Researchers at Baylor University in Waco, Texas studied an earplug that was extracted from a blue whale that had washed on shore in Santa Barbara, California following a deadly collision with a ship in 2007. They found that the whale had been exposed to several pollutants and experienced periods of high stress.
“It’s difficult to recover time-specific information on chemical exposure for almost any animal,” says Stephen Trumble, a biologist at Baylor and a co-author of the study, published in the Sept. 16 issue of Proceedings of the National Academy of Sciences. “It might be the only life history of any free-ranging animal,” he told NBC News.
Whale ear wax is a fat-rich deposit that stores native and foreign chemical data, as well time. “It’s keeping a journal,” explains Trumble. The wax records time with light and dark bands, similar to the rings of a tree trunk. Each band roughly correlates to a six-month period.
The 10-inch earplug, recovered from a 12-year-old male blue whale, has 24 bands that alternate between feeding and fasting seasons. Researchers discovered that he came into contact with 16 pollutants, including pesticides and flame retardants. Exposure was greatest in the first year, suggesting maternal transfer of pollutants – as is known to occur in seals and humans.
“Some of these chemicals are no longer in use, such as flame retardants that were outlawed in 2005, but they can stick around for 50 or 60 years,” says Sascha Usenko, an environmental scientist at Baylor and lead researcher on the study. Other contaminants found in the ear wax were picked up along the way. They noticed two spikes in the whale’s mercury levels – one at five years and the other at 10 – suggesting that the whale swam through polluted patches of ocean during a few months of his life.
Blue whales are known to cover thousands of miles of ocean in their lifetimes. They witness and record more about the world’s oceans than researchers could ever hope to. Tremble said, “The large whales … you can’t ask for any other kind of steward to let us know what’s going on.”
The team’s research was so successful that they are already planning their next study.
“We have a female earplug from 1964 we’re really excited about,” he said. They hope the whale’s chemical signatures will tell them how many calves she had, and at what age she gave birth.
More than 1,000 whale specimens sit in museums all over the world waiting to be studied. The Smithsonian alone has over 400 earplugs from fin, sei, humpback and gray whales.
Researchers hope that whale ear wax will provide a telling account of our changing oceans and how man-made pollutants affect marine life – even decades later.
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Image: Mike Baird