indicator of distress. Under optimal conditions, bivalve mollusks will keep their shells open, and are thought to shut them only when feeling stressed or threatened. Clamping their shells to screen out noise pollution or other artificial irritants could prevent oysters from perceiving important biological cues, said the authors of the study.
Oysters “must be able to hear breaking waves and water currents,” which could trigger their biological rhythms, said Jean-Charles Massabuau, research director at the French National Center for Scientific Research and an author of the study. “To hear the current arriving could prepare them for eating and digesting, possibly as when we hear and smell that somebody is preparing dinner.”
Not being able to detect other natural events, like rainfall or thunderstorms, could also prevent them from knowing when it’s time to spawn, Dr. Massabuau said.
Noise pollution has been a growing problem in the oceans and other large bodies of water for decades. Commercial shipping, oil exploration, recreation and even scientific research are all raising the decibel levels within marine habitats, adding to naturally occurring rackets like earthquakes, crashing waves and tidal changes. And because sound travels farther in water than air, each new source has an outsize effect.
Such noise has already been shown to have adverse effects in fish, whales and other marine mammals as well as cephalopods. But little is known about its effects on most invertebrates.