Scientists seeking cause of huge freshwater mussel die-off

In this Oct. 17, 2019, photo provided by the U.S. Fish and Wildlife Service, a pile of recently dead freshwater mussels are piled along the shore of the Clinch River near Wallen Bend, Tenn. While freshwater mussels have been plagued for decades by habitat loss, invasive species, pollution, sedimentation and other issues, there's a possibility that the die-off in the Clinch River could be connected to infectious disease. (Meagan Racey/U.S. Fish and Wildlife Service via AP)