Species distribution models are an important tool for resource managers and conservationists charged with protecting vulnerable ecosystems in the face of climate change. These models combine existing species range limits with potential climate change scenarios to estimate how species distributions will change in the future. Yet the inherent uncertainty of predictive models can create additional challenges for managers, as different models can generate sometimes wildly different projections.

In a recent study supported by the South Central CASC, researchers at the University of Oklahoma looked for areas of consensus between different species projection models. They focused their analysis on 31 species of freshwater fish living in the Red River Basin, a drought-prone river basin that stretches across northern Texas, Oklahoma, Arkansas, and Louisiana. They compared historical range limits to predicted range limits calculated from species distribution models under a variety of climate change scenarios, estimating how the spatial distribution of each species could change in the next fifty years. They then summarized the changes all the fish species experienced across the region to project which areas of the river basin will experience the highest species declines under each scenario.

They found that, although models varied widely in projected range shifts for many species, they showed remarkable consistency in which areas of the Red River Basin were likely to become hotspots of species loss. Air temperature, rock characteristics, stream flow, and elevation had the largest effects on species distributions, consistent with empirical studies on aquatic ecosystems. They also found that common species (e.g. Largemouth and Smallmouth Bass), which have historically received little conservation attention, experienced shrinking ranges in many climate change projections. These results can inform land managers’ plans for prioritizing areas for climate change mitigation and highlight the importance of protecting common species.

This study is part of the South Central CASC funded project Balancing Water Usage and Ecosystem Outcomes Under Drought and Climate Change: Enhancing an Optimization Model for the Red River.