Marine biologists have stumbled on an interesting new way of examining the impact of human actions on the ocean: they're looking at blue whale earwax.
A team of researchers has published a paper explaining the technique. Basically, a whale's earwax builds up in layers over the years, which then harden, resulting in something like a tree's annual rings. Scientists can examine the layers to figure out a whale's age — but a team at Baylor University wondered what else they could find out from the waxy deposits.
They got hold of a 25.4 cm-long plug of earwax from a deceased blue whale, and what they discovered is very rare in the world of science: the wax offered them a lifetime biological record that they could use to determine what kind of contaminants the whale was exposed to at different points in its life.
"You have this 100-year-old question: How are we impacting these animals? There is ship traffic, environmental noise, climate change and contaminants," assistant professor Sascha Usenko said in a statement. "Now, we are able to provide definitive answers by analysing whale earwax plugs."
One interesting finding was that the amount of mercury in the whale's system spiked twice in the course of its life. The researchers theorized that the spikes happened when the whale moved to a new region. This particular whale was killed by a passing ship off the coast of California, leading the team to believe the mercury spikes were due to environmental factors created by humans.
In addition to mercury levels, the study examined the animal's stress levels and the presence of organic pollutants like pesticides in its system. The biggest spike in pollutants occurred during the whale's first year of life, leading the team to conclude that they were passed to the animal through its mother's milk during nursing, National Geographic reports.
The team, which is now solliciting ear wax plugs from other beached wales, concludes, "We anticipate that this technique will fundamentally transform our ability to assess human impact on these environmental sentinels and their ecosystems."