PS 64-61
Assessing desert aquatic habitat under varying management and climate scenarios

Friday, August 15, 2014
Exhibit Hall, Sacramento Convention Center
Mark B. Hausner, Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, NV
Kevin P. Wilson, Pahrump Field Office, Death Valley National Park, Pahrump, NV
D. Bailey Gaines, Pahrump Field Office, Death Valley National Park, Pahrump, NV
Francisco Suárez, Hydraulic and Environmental Engineering, Pontificia Universidad Católica de Chile, Chile
Gayton G. Scoppettone, United States Geological Survey Biological Resources Division
Scott W. Tyler, Geological Sciences and Engineering, University of Nevada Reno, Reno, NV
Background/Question/Methods

Desert aquatic ecosystems are understudied systems, and many such systems have been altered by both direct and indirect human development. Because the species that occur in these systems are often adapted to extreme conditions, small changes in water level or climate may have enormous impacts on the ecosystem. One such system is Devils Hole, a small pool ecosystem in the southwestern United States that is home to the only extant population of the endangered Devils Hole pupfish (Cyprinodon diabolis). In this study we combine computational fluid dynamic (CFD) modeling with a conceptual ecological model to examine the impacts of simultaneous changes in the water level and climate of Devils Hole. The CFD model predicts water temperatures as a response to climate and water level, and the ecological model is used to determine the timing of the environmental thresholds that limit the annual recruitment of C. diabolis. We consider three climate scenarios, mid-century and long-term projections, and water depths varying up to 30 cm from the current mean depth of 35 cm. The combination of interdisciplinary modeling approaches offers a method to quantify and compare the suitability of habitat under a range of management and climate scenarios.

Results/Conclusions

Results show that both climate change and depth of water affect the ecosystem’s suitability as habitat, but that they do not exert equal influence. While climate change does result in higher peak water temperatures and a shortened annual recruitment period, the influence of water depth on these temperatures is an order of magnitude greater than that of climate change. Increasing the average depth in the ecosystem has the potential to mitigate the impacts of even the most extreme climate scenarios. Although there is significant concern about the effects of climate change on aquatic ecosystems, our work shows that the more immediate driver of habitat degradation in Devils Hole is the local and regional groundwater development that controls the depth of water in the system. The drivers of climate change are typically addressed on a national and international level, but our results show that local management and conservation efforts can have as great or greater influence on at-risk aquatic ecosystems.