THE ENVIRONMENT REPORT Endangered Mussel Rides to Renewal Up and down the Mississippi River, people once collected tons of mussels for the pearl button industry. Factories stamped out pearl buttons from the shells, sometimes wiping out 50,000 tons of mussels annually in the early part of the last century. In recent years, the biggest threat to local mussel species has come from the zebra mussel. That invasive species came to North America in the ballast water of ships and has since disrupted many local ecosystems. Today, there’s a new effort underway to bring back local species like the Higgin’s Eye Pearly Mussel, and it’s in an unlikely place. Audio is here .