Honors Projects for Global Environmental Science

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Now showing 1 - 8 of 8
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    (University of Hawaii at Manoa, 2022) Liu, Dingyi ; Shen, Suwan ; Global Environmental Science
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    The Upper Layer Structure and Variability of an Antarctic Glacio-marine Fjord: Andvord Bay, Western Antarctic Peninsula
    (University of Hawaii at Manoa, 2017-05) Christensen, Katy ; Merrifield, Mark ; Global Environmental Science
    Glacio-marine fjords on the Western Antarctic Peninsula (WAP) are relatively unstudied, rapidly changing systems of high biological productivity. The goal of this research is to characterize the upper layer physical structure and variability of a representative fjord, Andvord Bay, to determine how it changes in time and space in response to external forcing on seasonal and shorter time scales. To analyze the upper layer of Andvord Bay, CTD (Conductivity/Temperature/Depth) profiles and shipboard thermosalinograph data are used from two cruises in the National Science Foundation (NSF) supported project, Fjord ECO. First, the mixed layer depth (MLD) is determined using two different methods: higher order weighting and vertical differences of density above threshold with different commonly used threshold values. The variability of the upper layer salinity, temperature, density, and MLD are analyzed in relation to changes in space, time, and wind forcing. The threshold method using a threshold value of ∆σ = 0.03 kg/m3 is used to define the MLD, with inaccuracies in detection primarily due to the presence of weakly stratified layers at the surface. In the variability analysis, results show that seasonal heat flux is the largest factor impacting the changes in the upper layer of WAP fjords, although wind forcing does play an occasional role. Geographic influences are less prominent and are only relevant between the inside and outside of the fjord. Understanding the upper layer is an important part of understanding the water column dynamics, the chemical characteristics, and the biological diversity of glacio-marine fjords along the WAP.
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    Heritability of Coral Calcification Rates and Potential for Adaptation to Ocean Acidification
    (University of Hawaii at Manoa, 2017-12) Delano, Mia ; Toonen, Robert ; Global Environmental Science
    The increasing concentration of atmospheric carbon dioxide due to human activities is contributing to ocean acidification, which leads to a reduction in coral growth rates, but the mechanism by which this reduction occurs is unknown. Heritable variation underlies the potential for evolution over time, but the degree of variation in pH tolerances among corals, as well as the heritability of any such variation, was previously unknown. In this project, I calculated the heritability of calcification among eight of the dominant Hawaiian coral species under both ambient and low pH conditions predicted for the end of the century. Coral colonies were sampled across natural gradients in seawater chemistry from a total of six different locations around Oʻahu, Hawaiʻi. Coral calcification response was assessed per colony by comparing growth in grams per mg per day between replicate samples in low and ambient pH water. Heritability was assessed using an R package to calculate the amount of variation in calcification rates that is due to genetics and may be passed on to offspring. The results show that calcification rates are highly heritable across all eight species, and all eight may experience selective pressure for calcification rate under acidification. M. patula, P. meandrina, and P. evermanni in particular show statistically significant variation in pH tolerance among colonies, making these especially good candidates for future studies on adaptation to ocean acidification. Further studies combining additional variables such as sea surface temperature and nutrient availability may lead to the creation of a holistic predictive model of Hawaiian reef composition in the future.
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    Maintenance of Diversity through Multiple Timescales of Variation
    (University of Hawaii at Manoa, 2016-12) Smith, Alaina ; Edwards, Kyle ; Global Environmental Science
    Understanding the maintenance of diversity in phytoplankton is important because they are the base of the food web and they play a major part in biogeochemical cycles including the carbon cycle, which affects how the biosphere reacts to climate change. Diversity can be maintained through resource fluctuation because species can evolve different strategies to thrive under different conditions. These strategies include being able to grow the fastest, being able to store the most resources, or being able to use resources more efficiently, thus being the best competitor under limited resources. Nutrient supply in the ocean likely varies over multiple time scales (e.g., seasonal variation vs. storms); however, we do not understand how multiple frequencies of variation affects phytoplankton communities. To test the role of multiple frequencies of variation, I am using a model describing how phytoplankton respond to varying nutrient supply. I compared how the community structure during conditions where there were two pulse frequencies differ from communities under one-pulse frequency conditions. Under one-pulse conditions it was reiterated that species with different strategies did better under competition at different periods. As the pulse periods increased there were clear shifts in the community structure with respect to the strategies. However, when a second pulse frequency was added, pulse periods where species with one strategy usually dominated, were found to contain a co-existence between species with multiple strategies. In short, it was found that multiple frequencies of resource variation allow for a greater diversity of strategies present in the community.
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    Investigation Of Layered Lunar Mare Lava Flows Through Lroc Imagery And Terrestrial Analogs
    (University of Hawaii at Manoa, 2014-09-26) Needham, Heidi ; Fagents, Sarah ; Global and Environmental Science
    The lunar surface contains considerable amounts of information regarding the formation of the Solar System and more recently the Earth-Moon system. This makes it the ideal place to “Expand scientific understanding of the Earth and the universe in which we live,” a primary goal stated by NASA. The main objective of this project was to estimate the number and thicknesses of specific mare flow locations on the Moon visible within the walls of impact craters in Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images. This work was motivated by a need to understand flow thicknesses in models of mare flow emplacement and cooling. We focused primarily on layered deposits exposed in the walls of impact craters consistent with stacked lava flows. Our approach involved mapping inferred flow units in LROC data and determining the average thickness of flows using Lunar Orbiter Laser Altimeter (LOLA). However, image resolution prevents determination of whether each mapped layer contains a single flow unit or several flows. The precision of this method is therefore difficult to determine without ground-truth confirmation. To further examine the accuracy of this method to determine remotely sensed flow thicknesses, this study was complemented with analysis of Earth-based satellite imagery of Hawaiian basalt lava flows as analogs to lunar mare lava flows. Through field analysis, ground-truthed data for the terrestrial imagery was obtained to assess the accuracy of the inferences acquired from the LROC images. The terrestrial analog study of satellite images showed average flow thicknesses of 2.0 to 7.7 m. Measurements collected in the field yielded thicknesses ranging from 1.6 to 2.0 m. The lunar results compiled from Dawes Crater show an average mare flow thicknesses of 5.7 ± 4.7 m to 18.1 ± 8.9 m. Based on the terrestrial analog study, the image-derived flow thicknesses were overestimated by factors ranging from 1.0 to 4.5. This was primarily due to the difficulty of identifying all flow contacts in the images. Although flow thicknesses can be better constrained with the high resolution LRO images, these estimates are most likely larger than true flow thicknesses.
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    Assessment of the Wind Resource at the Grace Pacific Quarry site in Kapolei, Oahu
    (University of Hawaii at Manoa, 2014-01-15) Tu, Jiayu ; Businger, Steven ; Global Environmental Science
    The goal of this research project is to determine the feasibility of building a wind farm at Grace Pacific Quarry (GPQ) in Kapolei. This location was chosen because wind maps for Oahu suggest that the location of GPQ has a sufficient wind resource for a wind farm. Meteorological data from Grace Pacific Wind Towers were used to analyze the quality of the wind resource at GPQ. The people who work at First Wind in Hawaii were interviewed, and the wind resource at their wind farms was compared with that at GPQ. Finally, the thesis discusses local and political considerations and environmental impact studies needed to assess the feasibility of constructing a wind farm in Hawaii.
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    Environmental Influences on Vibrio vulnificus Abundance in the Ala Wai Canal
    (University of Hawaii at Manoa, 2012-12) Giancaterino, Shaun ; Grieg, Steward
    Vibrio vulnificus is a potentially fatal human pathogen indigenous to coastal ecosystems worldwide. This free-living bacterium is ubiquitous in the Ala Wai Canal in Honolulu, Hawaii, and can pose a significant threat to human health when found in elevated concentrations. Two major routes of infection are direct ingestion of contaminated seafood and direct exposure of open wounds to contaminated seawater. Many of Honolulu’s recreational waters and beaches (e.g., Waikiki beach, Ala Moana Beach Park) are located close to the Ala Wai Canal, and thus it is critical to understand when and where environmental pathogens such as Vibrio vulnificus are most prevalent there. Correlations between environmental variables and the abundance of V. vulnificus have been described for temperate and subtropical environments. Unfortunately, these correlations have little predictive power, may not apply in tropical waters, and ignore differences among strains of V. vulnificus. In this study, I measured how the growth rates of two strains of V. vulnificus are affected by varying organic matter concentrations, and by variations in temperature and salinity, under controlled conditions in the laboratory using basal media derived from natural stream and harbor waters. Preliminary experiments showed that the basal medium, or medium supplemented with 0.2 ?m glucose, contained insufficient organic matter to promote robust growth. I found that the addition of organic carbon in the form of protein digests did result in measurable changes in optical density in the cultures. Data from the subsequent experiments show that both A- type and B-type strains of V. vulnificus were strongly affected by temperature in the range typically observed in coastal waters of Hawaii (24 to 36 °C), with warmer temperatures resulting in higher growth rates. Both strains had a very broad tolerance to salinity. Growth rates increased most significantly when salinity was increased from around 5 to 10, but the growth rates were indistinguishable in the salinity range of 10 to 35. These results will contribute to the development of a coupled biological-physical model describing the dynamics of V. vulnificus in coastal waters. Such a model can then serve as the basis for quantitative microbial risk assessments to better understand and manage the risks of infection in coastal recreational waters.
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    Anthropogenic activities have altered the pristine environment of many coastal ecosystems (Valiela et al., 1997). Urbanization of coastal regions has lead to increased nutrient loading from both point sources, such as sewage treatment outfalls, and nonpoint sources, such as artificial fertilizers used in agriculture and detergents made for domestic and industrial use (de Jonge et al., 2002). Nutrient loading to shallow coastal systems with low hydrodynamic energy is of particular concern because these systems are generally rich in organic matter and do not require much additional nutrient or organic matter input to become eutrophic (de Jonge et al., 2002).
    (University of Hawaii at Manoa, 2013-07-16) Ricardo, Amanda ; Glazer, Brian
    In aquatic systems, benthic microbial respiration can have a profound effect on nutrient cycling and overall ecosystem health. Respiration results in the release of bioavailable nutrients as well as series of redox species which can be used as a proxy to identify reduced benthic conditions. He’eia Fishpond, located in Kane’ohe, Hawai’i, is a low energy, shallow coastal system influenced by an influx of both riverine freshwater and marine seawater, as well as by mangrove forests located along its terrestrial periphery. Voltammetric solid-state microelectrodes were used to simultaneously identify and measure changes in redox speciation over time in dark incubations of fine grained to coarse grained sediment core samples taken from the pond. The primary objective of this study was to evaluate the synergy between sediment heterogeneity (i.e., varying grain size, permeability, mineralogy and organic matter content) and sediment redox chemistry.