Air breathing cetaceans--dolphins and whales--are built for diving. They have many physiological adaptations for storing oxygen and resisting the tremendous water pressure as they dive to depths of up to two miles. But a new study has linked noise exposure and dive response in dolphins. The findings published in the journal Experimental Biology indicate that a beaked whale, one of the deepest diving cetacean fleeing noise by an emergency dive may expend up to 30% more energy than in unstressed diving (calculated). Test dolphins in a deep water aquarium expended twice as much physiologically performing escape dives. Fish, birds and cetaceans all swim relatively slowly to conserve energy, but when faced with disturbingly loud man-made noise like sonar, cetaceans flee at high speed and that costs them a lot of energy and stored oxygen.
No one knows what causes mass standings like the one that killed more than one hundred pilot in New Zealand in February [photo credit: Getty Images], but disorientation and exhaustion caused by human noise is suspected as one reason. A marine mammal expert with NRDC says anthropomorphic noise is a "death of a thousand cuts" for marine mammals because it degrades their foraging, interferes with breeding behavior, silences their own prodigious vocal activity, and drives them from their homes. Ocean noise is becoming an increasingly serious environmental threat. Scientists are now working on the link between human noise in the ocean and the morbidity of cetaceans. Once this link has been proven to be scientific fact, legal steps can be taken to protect them from yet another form of human pollution of the natural world.
one hundred pilot whales on Fairwell Spit