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Use of geographic information systems (GIS) to assess environmental risk factors threatening rare redeye bass (Micropterus coosae) in the southeastern United States
Citation:
OSWALD, K., J. Quattro, AND M. BAGLEY. Use of geographic information systems (GIS) to assess environmental risk factors threatening rare redeye bass (Micropterus coosae) in the southeastern United States. Presented at American Fisheries Society, Nashville, TN, August 30 - September 03, 2009.
Impact/Purpose:
Biological resource conservation and management programs have benefitted greatly over the last decade from advances in population genetics research. The EPA, while having very similar goals to these programs, has yet to capitalize on the rapid advances in molecular population genetic methods. This research aims to evaluate the utility of population genetic measurements for describing the current condition and vulnerabilities of biological populations exposed to anthropogenic stressors. A key objective of the Clean Water Act is "to restore and maintain the chemical, physical, and biological integrity of the nation’s waters." Biological integrity is defined as the ability of an aquatic ecosystem to support and maintain a diverse, balanced, integrated, adaptive community of native organisms. A primary focus of this research effort is the molecular characterization of genetic diversity, a fundamental component of biodiversity and an important indicator of biological integrity. This research will assess and define biological integrity with scientific rigor, using population genetics as the basis for understanding biological diversity and functional organization. A completely developed indicator of genetic diversity will bring significant new data to the assessment of the biological integrity of aquatic resources and the sustainability of fish, invertebrate, and plant communities. These new data will be used to help characterize (1) appropriate ecological units (including cryptic species and biological populations) for assessment of fish and macroinvertebrate communities; (2) the inherent vulnerability of aquatic species to further exposure to stressors; (3) the relationship between genetic diversity and environmental condition; (4) temporal trends in the condition of fish and invertebrate populations; and (5) linkages between landscape-level stressors and population-level outcomes for aquatic organisms. By identifying the spatial scale at which individuals migrate and breed, measures of genetic diversity define biological populations, which are the most meaningful units for assessing species and communities. A significant loss of genetic diversity is detrimental to populations and affects their sustainability into the future. In the short term, reduced genetic diversity can contribute to inbreeding depression, lowering population fitness. In the long term, it reduces the population’s resilience because the population's genetic pool of potential responses to stress is restricted. The population’s lack of selectively propitious genes may lead to further population declines and eventual extirpation when faced with novel stressors or changes in stressor intensity. In addition, since past and present environments have shaped current levels of genetic diversity, molecular genetic markers are natural indicators of cumulative population exposure. Habitat degradation (chemical, physical, or biological), hybridization with introduced taxa, and habitat fragmentation have predictable effects on genetic diversity. Coupling of these molecular genetic data with quantitative environmental data and landscape data gathered through EMAP and other initiatives will allow powerful inferences to ecological condition and population responses to environmental stressors.
Description:
Habitat destruction, pollution, species introductions, and drainage alterations are frequently cited as the principal anthropogenic stressors responsible for wide-scale imperilment of the freshwater ichthyofauna of the southeastern United States. Quantification and assessment of the relative contribution and influence of each is vital information for conservation and management plans whose goals include species recovery and long-term persistence. Redeye bass (Micropterus coosae), a rare southeastern U.S. endemic, is restricted to only six drainages within the region, and one Atlantic Slope population has been recently designated as imperiled. Further, population genetic studies have identified multiple Evolutionarily Significant and Management Units distributed within and among these drainages. We have used geographic information system (GIS) data and analyses to preliminarily assess the individual and cumulative risks from exposures to various anthropogenic environmental stressors upon these genetically unique populations. We present initial results from our analyses and evaluate the future utility of this combined conservation genetic and GIS-based approach to aid in efforts to conserve redeye bass.