One of our sciences’ great frustration with the planet Earth is that our planet keeps hiding its past. Other worlds without weather preserve things on their surface for millennia, and while Mars’ polar ice caps do show seasonal changes and record changing weather, most of the surface of Mars is just hanging out, displaying features that formed millions to billions of years ago.
On Earth, that pretty much doesn’t happen. Each year, the weather wears away new surfaces, reveals new fossils, and plants hide, consume, and tear apart weaker rock. Trying to understand Earth’s past requires all sorts of creativity, and scientists are here to deliver.
A new paper in Palaeogeography, Palaeoclimatology, Palaeoecology, and led by Tsuyoshi Watanabe, shows how freshwater mussels in the Shiribetsu River in Japan can be used to track information on the mountain snowpack.
Melting snow is responsible for a significant portion of the river’s water, and when the temperatures are above 9˚C, river mussels will deposit layers in their shells on a daily basis. These mussels can live up to 200 years, and a collection of just twelve mussels allowed researchers to determine the past 67 years of annual snowfall data as reflected in water chemistry and flow. The shells also show variations on decadal scales that match with the known Pacific Decadal Oscillation, which is an oscillation in the temperature of the ocean. This work is new and indicates there is a new tool, or at least a new shell, in the scientific toolbox that we can use to measure the history of our world wherever mussels may live.
“Daily and annual shell growth in a long-lived freshwater bivalve as a proxy for winter snowpack,” Tsuyoshi Watanabe et al., 2021 May 1, Palaeogeography, Palaeoclimatology, Palaeoecology