Conservation of Southeastern Mussels

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Overview

Freshwater mussels are an integral component of aquatic ecosystems and are indicator species for assessing the health of freshwater systems.  Approximately 90% of the 300 species of mussels found in the United States occur in the southeastern states. During the past 30 years, freshwater mussels have experienced a dramatic decline.  Extinction rates for freshwater mussels are orders of magnitude higher than expected background levels. Attempts to address causal factors of mussel declines are hampered by the lack of knowledge of even basic aspects of their life history and habitat requirements.

Beginning in the early 1990s, FISC researchers initiated inventory and monitoring projects for southeastern freshwater mussels.  Simultaneously, studies were undertaken to examine the zoogeography, taxonomy, life history, ecology, and population biology of endangered and at-risk species.  In addition, investigators examined the relationship between native mussels and the nonindigenous Asian clam, sedimentation processes, and fish community structure in southeastern rivers to better understand the potential causes of freshwater mussel declines.

Research conducted by FISC scientists was instrumental in the recent federal listing of seven freshwater mussel species from eastern Gulf of Mexico drainages as threatened or endangered and in the development of recovery strategies for those species.  Current FISC projects will provide mussel data to state and federal agencies, natural resource managers, as well as private organizations in Alabama, Florida, and Georgia that will aid in the protection and recovery of freshwater mussel populations.

Program Goals

• To support objectives outlined in the "National Strategy for the Conservation of Native Freshwater Mussels" by conducting sound scientific research on the distribution, conservation status, and ecology of freshwater mussels, especially those that are endangered or at-risk species.
   
• To determine the causal factors of decline in freshwater mussels.
   
• To provide biological and ecological data to natural resource management agencies to aid in the protection, recovery, and management of native freshwater mussels.

Projects

Effects of urban growth in the Atlanta metro area on freshwater mussels in the Line Creek watershed

Line Creek, a major tributary of the upper Flint River drainage, has its headwaters in Fulton County, southwest of Atlanta.  Historically, Line Creek harbored a diverse mussel fauna that included at least 14 species, including three currently federally listed as endangered, as well as a fourth species now considered extinct. Unprecedented urban growth in the Atlanta area is often cited as a factor in the decline of aquatic species in the upper Flint River system, but empirical data are lacking. In this study, a multidisciplinary approach was used to correlate changes in land use, vegetation cover, stream channel geomorphology, and hydrology to the decline of aquatic species in Line Creek over the past 30 years.  FISC collaborated with scientists from the University of Florida, Utah State University, and UC Berkeley to investigate how land use changes and urbanization in the Line Creek watershed are linked to the imperilment of aquatic faunas in the Atlanta area.

Examination of the federally endangered Pleurobema decisum, within the Old Channel of the Coosa River, Alabama

The endangered southern clubshell historically occurred throughout the Mobile Bay drainage of Alabama, Georgia, Mississippi, and Tennessee. Today, there are only three isolated populations known to exist. One of these populations is in a short reach (about 6 miles) of the Coosa River below Weiss Dam in east Alabama. The objectives of this study are to determine the range and density of this population of Pleurobema decisum and to quantify the size structure and variation. The health of this population will also be assessed through glycogen analysis using a surrogate mussel species.