Alabama Mollusks

Overview

Overview
Endangered and Candidate species
Examples/lists of Alabama Mollusks: Freshwater, Marine, Land, Fossil
Zebra Mussels
Bibliography
Additional Resource Links


Alabama ranks first, or second only to Tennessee, in the diversity and number of its mollusk species. In fact, some species are endemic to (only found in) Alabama, or Alabama and a bordering state. Some of this diversity can be attributed to the variety of ecosystems found in Alabama's beautiful land formations, river systems and coastline. Another factor contributing to this diversity may be the fact that during the ice age, glaciers did not cover Alabama killing the mollusks.

Alabama's coastline may be small in comparison to other Gulf Coast states, but over five hundred species of marine mollusks have been found in the coastal sand and waters of Alabama. Visitors to Alabama's beaches may not always see evidence of this variety, but a walk on the beach after a heavy storm or hurricane will usually yield shells which have been washed ashore from deeper waters. In fact, one of these deeper water species--Johnstone's Junonia (Scaphella junonia johnstoneae Clench, 1953)--was chosen as Alabama's State Shell in 1990. This shell was named in honor of Kathleen Yerger Johnstone, an amateur conchologist who lived in Mobile.

In spite of the wide variety of land snails in Alabama, not much is known about them. The last major study on Alabama land snails was performed in the 1920s when Bryant Walker wrote the classic The Terrestrial shell-bearing mollusca of Alabama. It is hoped that more studies on Alabama's land snails will be conducted in the future.

One area of increased study concerns freshwater mollusks. Recent reports and newspaper articles have stated that Alabama is home to 43% of the native freshwater gill-breathing snails and 60% of the native freshwater mussels which are found in the United States. Of those, 77% of the snails and 34% of the mussels are endemic to Alabama, or the river system shared by Alabama and a neighboring state. Unfortunately, the reports also state that 65% of the snails and 69% of the mussels are considered either endangered, threatened, or of special concern.

What has changed in Alabama that so many of its freshwater mollusk species are considered endangered, or "at risk?" Some of the changes are increased pollution, impoundment (damming) of rivers, stream/river channelization, over-harvesting of commercial species, and the zebra mussel. Pollution destroys the freshwater environment in that it kills the mollusks, their food, and/or any fish-host needed for reproduction. Impoundment of rivers and channelization of streams/rivers destroys or changes the ecosystem some mollusks need to survive. Over-harvesting and the cleaning out of mussel beds by musselers not only severely limits the viable population of commercial species, but also affects the population of any non-commercial species which might be in that same bed. Introduced, or non-native, species such as the zebra mussel compete for limited food resources starving out native mussel species.

What can Alabamians do to protect our natural mollusk species? One way is to become aware of the species we do have, their value as a natural and economic resource, and the environmental problems which might endanger their existence. New State rules and regulations are being implemented to help protect commercial mussels from being over-harvested and to prevent musselers from removing any non-commercial species from the mussel bed. River and stream surveys for sources of pollution (including non-point sources) will help identify areas which need attention. Groups of private citizens can work with State agencies to help monitor and/or improve waterways in their area.

These Internet pages are being developed in an effort to provide basic information about Alabama mollusks to teachers, students and the general public. It is my understanding that several books about Alabama mollusks are in the early stages of preparation. Hopefully, these projects will be completed soon.

REFERENCES:

Garner, Jeffrey. 1996.
Freshwater mollusks. (A presentation to the North Alabama Shell Club on January 18, 1996).

Lydeard, Charles, and Richard L. Mayden. 1995.
A Diverse and endangered aquatic ecosystem of the Southeast United States. Conservation Biology 9 (no.4): 800-805.

Walker, Bryant. 1928.
The Terrestrial shell-bearing mollusca of Alabama. Ann Arbor, Mich.: University of Michigan Museum of Zoology. (Misc. Pub. 18). Alabama Museum of Natural History. (Museum Paper No. 8)

Wills, Deborah. 1995.
Freshwater mussels of the Tennessee River near Decatur, Alabama. Privately published.


[Top of Page] - [North Alabama Shell Club]

© 1996, 1997, 1998 by Deborah Wills (dwills@HiWAAY.net)
This page has been accessed times since January 24, 1996.
Last Revised: 24 March 2000