Evaluating the Efficacy of Stream Restoration Utilizing Biotic Indices

Robin M. Henderson

doi:10.7273/000004335

Annually, significant resources are utilized to restore ecological function in streams degraded by anthropogenic activities. Consequently, stream restoration is an increasingly common approach utilized to ameliorate past degradation of freshwater ecosystems. The underlying assumption of stream restoration programs is that biological integrity will improve following restoration; however, there is little scientific evidence to support this assumption since most projects lack effectiveness monitoring and results have been widely variable. This dissertation focuses on evaluating the efficacy of stream restoration using benthic macroinvertebrates as biotic indicators. I first evaluated if the overall performance (i.e., accuracy, precision, bias, responsiveness, and sensitivity) of Observed/Expected indices improved by adding additional references sites to River Invertebrate Prediction and Classification System models for two restoration projects (Eldorado Creek Restoration Project, AK and the Middle Fork John Day River Intensively Monitored Watershed (MFJDR IMW), Oregon). Additionally, since the differences necessary to discriminate between sites increases as variability increases, the variability for multiple biotic indices (Simpson’s Diversity index, Hilsenhoff’s biotic index, Observed/Expected index, and multi-metric index metrics) were compared for both projects. Lastly, I evaluated the efficacy of stream restoration for a seven-year dataset representing benthic macroinvertebrates for the MFJDR IMW restoration project. In this research, I detailed how combining datasets using consistent, reproducible methodology created a system of reference sites which greatly increased the sample size of the reference network as well as representation in each reference group. This subsequently increased the accuracy of the predictive models for all models for MFJDR IMW restoration project and half the models for the Eldorado Creek restoration project. Therefore, datasets among organizations can thus be combined and used to inform macroinvertebrate assessment tools like biotic indices. Additionally, this research has shown that the spatial and temporal variability for all indices, including the Observed/Expected index, Simpson’s Diversity index, and Hilsenhoff’s biotic index, was low, but it was still high enough to result in variable ecological status assessments. Furthermore, this research showed that while there may be significant differences in streams and years using ANOVAs and multiple comparisons, there is not yet evidence of improvement in biotic integrity scores for restored MFJDR sites.

Evaluating the Efficacy of Stream Restoration Utilizing Biotic Indices

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