The unsung soldiers of science
The stench is overwhelming, a rancid sweetness that stings the eyes and lungs, clinging to hair and clothes like a vile perfume.
This is the smell of global warming research at work, inside a sealed room at the University of Alaska's Museum of the North in Fairbanks, the largest US repository for high-latitude species. Beneath the lids of large coolers, thousands of tiny beetles are devouring the desiccated flesh of carcasses destined for the museum's vast specimens collection.
It's a process used by museums for decades because of the dermestid beetle's unmatched ability to strip bones without damaging even the smallest, most delicate specimens. But today that skill is increasingly crucial in gauging the long-term implications of climate change, particularly in the Arctic where effects of warming appear first and with greater intensity.
These drab little bugs are common household pests that eat through furs, clothing and cereal, shedding their telltale exoskeletons in drawers and cupboards. But in science, dermestids unveil the most minute changes in a species, as illustrated by a study comparing hundreds of martens _ a type of weasel _ from the Alaska museum's collection.
Israeli scientist Yoram Yom-Tov measured about 400 marten specimens obtained by the museum over the past 50 years. Excluding such factors as gender and high latitude-norms, Yom-Tov found the small carnivore had grown over the years by a few percentage points. That's enough to suggest something significant about global warming, he said.
The most plausible explanation is that winters in Alaska are shorter and warmer, said Yom-Tov, a professor of zoology at Tel Aviv University. Plants are more available to such prey as voles, so martens have more food.
Yom-Tov recently submitted his conclusions for publication and said he would like to study more Alaska species.
The Alaska museum has two advantages, he said. It's a treasure trove of species from the Arctic, where temperature averages have inched up, shrinking the year-round icepack and exposing shorelines to powerful storms. Such changes can disrupt wildlife habitat, altering historical ranging patterns.
Also, Alaska has not fallen victim to "an infectious disease called political correctness," Yom-Tov said, which has slowed collections in other US museums.
"Many people objected to museums collecting animals for many years," he said. "Fortunately, this disease did not affect Alaska so much."
Trappers and wildlife managers are part of the reason the museum continually adds to its nearly 100,000-specimen collection of mammals ranging from the tiniest voles and shrews to whales and bears _ and every species in between. The specimens come mostly from Alaska and adjacent sections of Canada and Russia. In December, much of the collection was moved into larger quarters at the newly expanded museum.
The preparation lab, however, remains secluded out of necessity. A dermestid infestation is a curator's worst nightmare. There's not much the bugs won't eat. That much was evident on a recent evening when Olson and mammals collection manager Brandy Jacobsen transferred frozen pieces of a musk ox to the "bug room."
Olson and Jacobsen repeatedly warned visitors about the revolting but harmless odor they were about to encounter in the room. "It gets more bearable as you get used to it," Jacobsen said as the visitors pressed noses to their sleeves.
Seemingly oblivious to the smell, Jacobsen set an ox leg and other chunks of meat under a range hood, where they would air dry for at least two days. Otherwise the meat would be too wet for the carrion-eating bugs, which on this night were crawling all over the skull of a Sitka blacktail deer and the bones of other mammals, including a polar bear.
"They only eat dead flesh," Olson said. "They like jerky basically."
Whether doing their work in coolers or small boxes, the beetles have to be carefully contained, given their voracious appetite. They can subsist on almost anything, including dust bunnies, drywall, cardboard, skin and leather. The more food they get, the more they reproduce.
But there are some things the bugs won't eat, such as rotting meat or bones with high fat content.
"Even they have their standards," Olson said. A dermestid colony would have snubbed the walrus head and the flipper of a beaked whale that were sitting in tubs of greasy water. They were going through an older process called maceration, which involves soaking bones in bacteria-laden water to break down soft tissue.
Maceration, however, can loosen teeth or weaken sutures in skulls or long bones. That's one reason the dermestid method is preferable, according to Larry Heaney, a longtime member of the American Society of Mammalogists.
Another is their cleaning prowess, especially invaluable when measuring changes over extended periods of time, said Heaney, curator of the division of mammals at the Field Museum of Natural History in Chicago.
Besides size, bones can change in density, proportion and shape, reflecting deviations in resources. Teeth on a 20-year-old animal alive decades ago can show different wear patterns from a modern animal the same age.
"What researchers are often looking for at this point are very subtle changes taking place," Heaney said. "With specimens cleaned by beetles, you can look very precisely at tiny changes in the anatomy of the animals."