Year of Award

2010

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Environmental Studies

Department or School/College

Environmental Studies Program

Committee Chair

Vicki Watson

Keywords

Bioassessment, Macroinvertebrates, Restoration

Abstract

Since the turn of the twentieth century, mining activities have contaminated the floodplain and streambed of Silver Bow Creek, Montana, resulting in a streambed devoid of life and severely contaminated with heavy metals. In the mid nineteen seventies, up-stream water treatment facilities were upgraded and water quality improved, bringing benthic invertebrates back to reaches of Silver Bow Creek. The extent and concentration of toxicants in and around the streams of the Upper Clark Fork River Basin resulted in the designation of over 100 miles of river as Federal Superfund sites. Since 1999 reclamation and restoration efforts have been implemented on Silver Bow Creek. This analysis evaluates changes in benthic biotic community composition throughout the period of record (1986 to 2009). Transformations of historical data were necessary to standardize community information and calculate indices of biotic integrity. A multivariate method, Classification Strength (CS), used in conjunction with non-parametric tests of significance, demonstrated data comparability over the period of record both taxonomically and ecologically. Biotic index results indicate that remedial efforts to remove metals laden sediment from the stream bed and surrounding floodplain have resulted in a decline in the numbers of metal-tolerant organisms. Generalized indices of biotic integrity show no significant changes throughout the period, while specialized indices demonstrate increases in organic-pollutant-tolerant taxa. Multivariate analysis of community composition demonstrates taxonomic changes to the resident community throughout the period of record, and Indicator Species Analysis corroborates the results of the biotic indices. Using these methodologies as a template to measure change throughout the restored reaches of Silver Bow Creek will increase the ability of resource managers to measure the success of restoration of the ‘Last Best Disturbance’.

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© Copyright 2010 Sean Patrick Sullivan