Effects of groundwater fluctuations on the distribution and population structure of two cyprinid fishes in a desert spring complex

Abstract

Relationships between groundwater levels, surface water levels, and the distribution and habitat use of two cyprinid fishes, Least Chub (Iotichthys phlegethontis) and Utah Chub (Gila atraria), were examined at a spring complex in the Snake Valley of the Great Basin, USA to test the hypothesis that the distribution and structure of fish populations in the spring complex is regulated by the influence of shallow groundwater levels on the depth and distribution of surface water and the availability of suitable spawning and juvenile habitat. Groundwater levels explained 97% of the temporal variation in surface water levels measured at 47 monitoring points and exhibited annual cycles linked to evapotranspiration rates. Least Chub and Utah Chub migrated from springs to ponds, which were used as spawning and juvenile habitat, when groundwater and surface water levels were high during the early spring, but became concentrated in deep springs as ponds receded during the late summer and early fall. Populations of both species became increasingly fragmented as groundwater and surface water levels declined. Specific differences in the relative abundances and body sizes of juvenile Least Chub inhabiting different seasonally isolated regions of the spring complex persisted over multiple years, suggesting that juvenile growth rates and survival were influenced by connectivity of core spring habitats to seasonally deep ponds. The nature of the relationship between groundwater and surface water levels indicated that long-term declines in shallow groundwater levels of ≥ 40 cm would eliminate most of the spawning and juvenile habitat in the spring complex.

Keywords:

• Gila atraria
• Great Basin
• groundwater
• habitat fragmentation
• Iotichthys phlegethontis
• Snake Valley
• springs

Acknowledgments

Thanks to Tiffanee Hutton and Danielle Voisin for assistance with bathymetric surveys and GPS mapping of surface waters at the Leland Harris Spring Complex during 2013–2014. Thanks especially to Ed Alder for providing access to his property, which encompasses the northeastern half of the Leland Harris Spring Complex, and for many years of cooperation with monitoring and management efforts. Rich Emerson provided valuable data from groundwater monitoring and LIDAR mapping of surface elevations conducted by the Utah Geological Survey.

Disclosure statement

No potential conflict of interest was reported by the author.

Funding

This project was funded through a grant (F12AP00521) from the U.S. Fish and Wildlife Service and by additional funding from the U.S. Bureau of Land Management, Utah Endangered Species Mitigation Fund, and State Wildlife Grants received by the Utah Division of Wildlife Resources.

Data availability

The data collected and analyzed in this study is accessible to the public under the DOI: 10.6084/mp.figshare.7121699.

Additional information

Notes on contributors

Mark C. Grover

Mark C. Grover is an aquatic ecologist whose research interests include landscape ecology and conservation biology. He currently works as the Colorado River Basin Native Aquatics Coordinator for the Arizona Game and Fish Department.