Processes controlling thermokarst lake expansion rates on the Arctic coastal plain of Northern Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2017Thermokarst lakes are a dominant factor of landscape scale processes and permafrost dynamics in the otherwise continuous permafrost region of the Arctic Coastal Plain (ACP) of northern Alaska. Lakes cover greater than 20% of the landscape on the ACP and drained lake basins cover an additional 50 to 60% of the landscape. The formation, expansion, drainage, and reformation of thermokarst lakes has been described by some researchers as part of a natural cycle, the thaw lake cycle, that has reworked the ACP landscape during the course of the Holocene. Yet the factors and processes controlling contemporary thermokarst lake expansion remain poorly described. This thesis focuses on the factors controlling variation in extant thermokarst lake expansion rates in three ACP regions that vary with respect to landscape history, ground-ice content, and lake characteristics (i.e. size and depth). Through the use of historical aerial imagery, satellite imagery, and field-based data collection, this study identifies the controlling factors at multiple spatial and temporal scales to better understand the processes relating to thermokarst lake expansion. Comparison of 35 lakes across the ACP shows regional differences in expansion rate related to permafrost ice content ranging from an average expansion rate of 0.62 m/yr on the Younger Outer Coastal Plain where ice content is highest to 0.16 m/yr on the Inner Coastal Plain where ice content is lowest. Within each region, lakes vary in their expansion rates due to factors such as lake size, lake depth, and winter ice regime. On an individual level, lakes vary due to shoreline characteristics such as local bathymetry and bluff height. Predicting how thermokarst lakes will behave locally and on a landscape scale is increasingly important for managing habitat and water resources and informing models of land-climate interactions in the Arctic

Design standards within constructed wetlands for the reduction of mosquito populations in Clark County, Nevada

Wetlands are considered one of the most productive ecosystems in the world and provide many benefits to the environment. However, the slow moving and sometimes stagnant water created by the vegetation in the wetland creates an ideal environment for the proliferation of mosquitoes. Mosquitoes are the most important insect disease vector worldwide. The presence of mosquitoes within wetlands increases the risk of disease transmission among workers and visitors creating a public health concern. Effective design standards aimed at reducing mosquito breeding habitat should be implemented during the construction and planning phase of wetland development to effectively reduce the mosquito populations. This research evaluated the presence of mosquitoes within two wetlands in Clark County, Nevada; one constructed using the Environmental Protection Agencies suggested guidelines for mosquito reduction, the other not. During the peak mosquito season (March-October), traps were set at two wetland sites on a monthly basis. This trapping occurred for the span of two mosquito seasons in the Las Vegas valley. Trapping data were evaluated to determine if one location produced a lower mosquito population when compared to the other. It was found that the amount of mosquitoes produced between these two locations were statistically different. Furthermore, the same information was used to determine the dominant mosquito species within the wetland and then evaluate the possibility of disease transmission among this species. Culex (Cx.) tarsalis was the most common mosquito species from both wetlands making up 56% (2829 of 5059) of all mosquitoes captured and consequently the most important mosquito-borne disease vector in Clark County. However, 97% of the Cx. tarsalis samples originated from site one (2741 vs. 88). The results of this study showed that wetland location two, constructed using EPA supported guidelines and through the implementation of these designs, limited the overall mosquito population, thereby reducing the potential for disease transmission among known disease vectors within Clark County, NV

Vaccines against sexually transmitted diseases

Human sexually transmitted infections are prevalent throughout the world. Several have been associated with adverse pregnancy outcome and increased susceptibility to HIV infection, in addition to the discomfort of inflammation of the genital tract. Yet vaccines to protect against the infection at the genital mucosa are not available. Hepatitis B is an exception, but this virus becomes systemic and protection may be at the systemic level. Sexually transmitted diseases (STDs) have long been associated with reproductive failure in cattle. These infections cause considerable economic loss, which has been a stimulus to investigation. Consequently, vaccines and mechanisms of immune protection have been studied quite thoroughly. The results obtained with two commercially available vaccines will be used to illustrate principles of protective immunity against STDs. Both Campylobacter fetus subsp. venerealis and Tritrichomonas foetus are only transmitted sexually and both cause reproductive failure in cattle

Steer Performance Grazing Corn Residue and Supplemented with Modified Distillers Grains plus Solubles with or without Urea

A growing study was conducted to evaluate the effects of supplementing growing calves grazing corn residue with modified distillers grains plus solubles (MDGS; 3 or 5 lb/d) and with or without urea on growth performance. There were no significant MDGS × urea inclusion interactions observed. Urea inclusion level (0 and 0.12 lb/d) did not affect supplemental intake, ADG, or ending BW. Steers fed 5 lb of MDGS had an increased ADG and a heavier ending BW compared to steers fed 3 lb MDGS daily. Supplemental urea is not necessary when supplementing at least 3 lb MDGS to steers grazing corn residue

Effect of Crude Glycerin Concentration on Growing Steer Performance in Forage Diets

The effect of increasing crude glycerin concentration was evaluated in a 91- d growing trial utilizing 60 steers. Crude glycerin was included at 0, 4, 8, and 12% of dietary DM in diets consisting of 50% wheat straw; 22.9- 37.0% wet corn bran, and 8.0- 10.1% soybean meal. Crude glycerin replaced wet corn bran and soybean meal was added to maintain dietary CP. Steer ending BW was not different among treatments. Th ere was a quadratic increase in DMI from 0 to 8% crude glycerin and subsequent decrease at 12%. Th ere was no difference in ADG or feed efficiency among crude glycerin concentrations. Therefore, crude glycerin appears to have an energy value slightly less than wet corn bran in a forage- based diet

Dried Distillers Grains Supplementation of Calves Grazing Irrigated Corn Residue

Steer calves grazing irrigated corn residue received supplementation of dried distillers grains plus solubles (DGS) at 0.3, 0.5, 0.7, 0.9, or 1.1% of body weight. Steers were individually supplemented daily through Calan gates. Daily gain improved linearly (0.77 lb/head/day to 2.21 lb/head/day) with increasing supplementation (1.5 lb/day to 7 lb/day). Supplementing DGS to calves grazing corn residue increased gain during the winter period

The Effect of Harvest Method and Ammoniation of Corn Residue on Growing Calf Performance

A growing trial was conducted to determine the effect of feeding baled corn residue harvested using three different methods, with and without ammoniation of the residue. Residue harvested with the New Holland Cornrower™ with two rows of chopped stem added to the windrow resulted in a 9% increase in ADG compared to conventional rake and bale harvest or turning off the combine spreader and baling tailing. Ammoniation of residue increased ADG 67% (increase of 1.1 lb/d) over non-ammoniated residue. Feed efficiency was not affected by harvest method, but ammoniation decreased F:G by 13% compared to cattle fed non-ammoniated residue. Although alternative harvest technologies can improve ADG, ammoniation of corn residue has a considerably greater impact on cattle performance

Rumen Undegradable Protein and Bambermycins Supplementation of Calves Grazing Corn Residue

Steer calves grazing non- irrigated corn residue were supplemented with a corn residue and by- product pellet that contained either Soypass, soybean meal, or processed soybean meal at a rate of 4 lb / d. Additionally, a supplement was fed at 1 lb / d that provided 0 or 20 mg / steer daily of bambermycins (Gainpro®). There was no interaction between bambermycins inclusion and pellet type. Likewise, there was no effect of pellet type or bambermycins on ending BW or ADG. In order to maximize gain of calves grazing corn residue it is important to provide a supplement that ensures adequate levels of both energy and rumen undegradeable protein

Effects of Modified Distillers Grains and Corn Ratios as Supplements in Diets Varying in Forage Quality on Performance of Growing Beef Steers

Distillers grains (DG) have been intensively used for beef production, but prices relative to corn vary such that it may be beneficial to displace a portion of DG with corn in certain circumstances. Four ratios of supplemental energy (40% of diet DM) from modified distillers grains and corn (100:0, 80:20, 60:40, and 40:60) were supplemented in one of 3 forage diets (56% of diet DM) and evaluated for performance. Forages were high (brome hay + sorghum silage) or low quality. Low quality forages were corn residue baled through conventional rake and bale, or by disengaging the spreader on the combine and baling the tailings (easy bale). Steers fed the high quality forage had greater ADG due to greater DMI, but similar F:G as both residue forage diets, which were not different. Decreasing the ratio of modified DG:corn linearly decreased ADG and resulted in poorer F:G