• Research

• Longleaf Pine Research
• Aquatics Research
• Wetlands
• Streams/Rivers
• Water Chemistry and Nutrient Dynamics in the Lower Flint River
• Coupling Source Water Chemistry to Microbiological Processes
• Annual Summary of Water Resources Conditions in Southwestern Georgia
• Effects of Flooding
• Changes in Mussel Assemblage Composition in the Lower Flint River Basin from 1999 to 2001: An Assessment of the Impacts of 2000 Drought
• Effects of Drought on Freshwater Mussels and Instream Habitat in Coastal Plain Tributaries of the Flint River, Southwest Georgia (July-October, 2000)
• Hydrologic and geomorphic controls on suspended particulate organic matter concentration and transport in Ichawaynochaway Creek, Georgia, USA
• Wood Debris Recruitment and Movement Across Differing Riparian landforms in a Coastal Plain Stream
• Groundwater
• Land-Use Impacts
• Wildlife Research
• Research Publications
• Graduate Projects

Changes in Mussel Assemblage Composition in the Lower Flint River Basin from 1999 to 2001: An Assessment of the Impacts of 2000 Drought

Research Team: Dr. Stephen W. Golladay (Associate Scientist), Paula Gagnon, Margaret Kearns, Juliann M. Battle (Research Technician III), and David W. Hicks (Scientist)

Freshwater mussel assemblages in the Flint River Basin of southwest Georgia are among the richest in the world. Historically, 29 species including 7 endemics occurred in the Flint Basin. A drought during the summer of 2000 caused record low flows and many perennial streams dried or became intermittent. Pre-drought surveys conducted in 1999 allowed an assessment of the impact of the drought on mussel assemblages. During 2001, 21 stream reaches which had abundant or diverse mussel assemblages were resurveyed. Where possible, study sites were classified as flowing or non-flowing during the drought. Ten sites were classified as non-flowing and seven of those occurred on the Dougherty Plain. Taxa richness was stable across the drought, only two of the non-flowing sites showed a loss of more than three taxa. Mussel abundance at sites classified as non-flowing showed significant declines (median value 80% decrease) compared to flowing sites (median value 5% increase). Riffle associated and non-specialist rare taxa showed the greatest declines. Mussel taxa that appear resistant to drought conditions included: Elliptio complanata/icterina, Toxolasma paulus, Uniomerus carolinianus, Villosa lienosa, and Villosa vibex. Mussel taxa that were intolerant of drought conditions included: Elliptio purpurella, Elliptio crassidens, Lampsilis straminea claibornensis, Quincuncina infucata, Strophitus subvexus, Villosa villosa, Lampsilis subangulata, Medionidus penicillatus, and Pleurobema pyriforme. Generally, greatest declines in mussel abundance occurred in the mid-reaches of the major tributaries of the lower Flint River (see map). These reaches depend on the Upper Floridan aquifer system, heavily used for irrigation, to maintain baseflows. Declines in mussel populations appear to be associated with unusual climatic conditions and increasing demand on the area streams and the regional aquifer system for irrigation water supply.

Additional Information: pdf version of project report

Funded by: The Joseph W. Jones Ecological Research Center and Georgia Environmental Protection Division