Personal tools
You are here: Home News Headlines Two mussel species once native to Alabama could be declared extinct
Sections
Document Actions

Two mussel species once native to Alabama could be declared extinct

by Katie Shaddix last modified February 23, 2009 02:06 PM

The U.S. Fish and Wildlife Service has proposed listing as extinct two more species of mussels native to Alabama rivers, but notes improvements in populations of other endangered mussels.

 

Two mussel species once native to Alabama could be declared extinct

Meanwhile, others show improvement
Sunday, February 22, 2009
THOMAS SPENCER
News staff writer

The U.S. Fish and Wildlife Service has proposed listing as extinct two more species of mussels native to Alabama rivers, but notes improvements in populations of other endangered mussels.

Alabama is an international hotspot for its diversity of freshwater aquatic species, but it also is a hotspot for extinctions.

There are 180 freshwater mussel species found in Alabama, representing 60 percent of the mussel species found in the United States and 26 percent of the world's known mussel species.

In the past century, about 28 Alabama mussel species have become extinct, primarily due to the damming of free-flowing rivers and pollution in streams. Beyond the concern of protecting species, scientists say these creatures serve as indicators of the quality of the state's water.

The latest candidates for extinction, the upland combshell and the southern acornshell, once could be found in the Cahaba and Coosa rivers. Neither has been found in Alabama since the early 1970s.

Historically, the southern acornshell lived in the Mobile River Basin's upper Coosa River system and the Cahaba River, in Alabama, Georgia and Tennessee.

The historical range of the upland combshell included portions of the Black Warrior, Cahaba and Coosa rivers of the Mobile River Basin and some of their tributaries in Alabama, Georgia and Tennessee. When the species were protected under the Endangered Species Act in 1993, scientists believed they persisted in low numbers in the upper Coosa River drainage and possibly in the Cahaba River.

A five-year review:

After decades of searching in vain, the Fish and Wildlife Service is recommending the species be presumed extinct as part of a five-year status review on the health of 11 endangered mussel species in the Mobile River Basin.

A separate review of the Tombigbee watershed scheduled for release later this year may add two additional mussels, the flat pigtoe and the stirrupshell mussel, to the "presumed extinct" list.

"We've looked under a lot of rocks for these creatures," said Paul Hartfield, a Fish and Wildlife endangered species biologist based in Jackson, Miss.

But there is better news for other species.

"The good news is that in those 20 years we have discovered a number of populations of these other things," Hartfield said.

The endangered mussels for which additional populations have been found are the fine-lined pocketbook, orange-nacre mucket, Alabama moccasinshell, southern clubshell, southern pigtoe, ovate clubshell and triangular kidneyshell. Because of continuing threats to the limited populations, Fish and Wildlife is recommending they stay on the endangered-species list.

Two other species, the Coosa moccasinshell and the dark pigtoe, also will remain on the list because of no indication of improvement in their numbers.

A confluence of nature:

Alabama is so rich in species because it has multiple distinct river basins and an abundance of stream miles. The major blow to these species began with the damming of main channels of major mainstem rivers, which eliminated free-flowing waters mussels need to survive.

The populations that survived existed in fragmented and isolated spots on smaller tributaries.

"So you are left with these small islands of habitat," Hartfield said. Those populations are then left more vulnerable to drought or excessive rainfall or pollution.

Hartfield said the Clean Water Act has improved conditions in the streams, making recovery possible. He also noted Alabama's establishment of the Alabama Aquatic Biodiversity Center, a state-supported effort to breed endangered aquatic species, then reintroduce the animals to their former habitats.

Paul Johnson, the center's director, said the center is working with Alabama Power Co. to restore some areas of regular stream flow in the Coosa basin and with the Tennessee Valley Authority to restore flows in the Tennessee basin.

Even with the extinctions, the state of Alabama still has the highest diversity in the nation for freshwater mussels, freshwater turtles, freshwater snails and crayfish.

"These species signal the problems that we have with our freshwater systems," Johnson said. "The loss of these species represents the degredation of riverine systems in this state."

By keeping the water cleaner and flowing, the state will save money on water treatment cost and sewage treatment, he said. "If we restore habitats and flows we basically improve our water supply and water quality," Johnson said. "The dirtier your water is, the more it costs to clean it up."

E-mail: tspencer@bhamnews.com


¬©2009 Birmingham¬© 2009 al.com All Rights Reserved.

 

Powered by Plone CMS, the Open Source Content Management System

This site conforms to the following standards: