It’s time to declare mussel extinct, U.S. Fish and Wildlife Service says
Posted on Monday, August 11, 2008
The U. S. Fish and Wildlife Service wants to declare extinct a species of mussel once found in the Black and White rivers in Arkansas, as well as parts of Tennessee and Alabama, that hasn’t been spotted in 43 years.
The turgid-blossom pearly mussel — a shiny yellow-green mollusk less than 1. 6 inches in length — has been on the endangered species list since 1976. But a five-year review completed by the federal agency found that the mussel, along with two other southeastern mussels, is likely extinct and should be removed from the endangered list, said Jim Widlak, a fish and wildlife biologist in the agency’s Cookeville, Tenn., office, which conducted the review.
“We really have no idea what caused it [to become extinct ],” Widlak said. “In the area the species occurred, there are still excellent mussel communities. Other species are doing very well. What we are thinking is maybe these particular species... are very sensitive to some kind of disturbance or pollutant.”
The other mussels now considered extinct are the yellowblossom pearly mussel, which lived in parts of Tennessee and Alabama and hasn’t been seen in 41 years, and the green-blossom pearly mussel, which lived in parts of Tennessee and Virginia and hasn’t been seen in 26 years.
The turgid-blossom pearly mussel lived in the Tennessee River and Cumberland River drainages in Tennessee as well as in Spring Creek, the Black River and the White River in Arkansas and in Shoal Creek and Bear Creek in Alabama. It made its home along the shoals of rivers in areas with rapid currents.
The last known collection of the species was found in the Duck River in Tennessee in 1965 by biologists with the Tennessee Valley Authority, according to the five-year review.
Since that time, several mussel surveys have been completed in the areas where the mussels had previously been located and none has been found, Widlak said.
While it is possible that the species still exists, it is not likely, he said.
“We are kind of hoping that somebody might find one or more of those species,” Widlak said. “They could still be out there, but with all the surveys that have been done in the rivers... they just haven’t found these.”
The ivory-billed woodpecker was considered extinct for six decades until the April 2005 announcement it had been rediscovered in Arkansas. There have been several unconfirmed sightings since then but no conclusive evidence of the bird’s existence.
It is not surprising that this mussel has been recommended for the extinction list, said John Harris, a mussel expert and the assistant division head with the environmental division of the Arkansas Highway and Transportation Department.
“I have never seen one except in a museum before,” Harris said. “It is disappointing that we haven’t been able to find it.”
Arkansas is home to between 75 and 85 species of freshwater mussels, Harris said. Among those, eight — including the turgid-blossom pearly mussel — have been placed in the federally endangered category; two are classified in the less severe, federally threatened category, and three are considered by the state to be of “special concern.”
While some mussel species are doing well, generally southeastern freshwater mussels are believed to be in danger because of pollution or the destruction of their habitat through the building of dams and other obstructions in the water.
“The habitat in which they evolved eons ago has just radically changed over time, and they are not able to evolve as quickly to keep up with the changes,” Harris said. “Not all of them are able to adapt.”
The mussel species are important because they can serve as an indicator species of what is happening in the environment and they are part of the larger food chain, said Alan Christian, associate professor of biological sciences at Arkansas State University in Jonesboro.
“One of the things that we say as biologists is that these are kind of like canaries in a coal mine,” Christian said. “They are an indicator that environmental conditions aren’t good, and that may be an indicator of water quality.”
Now that the five-year review has recommended the creatures be labeled extinct, the next step is a rule-making process, which includes time for public review and comment, Widlak said.
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