Ocean Noise Could Harm Squid and Their Ilk
Most years, Spaniards encounter just one giant squid as long as a city bus along their northern shores—a fisherman might haul one up from the depths accidentally, or beachgoers might stumble across a carcass stranded on a beach. So it was surprising in 2001 when five squid littered the beaches over a 2-month period and in 2003 when four washed up or were found floating at sea near death in a single month.
At the time of the strandings, ships offshore were exploring for oil and gas with air guns, which produce high-intensity, low-frequency sounds. Some researchers suspected that the loud noises were harming the squid, just as they are known to harm marine mammals. A new study supports that hunch, reporting massive damage to the sound-detecting structures of squid and other cephalopods that were exposed to loud noises.
In recent years, scientists have gathered evidence that sonar and other humanmade noises may hurt everything from whales to crustaceans. But they didn't know whether this audio pollution could perturb cephalopods—the animal group that includes cuttlefish, squid, and octopuses—because researchers have only recently demonstrated their ability to hear.
To find out, a team led by marine bioacoustician Michel André of the Technical University of Catalonia in Spain brought 87 wild cephalopods back to laboratory aquariums. For 2 hours, the researchers blared low-frequency sounds that were between 157 and 175 decibels at the animals. For comparison, a supertanker's engine noise might hit 190 decibels in the water 1 meter away from the ship. At intervals up to 96 hours after the sound barrage, the researchers killed the animals and preserved their statocysts—the sound-detecting structures behind their eyes—for microscopic analysis. For controls, the researchers killed and collected the statocysts of 100 wild cephalopods immediately after they were captured.