PARENT SESSION
Oral Session 73: Aquatic Ecology VI: System Processes.
Presiding: K Manoylov and K Nydick
Wednesday, August 4, 1:30 PM to 5:00 PM, Meeting Room A 105.

Scenarios of global loss of freshwater fish biodiversity from climate change and water withdrawal.

Xenopoulos, Marguerite ^*,1, Marker, Michael², Alcamo, Joseph³, Lodge, David¹, ¹ University of Notre Dame, Notre Dame, IN, USA² Universität Potsdam, Potsdam, Germany³ University of Kassel, Kassel, Germany

ABSTRACT- The rate of water flow in rivers (discharge) is one index of aquatic habitat heterogeneity. Analogous to a species-area curve, fish species richness increases with greater river discharge. Reduced discharge in rivers will result from climate warming and/or reduced precipitation and human use of water, but the possible consequences of these changes on fish richness is poorly quantified. We used the three scenarios developed by the Millenium Ecosystem Assessment to build scenarios of losses in river discharge and therefore losses of freshwater fish richness that will result from climate change and increased water withdrawal for agriculture and other human uses over the next 100 years. Geographic regions that the scenarios indicate would experience reduced discharge are concentrated in rivers that are rich in total and endemic species, including rivers in Central America, West Africa and India. While results differ somewhat across scenarios, typical losses are 1-55% of riverine fish biodiversity by 2100 due to climate change and an additional 1-5% loss of richness due to water use. However, some rivers (e.g., Euphrates R., Indus R.) are predicted to have more substantial fish loss from water use alone. Our approach estimates losses of freshwater fish conservatively (given the scenario assumptions) because losses are driven exclusively by climate change and water withdrawal. If any scenario became reality, much greater declines in freshwater biodiversity would result because interactive, cumulative, and long-term effects of additional environmental drivers (in addition to discharge) would occur.

Key words: discharge, global rivers, freshwater fish, richness