Featured Image Credit: Sea Shell Travel Desk
By Alice Morris
We’ve all paused to admire the iridescent beauty of mother of pearl, that shiny material that builds up on the insides of mollusk shells.
As it turns out though, this tough, shimmering substance, also known as nacre, is far more than just a pretty decoration and recent findings suggest it could actually aid scientists in determining historical ocean temperatures.
Pupa Gilbert, a biophysicist and geobiologist at the University of Wisconsin at Madison believes that the structure of nacre could provide an estimate of the ocean temperatures that it grew in.
“The thickness of the layers becomes larger as the temperature increases, and then goes back down when the temperature decreases – so you can track the seasons based on it,” she explains.
The breakthrough came after a team of researchers examined fossil samples of ancient saltwater clams, some which died 200 million years ago. They found that there was a strong linear relationship between water temperatures and nacre thickness.
The team published their fascinating findings in the scientific journal, Earth and Planetary Science Letters.
Until now, the principle method of determining oceanic temperatures has been to study the chemical composition of fossil shells.
However, this approach can be inaccurate because after a mollusk dies, the shell will dissolve and recrystallize, forming new crystals that record ocean temperatures from a different period.
“You have one part of the shell that recrystallizes a million years after [the mollusk] died,” says Gilbert. “And another that did so 20 million years later so when you measure the entire shell, you have a mess.”
This new method of measuring nacre tablets avoids this basic problem, but the researchers admit there are a few potential complications that arise from measuring the physical properties of nacre.
For example, the fluids inside a mollusk shell can alter its physical state after the animal dies by eating away some of the nacre. However, this is generally a much slower process than the chemical changes that occur after a mollusk dies.
The new method is also simpler, cheaper and requires less equipment than examining the chemical composition of mollusk fossils.
“It basically makes it possible for anybody to measure ancient temperature. The potential impact is huge, because any undergrad who knows how to do this can acquire the data and simply convert that into temperature,” says Gilbert.
“Of course this all becomes relevant only once we have a ton of data from lots of people around the world. But because it’s so easy, I expect it to reach a lot of people.”
For researchers around the world, this news should make them happy as…. well, you know.