Browse more than 100 theses authored by our scientists going back to 1959 and refine search by topic, location, year, and advanced search.
Filter Total Items: 157
Freshwater cyanotoxin mixtures in recurring cyanobacterial blooms in Voyageurs National Park
Algal and cyanobacterial blooms can foul water systems, inhibit recreation, and produce cyanotoxins, which can be toxic to humans, domestic animals, and wildlife. Blooms that recur yearly present a special challenge, in that chronic effects of most cyanotoxins are unknown. To better understand cyanotoxin timing, possible environmental triggers, and inter-relations among taxa and toxins in bloom co
The lethality of hot water and ozone to aquatic invasive species
The spread of Aquatic Invasive Species (AIS) between the Great Lakes and Mississippi River Basin by way of the Chicago Area Waterway System (CAWS) is a pressing concern to resource managers in the Midwest region. Augmenting this spread are watercrafts traveling through the CAWS locks and dams. AIS are able to attach to boat hulls, equipment, or are present in the surrounding water during lock tran
Modeling the hydroclimatology of the San Francisco Bay-Delta estuary and watershed
No abstract available.
Aerial survey methodology for bison population estimation in Yellowstone National Park
I developed aerial survey methods for statistically rigorous bison population estimation in Yellowstone National Park to support sound resource management decisions and to understand bison ecology. Survey protocols, data recording procedures, a geographic framework, and seasonal stratifications were based on field observations from February 1998-September 2000. The reliability of this framework an
Automated lidar-derived canopy height estimates for the Upper Mississippi River System
Land cover/land use (LCU) classifications serve as important decision support products for researchers and land managers. The LCU classifications produced by the U.S. Geological Survey’s Upper Midwest Environmental Sciences Center (UMESC) include canopy height estimates that are assigned through manual aerial photography interpretation techniques. In an effort to improve upon these techniques, thi
Soil ecology of a rock outcrop ecosystem: Abiotic stresses, soil respiration, and microbial community profiles in limestone cedar glades
Limestone cedar glades are a type of rock outcrop ecosystem characterized by shallow soil and extreme hydrologic conditions—seasonally ranging from xeric to saturated—that support a number of plant species of conservation concern. Although a rich botanical literature exists on cedar glades, soil biochemical processes and the ecology of soil microbial communities in limestone cedar glades have larg
Ecology of bison, elk, and vegetation in an arid ecosystem
Herbivory has profound effects on vegetation production and structure in many different plant communities. The influence of herbivory on plants and ultimately ecosystem processes is shaped by the types of plants consumed, the intensity of herbivory, the evolutionary history of grazing, and the availability of water and nutrients to plants. The effect of ungulate herbivores on vegetation is of grea
Fish population failure caused by an environmental estrogen is long-lasting and regulated by direct and parental effects on survival and fecundity
Despite significant research demonstrating effects of estrogens such as 17α - ethinylestradiol (EE2) on fish, the underlying mechanisms regulating population failure are unknown. Projected water shortages could leave waterways increasingly dominated by wastewater effluent and understanding mechanisms is necessary for conservation and management. Here we identify mechanisms of population failure in
Fate(s) of injected CO2 in a coal-bearing formation, Louisiana, Gulf Coast Basin: Chemical and isotopic tracers of microbial-brine-rock-CO2 interactions
Coal beds are one of the most promising reservoirs for geologic carbon dioxide (CO₂) sequestration, as CO₂ can strongly adsorb onto organic matter and displace methane; however, little is known about the long-term fate of CO₂ sequestered in coal beds. The "2800' sand" of the Olla oil field is a coal-bearing, oil and gas-producing reservoir of the Paleocene–Eocene Wilcox Group in north-central Loui