> TLDR: Consequently many freshwater mussel species are now extinct

The problem with the DR part of TLDR is that you miss a lot of detail. There are more factors than just the button industry.

> To survive past the larvae stage, they must become parasites that attach themselves to fish. If the fish populations are declining, that oftentimes has an indirect effect on mussel abundance

> the U.S. Army Corps of Engineers deepened the rivers and constructed a system of dams, destroying the habitats of mussels that had evolved to live in shallower waters.

> Increasingly polluted waters also took a toll.