Going with the flow: using species-discharge relationships to forecast losses in fish biodiversity

• Published in: Ecology (Durham) 2006-08, Vol.87 (8), p.1907-1914
• Main Authors: Xenopoulos, Marguerite A., Lodge, David M.
• Format: Article
• Language: English
• Subjects: Acipenser; Animals; anthropogenic activities; Biodiversity; Climate change; Conservation of Natural Resources; Environmental conservation; Extinct species; extinction; Extinction, Biological; Fish; Fishes; Forecasting; Forecasting models; Fresh water; Freshwater; freshwater biodiversity; Freshwater ecology; freshwater fish; Freshwater fishes; Habitat conservation; Lower Ohio–Upper Mississippi River Basin; Models, Theoretical; Pisces; prediction; River basins; riverine fish; Rivers; scenarios; Southeastern USA; Special Feature: Determinants of Biodiversity Change: Ecological Tools for Building Scenarios; Species; species diversity; Species extinction; species–discharge curves; statistical models; stream flow; stream flows; water consumption; Water Movements; water use
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/0012-9658(2006)87[1907:GWTFUS]2.0.CO;2

In response to the scarcity of tools to make quantitative forecasts of the loss of aquatic species from anthropogenic effects, we present a statistical model that relates fish species richness to river discharge. Fish richness increases logarithmically with discharge, an index of habitat space, similar to a species-area curve in terrestrial systems. We apply the species-discharge model as a forecasting tool to build scenarios of changes in riverine fish richness from climate change, water consumption, and other anthropogenic drivers that reduce river discharge. Using hypothetical reductions in discharges (of magnitudes that have been observed in other rivers), we predict that reductions of 20-90% in discharge would result in losses of 2-38% of the fish species in two biogeographical regions in the United States (Lower Ohio-Upper Mississippi and Southeastern). Additional data on the occurrence of specific species relative to specific discharge regimes suggests that fishes found exclusively in high discharge environments (e.g., Shovelnose sturgeon) would be most vulnerable to reductions in discharge. Lag times in species extinctions after discharge reduction provide a window of opportunity for conservation efforts. Applications of the species-discharge model can help prioritize such management efforts among species and rivers.