Committee Chair

Schorr, Mark

Committee Member

Litchford, Gary; Nelson, Charles; Johnson, Paul

Department

Dept. of Biology, Geology, and Environmental Science

College

College of Arts and Sciences

Publisher

University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)

Abstract

The Conasauga River, an upper Coosa River tributary, was historically one of the most diverse rivers within the Mobile basin drainage for freshwater mollusks. The Conasauga River historically supported 37 species of unionids (Bivalvia: Unionidae), 11 species of prosobranch gastropods (Mollusca: Gastropoda), and 3 species of sphaerid (Bivalvia: Sphaeridae) clams. I collected records from several museums ranging from 1914 to 1990 to chronicle the historical diversity of the Conasauga River system, and conducted a contemporary survey to compare changes in species distributions and richness over the twentieth century. During this study, a total of203 collections were made in the mainstem ofConasauga River in 1998-1999, ranging from the headwaters downstream to US Highway 76 bridge in Dalton, Georgia. Additionally, all major tributaries to the Conasauga River above US Highway 76 were sampled, in addition to several sites in the Holly Creek and Swamp Creek systems. Overall species richness of unionids decreased from 37 species in 1917 to 27 species in 1998-1999. Additionally, species richness at 4 well-collected historical sampling locations dropped from x = 23.5 in 1917 to x = 7.5 in 1998-1999. By consistently searching various microhabitats, an increase in species richness for gastropods was recorded, with 20 species collected in 1998-1999 versus 11 species in 1914-1919. Six new gastropod species records for the Conasauga River system are recorded, as well as a Pleurocera sp. that may be undescribed. Three species of sphaerid clams were collected in 1998-99, which agrees well with historical species richness values by H. D. Athearn. Overall, mollusk distributions were observed to be fragmented. An extremely small number of individuals were found of many un ionid species, and several species of pleurocerid snails were restricted to shoal areas. Specific factors contributing to this overall decline of mollusks in the .Conasauga River system were not examined in this study, but general declines in water quality and reduced in-stream habitat quality due to poor land use practices are suspected.

Acknowledgments

Without the lifelong support ofmy parents, I may not have been given the opportunity to pursue my dreams in the natural sciences. I wish to thank Dr. Paul Johnson for giving me the opportunity to work with freshwater mollusks. I will be forever grateful for his tutelage. Dr. George Benz offered advice on writing design and manuscript revisions. Byron Brooks, Angela Collier, Amanda Evans, Paul Freeman, Tara Hodge, Chris Leary, Abigail Prater, Alby Saunders, and Doug Shelton assisted with various phases of the fieldwork. Steve Ahlstedt of United States Geological Survey offered invaluable advice about field collection of freshwater mollusks and supported some phases of the fieldwork. Dr. Mark Gordon assisted in correctly identifying hydrobiid gastropods. My committee of Dr. Paul Johnson, Dr. Gary Litchford, Dr. Charles Nelson, and Dr. Mark Schorr offered advice in survey design. I would like to acknowledge the USGS Biological Resources Division Species-at-Risk program and USFWS for providing financial support to this project. Last I wish to thank my wife, Amanda, for encouraging and supporting me despite my arriving home absurdly late on numerous occasions. She was willing to trudge through several mucky creeks and sinkholes throughout northwest Georgia with a smile on her face to help me complete this research.

Degree

M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.

Date

5-2001

Subject

Mollusks--Effect of habitat modification on; Stream ecology--Coosa River (Ga. and Ala.); Unionidae; Gastropoda; Sphaeriidae (Mollusks)

Discipline

Environmental Monitoring

Document Type

Masters theses

DCMI Type

Text

Extent

vi, 276 leaves

Language

English

Call Number

LB2369.2 .E926 2001

Rights

http://rightsstatements.org/vocab/InC/1.0/

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