Evaluation of Biotic Metrics to Distinguish Between Reference and Impacted Rheocrenes (Springbrooks) in Southern Idaho

Publication Date


Type of Culminating Activity


Degree Title

Master of Science in Biology



Major Advisor

Peter Koetsier, Ph.D.


Because of their small size and patchy distribution, the structure and function of desert springbrooks are not well-understood. As a result, springbrook conservation usually is not a management priority. Although these systems provide important habitat for a variety of plants and animals in the arid environment, many are heavily affected by anthropogenic activity. In this study my objective was to determine if there are physical, chemical, and biological differences between impacted (i.e., grazed) and reference springbrooks.

I collected samples from 5 reference, 5 impacted, and 6 indeterminate springbrooks in the Great Basin of southwest Idaho. I gathered qualitative and quantitative habitat information, collected biofilm and benthic macroinvertebrate samples, and collected water column sam&les for assessing microbial carbon source utilization patterns using Biolog EcoPlatesTM I found significant differences in the macroinvertebrate communities between springbrooks that had been utilized by cattle (impacted) and those that were enclosed (reference). An index of biotic integrity consisting of six macroinvertebrate metrics (species richness, EPA richness, proportion Plecoptera, Hilsenhoff Biotic Index, intolerant taxa (0-1) richness and proportion intolerant (0-3) taxa) was found to differentiate reference and impacted springbrooks (t(8) = -4.95, P < 0.001). No significant differences in chlorophyll a (t(8) =1.209, P = 0.26) and ash free dry weight (t(8) = 1.509, P = 0.17) between impacted and reference sites was found; however, this was likely influenced by my small sample size. There were no statistically significant differences in the overall average well color development (AWCD) or guild-specific AWCD between reference and impacted springbrooks. Principle components analysis of the carbon source utilization patterns did not reveal obvious groupings of impacted, reference, and indeterminate springbrooks.

This study demonstrates that characteristics of the macroinvertebrate assemblages can be used to assess the ecological integrity of springbrooks. Future work should include species identification of the algal components in the biofilm because it will provide more useful information than biomass measures. At this time, it is premature to use carbon source utilization patterns for assessing ecological integrity; however, this technology may become a viable tool. Once methodologies are established to characterize reference springbrooks and quantitatively distinguish impacted from reference springbrooks, then natural resource management agencies can begin to take appropriate actions identifying, prioritizing, restoring, and conserving these vital habitats.

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