Theses and Dissertations at Montana State University (MSU)
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Item Environmental drivers of salmonfly ecology in southwest Montana(Montana State University - Bozeman, College of Letters & Science, 2018) Anderson, Heidi Elise; Chairperson, Graduate Committee: Lindsey Albertson; Lindsey K. Albertson and David M. Walters were co-authors of the article, 'Temperature-driven range contraction and body size reduction of an iconic aquatic insect' submitted to the journal 'Freshwater science' which is contained within this thesis.; Lindsey K. Albertson and David M. Walters were co-authors of the article, 'Landscape features drive synchronicity of an aquatic insect resource pulse' submitted to the journal 'Ecological applications' which is contained within this thesis.Aquatic insects have ecological, cultural, and economic value throughout the American West. They can control the processing of in-stream nutrients, are a vital component of both aquatic and terrestrial food webs, and support economically important species such as trout and the eco-tourism industries structured around these fisheries. Salmonflies (Pteronarcys californica) are one of the most well-known aquatic insects in the American West due to their large size and popularity among fly-fishers. However, mounting anecdotal evidence suggests that salmonfly populations could be in decline. We conducted surveys and compiled historical datasets that quantified salmonfly abundance, body size, and emergence timing along the Gallatin and Madison Rivers in southwest Montana to determine the status of salmonfly populations in these rivers, understand environmental drivers that are constraining their distribution and driving their development, and initiate long-term monitoring. Most notably, we found evidence for temperature-driven changes in salmonfly distribution and body size along the Madison River in the last four decades and observed marked differences in salmonfly emergence phenology and duration at multiple spatial scales between the Madison and Gallatin Rivers. Above-optimal summer water temperatures appear to be the major constraint on salmonfly populations in the Madison River, but only play a minimal role in dictating salmonfly distribution along the Gallatin River. This research provides rare empirical evidence of long-term biological change of an aquatic insect and highlights the importance of combining temporal and spatial datasets to explicitly address species' responses to environmental stressors across multiple spatial and temporal scales. Freshwater habitats are increasingly imperiled by climate change and human-induced habitat alteration, which will invariably continue to impact the ecology of aquatic insects like salmonflies. This work contributes to the understanding of how these ongoing changes will influence the structure of aquatic communities, the flow and transfer of energy and nutrients, consumer-resource dynamics, and stream--riparian food web linkages.Item The distribution and abundance of aquatic insects in the middle West Gallatin drainage(Montana State University - Bozeman, College of Agriculture, 1973) Garrett, Paul AllenItem Plecoptera of the West Fork of the West Gallatin River and factors influencing their distribution(Montana State University - Bozeman, College of Agriculture, 1973) Burns, David CharlesItem Aquatic insects in sediment traps(Montana State University - Bozeman, College of Agriculture, 1976) Mangels, Francis Wayne; Chairperson, Graduate Committee: George R. RoemhildSediment traps were set in three tributaries and in three areas of the upper Gallatin River. The kind, sizes and amount of sedimentation was analyzed and related to numbers and orders of aquatic insects found in gravel in the traps. From August, 1972, to October, 1973, samples were taken at monthly intervals in a monthly renewed sample and in a cumulative sample undisturbed since the beginning of the project. These sampling methods show that living space is of prime importance to aquatic insects and sculpins, and that it is a limiting factor for insect communities presently in the upper Gallatin. Measurable current speeds (up to 2.5 fps) did not seem to affect insect numbers. High percentages of organic matter in sediment coincided with high insect numbers, but actual weight had no apparent relationship. High numbers of insects were present in the spring, but were drastically reduced after runoff. They recovered much more slowly and to lower levels in the cumulative traps, which remained filled with sediment. The low sedimentation rates through fall and winter resulted in higher insect numbers in cumulative traps, presumably because they were undisturbed. Diptera was the dominant order in all areas.