Wax Eloquent
The stuff that builds up in a whale’s ear can teach us much about the changing Arctic
A PHYSIOLOGIST with wide-ranging interests, Stephen Trumble studies everything from rats to zebrafish, but these days whale earwax is taking over his Baylor University lab. There are already 30 pieces of it lined up, each requiring about a year’s worth of analysis—and he hopes to obtain five times as many. He’s doing this because hidden in all that wax is information that could tell us how life has been changing for whales and the Arctic in the past 100 years or more.
For decades, cetologists, the marine scientists who study whales and dolphins, have had to gather data from dozens of different sources to reconstruct the life story of a specific sea mammal. For example, studying the scars in the ovaries could reveal the number of pregnancies a female whale had experienced; the bristly, filter-like baleen used to feed could give scientists information on what sorts of contaminants might have entered the whale’s food source in the most recent decade or two. Whale earwax has long had some use in this accounting.
Earplugs— the scientific term for the lengths of wax that accumulate in the ears of some whales—grow in annual layers like tree rings, revealing the number of years a whale has lived.
But Trumble’s team has discovered that much more can be learned from the aquatic mammal’s earwax—a veritable one-stop shop for all the whale data they’ve been dreaming of. Using the foot-and-a-half-long earplug from one bowhead
whale, Trumble and his lab collaborators were able to obtain the whale’s history, including its age, migrations and pregnancy. That small piece of wax—at 2 pounds, it’s 1/100,000th the size of a typical bowhead whale’s body—has also given Trumble and his team a history of the buildup and decline of pesticides like DDT in recent decades, as well as today’s rapidly growing carbon concentrations in the Arctic.
A research group with unlimited resources could attempt to track a whale throughout its life, showing up every year to take a skin sample. That’d provide great information on where the whale had been and what sorts of things it had been exposed to. But the logistical and financial costs of that sort of project make it essentially impossible. Trumble’s work offers a realistic way to obtain all that Arctic intelligence.
Since U.S. and international regulations protect whales—even when they wash ashore dead—fresh earplugs are hard to come by, so Trumble’s project is at least as much about searching for earplug samples as making sense of them. Evolutionary biologist Hans Thewissen says he happened to be in Barrow, Alaska, the day that bowhead was brought ashore in a traditional, tightly controlled annual subsistence hunt. (Native communities in the region can take at most 67 bowheads in a year.)
Every animal harvested during such a hunt is towed back to the beach, and the meat is divvied up for the community; then wildlife managers begin taking measurements for research and extracting body parts to learn more about the whale population. At that point, “the scientists stand around, and when there’s an organ they want they ask for permission to sample it,” says Thewissen, a professor at Northeast Ohio Medical University. He had his eye on the earplug because Trumble had told Thewissen how much information this tiny piece of whale might hold.
Trumble describes extracting the earplug of a beached whale as “a crazy amount of work.” The dead whale needs to be turned the right way, and bones and tissues—particularly their massive jawbone—might be obstacles. Heavy-duty construction equipment like front-end loaders are sometimes used. And that’s assuming the whale has an earplug. Not every species does, and sometimes within a species some individuals do and others don’t—an apparent randomness researchers don’t fully understand. “It’s like humans,” says Thewissen. “Some people have more earwax than others.”
Trumble has been traveling all over the world to raid museum collections for earplugs, and the backlog of work is growing at his lab. The analysis is labor-intensive; it takes about a year to separate each wax layer from adjacent ones. Researchers then run numerous tests to determine chemical composition. Each layer becomes its own sample, its own record of that year in Arctic living, and requires its own extensive tests and calculations. It adds up, but
THE WHALE WAX ACTS AS A RECORD OF WHICH POISONOUS CHEMICALS PRODUCED IN THE U.S. AND OTHER MORE SOUTHERLY LATITUDES MAKE THEIR WAY UP NORTH.