Print PageIncreased inter-annual variability of precipitation and prolonged durations of droughts have already increased during the last 10 years and more extreme droughts are predicted for Georgia over the next several decades. Moreover, the increasing demand for freshwater resources for municipal uses as well as for irrigation, hydropower, and cooling waters, make it difficult to provide environmental flows can sustain the aquatic biodiversity of native freshwater species. In addition to these lower flows, the proposed deepening of the river channel and estuary to begin in 2012 will increase the capacity of larger cargo ships to use the harbor at Savannah, Georgia but alter the sediments and benthic populations by dredging activities. All these changes combine to increase uncertainties for sustaining populations of native freshwater species. More detailed studies of their resilience to cumulative effects of natural variability and management activities are needed. The current high species richness among the native mussel communities contributes to essential ecosystem processes such as nutrient cycling, detrital processing and biofiltration. We are investigating the importance of biofiltration in sustaining ecosystem services provided by the high diversity of mussels and other freshwater invertebrates. These services depend on sustaining the diversity of mussels and other species that contribute to biofiltration.
Results/Conclusions
Although mussels provide important ecosystem services by actively filtering suspended organic materials during base flows, they shut down their filtration activities and remain inactive in sediments during very low flows. Because these species and their complex life histories are highly vulnerable to drought, we are examining how flows can be released from reservoirs during periods of prolonged drought to protect mussels. The Savannah River Basin provides examples of how to evaluate tradeoffs regarding the relative benefits by different species. We compare methods used for economic valuation of passive and active uses of ecosystem goods and services to determine how biofiltration can be sustained to reduce the costs of water treatment. The cost of providing high-quality water for municipal uses rises as turbidity and suspended solids increase in raw waters used in treatment plants. These species and others will need to adapt to climatic impacts such as sea-level rise and other shifts in salinity from inter-annual variability of rainfall if biofiltration can continue to improve water quality.
