Julian D.Olden (1)
1 School of Aquatic and Fishery Sciences,University of Washington, Seattle, Washington USA, olden@uw.edu, @oldenfish
Climate change is poised to challenge the future persistence of organisms across the globe, and many uncertainties remain to whether, and if so how, species will cope. Despite mounting evidence in terrestrial and marine ecosystems that the rapidity of climate change may exceed the dispersal ability of many species, the question of whether freshwater species will be able to keep respond has not been considered. My presentation provides the first evaluation of whether freshwater fishes will keep pace with projected climate warming in contemporary riverscapes where dams represent ubiquitous barriers to dispersal and habitat may simply run out at watershed divides. By linking geographic patterns and variability in climate change velocity to spatially explicit estimates of maximum dispersal rates and physiological tolerances, I quantify the fate of 862 fish species in over 6 million river kilometers across the contiguous United States. I illustrate that freshwater fishes will be required to disperse considerable distances to track geographic shifts in isotherms and that many species lack the dispersal ability to keep pace with stream warming. Large dams will only serve to worsen the situation by blocking upstream movement. Non-‐native fish species show, on average, five times greater dispersal ability compared to native species. Time lag responses between projected climate velocity and fish dispersal abilities highlight the species and locations where adaptive capacity may allow for resilience to climate change versus where barrier removal/passage and species translocation via assisted colonization may be necessary to ensure the future persistence of freshwater fishes.
Climate change is poised to challenge the future persistence of organisms across the globe, and many uncertainties remain to whether, and if so how, species will cope. Despite mounting evidence in terrestrial and marine ecosystems that the rapidity of climate change may exceed the dispersal ability of many species, the question of whether freshwater species will be able to keep respond has not been considered. My presentation provides the first evaluation of whether freshwater fishes will keep pace with projected climate warming in contemporary riverscapes where dams represent ubiquitous barriers to dispersal and habitat may simply run out at watershed divides By linking geographic patterns and variability in climate change velocity to spatially explicit estimates of maximum dispersal rates and physiological tolerances, I quantify the fate of 862 fish species in over 6 million river kilometers across the contiguous United States. I illustrate that freshwater fishes will be required to disperse considerable distances to track geographic shifts in isotherms and that many species lack the dispersal ability to keep pace with stream warming. Large dams will only serve to worsen the situation by blocking upstream movement. Non-‐native fish species show, on average, five times greater dispersal ability compared to native species. Time lag responses between projected climate velocity and fish dispersal abilities highlight the species and locations where adaptive capacity may allow for resilience to climate change versus where barrier removal/passage and species translocation via assisted colonization may be necessary to ensure the future persistence of freshwater fishes.