Climate Change Drives Divergent Outcomes for Stream Fishes in the Red River

Abstract

Climate change is expected to alter the distributions of stream fishes in ecosystems around the world, but climate projections vary widely among competing climate models. Conservation practitioners face the challenge of designing conservation strategies that are robust to the uncertainty surrounding future climatic conditions. Here, we use species distribution models (SDMs) for 31 fish species in the Red River basin to quantify the variation in potential species distributions across 9 different climate scenarios. We created SDMs by pairing historical fish occurrence records with a set of temporally dynamic South-Central Climate Adaptation Science Center (SC-CASC) built climate covariates and temporally static lithospheric and anthropogenic covariates that are known to drive species’ distributions. We find that the range width of most fish species in the Red River Basin will contract by 2050 and 2070; this was true for both MAXENT and BRT models and across all climate scenarios. However, species also varied dramatically in the uncertainty associated with their future distributions, with the range in outcomes across climate scenarios being more than 10 times higher for some species than for others. Our analysis also revealed that the greatest absolute changes in range width are projected to occur for those species which have historically been the most widespread. This comprehensive assessment on Red River stream fishes suggests a general decline in range width across the basin due to climate change and anthropogenic stressors.