WASHINGTON (CN) - The U.S. Fish and Wildlife Service has listed the fluted kidneyshell and the slabside pearlymussel as endangered under the Endangered Species Act, and has designated 1380 river miles of critical habitat for the two mussel species in a separate action.
The listing action was "fast-tracked" due to a settlement between the USFWS and the Center for Biological Diversity (CBD) in 2011 to speed listing decisions for hundreds of species across the country in a court-approved five-year workplan, the CBD said in its press release.
Both species are "endemic to the Cumberland and Tennessee River drainages," according to the action. The mussels are found in Alabama, Kentucky, Mississippi, Tennessee and Virginia.
Noting that both the kidneyshell and the pearlymussel have lost over 50 percent of their historical populations, and that remaining populations have few members, the USFWS determined that the mussels are currently endangered throughout their ranges.
The mussels face ongoing threats from "impoundments, mining, oil and gas exploration, sedimentation, chemical contaminants, temperature alterations, recurring drought and flooding, population fragmentation and isolation, loss of fish hosts and competition from the introduced Asian clam," the agency said in its statement.
The kidneyshell is estimated to live from 26-55 years and the pearlymussel can live to be over 40. The long life spans mean that some populations are still considered to be potentially viable even if specimens have not been found since the large number of collections made in the 1980s.
Many of the threats to the mussels are especially harmful to reproduction and the early life stages.
"[Mussels] reproduce by making a lure that looks like a young fish; when larger fish attempt to prey upon the lure, the mussels release their fertilized eggs onto the fish's gills. Juvenile mussels develop as parasites on the gills before dropping off to begin life on their own. In dirty water, the fish cannot see the mussel's lure, so the mussel cannot reproduce," the CBD said.
Waterborne pharmaceutical chemicals present downstream from urban development and livestock areas can affect the reproductive cycles of the mussels, and herbicides are "acutely toxic" to juveniles and glochidia, or larval stage, according to the action.
The USFWS made some changes from the proposed rule by adding life-history information and making some revisions to the taxonomy of the pearlymussel, and to the current and historical populations. The agency deleted several "may" statements regarding climate change and cited studies on how increased temperatures are already impacting larval and juvenile mussels.
"Even small increases in temperature can cause reductions in the survival of freshwater mussel glochidia and juveniles, and temperatures currently encountered in the temperate United States during summers are close to or above the upper thermal tolerances of early life stages of freshwater mussels," the action said.
The critical habitat designation offers 1380 combined river miles of protection for the two mussel species, with some of the areas overlapping. Critical habitat designation helps to raise awareness of the needs of the protected species and has no impact on private landowner activities that do not require federal funding or a federal permit, the agency said.
Both actions are effective Oct. 28.
Read the Top 8
Sign up for the Top 8, a roundup of the day's top stories delivered directly to your inbox Monday through Friday.