National Water Census
Ecological Limits of Hydrologic Alteration in the Apalachicola-Chattahoochee-Flint Basin
As part of the WaterSMART ACF Basin Focus Area, USGS biologists are researching meta-population or 'community-level' dynamics of fishes and mussel species in six ACF sub-basins during different seasons. These sample sites are spread throughout sub-basins in each of Apalachicola, Chattahoochee, and Flint River systems and provide samples within the Blue Ridge, Piedmont, Southeast Plains, and Coastal Plain ecoregions. Researchers will incorporate data from the field studies into fine-scale hydrologic models within each sub-basin. This will allow them to investigate how species distributions are likely to change in response to streamflow variation, including drought, flood and intermediate flow conditions.
An example ecological water product would be a graph relating simulated daily water withdrawals and the predicted change in the richness of fish species in Potato Creek, Georgia (Freeman and others, 2012). In the example given, the graph shows that changes in water withdrawals from 0.5 to 4.0 million gallons per day (MGD) may result in a 16% loss in the richness of fluvial specialist species (pink line). Such relations may provide water managers, stakeholders, and policy makers with insight into how best to meet ongoing human water demand while minimizing the proportional loss of important recreational fish species that are dependent upon stream flow for survival and reproduction.
Simulating changes in persistence of fish and mussel species in relation to different water management scenarios can provide a powerful tool for planning to meet human demands while conserving imperiled species, recreational fisheries, and stream biotic integrity. Models developed for the ACF will help scientists and managers understand how species characteristics (such as body size and shape, or reproductive season) influence population responses to changes in stream flows, as well as how flow variability affects species differently in mountain, Piedmont and Coastal Plain streams. Patterns quantified for ACF streams could provide a template for developing similar models for other river systems where resource managers need quantitative forecasts of ecological responses to potential changes in water use and stream flow regimes.
Freeman, M. C., G. R. Buell, L. E. Hay, W. B. Hughes, R. B. Jacobson, J. W. Jones, S. A. Jones, J. H. LaFontaine, K. R. Odom, J. T. Peterson, J. W. Riley, J. S. Schindler, C. Shea and J. D. Weaver. 2012. Linking river management to species conservation using dynamic landscape-scale models. River Research and Applications, Wiley Online Library.