Researchers have launched a new effort to monitor the briny bivalves, which could be as important to life underwater as honeybees are to life ashore.

European Mussel Catalogue
Credit: © ROBIN VAN LONKHUIJSEN / Stringer / Getty Images

Europe's freshwater mussels are being cataloged for the first time ever.

If you've ever enjoyed a bottomless bucket of mussels at a seaside bar, you might get the impression that these delicious little mollusks are infinitely abundant. But mussel populations are on the decline owing to pollution, climate change and man-made barriers like dams. Some species even face extinction. That's why, in a pan-European effort, researchers from the Technical University of Munich and The University of Porto in Portugal have teamed up to catalogue Europe's freshwater mussels in 26 countries. The data will allow scientists to keep closer tabs on mussel populations and, hopefully, lead to solutions that will slow or reverse their decline.

Why do mussels matter? Because they're the waste treatment plants of the deep, and their decline is as quiet and potentially harmful to aquatic life as honeybee colony collapse is to life ashore. In order to eat the tiny particulates that make up their diet, each shellfish filters about ten gallons of water every day. They not only remove contaminants, but also consume excess nutrients to stave off invasive species like algae. Making up 90 percent of the biomass on the floor of the bodies of water they occupy, a healthy mussel population is essential for fish and invertebrates in the food chain to thrive—and thus for humans to thrive, too.