Theses and Dissertations at Montana State University (MSU)
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Item Biotic and physical responses to biomimicry structures in a Rocky Mountain incised stream(Montana State University - Bozeman, College of Letters & Science, 2020) Reinert, James Holden; Chairperson, Graduate Committee: Lindsey Albertson; Lindsey K. Albertson and James R. Junker were co-authors of the article, 'Biotic and physical responses to biomimicry structures in a Rocky Mountain incised stream' submitted to the journal 'River research and applications' which is contained within this thesis.An increase in stream degradation resulting from land use change has motivated an increase in restoration efforts across the globe. Post-restoration monitoring is still lacking, however, and does not always incorporate biotic responses to changes in the physical template. Beaver mimicry structures (BMS) are becoming a popular tool to restore degraded streams throughout the American west, but relatively little is known about how these installations influence both biotic and abiotic factors, with consequences for ecosystem functioning. We monitored basal resource deposition and macroinvertebrate density, biomass, and production to quantify functional responses to BMS installations. We compared conditions at BMS sites to naturally occurring beaver dam and reference riffle sites in a low-gradient stream in southwest Montana. Thermal ranges were contracted, and daily maximum temperatures increased at BMS sites compared to reference riffle sites. Deposition of fine sediment and basal resources was similar at beaver and BMS sites, and both were higher than reference riffles. Densities and production of macroinvertebrates were higher at the BMS sites compared to reference sites and similar to beaver sites due to changes in physical habitat and basal resource availability, reflected by increases in production of shredders (beaver) and collector-gatherers (BMS). In this study site, changes to the physical template using BMS appear to have strong impacts on biotic functional responses, creating habitats similar to target conditions of natural beaver dams. Future research should consider the extent of degradation and temporal limitations of monitoring schemes to incorporate BMS into standard restoration practice. Functional response metrics provide an important and mechanistic approach to determine the efficacy of process-based stream restoration practices.Item Influence of thermal regime on the life histories and production of Rocky Mountain aquatic insects(Montana State University - Bozeman, College of Letters & Science, 2019) McCarty, Jennifer Denise; Chairperson, Graduate Committee: Wyatt F. CrossLife history traits of aquatic insect taxa such as metabolism, terminal body size, and fecundity vary along natural thermal gradients. Body size, in particular, is expected to respond to temperature and may have important consequences for fecundity and the production of insects. The Thermal Equilibrium Hypothesis (TEH) predicts that aquatic insect taxa are most abundant at an intermediate 'optimal' temperature where life history traits such as terminal body size and reproductive potential are maximized, i.e., the thermal 'optimum'. A competing hypothesis, the Temperature Size Rule (TSR), predicts that individuals developing at the coldest temperatures in their range will grow more slowly, but attain the largest body sizes and therefore exhibit greater fecundity than individuals growing at warmer temperatures. Implicit in both of these theories is that population-level production, a measure of population 'success', will be greatest where terminal body size and fecundity are maximized. Few studies have investigated the TEH in the field, and none have measured the relationship between production and other life history traits in the context of these theories. Our study focused on three common Rocky Mountain aquatic insect taxa: Drunella doddsii, Hydropsyche cockerelli, and Ephemeralla infrequens. We quantified the influence of thermal regime on growth rates, terminal body size, reproductive potential, and population-level biomass and production, all of which potentially limit the longitudinal distribution and success of these taxa. We found that growth varied strongly with season and site, leading to significant variation in the timing of growth and terminal body size. Reproductive potential was negatively associated with mean annual temperature as predicted by the TSR. Unexpectedly, reproductive potential was not always correlated with terminal body size. Population density, biomass, and secondary production were generally positively correlated with terminal body size for D. doddsii and H. cockerelli, as expected from both predictive models. In contrast, these relationships were not as consistent for E. infrequens. Our findings provide new insight as to how thermal variation influences the ecology of aquatic insects in the context of the TEH and TSR. Our results should be valuable for predicting population and community responses to ongoing changes in climate.Item The effects of temperature on stream ecosystem structure, secondary production, and food web dynamics(Montana State University - Bozeman, College of Letters & Science, 2019) Junker, James Robert; Chairperson, Graduate Committee: Wyatt F. Cross; Wyatt F. Cross, Jonathan P. Benstead, Alexander D. Huryn, James M. Hood, Daniel Nelson, Gísli M. Gíslason and Jón Ólafsson were co-authors of the article, 'Patterns and drivers of ecosystem-level biomass and stoichiometry in streams' submitted to the journal 'Ecosystems' which is contained within this thesis.; Wyatt F. Cross, Jonathan P. Benstead, Alexander D. Huryn, James M. Hood, Daniel Nelson, Gísli M. Gíslason and Jón Ólafsson were co-authors of the article, 'Resources govern the temperature-dependence of animal production at multiple timescales' submitted to the journal 'Ecology letters' which is contained within this thesis.; Wyatt F. Cross, Jonathan P. Benstead, Alexander D. Huryn, James M. Hood, Daniel Nelson, Gísli M. Gíslason and Jón Ólafsson were co-authors of the article, 'Responses of food web organic matter fluxes to temperature and their implications for food web stability' which is contained within this thesis.Since 1880, Earth's mean temperature has risen ~0.85 °C, and increases >1.5 °C are likely by the end of the 21st century. Warming temperatures will continue to shuffle and restructure ecological communities and the consequences of these changes for ecosystem processes and services are largely unknown because of the difficulties in measurement and understanding in complex ecological systems. Yet, isolating temperature's influence is crucial to predicting how ecosystems will look and operate in a 'no-analog' future and to begin to integrate warming with the myriad other stressors affecting natural systems. In this dissertation, I leverage a natural stream temperature gradient (~5 - 25 °C) within a geothermal watershed to investigate the effects of temperature on stream ecosystems--with three specific questions: 1) what is the relative influence of temperature and stream flow on whole-ecosystem biomass and element storage? 2) how does temperature shape patterns of animal production across and within streams? and 3) how does temperature modify the seasonal patterns of consumer-resource interactions in stream food webs? I found stream flow to have primacy in driving the 2 orders of magnitude variation in ecosystem biomass and element storage--mediated through flow's effect on plant body size. At higher trophic levels, temperature strongly shaped the patterns of secondary production coinciding with a 45-fold increase in annual secondary production across streams. This positive relationship was mediated through covariation between temperature and basal resource availability, both across and within streams. Consumer interactions with basal resources showed differing seasonality with increasing temperature. At higher temperatures, consumer demand and resource availability were strongly coupled seasonally compared to cooler streams. Tighter coupling between consumers and resources with temperature lead to more consistent, if higher, interaction strengths through the year. My work shows temperature as an important structuring driver of ecosystem structure and process, however, a common thread through each chapter shows the influence of temperature is mediated through its interactions with other ecosystem drivers. Ultimately, as the covariation between temperature and other environmental drivers (e.g., disturbance, nutrient and light availability, etc.) shift globally, recognizing these interactions is increasingly important.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 Relations among arctic grayling, nonnative salmonids, and abiotic conditions in the Big Hole River, Montana(Montana State University - Bozeman, College of Letters & Science, 2017) McCullough, Austin Robert; Chairperson, Graduate Committee: Christopher S. GuyArctic Grayling Thymallus arcticus in Montana have experienced declines in abundance and distribution over the last century, which contributed to the species being designated as a Species of Concern and petitioned for protection under the Endangered Species Act. Conservation of Arctic Grayling in the Big Hole River watershed was based on presumed environmental influences. Interactions with nonnative species, increasing stream water temperatures, drought, and habitat alterations are suggested to influence Arctic Grayling abundances, although sparse quantitative information exists to support these hypotheses. My objective was to evaluate the influence of these biotic and abiotic factors on Arctic Grayling abundances using data collected in the Big Hole River drainage from 1983 through 2015. Arctic Grayling and nonnative salmonids were sampled at 32 sites, stream temperature data were collected at 33 sites, stream discharge data were collected at 21 sites, and habitat data were collected at 441 sites. Ordinary least squares and quantile (Tau = 0.90) regression analyses were used to evaluate the relationships among Arctic Grayling catch per unit effort (CPUE), nonnative salmonids CPUE, stream temperature, stream discharge, and habitat condition. The strongest univariate relationship was a positive correlation between the CPUE of Arctic Grayling > or = age 1 and Brook Trout Salvelinus fontinalis CPUE (r = 0.55, N = 77), which was contrary to the a priori predicted relationship. Multivariate analyses suggested that high water temperatures and low discharges during drought conditions have the greatest limiting influences on the CPUE of Arctic Grayling > or = age 1; Brown Trout CPUE, low water temperatures, and high maximum discharges were suggested as having the greatest limiting influences on age-0 Arctic Grayling CPUE. My findings support current management to increase discharge during drought conditions and further explore relationships between Arctic Grayling CPUE, habitat conditions, and Brown Trout CPUE.Item Temperature and energy characteristics of the sagebrush lizard in Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 1967) Mueller, Charles FrederickItem Distribution, temperature and population studies of Sceloporus graciosus graciosus in Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 1968) Algard, George AllenItem Some effects of ACTH, STH, noradrenaline and thyroid hormone on young rats starved at two different temperatures(Montana State University - Bozeman, College of Agriculture, 1969) Bradshaw, Blaine StuartItem Temperature acclimatization in the black-billed magpie (Pica pica hudsonia, Sabine)(Montana State University - Bozeman, College of Agriculture, 1971) Stevenson, Robert EugeneItem Coupling energy and elements in a warming world : how temperature shapes biofilm ecosystem structure and function(Montana State University - Bozeman, College of Letters & Science, 2014) Williamson, Tanner John; Chairperson, Graduate Committee: Wyatt F. CrossFreshwater ecosystems are key contributors to global fluxes of energy and materials. Within freshwater ecosystems, benthic biofilms (i.e. thin streambed mats of algae, bacteria and detrital matter) act as biogeochemical hotspots, contributing to these important fluxes. Understanding how temperature shapes the structure and function of biofilm communities, and thus the coupling of energy and material fluxes, is important to our ability to predict the effects of climate change. We cultivated stream benthic biofilm communities in experimental streamside channels under a range of warming scenarios (7.5-23.6°C) that maintained natural diel and seasonal temperature variation. We quantified autotrophic community structure, biomass, ecosystem metabolism, stoichiometry, and nutrient uptake. Biological N 2-fixation was quantified as part of a concurrent study (Welter et al. in review). We found that temperature had strong effects on many metrics of ecosystem structure and function. Biofilm communities were dominated by cyanobacteria at all temperatures, which comprised >91% of total biovolume. Temperature had strong positive effects on biofilm biomass (2.8 to 24-fold variation) and net ecosystem productivity (44 to 317-fold variation). Temperate had minimal effects on biofilm stoichiometry; carbon:nitrogen (C:N) was constant across all temperatures, and carbon:phosphorus (C:P) declined slightly with temperature (a product of high C:P at the coldest temperature). Although ammonium uptake increased with temperature (2.8 to 6.8-fold variation), the magnitude of this response was not sufficient to meet total predicted N demand. We found that this shortfall was met by N 2-fixation, particularly at warmer temperatures. In contrast, increases in dissolved SRP uptake across the thermal gradient were sufficient to meet the predicted demand. This study is one of few to isolate the effects of temperature on benthic biofilms, improving our understanding of how climate change may impact freshwater ecosystems.