thejives

Ships’ propellers emit sound in the same frequency range that some whales use for communicating, and previous studies have shown the whales change their calling patterns in noisy places. Now, researchers have measured stress hormones in whale faeces, and found they rose with the density of shipping.

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Following the al-Qaeda attacks on New York and Washington DC on 11 September 2001, ship traffic in the bay dropped off. Mothers and calves communicate with each other and other whales using low-frequency sound Whale researchers registered a 6 decibel (dB) fall in the intensity of underwater noise, with the change particularly pronounced at frequencies below 150Hz.

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Faeces gathered during the 2001 period of light shipping showed a significantly lower level of metabolites of glucocorticoid hormones, which are associated with stress, than in subsequent summers when marine traffic returned to normal levels. “This is the first time that anyone’s documented any physiological effect - these are after all 50 tonne animals so they don’t make terribly easy things to study,” said Dr Rolland.

Full BBC article

New England Aquarium Marine Stress Research Program