Volume 36, Issue 1 p. 147-160
Article

A Simple Prioritization Tool to Diagnose Impairment of Stream Temperature for Coldwater Fishes in the Great Basin

Jeffrey A. Falke

Corresponding Author

Jeffrey A. Falke

U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks, Post Office Box 757020, Fairbanks, Alaska, 99775 USA

Corresponding author: [email protected]Search for more papers by this author
Jason B. Dunham

Jason B. Dunham

U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 Southwest Jefferson Way, Corvallis, Oregon, 97331 USA

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David Hockman-Wert

David Hockman-Wert

U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 Southwest Jefferson Way, Corvallis, Oregon, 97331 USA

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Randy Pahl

Randy Pahl

Nevada Division of Environmental Protection, 901 South Stewart Street, Suite 4001, Carson City, Nevada, 89701 USA

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First published: 01 February 2016
Citations: 7

Abstract

We provide a simple framework for diagnosing the impairment of stream water temperature for coldwater fishes across broad spatial extents based on a weight-of-evidence approach that integrates biological criteria, species distribution models, and geostatistical models of stream temperature. As a test case, we applied our approach to identify stream reaches most likely to be thermally impaired for Lahontan Cutthroat Trout Oncorhynchus clarkii henshawi in the upper Reese River, located in the northern Great Basin, Nevada. We first evaluated the capability of stream thermal regime descriptors to explain variation across 170 sites, and we found that the 7-d moving average of daily maximum stream temperatures (7DADM) provided minimal among-descriptor redundancy and, based on an upper threshold of 20°C, was also a good indicator of acute and chronic thermal stress. Next, we quantified the range of Lahontan Cutthroat Trout within our study area using a geographic distribution model. Finally, we used a geostatistical model to assess spatial variation in 7DADM and predict potential thermal impairment at the stream reach scale. We found that whereas 38% of reaches in our study area exceeded a 7DADM of 20°C and 35% were significantly warmer than predicted, only 17% both exceeded the biological criterion and were significantly warmer than predicted. This filtering allowed us to identify locations where physical and biological impairment were most likely within the network and that would represent the highest management priorities. Although our approach lacks the precision of more comprehensive approaches, it provides a broader context for diagnosing impairment and is a useful means of identifying priorities for more detailed evaluations across broad and heterogeneous stream networks.

Received July 8, 2014; accepted October 22, 2015