What Can Shells Tell Us?

Nacre is created by the shell’s living inhabitant, the mollusc, which lays down microscopic layers of calcium carbonate alternating with organic materials like proteins, in a brickwork pattern. And it can, she explains, be analysed in the same way as a sediment core to reveal information about the environment it lived in.

“If we look at these layers in cross section, then we can go back in time, and reconstruct things like the water temperature, and see how the ocean temperature has changed. It’s super mind-blowing, really.”

In the ANU aquaculture lab, Dr Otter grows the shells in a stable environment, observing and measuring changes according to different conditions such as salinity, water temperature and the presence of trace elements.

“So then we have this this way of calibrating any wild shell,” she says. “After measuring, for example, oxygen atoms in the shell by looking at the ones grown in controlled conditions here, we can then know exactly what temperature a wild shell was at a particular time.”

Her research has revealed the impact of the changing climate on the mollusc’s nacre production, which is vital information for the pearl industry.

SOURCE: https://science.anu.edu.au/news-events/news/pearls-wisdom-what-can-shell-tell-us