TRAVERSE CITY, Mich. – Federal regulators on Wednesday designated two U.S. freshwater mussels as threatened, another sign of trouble for the native molluscs that help clean waters by filtering out pollutants as they feed.
The U.S. Fish and Wildlife Service said it was granting protection to long, round hickorynut mussels, which have declined in many streams in the East and Midwest.
The primary cause is habitat damage from urban sprawl, agriculture, oil and gas development, pipelines, and mining. Other factors include competition from non-native mussels and rising stream temperatures linked to climate change.
“These two mussels have suffered proverbial deaths by a thousand cuts,” said Gary Peeples, deputy supervisor at the agency’s field office in Asheville, North Carolina. “A lot of little things have added up.”
Blooming mussel populations indicate healthy streams, he said. North America is a historic showcase of mussel diversity, home to about 300 of the world’s approximately 900 types. But about two-thirds of the continent’s freshwater mussels are endangered.
The newly designated threatened species have a much wider range than many struggling mussels, Peeples said. Both favor stream bottoms with mixtures of sand, gravel and cobblestones.
The long solid can reach 5 inches in length and live up to 50 years. It is located in Alabama, Indiana, Kentucky, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia.
Of the 60 known populations, 48 are in a limited area with no indication that young mussels reach adulthood, according to the Fish and Wildlife Service.
Previously, there were 160 known populations. The mussel has disappeared from Georgia and Illinois.
The round hickorynut grows up to 4 inches and is found in Alabama, Indiana, Kentucky, Michigan, Mississippi, Ohio, Pennsylvania, Tennessee, and West Virginia.
Only 69 populations are thought to remain, down from an all-time high of 301. Of the survivors, 49 are in a narrow area and show no signs of young mussel maturity. They are no longer in Georgia, Illinois or New York.
Threatened species are considered to be in danger of extinction within much or all of their range.
Protection under the Endangered Species Act will help the mussels “by raising awareness, inspiring conservation partnerships and making funds available for their recovery,” said Mike Oetker, regional director of the Fish and Wildlife Service. Wildlife
The agency will designate critical habitat and work with state wildlife biologists to promote recovery, he said. For long solids, protected areas include 12 units along 1,115 river miles, while critical habitat for round hickorynut has 14 units along 921 river miles.
Both species are largely found in the same areas as other federally protected mussels. Federal agencies will be required to consult the service before allowing potentially harmful activity.
Under the law, the service can authorize actions that cause “a minimal level of disturbance” to the mussels, Peeples said.