ST. PETERSBURG, Fla.— In response to a settlement agreement with the Center for Biological Diversity, the U.S. Fish and Wildlife Service today proposed designating critical habitat for the Suwannee moccasinshell, a freshwater Florida mussel. Its habitat has been harmed by pollution and reduced flows throughout its range, and by channel instability and excessive sedimentation.

“Just as people need an environment free from toxic levels of pollutants, so does the Suwannee moccasinshell,” said Jaclyn Lopez with the Center for Biological Diversity. “This critical habitat proposal will give these imperiled mussels the protection they need to survive Florida’s water crisis.”

Until its recent rediscovery, the moccasinshell hadn’t been seen since 1994 and was feared extinct. The Center filed a scientific petition seeking protection for the 2-inch mollusk in 2010 and followed up with several lawsuits to force decisions leading to its protection. The Suwannee moccasinshell now has threatened status under the Endangered Species Act.

Today’s proposal identifies 116.2 miles of the Suwannee River, 26.7 miles of the Upper Santa Fe River and 46.9 miles of the Withlacoochee River for designation as critical habitat.

Originating in the Okefenokee Swamp, the Suwannee River meanders more than 249 miles through south-central Georgia and north-central Florida before emptying into the Gulf of Mexico. An increase in center-pivot irrigation has lowered the Upper Floridan aquifer near the Suwannee River Basin by more than 24 feet, severely threatening the mussel.

Pollution is another significant threat to the mussel. The Suwannee River and its tributaries are polluted by runoff from crop fields and poultry and dairy operations, and by pesticides, pharmaceuticals from municipal wastewater and phosphate mining. The mussel is also threatened by climate change.

Freshwater mussels are very important in the food web because juveniles and adults are eaten by many other animals, including dragonfly larvae, crayfishes, turtles, fish, otters and birds. Mussels improve water quality by constantly filtering the water for breathing and feeding, but they accumulate pollutants in their bodies and are very sensitive to poor water quality.

Mussels reproduce by making a lure to attract host fish and then shooting their fertilized eggs onto the fishes’ gills. Each mussel species has a unique lure and depends on specific host fish for survival. The Suwannee moccasinshell lure has a vibrant blue patch and bumpy edges that wiggle. It is dependent on darters to be able to reproduce, including blackbanded and brown darters. Darters are themselves sensitive to water-quality degradation, and threats to the fish also threaten the mussel.

The southeastern United States has more kinds of freshwater mussels than anywhere else in the world. The Center is working to save more than 400 imperiled freshwater species from extinction.