Studies of internal gravity waves in the earth's upper atmosphere are of considerable interest. These waves play a very important role in the dynamics of the mesosphere and lower thermosphere (ML T) region where they can transfer large amounts of energy and momentum from the lower atmosphere via wave saturation and dissipation. In particular, small-scale short-period (50ms"1) . Another unusual characteristic of "frontal events" is an apparent reversal in contrast of the wave structures as imaged in the hydroxyl (OH) emission (peak altitude- 87 km) when compared with the oxygen (OJ) "green line" (557.7 nm) emission (peak altitude -96 km) that can sometimes occur. In one isolated case, observed from Haleakala, Hawaii, the bright wave crests in the OH emission appeared to propagated through a dark structureless sky, whereas in the OI emission the same waves appeared to propagate into a bright sky, leaving an apparently depleted emission in its wake. Recent theoretical studies based on noble measurements have shown that frontal events may be due to a "bore-like" intrusion that raises the OJ (557. 7 nm) layer by a few km and at the same time depresses the OH layer by a similar amount. However, studies of fronts and bores in the ML T region are exceptionally rare. I have discovered and analyzed 16 frontal events from image data recorded at Bear Lake Observatory, Utah ( 41.6°N, 111.6°W), over the past four years. I have investigated some of their properties such as their horizontal wavelengths, horizontal phase speeds, observed periods, and their directions of motion. In addition, I have made comparative measurements of their relative intensities in the OH and OI emissions. These studies provide the first "extensive" data set on such events detailing their morphology and dynamics and should provide important information necessary for a deeper understanding of their occurrence frequency and properties.

The purpose of this thesis was to determine the criteria necessary for an analysis of site suitability for locating a marina at Bear Lake. Once criteria were defined and pertinent resource factors collected, a method to analyze the criteria was utilized to aid in the selection of the best site for locating this marina. Various methods to analyze site suitability were evaluated and the pros and cons of the chosen approach, a cluster analysis of existing resource transect data with hypothetical transect criteria, were discussed. Based on this study, no optimum sites were located at Bear Lake for a marina facility. However, it was concluded that transect number 3, near Garden City, is the most acceptable area for the development of a marina. It was also concluded that other areas of Bear Lake's shore zone are very sensitive and in order to protect the shore zone environment and water quality of Bear Lake, strict planning and development guidance needs to be generated and enforced for the Bear Lake shore zone.

The mountain whitefish (Prosopium williamsoni) has been largely overlooked in population genetic analyses despite its wide distribution in discrete drainage basins in western North America for over four million years. Its closest sister taxa the Bear Lake whitefish (P. abyssicola), Bonneville cisco (P. gemmifer), and Bonneville whitefish (P. spilonotus) are found only in Bear Lake Idaho-Utah and were also included in the analyses. A total of 1,334 cytochrome b and 1,371 NADH dehydrogenase subunit 2 sequences from the Bonneville Basin, the Columbia River Sub-basin, the lower Snake River Sub-basin, the upper Snake River Sub-basin, the Green River Basin, the Lahontan Basin, and the Missouri Basin were examined to test for geographically based genetic differentiation between drainage basins and sub-basins and phylogeographic relationships to determine the invasion route of Prosopium into western North America and to aid in understanding current relationships. Prosopium entered the region via the Missouri River connection to Hudson Bay and moved in two waves: one colonized the lower Snake River Sub-basin, Columbia River Sub-basin, and the Lahontan Basin; the second wave colonized the upper Snake River Sub-basin, Bonneville Basin, Green River Basin, and established the Bear Lake Prosopium. Mountain whitefish exhibit a large amount of geographical genetic differentiation based on drainage basin except between the upper Snake River and the Bonneville Basin while the Bear Lake Prosopium show large amounts of gene flow between the three species. The apparent paraphyly of the mountain whitefish and the limited genetic structure of the Bear Lake Prosopium warrant recognition in the management of Prosopium and raise questions regarding species definitions in the group.

The study characterized the morphological differences among Cisco between geographic arms and depth strata, and determined the trophic positioning of various morphs, based on twelve years of capture data and specimens using morphological measurements, meristic counts, stomach contents, stable isotopes and fatty acids. Two main Cisco morpho-types were identified, a shallow water form and a deep water form that mainly differed in traits associated with swimming and feeding. These results were reinforced by the results on trophic ecology of morphs that demonstrated that each morph occupied a distinct niche. Results showed that shallow water groups had a more varied diet with a high percentage of copepods being ingested whereas deep-water groups showed preferences towards mysids. Although a consistent pattern in differences among shallow and deep morphs was observed, there was some degree of variation among arms of the lake suggesting a degree of isolation and adaptation to local conditions in each area of the lake. For example, in Smith Arm, morphological and dietary differences were found such as narrower body depth and a dietary preference towards daphnia. / February 2017

The project was initiated in June of 1958 and financed by the National Science Foundation and the Wildlife Management Department of Utah State University. The broad aspects of the study were to determine if a relationship exists between certain physical and biological factors and benthic fish densities. The project vas divided into two parts: (l) to determine the time and extent of thermal stratification, zooplankton densities, conductivity changes within the lake and conductivity differences between the lake and its tributaries; (2) to determine it a relationship exist between benthic fish densities, temperatures, depths, conductivities and benthic zooplankton densities. The data were analyzed statistically and a separate regression analysis was run on each factor to determine the degree of relationship between that factor and benthic fish densities.

Bear Lake is located in southeastern Idaho and north-central Utah. The lake has a maximum altitude of 5923 feet and an area of approximately 110 square miles. Surrounding the lake are carbonates, shales, and sandstones of lower Paleozoic through middle Mesozoic ages. The many streams and springs that originate in these rocks are probably the main contributors to the chemistry of the lake. Water from Bear River, which flows into the north end of the lake, also contributes to its chemistry. Quartz, aragonite, dolomite, calcite and clay minerals are the main minerals in the lake-bottom sediments. Quartz is generally the dominant mineral in shallow, shoreline areas, whereas aragonite is generally the dominant mineral in deep water. Dolomite occurs in patches near the shoreline along the west and south sides, whereas calcite is fairly evenly distributed throughout the lake. Grains of quartz are detrital in origin. Grains of dolomite and calcite are detrital in origin. Mud-sized aragonite is a primary precipitate that forms pseudoolites around detrital sand grains and lumps of mud-sized particles. The solubility products of aragonite, calcite, and dolomite all are exceeded in the lake water, which, therefore, is supersaturated with respect to all three. Aragonite is more soluble than calcite in water, but chemical and mineral analyses show that mud-sized aragonite is precipitating directly from solutions in Bear Lake, whereas calcite apparently is not. Other workers have attributed the preferential precipitation of aragonite to the inhibition of calcite nucleation in the presence of a high Mg++/Ca++ ratio, a condition present in Bear Lake. Mud-sized calcite and dolomite may be forming syngenetically in the lake sediments as a result of inversion of aragonite to calcite and subsequent replacement of calcite to dolomite, or may be entirely detrital in origin.

Ecological traits of the endemic Bear Lake whitefish Prosoopium abyssicola and the Bonneville whitefish prosopium silonotus were investigated. Spatial distributions indicated distinctive differences in depth contour preference. Catch per unit effort data indicated that Bonneville whitefish prefer shallow depths and warmer water temperatures, whereas Bear Lake whitefish prefer deep, cold water. Diet differences between the two species were large. Differences in both age distribution and growth rate patterns were also observed. The Bonneville whitefish population was predominantly composed of juvenile age classes. Very large adults reached ages of 12-14 years. Bear Lake whitefish exhibited a different population structure with few young fish and larger proportions of older age classes. Some of these fish were aged over 35 years old. Both analyses suggest that the population structure of each species is the result of a stable or growing population.

Bear Lake, a large oligotrophic lake (282 km2), was studied from October 1986 to December 1987 to determine the temporal changes in the zooplankton assemblage at one site in the pelagic zone and one in the littoral area. In this study, species composition, abundance, biomass, and size frequency distribution were determined. Additionally, chlorophyll a, water transparency, and temperature and oxygen profiles were measured to help interpret zooplankton changes during the study. The zooplankton species assemblage comprised eight species of cladocera, seven species of copepods, and five species of rotifers. The abundance and biomass of the zooplankton assemblage, particularly that of crustaceans, were very low and comparable with those of oligotrophic systems. Mean densities of crustaceans in the pelagic zone, excluding copepod nauplii, varied from 250 to 1,700 organisms/m3. The analysis of the size structure of the zooplankton indicated the dominance of small organisms and the scarcity of large organisms, particularly cladocera. The zooplankton assemblage in the littoral zone was similar in species composition, abundance, and size structure to that in the pelagic zone. Many results suggest the littoral zooplankton assemblage is an extension of the pelagic assemblage. Low zooplankton food resources and interference of calcium carbonate particles in the feeding behavior of crustaceans are suggested as the primary factors controlling the low abundance and biomass of zooplankton in Bear Lake. Size-selective fish predation probably causes the assemblage to be dominated by small species. The analysis of Epischura nevadensis, the dominant species in the system, indicated that this species is bivoltine in Bear Lake. In the spring and summer, adult E. nevadensis were more abundant in the littoral zone, whereas copepodites were more abundant offshore. The low density, biomass, and small size structure of the zooplankton in Bear Lake limits its importance as a source of food for fishes.

Whitefish populations around the world have long been difficult to categorize taxonomically. The whitefish of Bear Lake, Utah/Idaho are no exception. There are three recognized species of Prosopium that are endemic to the lake. Two of these species, Prosopium spilonotus and Prosopium abyssicota, have previously been indistinguishable outside of spawning times. Previous studies have proposed additional taxa within P. spi/onotus to further complicate the identification among these taxa. Morphological characteristics were quantified on wild whitefish from Bear Lake, as well as from progeny reared in the laboratory from the wild adult fish. The purported taxa were separated in the field using the best characteristics presented in previous studies, and the progeny were reared separately in these groups. Otolith aging was also done on the wild adult fish to understand the age structure of the spawning populations. Results from otolith aging and morphological analyses on the laboratoryreared fish indicated that there is only one taxonomic group of P. spilonotus. By using scale counts, it was determined that P. spilonotus and P. abyssicola can be distinguished from each other with considerable reliability.

Dingle Marsh is a wetland complex separating the Bear River from Bear Lake. Flow direction through the marsh is controlled at four major inflow and outflow sites. These sites were chosen as monitoring sites to assess the suspended solid and nutrient transport through the marsh. High frequency turbidity measurements were collected at each site and used as a surrogate for total phosphorus (TP) and total suspended solid (TSS) concentrations. Loads of TP and TSS were calculated using flow data from the 2008 water year. Load calculations for TP and TSS were compiled at 30-minute intervals and annual mass balances were calculated for Dingle Marsh and Bear Lake. These calculations were used to identify the seasonal loading patterns within this system. This study found the majority of TSS and TP loading entered the marsh from the Bear River. As flows moved across the marsh, the loading of TSS and TP was greatly reduced. Seasonal flow patterns were analyzed to determine the loading patterns to Dingle Marsh, Bear Lake, and the Bear River. This study also identified water management strategies aimed at setting a target endpoint for TSS and TP loads.