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1
Whitehead, Ayesha L. "The effects of isolation and environmental heterogeneity on intraspecific variation in Calamoecia clitellata, a salt lake-inhabiting copepod." University of Western Australia. School of Animal Biology, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0092.
Testo completoAbstract (sommario):
[Truncated abstract] This study focussed on how isolation and environmental heterogeneity in salt lakes has influenced intraspecific variation in the calanoid copepod Calamoecia clitellata. Calamoecia clitellata relies on passive vectors for dispersal, and this, coupled with the insular nature of salt lakes, may promote genetic divergence at a molecular level. When contrasting environments are involved, genetic divergence may also occur at the life history level, possibly due to local adaptation. I examined the distribution of genetic variation among 14 populations in Western Australia using molecular genetic markers, and examined variation in life history traits among contrasting environments. To ascertain how isolation had influenced molecular genetic variation, I determined population genetic structure and used a phylogeographic approach to infer the impact of historical events. Environmentally induced variation was also evident in the field, with a switch from subitaneous egg production to resting egg production coinciding with changing environmental conditions. It is proposed that plasticity in life history traits has evolved in response to temporal environmental heterogeneity … It can be concluded that isolation in salt lakes in Western Australia has influenced molecular and phenotypic variation in C. clitellata in contrasting ways. At the molecular level, contemporary and historical isolation have promoted genetic divergence of populations, yet when coupled with environmental heterogeneity, marked phenotype plasticity has arisen. This study raises questions as to whether phenotype plasticity is a widespread phenomena in zooplankton found in temporary saline waters and an adaptive strategy to tolerate marked temporal environmental heterogeneity
2
Cranney, Chad R. "Control of Large Stands of Phragmites australis in Great Salt Lake, Utah Wetlands." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4988.
Testo completoAbstract (sommario):
Phragmites australis (hereafter Phragmites) often forms dense monocultures, which displace native plant communities and alter ecosystem functions and services. Managers tasked with controlling this plant need science-backed guidance on how to control Phragmites and restore native plant communities. This study took a large-scale approach - to better match the scale of actual restoration efforts - to compare two herbicides (glyphosate vs. imazapyr) and application timings (summer vs. fall). Five treatments were applied to 1.2 ha plots for three consecutive years: 1) summer glyphosate; 2) summer imazapyr; 3) fall glyphosate; 4) fall imazapyr; and 5) untreated control. Dead Phragmites following herbicide treatments was mowed in the first two years. Efficacy of treatments and the response of native plant communities were monitored for three years. We report that fall herbicide applications were superior to summer applications. No difference was found between the two herbicides in their ability to reduce Phragmites cover. Plant communities switched from emergent to open water communities and were limited by Phragmites litter and water depth. Although, some plant communities showed a slow trajectory towards one of the reference sites, cover of important native emergent plants did not increase until year three and remained below 10%. These results suggest that fall is the best time to apply herbicides for effective large-scale control of Phragmites. Active restoration (e.g. seeding) may be needed to gain back important native plant communities. Methods to reduce Phragmites litter after herbicide applications should be considered.
3
Long, Arin Lexine. "Distribution and Drivers of a Widespread, Invasive Wetland Grass, Phragmites australis, in Great Salt Lake Wetlands." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3869.
Testo completoAbstract (sommario):
Non-native invasive plant species can often have negative effects on native ecosystems, such as altered nutrient cycling, decreased habitat for wildlife, and outcompeting native plants. Around the Great Salt Lake (GSL), Utah, the invasive wetland grass Phragmites australis has become abundant in wetlands around the lake. Phragmites is replacing many native wetland plants provide important waterfowl habitat around the GSL. For successful management of Phragmites in GSL wetlands, it is important to know the current distribution of Phragmites, as well as areas that might be vulnerable to future invasion by Phragmites. To do this, we used multispectral aerial imagery to map the current distribution of Phragmites. We then created a model that statistically related the Phragmites distribution data to a suite of environmental predictor variables such as salinity, proximity to nutrient sources, or proximity to roads. Results from our model suggest that Phragmites is more likely to be found in wetland areas close to point sources of pollution, with lower elevations with prolonged inundation, and with moderate salinities. We used these results to identify areas around GSL that might be vulnerable to future invasion. Results from our study will assist wetlands managers in prioritizing areas for Phragmites monitoring and control by closely monitoring areas of prime Phragmites habitat.
4
Boggs, Dimity. "Playas of the Yarra Yarra drainage system, Western Australia." University of Western Australia. School of Earth and Geographical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0074.
Testo completoAbstract (sommario):
This thesis examines playas as integrated ecosystems, through investigation of long- and short-term processes associated with playa geomorphology, hydrology and diatom ecology, in playas of the Yarra Yarra drainage system of Western Australia. This landscape approach was conducted at a range of scales and consequently revealed a level of heterogeneity not previously described in Australian playas. The key result and common thread linking the three facets of the playas investigated is the importance of hydroperiod in defining the playa environment. The morphology and distribution of playas are described and the results presented of an examination of potential mechanisms determining intra-system variability. Measurements of the physical attributes of the playas, including length, area, shape, density and orientation, were made through Geographic Information System analysis and detailed interpretation of aerial photography. Two main morphological groups are distinguished: small (<10 ha), elliptical to circular playas with a NNW-SSE orientation; and large (>30 ha), elongated playas. Regional patterns in geomorphic attributes are markedly different between the west and east sides of the system. The boundary between the two regions coincides approximately with rainfall distribution. In this respect, climate is an overarching driver of geomorphological variation but sub-catchment characteristics are also critical determinants. Littoral drift and segmentation processes that are common to coastal lagoons but not commonly described in playas were identified from visual interpretation of aerial photographs of spits, bars and cuspate shorelines. Six small playas, representing an hydrological continuum from mostly wet to mostly dry, were selected for investigation of their hydrology and diatom ecology, enabling assessment ii of the variability of hydrology, hydrochemistry and of the effects of different hydrological environments on the distribution of taxa. Hydroperiod was highly variable and central to determining playa geomorphology and biology. In the six playas it ranged from 19 to over 211 days, and filling frequency from 1 to 3 cycles between 2002 and 2004, reflecting rainfall and sub-catchment variability. Monitoring a series of nested piezometers revealed that the playas were net discharge points for ground water over the period of survey. However, small local vertical head variations indicate ground water does not discharge at the same rate across the playa surfaces and that playas may have short-lived phases of ground water recharge. Hydrochemically, the playas are typical of salt lakes in Australia. They displayed a wide range of salinity values, neutral to alkaline pH and ionic composition similar to sea water. It is postulated that the geochemical evolution of waters in the playas follows a pathway where low salinity recharge waters with dilute sea water salts progress to Na-Cl dominated brines through evaporative concentration. Surface waters showed an ionic dominance consistent with sea water with minor variations attributed to transitional phases in the geochemical evolution of the waters. Shallow ground waters showed a common and consistent pattern of ionic dominance: Na+ >Mg2+ >K+ >Ca2+ : Cl- >SO4 2- >HCO3 ->CO3 2-.
5
De, Deckker P. "Australian Quaternary studies : a compilation of papers and documents submitted for the degree of Doctor of Science in the Faculty of Science, University of Adelaide /." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09SD/09sdd299.pdf.
Testo completo
6
Rohal, Christine B. "Invasive Phragmites australis Management in Great Salt Lake Wetlands: Context Dependency and Scale Effects on Vegetation and Seed Banks." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7228.
Testo completoAbstract (sommario):
Invasive plants can outcompete native plants, replacing diverse plant communities with monocultures, which can negatively impact the whole ecosystem. One invasive plant, Phragmites australis, has invaded wetlands across North America. In Utah’s Great Salt Lake, it has greatly reduced the area of native plants that are important habitat for migratory birds. Here we describe experiments that assess multiple treatments for Phragmites removal and evaluate the return of native plants after Phragmites management. The treatments were applied to Phragmites patches at two scales (small 1/4-acre plots and large 3-acre plots) and across multiple sites to evaluate how patch size and environmental differences can influence the plants that return after Phragmites removal. The treatments (applied over 3 years and monitored two more) compared two different herbicides (glyphosate and imazapyr) and different herbicide and mowing timings. The treatments evaluated in the large patch study were 1.) untreated control 2.) fall glyphosate, winter mow, 3.) summer imazapyr, winter mow, 4.) summer glyphosate, winter mow. The treatments evaluated in the small patch study included treatments 1-4 above plus 5.) summer mow, fall glyphosate, 6.) summer mow, then black plastic solarization. In the small patches, we also monitored the seeds in the soil to assess how Phragmites management treatments can change the densities of Phragmites and native seeds. Fall glyphosate treatments were superior for Phragmites cover reduction. After the initial treatment, summer herbicide and mow treatments reduced Phragmites seed production, while fall glyphosate did not. Phragmites seeds were plentiful in the soil but were reduced following three years of all herbicide treatments. Native plant recovery following Phragmites management was extremely variable across sites. Sites with high soil moisture had better Phragmites removal and more native plants. But when flooding was deep, native plants were rare. Native seed density in the soil did not change due to Phragmites management, but soil seed densities were different across sites, which influenced native plant recruitment. Phragmites was removed more effectively and native plants returned in greater numbers in small patches compared with large. This was because small patches were typically near established native plant communities, which likely provided more native plant seeds and had hydrology that was less disturbed by human activity. In sites where native plants do not return after Phragmites management, practitioners may need to try revegetation with native plant seeds to restore important native plant communities.
7
Campagna, Veronica. "Limnology and biota of Lake Yindarlgooda - an inland salt lake in Western Australia under stress." Curtin University of Technology, Department of Environmental Biology, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17473.
Testo completoAbstract (sommario):
Inland salt lakes of the arid and semi-arid zones of Western Australia are unique systems. An unpredictable rainfall pattern and a transient water regime ensure these lakes remain dry for much of the year. Lake Yindarlgooda in the Eastern Goldfields of Western Australia is a typical inland salt lake that has been subjected to additional stresses. This thesis is the outcome of investigations conducted on the lake from 2001 to 2003. Emphasis is on the limnology and biota of the lake, including an adjacent wetland, and impacts on the aquatic ecosystems caused predominantly by mining. Lake Yindarlgooda is a large, shallow hypersaline lake situated on the Yindarlgooda Palaeoriver. It is sodium chloride dominated and has naturally high background levels of nickel. Sites impacted by the leaching of hypersaline decant water from a leach residue storage facility (LRSF) were differentiated from control sites using multivariate statistics. Salinity was found to be a major determinant in the structure of the biological communities in the lake systems.<br>Different biotic communities with low taxonomic diversity were recorded in Lake Yindarlgooda and Swan Refuge, a nearby hyposaline clay pan. The benthic microbial communities were dominated by halotolerant diatoms, notably Amphora coffeaeformis, Navicula incertata and Hantzschia baltica. Variation in the diatom assemblages between the playa sites and the clay pan were noted, influenced by habitat type and salinity. Within Lake Yindarlgooda, the diatom assemblages in the control and impact sites were found to be similar. A narrow salinity spectrum dictated the taxa present. Many of the benthic diatoms collected during the dry phase were encysted, having entered dormancy. The invertebrate fauna in Lake Yindarlgooda and Swan Refuge belonged to the Crustacea. A larger percentage of hyposaline invertebrate taxa were recorded from Swan Refuge, while those in Lake Yindarlgooda were typically halotolerant species. The Ostracoda showed the greatest diversity and their abundance was higher in the southern control sites while the Anostracan, Parartemia sp., dominated the northern impact sites of the playa.<br>The riparian zone of Lake Yindarlgooda supported a diverse plant community, dominated by the Chenopodiaceae. The marginal vegetation communities along the shores of Lake Yindarlgooda were found to be similar, indicating habitat homeogeneity. Within the riparian zone both biological and physical soil crusts occupied large areas not inhabited by vascular plants. The biological soil crust identified was composed of an association between the filamentous cyanobacterium Microcoleus sp. and a moss species (Musci). Both biological and physical soil crusts were found to have functional roles in stabilising the surrounding low dunes. The soil crusts in the northern control sites were badly degraded as a result of trampling by livestock, while those in the southern control sites were protected and were intact. Only one Parartemia species was found to inhabit Lake Yindarlgooda, Parartemia n. sp. d. It was collected in salinities ranging from 50 to 140 g L-1. The population appeared to be oviparous, recruitment mostly from resting eggs. The male to female ratios varied between sites, as did the number of juveniles compared to the adults. The northern impact sites had a more mature Parartemia population than the southern control sites and appeared to have undergone a second recruitment. Examination of the surface sediment found a well established Parartemia “egg bank” in the northern impact sites with egg numbers much higher than in the southern control sites.<br>The ultrastructure of the Parartemia resting egg was identical to that of Artemia. Differences in the external features and internal structure of the resting egg of Parartemia n sp. d and Parartemia n. sp g from Lake Miranda, another saline lake, were identified. This study showed morphological variation of the egg within Parartemia, a finding not previously recorded. Rehydration trials on the Parartemia egg bank indicated that the increase in sediment salinity from the LRSF had a negative effect on the hatching of the resting eggs. In salinities above 60 mS cm-1 hatching was less successful. The conditions provided in the trials were similar to those in Lake Yindarlgooda. The hatching technique was repeated on sediment from Lake Miranda with similar results. These trials were considered a valuable monitoring tool in the assessment of impacts on the biota of temporary lakes in the absence of water. This study demonstrated that in the absence of water the egg and spore/seed bank can be used as a proxy for monitoring temporary lakes. It was also found to be valuable in understanding the distribution and diversity of the biotic communities in Lake Yindarlgooda. This study provides the first integrated reference information on a Western Australian inland salt lake against which any future impact may be assessed.
8
Campagna, Veronica S. "Limnology and biota of Lake Yindarlgooda - an inland salt lake in Western Australia under stress /." Full text available, 2007. http://adt.curtin.edu.au/theses/available/adt-WCU20071128.103345.
Testo completo
9
Vest, Josh L. "Winter Ecology of Waterfowl on the Great Salt Lake, Utah." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/2051.
Testo completoAbstract (sommario):
I designed a suite of studies in coordination with Utah Division of Wildlife Resources (UDWR) to evaluate waterfowl use of the GSL in winter and ecological aspects associated with GSL use. These studies provided insight into key information gaps previously identified by UDWR regarding management of GSL resources. Population surveys indicated total duck abundance was low when GSL surface elevations were low and wetland resources diminished because of persistent drought in the system. Also, ducks appear to use hypersaline parts of GSL more when freshwater habitats are limited from either drought or ice conditions. Common goldeneye, northern shoveler, and green-winged teal exhibited the most use of hypersaline areas. Dietary evaluations indicated all three species feed on hypersaline invertebrates from GSL to meet energetic and nutritional needs in winter. Brine shrimp cysts were important foods for northern shoveler and green-winged teal. Fat levels of ducks are important determinants of survival and fitness. Fat reserves of goldeneye were generally lower in the winter when both GSL and wetland habitat resources were lower. Results suggest brine fly larvae productivity, freshwater habitat availability, and temperature and wind speed likely play a more prominent role in goldeneye fat reserves than osmoregulation. Also, common goldeneye and northern shoveler using the GSL apparently accumulated biologically concerning amounts of mercury and selenium during winter. However, further research is needed to evaluate the effect of these elements on GSL ducks.
10
Pendleton, Maya Cassidy. "Ecosystem Functioning of Great Salt Lake Wetlands." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7557.
Testo completoAbstract (sommario):
The Great Salt Lake (GSL) wetlands account for ~75% of all Utah wetlands and provide not only critical habitat for millions of migratory birds, but also provide valuable ecosystem functions and services as well as economic benefits to Utahns. However, these wetlands are facing an aggressive invader, Phragmites australis, that has spreading across the GSL wetlands and replacing native wetland habitats. Wetland managers have spent countless resources and time trying to control the spread of P. australis and restore GSL wetlands. However, we do not fully understand how these wetlands functions and services are being altered with this habitat homogenization because functional data for our wetland species have not been well documented. This lack of knowledge may hinder wetland restoration efforts.
To create baseline functional data for the GSL wetland species and better understand how the spread of P. australis might be affecting the overall health of the system, I measured eight individual ecosystem functions for seven dominant habitat types found across the GSL wetlands. I compared these individual functions across habitat types as well as created two different multifunctionality indices using an averaging and a thresholds approach. With these comparisons, I was able to determine the distinct functional strengths of different wetland habitat types and their overall functional abilities.
I found that functional abilities varied greatly by habitat type and that not one single habitat could support every function even at the lowest threshold measured. I found that Typha latifolia, Schoenoplectus acutus, and P. australis, had the highest multifunctional values. However, I also found that some habitats offered unique functions, such as Salicornia rubra and playa, and that these functions were lacking in other habitats, including the most multifunctional habitats. These findings suggest that maintaining habitat heterogeneity will be critical in ensuring a fully functioning wetland system that can provide a multitude of ecosystems services that benefit both humans and wildlife. The findings of this study will supply wetland managers with a better understanding of the functional strengths of different wetland habitats. This data will aid in ongoing restoration efforts by enabling managers to target certain functions and create more efficient and effective management plans.
11
Haws, Emily S. "Ecology of culturable organisms at Rozel Point, Great Salt Lake, Utah /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1741.pdf.
Testo completo
12
Haws, Emily Sarah. "Ecology of Culturable Organisms at Rozel Point, Great Salt Lake, Utah." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/857.
Testo completoAbstract (sommario):
The study of organisms from extreme environments is an emerging field of research with applications to multiple scientific areas. One of these extreme environments is Great Salt Lake (GSL), whose microbiology has yet to be extensively studied. This dynamic and unique environment offers an excellent opportunity to increase understanding of hypersaline ecology. Cultivation of microorganisms remains an important part of ecology research, as it is essential for understanding microbial physiology. We report here the culturing and characterization of isolates from Rozel Point, located on the northeastern shore of Great Salt Lake. This site was chosen because of the presence of petroleum seeps at Rozel Point and the extreme salinity of the North Arm of GSL. We hypothesize that culturing at GSL will reveal a diverse prokaryotic population, with both commonly isolated and novel organisms. We would predict that prokaryotes at GSL will share many features in common with other hypersaline microbial communities, but that given the distinctive properties of the site, there will be unique characteristics as well. Samples were taken from Rozel Point and cultured using direct plating, enrichment cultures, and dilution cultures with a variety of minimal and complex halophilic media. Fluorescence in situ hybridization (FISH) was used to examine abundance of cultured organisms in the environment. Culturing and characterization has revealed both isolates novel and previously uncultured, with many unique characteristics. FISH demonstrated that, unlike most environments, in GSL the dominant species are culturable. These results show the value of culturing in discovering new organisms and demonstrating diversity at the microbial level. Culturing of these organisms will allow for further research to be done on microbial processes that occur in this system and the unique properties of halophilic microbes.
13
Delahoussaye, Leah M. "Eared Grebe Nesting Ecology and Chronology Along the Great Salt Lake, Utah." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7524.
Testo completoAbstract (sommario):
Eared Grebes (Podiceps nigricollis) are migratory birds that build their nests over water and in large groups called colonies. Their typical breeding range is in central southern Canada and northern United States; however, a previously uncertain number of Eared Grebes (grebes) also nest around the Great Salt Lake (GSL), Utah, at the southern edge of their breeding range. Little is known about the habitat requirements for grebe nesting colonies at such low latitudes and if they are different from colonies found elsewhere. My objectives for this research were to determine the status of the grebe nesting population as well as their habitat characteristics along the GSL in freshwater wetlands. I found over 4,280 grebe nests distributed among 35 colonies. Grebes built nests by mounding submerged aquatic vegetation (SAV) beginning the first week of June. The results from my habitat study show that grebes prefer to nest in areas with an average water depth of 48 cm, high invertebrate density, and abundant areas of floating SAV. Water depth and vegetation type at colony sites as well as timing of nesting and average number of eggs per nest of GSL colonies differed from colonies located at more northern latitudes. The differences in nesting could be attributed to the need to wait for SAV to grow and form mats on the water’s surface, or a need to wait for their food source to reach harvestable size.
After grebes leave their nesting grounds, they stop at the GSL where they prepare for their final migration southward by consuming their fill of brine shrimp (Artemia franciscana). Brine shrimp are tiny invertebrates that are well-adapted to salty environments; they produce hard-walled eggs called cysts which are of great economic value and are commercially harvested from the GSL. I compared cyst viability, which is the percentage of cysts in a condition conducive to hatching, for cysts that had passed through the digestive tract of grebes and cysts samples obtained from the GSL. Only 30% of the cysts that had passed through grebes were viable, whereas 63% of cysts from the GSL were viable.
14
Frank, Maureen G. "Migratory Waterbird Ecology at a Critical Staging Area, Great Salt Lake, Utah." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4940.
Testo completoAbstract (sommario):
Despite the hemispheric importance of Great Salt Lake (GSL) as a staging area for migratory birds, little is known about the resources that GSL provides to these birds, or how changes to the GSL ecosystem might impact the avian community. Three species of migratory waterbirds that stage at GSL are Wilson’s phalaropes (Phalaropus tricolor), red-necked phalaropes (Phalaropus lobatus), and eared grebes (Podiceps nigricollis). My objective for this research was to study the impacts of prey availability on the staging ecology of these species. In Chapter 2, I examined the use of GSL habitats by both species of phalaropes. In the high-salinity bays of GSL, phalaropes were most strongly associated with shallow water. In the low-salinity bay, there were no strong associations between phalarope presence and particular habitat characteristics. In Chapter 3, I analyzed the behaviors of phalaropes relative to prey densities. Phalaropes commonly foraged in Carrington Bay, which had the highest densities of brine fly (Ephydridae) adults, and in Farmington Bay, which had high densities of benthic macroinvertebrates. Foraging behavior differed between Wilson’s and red-necked phalaropes, with Wilson’s phalaropes spinning more often than red-necked phalaropes.
In Chapter 4, I examined interannual and nightly variations in eared grebe fall migration departures in relation to prey availability and environmental conditions. Eared grebes began migration relatively early when lake temperatures were relatively warm, densities of brine shrimp (Artemia franciscana) adults were high, and densities of brine shrimp cysts were low. The likelihood that eared grebes would depart on a given night was positively associated with the average barometric pressure 12 hours prior to sunset.
The resources provided by GSL support substantial proportions of the staging populations of phalaropes and eared grebes. Management efforts should seek to maintain the habitats and resources needed by phalaropes and eared grebes at GSL. Future large-scale diversions of freshwater may threaten GSL’s suitability as a staging area for these birds.
15
Cox, Robert R. Jr. "Postbreeding Ecology of Adult Male Northern Pintails and Cinnamon Teal Near Great Salt Lake, Utah." DigitalCommons@USU, 1993. https://digitalcommons.usu.edu/etd/5281.
Testo completoAbstract (sommario):
I studied nutrient reserves, digestive organs, molt intensity, diets , and seasonal changes in food resources available to postbreeding adult male Northern Pintails (Anas acuta) and Cinnamon Teal (Anas cyanoptera) in marshes near Great Salt Lake, Utah. Total lipid and protein reserves of Northern Pintails were lower during the flightless period than before or after. For Cinnamon Teal, total protein was lowest during the flightless period, and total lipid showed a similar trend. Total mineral did not differ among plumage classes in either species. Use of nutrient reserves in these species may be an endogenous rhythm in response to increased predation risk or unpredictable food resources while flightless.
Digestive organ metrics of Northern Pintails generally were lower while flightless than before or after, apparently due to decreased dietary consumption. Cinnamon Teal digestive organ metrics changed little from preflightless to flightless stages, but generally increased while postflightless. Changes in Cinnamon Teal digestive organs may be related to increased dietary intake or increased dietary fiber consumption.
Total molt intensity in these species was generally high before and during wing molt, and decreased during the postflightless period. Mathematically weighting total molt scores produced results similar to those obtained without weighting, but selection of body/feather regions is critical to obtaining unbiased estimates.
Changes in relative availability of plant and animal foods during July and August were marked . Animal foods made up 96% of total foods measured in the study area during early July, but plant foods comprised 95% of available foods by late August. Changes in abundances of food resources are probably an important determinant of diet selection in postbreeding adult ducks and ducklings in marshes near Great Salt Lake.
Diets of postbreeding adult male Northern Pintails and Cinnamon Teal did not differ between species, but did among flight classes. Changes in use of food items and in use of animal and plant foods were consistent with changes in relative abundances of food resources. Postbreeding adult males of these species apparently foraged opportunistically.
16
Lowry, John H. Jr. "Spatial Analysis of Urbanization in the Salt Lake Valley: An Urban Ecosystem Perspective." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/746.
Testo completoAbstract (sommario):
Because urban areas comprise a variety of biotic (e.g. people, trees) and abiotic (e.g. streets, water) components that interact and are often interdependent upon one another, it is helpful to study urban areas as urban ecosystems. Our goal in Chapter 2 is to measure and quantify the spatial and demographic structure of the urbanized portion of Salt Lake County, Utah. We use 18 metrics from four broad categories (density, centrality, accessibility, and neighborhood mix) to measure urban form for three age-based residential neighborhood types. Using analysis of variance (ANOVA) we test for differences in mean values for the 18 urban form metrics. We find measureable differences in the spatial and demographic characteristics of these neighborhoods, suggesting that the rate of urban sprawl in Salt Lake County has been holding steady, if not increasing, during the last 20 years. Chapter 3 seeks to better understand how spatial heterogeneity in urban tree canopy is related to household characteristics, urban form, and the geophysical landscape of residential neighborhoods. We consider neighborhood age a factor that moderates the relationship between these determinants of tree canopy, and the abundance of tree canopy observed. Using linear regression analysis with neighborhood age as interaction term, we assess the relationship between tree canopy and 15 determinants of tree canopy abundance at three neighborhood ages. We find that neighborhood age has a significant moderating effect on the relationship between several determinants of canopy cover and the abundance of canopy cover observed. While the urban forest provides many benefits to human well-being, it also consumes considerable quantities of water. An important question in Chapter 4 is to determine whether a growing urban forest increases overall residential irrigation demand, decreases demand, or has no apparent effect. Using a water demand model borrowed from agronomy, we estimate irrigation water demand based on the area of three residential landscape types and climatic factors. We project future residential water demand by generating residential landscape scenarios based on predicted urban forest canopy growth. We find that urban forest growth has the effect of stabilizing or potentially decreasing overall residential irrigation water demand.
17
Roberts, Anthony J. "Winter Waterbird Ecology on the Great Salt Lake, Utah, and Interactions with Commercial Harvest of Brine Shrimp Cysts." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/2042.
Testo completoAbstract (sommario):
Interactions among commercial fisheries and birds have been studied in open ocean ecosystems and at aquaculture facilities. On the Great Salt Lake (GSL), Utah, USA, a commercial harvest of brine shrimp (Artemia franciscana) eggs (i.e. cysts) occurs annually during fall and winter. Coinciding with commercial harvest is the use of the GSL by millions of waterbirds which has the potential to result in conflict among industry and birds. The objectives of my research were to examine fall and winter ecology of birds using the GSL and interactions with the brine shrimp cyst harvest. I examined the influence of temperature and food availability on the number and distribution of waterfowl and eared grebes (Podiceps nigricollis). I also assessed the diets of the same species to see how much cyst biomass is being consumed by birds compared to removal by commercial harvest. A mass die-off (i.e. downing) of migrating eared grebes occurred during my research, so I assessed differences among birds that died and those that did not to better explain this phenomenon. Finally, I assessed the breeding origin of northern shovelers (Anas clypeata) wintering on the GSL using stable isotopeand banding data.I found that commercial harvest boats did not influence duck population numbersor distribution; rather temperature and food availability most influenced abundance and distribution, though this influence varied by species. Compared to commercial harvest, northern shovelers, green-winged teal (Anas crecca), and eared grebes removed a small fraction of the total amount of cysts that were removed from the GSL. Waterfowl diets were mainly wetland plant seeds during fall and spring, but when freshwater marshes were frozen in winter, ducks ate mostly brine shrimp cysts and brine fly (Ephydra spp.) larvae. Eared grebes are highly associated with saltwater habitats and they consumed adult brine shrimp most of the fall. Eared grebes that perished during the downing had mercury and selenium concentrations above levels seen in pre- and post-downing birds and higher than observed concentration that impact bird species, providing a potential ultimate cause of death during snowstorms that accompany most downings. Stable isotope analysis indicated northern shovelers that winter on the GSL had breeding origins throughout the specie’s range, but most came from local or southern Prairie Pothole Region breeding populations.
18
Segal, Richard Daniel. "Primary production and nutrient dynamics in solar salt ponds." University of Western Australia. School of Water Research, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0053.
Testo completoAbstract (sommario):
[Truncated abstract. Formulae and special characters in this field can only be approximated. See PDF version for accurate reproduction.] Solar salt producers use solar energy to evaporate seawater as it flows through a series of ponds. The Shark Bay Salt solar ponds, at Useless Inlet in Western Australia, vary in salinity from that of seawater to four times seawater, over the pond sequence. Water column photosynthesis and biomass decreased markedly with increasing salinity along the pond sequence, while benthic productivity increased as cyanobacterial mats developed. Correspondingly, net productivity shifted from autotrophy to heterotrophy in the water column and from heterotrophy to autotrophy in the benthos. Both shifts occurred at intermediate salinity in the pond sequence, where there was low production in both the water column and benthos. Within individual ponds, productivity, algal biomass and physico-chemical conditions were relatively constant over the year of study. Transitions between benthic and planktonic production along the pond sequence were driven mostly by direct responses to salinity stress, as well as the formation of a gypsum crust on the pond floors at higher salinity (>120 g kg-1). This transition is similar to that which occurs in saline lakes undergoing anthropogenic salinisation and identifies critical salinities for the restoration of these lakes.
19
Draper, Larry W. "A Demographic Examination of Household Heads in Salt Lake City, Utah, 1850-1870." Diss., CLICK HERE for online access, 1988. http://patriot.lib.byu.edu/u?/MTAF,28425.
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20
Bruce, Louise Christina. "A study of the interaction between the physical and ecological processes of three aquatic ecosystems." University of Western Australia. Centre for Water Research, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0178.
Testo completoAbstract (sommario):
Due to the complex nature of aquatic food webs, the interaction between abiotic and biotic factors that govern ecosystem dynamics is often elusive. Recent advancements in both the collection of reliable field data and the development of ecological models have enabled researchers to gain insights into these more complex interactions. In this study the relationship between physical and ecological processes has been explored by applying a process based coupled physical and ecological model (DYRESM-CAEDYM) to the data sets of three aquatic ecosystems. In the first, the role of zooplankton in the nutrient cycles of Lake Kinneret, Israel was quantified. The model was parameterized and calibrated using an extensive field data set. It was found that the excretion of dissolved nutrients by zooplankton accounted for up to 58% of phytoplankton demand and that this value varied seasonally in response to patterns of stratification and mixing. In the second ecosystem, Mono Lake, USA, results from model simulations were studied to determine the significance of the transport of nutrient rich hypolimnetic water via the benthic boundary layer (BBL) on lake productivity. Model results indicated that although on average the impact of BBL transport on Mono Lake ecology was not large, significant nutrient fluxes were simulated during periods when BBL transport was most active. The timing of these fluxes in the context of seasonal changes were found to be critical to specific aspects of food web dynamics. In the final application, the ecological gradients of the primary salt ponds of Shark Bay, Australia were studied with specific focus on the role of zooplankton as a determinant of ecosystem dynamics. Model results indicated that zooplankton grazing was responsible for reduced water column particulate organic matter and increased light available for the development of microbial mats. However, no direct 8 link between zooplankton grazing and observed changes in planktonic algal species composition or nutrient limitation across the salinity gradient of the ponds was found. Results from this study demonstrate the potential of a lake ecosystem model to extract useful process information to complement field data collection and address questions related to the relationship between physical and ecological processes in aquatic ecosystems.
21
Sarre, G. A. "Age compositions, growth rates, reproductive biology and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia." Murdoch University, 1999. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060818.135836.
Testo completoAbstract (sommario):
The aims of the studies undertaken for this thesis on the black bream
Acanthopagrus butcheri, a species which is confined to estuaries, were to determine the
following. (1) The age compositions, growth rates, reproductive biology and diets of the
populations of this species in four different estuaries (Swan River, Moore River,
NomaluplWalpole and Wellstead estuaries) and a landlocked saline lake (Lake Clifton)
and (2) the seasonal and regional distributions of this species within one estuary (Swan
River Estuary). Acanthopagrus butcheri were collected at regular intervals from
nearshore, shallow (< 2 m) and offshore, deeper (> 2.5 m) waters of the permanently open
Swan River Estuary and intermittently open Moore River Estuary on the lower west coast
of Australia and from the permanently open Nomalup/Walpole Estuary and normally
closed Wellstead Estuary on the southern coast of Western Australia. One hundred
A. butcheri were also obtained from a landlocked, coastal saline lake (Lake Clifton), 90 km
south of the Swan River Estuary. Sampling employed seine nets, composite gill nets and
rod and line.
In the Swan River Estuary, black bream typically occur in the saline reaches of the
tributary rivers which constitute the upper estuary. However, during heavy freshwater
discharge in winter, many individuals are swept downstream into the basins that constitute
the middle estuary. These fish migrate back into the upper estuary in spring and the larger
fish spawn in this region between the middle of spring and early summer. Although
smaller fish tend to remain in the upper estuary during summer as salinities increase, the
larger fish migrate further upstream where salinities are lower. The salinities in which
A. butcheri spawned in the different systems ranged from as low as 5.5 - 6.8 %CJin the
Moore River Estuary to as high as 40.7 - 45.2 %O in the Wellstead Estuary.
The use of marginal increment analyses demonstrated that the opaque zones
revealed in otoliths by sectioning are formed annually and could thus be used for ageing
individual fish and that the opaque zones visible in whole otoliths prior to sectioning could
be used for ageing fish up to six years old. The number of annuli on scales did not
provide a reliable estimate of age. The structure of the age compositions in the four
estuaries varied, presumably reflecting differences in fishing pressure and, in one case, the
lack of recruitment in some years. The growth rates of A. butcheri in the four estuaries
and landlocked lake differed, which is probably related to variations in one or more of the
following; water temperature, density of fish, salinity and the type of food available.
The monthly trends exhibited by gonadosomatic indices and the prevalence of
different gonadal maturity stages and mature oocytes demonstrate that spawning typically
occurs in spring and early summer. The frequent occurrence of yolk vesicle, yolk granule
oocytes and post-ovulatory follicles in the ovaries of some mature fish provides strong
circumstantial evidence that A. butcheri is a multiple spawner, i.e. spawns more than once
during each breeding season. Estimates of the minimum total fecundity ranged between
9.07 x lo4 and 7.09 x lo6, with a mean of 1.58 x lo6. Variations amongst the lengths and
ages at first maturity in three of the estuarine populations of A. butcheri could apparently
be attributed to the influence of variations in growth rate.
Female and male Acanthopagrus butcheri both possess an ovotestis, a feature
characteristic of the Sparidae. There is strong circumstantial evidence that, once a member
of this species reaches maturity, it can be considered a rudimentary hermaphrodite, i.e. it
possesses either functional ovaries and far smaller and immature testes or functional testes
and immature ovaries of variable size. There was no evidence that this species undergoes
either a protogynous or protandrous sex change.
Acanthopagrus butcheri can consume various benthic and epibenthic prey,
including crustaceans, polychaetes, molluscs and teleosts, and can also ingest considerable
volumes of algae. However, the dietary compositions of A. butcheri in the four estuaries
and Lake Clifton differed markedly, whch, together with information on the biota in those
systems, indicate that A. butcheri feeds on those prey items that are most abundant in their
environment. Yet, there is also evidence that, in any given system, A. butcheri will focus on
a particular prey, even when other prey, which are regularly consumed in considerable
volume in other systems, are abundant. The dietary compositions of A. butcheri in each
estuary underwent ontogenetic changes, which would reduce the potential for intraspecific
competition for food resources.
22
Marty, James. "Revegetation of Bulrushes Bolboschoenus Maritimus, Schoenoplectus Acutus, and S. Americanus in Great Salt Lake Wetlands: Seed Biology and Influence of Environmental Factors on Rhizomes." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5066.
Testo completoAbstract (sommario):
A primary goal of ecological restoration is to establish desirable plant species. This goal is particularly important following the removal of invasive plants. Understanding biological traits of plant species important to revegetation is crucial to plant establishment. In the globally important Great Salt Lake (GSL) wetlands, native habitat-forming bulrushes Bolboschoenus maritimus, Schoenoplectus acutus, and S. americanus are frequently displaced by the invasive grass Phragmites australis. Successful revegetation of bulrushes relies on improving our understanding of seed dormancy break, seed germination requirements, and the environmental factors affecting rhizome emergence and growth. We used a series of germination chamber and greenhouse experiments to examine effective seed dormancy break treatments and germination conditions for multiple collection sites of bulrushes B. maritimus, S. acutus, and S. americanus. We also performed a greenhouse experiment to investigate how water depth, nutrient, and salinity levels affect B. maritimus and S. acutus emergence and growth from rhizomes. Cold, moist stratification and bleach scarification were effective dormancy break treatments for all species, though magnitude of effect varied by species and source site. Soaking the seeds after application of dormancy break treatments improved germination for all species. Rhizome emergence of S. acutus was negatively affected by high water depth, likely due to oxygen limitation. Bolboschoenus maritimus was salinity tolerant relative to S. acutus. GSL wetland managers can use these findings to improve revegetation projects via seeding and planting.
23
McDonald, Kathi. "Variation in morphology, salinity and waterlogging tolerance and resource allocation in strawberry clover (Trifolium fragiferum L.) : implications for its use in mildly saline soils in southern Australian farming systems." University of Western Australia. School of Plant Biology, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0105.
Testo completoAbstract (sommario):
[Truncated abstract] In southern Australian farming systems the replacement of deep-rooted perennial native vegetation with shallow-rooted annual crops and pastures has resulted in rising groundwater tables and an increased incidence of dryland salinity. It has been suggested that to address this issue by restoring hydrological balance, large areas of agricultural land need to be vegetated with perennial plants. One of the most agriculturally productive ways to do this is to introduce perennial pastures, both into upslope groundwater
24
Ellis, Kristen Sue. "Habitat Selection and Nesting Ecology of Snowy Plover in the Great Basin." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3868.
Testo completoAbstract (sommario):
Snowy plovers (Charadrius nivosus) are small, ground-nesting shorebirds that are a species of conservation concern throughout North America. Despite increased efforts to understand factors contributing to the decline of snowy plover, little is known about habitat selection and breeding ecology of snowy plover for the large population found in the Great Basin. We tested hypotheses concerning the occupancy and nesting success of snowy plover. First, we identified factors influencing snowy plover nest survival at Great Salt Lake, Utah. We hypothesized that snowy plover would demonstrate differences in nest survival rates across years due to differences in habitat characteristics, predator abundance, human influence, resource availability, and fluctuating water levels. We conducted nest surveys at five sites along the Great Salt Lake to locate new nests or monitor known nests until nest fate was determined. We found 608 nests between 2003, 2005-2010, and 2012. The most common cause of nest failure was predation, followed by weather, abandonment, and trampling. Nest survival estimates ranged from 4.6 -- 46.4% with considerable yearly variation. There was no correlation between researcher activity (visits to nests and trapping of adults) and nest survival. Nests in close proximity to roads had lower survival than nests far from roads. Nests located on barren mudflats also had lower survival than nests in vegetated areas or near debris. We found that nests had a higher probability of survival as they increased in incubation stage. Because nesting areas around the Great Salt Lake host some of the largest concentrations of breeding snowy plover in North America, we suggest that managers consider measures to maintain suitable nesting habitat for snowy plover. Second, we determined factors affecting snowy plover occupancy and detection probabilities in western Utah between 2011 and 2012. We hypothesized that snowy plover would be associated with spring water flows and sparsely vegetated salt flats. We made repeated visits to randomly selected survey plots recording the number of snowy plover adults and habitat characteristics within each plot. We modeled the relationship between snowy plover detection probability and habitat and environmental characteristics. The detection probability was 77% (95% CI = 64 -- 86%) and did not vary by year. There was a positive relationship between ambient temperature and detection probability. Next, we modeled the relationship between snowy plover occupancy and individual habitat characteristics including distance to water, distance to roads, land cover types, and vegetative characteristics. Snowy plover occupancy did not vary by year and was estimated at 12% (95% CI = 7 -- 21%). Occupancy was best predicted by close proximity to water, playa land cover, and minimal shrub cover. We used habitat characteristics that best predicted snowy plover occupancy to generate a predictive habitat model that can help prioritize future snowy plover surveys and guide conservation efforts.
25
Ligman-McCormick, Etta Margo. "The Salton sea wetlands: A guidebook of curriculum based lessons." CSUSB ScholarWorks, 2003. https://scholarworks.lib.csusb.edu/etd-project/2292.
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26
De, Deckker P. (Patrick). "Australian Quaternary studies : a compilation of papers and documents submitted for the degree of Doctor of Science in the Faculty of Science, University of Adelaide." 2002. http://web4.library.adelaide.edu.au/theses/09SD/09sdd299.pdf.
Testo completoAbstract (sommario):
"April 2002" Includes bibliographical references and list of the publications and papers submitted. Pt. 1: section 1. Ostracod taxonomy and ecology -- section 2. Limnology of salt lakes -- section 3. Ostracod palaoecology - Quaternary environments -- section 4. Palaolimnology - Quaternary paleoenvironments and geology -- pt. 2: section 5. Geochemistry of ostracod shells -- section 6. Palaeoceanography Contains the majority of the author's scientific publications. Aims at reconstructing Quaternary paleoenvironments, mostly from the Australian region, using the fossil remains of organisms as well as new geochemical techniques.
27
Hillwalker, Wendy E. "Selenium and trace metal accumulation in detrital-benthic food webs of lotic and lentic wetlands, Utah, USA." Thesis, 2004. http://hdl.handle.net/1957/29920.
Testo completoAbstract (sommario):
Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead
(Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction
with selected physicochemical data, from representative wetland types at a mining site within
Salt Lake County, Utah, USA. The selected field sites included Oolitic Pond (lentic) and Lee
Creek (lotic), which are moderately contaminated brackish, alkaline aquatic wetlands
managed by a copper mining industry. These fishless wetlands are located in a geographic
region that poses risk to migratory shorebird populations from dietary Se. A spatial sampling
study demonstrated the extent of variation in total Se concentration within the wetlands. With
the exception of the sediment compartment, Se concentration did not differ significantly along
the 2-mile length of Lee Creek or within the Pond. The differences in sediment total Se
concentrations between the Creek East and West segments characterize lower Lee Creek as
having two segments distinguished by unique processes that influence the sediment Se
accumulation profiles. Se accumulation trends were observed temporally over 3-years (2000
to 2002) and over two seasons (spring and autumn). Total Se body burden in benthic
invertebrates was more clearly associated with sediment/detritus Se concentrations than with
surface water concentrations. Three invertebrate groups dominated the aquatic invertebrates
assemblage in the lotic and lentic benthos; primary consumers (Chironomidae, Diptera),
generalist feeders (Hemiptera) and predators (Odonata). The chironomid larvae accumulated
1.3 to 39 times the trace metal concentrations of the Hemiptera or odonate taxa, independent
of trace metal type (essential or non-essential) or wetland occupation. Organism-specific
factors, such as habitat selection and preferential feeding habits, were proposed to influence
benthic invertebrate accumulation profiles by modifying trace metal exposure. Mixed diets,
trophic omnivory and the complexity of wetland biogeochemistry limit the power of stable
nitrogen fractionation signatures to define benthic food web relationships. Wetland site-specific
processes impacted Se accumulating efficiency, with trace metal concentrations from
4 to 7 times greater within the lentic benthic system than the lotic. The fractionation of the
natural abundant stable carbon isotopes revealed the importance of sedimentary and detrital
organic carbon as dietary sources for the benthic food web. Sediment organic content was not
significantly associated with sediment, or invertebrate, Se accumulation profiles. Ecological
risk assessments based on sound understanding of metal chemistry and the interactions
between the sediment matrix and benthic organisms are necessary to provide tools for
environmental management.<br>Graduation date: 2005
28
Lemmons, Kelly K. "Salt Lake City’s Urban Growth and Kennecott Utah Copper: A Geographical Analysis of Urban Expansion onto a Previously Proposed Superfund Site Adjacent to the World’s Largest Copper Mine." 2008. https://scholarworks.umass.edu/theses/206.
Testo completoAbstract (sommario):
Kennecott copper mine is one of the largest producers of pollution in the United States: it has contaminated over 72 square miles in the Salt Lake Valley. In 1998 alone, Kennecott, which is located only 25 miles southwest of downtown Salt Lake City, released 439 million pounds of toxic material into the Salt Lake Valley. Kennecott was proposed as a Superfund site by the EPA in 1994. Today it is the largest manmade excavation in the world. When mining operations began in 1863 at what is now Kennecott, Salt Lake City was a small city of just over 8,000 (Census, 1860). In recent years, the city has expanded toward Kennecott, so that once distant hazards are now literally in Salt Lake City’s residents’ backyards. According to the basic patterns commonly identified in the academic literatures on environmental justice and urban growth, as the Salt Lake City metropolitan area grows towards Kennecott the assumptions would be (1) Kennecott’s mining activities would be severely hindered by the influence of the EPA or would be forced to close due to the proximity of residents. (2) Those living/moving nearest to the area would most likely be low income people with no other options. (3) Arousal of community opposition to Kennecott as residents continue to move closer, which in this paper is referred to as “reverse” NIMBYism. However, none of the assumptions are the case. Why is it that Kennecott continues to function at full capacity without direct influence by the EPA and those residents encroaching upon it are not of low income and are not in opposition? This study of social, urban and historical geography will address these questions by exploring the spatial, economic and political history of Kennecott, Salt Lake City and the EPA, with a focus on the recent and ongoing development of 20,000 new homes in the area called Daybreak.
The analysis will draw on analytical and theoretical approaches common to geographical analyses of urban growth and sprawl, environmental perception and environmental justice in relation to the nexus of spatial, economic and political circumstances which have led to the development of a new housing area on previously polluted land.
29
Caselmann, Meike. "Rezente und subfossile Mikrobialithe westaustralischer Salzseen." Doctoral thesis, 2005. http://hdl.handle.net/11858/00-1735-0000-0006-B32C-0.
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