Ahem: A cough cannot be hidden—and when scallops cough, scientists should listen. A scallop "coughs" to expel feces and water from its central cavity; the friction between the mollusk's two valves makes a sharp crack, followed by a drawn-out puffing noise as the valves quickly close. Now, a team of biologists and acoustics experts says those sounds can serve as an early warning system for worsening water quality. Because the sonically striking coughs are distinct from the choruses of other marine noisemakers such as shrimp and sea urchins, the researchers found that, by using submersible acoustic sensors called hydrophones, they could record the scallops' outbursts from up to 10 meters away , they reported this week in the Journal of Experimental Marine Biology and Ecology. Previous research suggests that scallops may feed less often and grow more slowly in the presence of toxic algae and decreased oxygen concentration. One way that biologists monitor these changes in water quality is to laboriously analyze fine-scale growth patterns in the tiny ridges of scallop shells. But, the scientists suggest, it would be far less labor-intensive to instead use a network of hydrophones to keep track of coughing behaviors that signal changes in scallop metabolism. The team suggests that the technique could also replace a current, disruptive method of tracking scallop behavior: attaching motion sensors directly to their shells. The scientists plan to explore other movements in the scallop repertoire, such as digging, swimming, jumping, and spinning, which may also have sonic qualities useful for diagnosing the ocean's ailments.
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