College of Letters & Science

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The College of Letters and Science, the largest center for learning, teaching and research at Montana State University, offers students an excellent liberal arts and sciences education in nearly 50 majors, 25 minors and over 25 graduate degrees within the four areas of the humanities, natural sciences, mathematics and social sciences.

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Enhanced trace element mobilization by Earth’s ice sheets
(Proceedings of the National Academy of Sciences, 2020-11) Hawkings, Jon R.; Skidmore, Mark L.; Wadham, Jemma L.; Priscu, John C.; Morton, Peter L.; Hatton, Jade E.; Gardner, Christopher B.; Kohler, Tyler J.; Stibal, Marek; Bagshaw, Elizabeth A.; Steigmeyer, August; Barker, Joel; Dore, John E.; Lyons, W. Berry; Tranter, Martyn; Spencer, Robert G. M.
Trace elements sustain biological productivity, yet the significance of trace element mobilization and export in subglacial runoff from ice sheets is poorly constrained at present. Here, we present size-fractionated (0.02, 0.22, and 0.45 µm) concentrations of trace elements in subglacial waters from the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Concentrations of immobile trace elements (e.g., Al, Fe, Ti) far exceed global riverine and open ocean mean values and highlight the importance of subglacial aluminosilicate mineral weathering and lack of retention of these species in sediments. Concentrations are higher from the AIS than the GrIS, highlighting the geochemical consequences of prolonged water residence times and hydrological isolation that characterize the former. The enrichment of trace elements (e.g., Co, Fe, Mn, and Zn) in subglacial meltwaters compared with seawater and typical riverine systems, together with the likely sensitivity to future ice sheet melting, suggests that their export in glacial runoff is likely to be important for biological productivity. For example, our dissolved Fe concentration (20,900 nM) and associated flux values (1.4 Gmol y−1) from AIS to the Fe-deplete Southern Ocean exceed most previous estimates by an order of magnitude. The ultimate fate of these micronutrients will depend on the reactivity of the dominant colloidal size fraction (likely controlled by nanoparticulate Al and Fe oxyhydroxide minerals) and estuarine processing. We contend that ice sheets create highly geochemically reactive particulates in subglacial environments, which play a key role in trace elemental cycles, with potentially important consequences for global carbon cycling.
Wildflower Seed Sales as Incentive for Adopting Flower Strips for Native Bee Conservation: A Cost-Benefit Analysis
(2019-07) Delphia, Casey M.; O'Neill, Kevin M.; Burkle, Laura A.
Improving pollinator habitat on farmlands is needed to further wild bee conservation and to sustain crop pollination in light of relationships between global declines in pollinators and reductions in floral resources. One management strategy gaining much attention is the use of wildflower strips planted alongside crops to provide supplemental floral resources for pollinators. However, farmer adoption of pollinator-friendly strategies has been minimal, likely due to uncertainty about costs and benefits of providing non-crop flowering plants for bees. Over 3 yr, on four diversified farms in Montana, United States, we estimated the potential economic profit of harvesting and selling wildflower seeds collected from flower strips implemented for wild bee conservation, as an incentive for farmers to adopt this management practice. We compared the potential profitability of selling small retail seed packets versus bulk wholesale seed. Our economic analyses indicated that potential revenue from retail seed sales exceeded the costs associated with establishing and maintaining wildflower strips after the second growing season. A wholesale approach, in contrast, resulted in considerable net economic losses. We provide proof-of-concept that, under retail scenarios, the sale of native wildflower seeds may provide an alternative economic benefit that, to our knowledge, remains unexplored. The retail seed-sales approach could encourage greater farmer adoption of wildflower strips as a pollinator-conservation strategy in agroecosystems. The approach could also fill a need for regionally produced, native wildflower seed for habitat restoration and landscaping aimed at conserving native plants and pollinators.
Short-Term Stable Isotope Probing of Proteins Reveals Taxa Incorporating Inorganic Carbon in a Hot Spring Microbial Mat
(2020-03) Steinke, Laurey; Slysz, Gordon; Lipton, Mary S.; Klatt, Christian; Moran, James J.; Romine, Margie F.; Wood, Jason M.; Anderson, Gordon; Bryant, Donald A.; Ward, David M.
The upper green layer of the chlorophototrophic microbial mats associated with the alkaline siliceous hot springs of Yellowstone National Park consists of oxygenic cyanobacteria (Synechococcus spp.), anoxygenic Roseiflexus spp., and several other anoxygenic chlorophototrophs. Synechococcus spp. are believed to be the main fixers of inorganic carbon (Ci), but some evidence suggests that Roseiflexus spp. also contribute to inorganic carbon fixation during low-light, anoxic morning periods. Contributions of other phototrophic taxa have not been investigated. In order to follow the pathway of Ci incorporation into different taxa, mat samples were incubated with [13C]bicarbonate for 3 h during the early-morning, low-light anoxic period. Extracted proteins were treated with trypsin and analyzed by mass spectrometry, leading to peptide identifications and peptide isotopic profile signatures containing evidence of 13C label incorporation. A total of 25,483 peptides, corresponding to 7,221 proteins, were identified from spectral features and associated with mat taxa by comparison to metagenomic assembly sequences. A total of 1,417 peptides, derived from 720 proteins, were detectably labeled with 13C. Most 13C-labeled peptides were derived from proteins of Synechococcus spp. and Roseiflexus spp. Chaperones and proteins of carbohydrate metabolism were most abundantly labeled. Proteins involved in photosynthesis, Ci fixation, and N2 fixation were also labeled in Synechococcus spp. Importantly, most proteins of the 3-hydroxypropionate bi-cycle for Ci fixation in Roseiflexus spp. were labeled, establishing that members of this taxocene contribute to Ci fixation. Other taxa showed much lower [13C]bicarbonate incorporation.
CLIMATE CHANGE AND HUMAN HEALTH IN MONTANA: A Special Report of the Montana Climate Assessment
(Montana Institute on Ecosystems, 2020-12) Adams, Alexandra K.; Byron, Robert; Maxwell, Bruce D.; Higgins, Susan; Eggers, Margaret; Byron, Lori; Whitlock, Cathy
The purpose of this assessment is to a) present understandable, science-based, Montana-specific information about the impacts of climate change on the health of Montanans; and b) describe how our healthcare providers, state leaders, communities, and individuals can best prepare for and reduce those impacts in the coming decades. This assessment draws from, and is an extension to, the 2017 Montana Climate Assessment (MCA1) (Whitlock et al. 2017), which provides the first detailed analysis of expected impacts to Montana’s water, forests, and agriculture from climate change. MCA explains historical, current, and prospective climate trends for the state based on the best-available science. The 2017 Montana Climate Assessment did not address the impact of climate change on the health of Montanans. This special report of the MCA fills that important knowledge gap; it represents a collaboration between climate scientists and Montana’s healthcare community and is intended to help Montanans minimize the impacts of climate on their health.
An investigation of coliform contamination in private well water on the Crow Reservation
(Montana State University - Bozeman, College of Agriculture, 2019) Three Irons, Emery UP; Chairperson, Graduate Committee: Scott Powell; Margaret Eggers (co-chair)
The Crow reservation has a rural population that depends on home well water for domestic use. Many of the home wells do not have a suitable well cap, allowing a potential pathway of bacterial contamination of groundwater. Fecal coliform is associated with acute health problems, such as gastrointestinal illness, diarrhea, and cramps. Therefore, total coliform contamination of well water is an important health concern among Crow home well users. This research examines patterns in total coliform contamination among home well samples with respect to a suite of well and local aquifer characteristics thought to influence vulnerability to contamination, including well protection factors. Well and aquifer characteristics considered in this research include: the geologic production formation, local land cover, and distance to the nearest river. Well protection factors include: cap type, cap condition, depth of completion and time since completion (or age). One hundred water quality samples were collected from home wells along the Little Big Horn River in 2017, and available data on the character of those wells and aquifers were collected for comparison with the patterns in fecal coliform contamination among the samples. Presence/absence of coliform contamination was assessed using the Colilert IDEXX Quanti-Tray 2000 method. Spatial variations in the characteristics of wells and aquifers were characterized through a combination of well logs, the National Land Cover Dataset, and the National Hydrography Dataset. Logistic regression was used to identify potential relationships between probability of coliform contamination and characteristics of associated wells and aquifers. Logistic regression models suggested two notable and statistically significant (? = 0.05 level) relationships: (1) wells completed in alluvium and farther from the river had a higher probability of total coliform contamination, and (2) wells with old style caps had a higher probability of total coliform contamination. The government of the Crow tribe can decide how to use the results for mitigation efforts and awareness for homeowners with contaminated wells. Also, the Crow Water Quality Project should archive and consider these results for future research, planning, development, and management.
Coliform Contamination in private well water on the Crow Reservation
(2018-10) Powell, Michaela
Emery Three Irons is a master’s level graduate student in the Department of Land Resources and Environmental Sciences (LRES) at Montana State University (MSU). Advised by Scott Powell, Ph.D., who is an Associate Professor in the Department of LRES at MSU, Emery is working on his master’s thesis which explores coliform contamination in private well water on the Crow Reservation. He has requested the assistance of the Statistical Consulting and Research Services in deciding on an appropriate analysis for the data he collected.
Checklist of bees (Hymenoptera: Apoidea) from small diversified vegetable farms in south-western Montana
(2019-01) Delphia, Casey M.; Griswold, Terry; Reese, Elizabeth G.; O'Neill, Kevin M.; Burkle, Laura A.
Background: Over three years (2013-2015), we sampled bees using nets and bowl traps on four diversified vegetable farms in Gallatin County, Montana, USA, as part of a study evaluating the use of wildflower strips for supporting wild bees and crop pollination services on farmlands (Delphia et al. In prep). We document 202 species and morphospecies from 32 genera within five families, of which 25 species represent the first published state records for Montana. This study increases our overall understanding of the distribution of wild bee species associated with agroecosystems of the northern US Rockies, which is important for efforts aimed at conserving bee biodiversity and supporting sustainable crop pollination systems on farmlands. New information: We provide a species list of wild bees associated with diversified farmlands in Montana and increase the number of published bee species records in the state from 374 to at least 399. The list includes new distributional records for 25 wild bee species, including two species that represent considerable expansions of their known ranges, Lasioglossum (Dialictus) clematisellum (Cockerell 1904) with previously published records from New Mexico, Arizona, California and Utah and Melissodes (Eumelissodes) niveus Robertson 1895 which was reported to range from New York to Minnesota and Kansas, south to North Carolina, Alabama and Mississippi.
Marsarchaeota are an aerobic archaeal lineage abundant in geothermal iron oxide microbial mats
(2018-05) Jay, Zackary J.; Beam, Jacob P.; Dlakic, Mensur; Rusch, Douglas B.; Kozubal, Mark A.; Inskeep, William P.
The discovery of archaeal lineages is critical to our understanding of the universal tree of life and evolutionary history of the Earth. Geochemically diverse thermal environments in Yellowstone National Park provide unprecedented opportunities for studying archaea in habitats that may represent analogues of early Earth. Here, we report the discovery and characterization of a phylum-level archaeal lineage proposed and herein referred to as the \'Marsarchaeota\', after the red planet. The Marsarchaeota contains at least two major subgroups prevalent in acidic, microaerobic geothermal Fe(III) oxide microbial mats across a temperature range from similar to 50-80 degrees C. Metagenomics, single-cell sequencing, enrichment culturing and in situ transcriptional analyses reveal their biogeochemical role as facultative aerobic chemoorganotrophs that may also mediate the reduction of Fe(III). Phylogenomic analyses of replicate assemblies corresponding to two groups of Marsarchaeota indicate that they branch between the Crenarchaeota and all other major archaeal lineages. Transcriptomic analyses of several Fe(III) oxide mat communities reveal that these organisms were actively transcribing two different terminal oxidase complexes in situ and genes comprising an F-420-dependent butanal catabolism. The broad distribution of Marsarchaeota in geothermal, microaerobic Fe(III) oxide mats suggests that similar habitat types probably played an important role in the evolution of archaea.
Vulnerability of dryland agricultural regimes to economic and climatic change
(2018) Lawrence, Patrick G.; Maxwell, Bruce D.; Rew, Lisa J.; Ellis, Colter; Bekkerman, Anton
Large-scale agricultural systems are central to food production in North America, but their ubiquity could be threatened by vulnerability to economic and climatic stressors during the 21st century. Prior research has focused on understanding the influence of climatic changes on physiological processes in these systems and has increasingly recognized that other factors such as social, economic, and ecological variation and the interaction among these factors may cause unexpected outcomes. We assess the vulnerability of large-scale agricultural systems to variation in multiple stressors and investigate alternative adaptation strategies under novel conditions. We examine dryland farms in Montana’s northern Great Plains (NGP), which represent large-scale semiarid agricultural systems that are likely to be affected by climate change. Farmers in the NGP have experienced three distinct periods of economic- and drought-related stressors since the 1970s, primarily driven by uncertainty in soil moisture, but at times amplified by uncertainty in nitrogen fertilizer and wheat prices. We seek to better understand how farmers evaluate and respond to these conditions. The results indicate that although farmers perceived few alternative agronomic options for adapting to drought, strategies for adapting to high input prices were more plentiful. Furthermore, we find that increasing the overall resilience of dryland agricultural systems to economic and climatic uncertainty requires intrinsic valuation of crop rotations and their field-specific response to inputs.
Prokaryotes in the WAIS Divide ice core reflect source and transport changes between Last Glacial Maximum and the early Holocene
(2018-05) Santibanez, Pamela A.; Maselli, Olivia J.; Greenwood, Mark C.; Grieman, Mackenzie M.; Saltzman, Eric S.; McConnell, Joseph R.; Priscu, John C.
We present the first long-term, highly resolved prokaryotic cell concentration record obtained from a polar ice core. This record, obtained from the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core, spanned from the Last Glacial Maximum (LGM) to the early Holocene (EH) and showed distinct fluctuations in prokaryotic cell concentration coincident with major climatic states. The time series also revealed a ~1,500-year periodicity with greater amplitude during the Last Deglaciation (LDG). Higher prokaryotic cell concentration and lower variability occurred during the LGM and EH than during the LDG. A seven-fold decrease in prokaryotic cell concentration coincided with the LGM/LDG transition and the global 19 ka meltwater pulse. Statistical models revealed significant relationships between the prokaryotic cell record and tracers of both marine (sea-salt sodium [ssNa]) and burning emissions (black carbon [BC]). Collectively, these models, together with visual observations and methanosulfidic acid (MSA) measurements, indicated that the temporal variability in concentration of airborne prokaryotic cells reflected changes in marine/sea-ice regional environments of the WAIS. Our data revealed that variations in source and transport were the most likely processes producing the significant temporal variations in WD prokaryotic cell concentrations. This record provided strong evidence that airborne prokaryotic cell deposition differed during the LGM, LDG and EH, and that these changes in cell densities could be explained by different environmental conditions during each of these climatic periods. Our observations provide the first ice core time-series evidence for a prokaryotic response to long-term climatic and environmental processes.

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