Honors Projects for Oceanography
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ItemAssessing the Down-Fjord Mechanistic Relationships of Biodiversity and Abundance of Antarctic Benthic Macrofauna of Andvord Bay(University of Hawaii at Manoa, 2018)Glaciomarine fjords exhibit substantially different ecosystem forcing than adjacent continental shelves and can be highly sensitive to climate warming. Subpolar Arctic fjords are heavily influenced by glacial meltwater and sediment inputs, resulting in hi
ItemGlutamate-Cysteine Ligase Modifier Subunit as a Possible Modulating Factor in Methylmercury-Induced Developmental Toxicity(University of Hawaii at Manoa, 2014-09-26)The US EPA recently released a fish-consumption advisory, recommending that pregnant mothers reduce their intake of certain fish. Concentrations of methylmercury (MeHg) in commonly consumed fish have raised concern for the health of women of childbearing age and their developing children. Previous experiments have implicated glutathione (GSH), an endogenous, tri-peptide antioxidant, as an ameliorative factor in MeHg toxicity. GSH biosynthesis is rate-limited by glutamate-cysteine ligase (GCL), a heterodimeric enzyme consisting of a catalytic and a modifier subunit (GCLC and GCLM, respectively). To examine the roles of GCLM and GSH synthesis in MeHg- induced developmental toxicity, experiments were conducted employing Gclm knockout and hemizygous mice. Eight breeding pairs were established and on gestational day 14, females were inoculated with MeHg or sesame oil vehicle. The animals were sacrificed on gestational day 17, with dissection of the embryos, placenta, and yolk sacs, and maternal brain, liver, and kidney. The genotype of each embryo was determined and tissues were assayed for Gclm transcription and GCLM protein expression. While the scale of this experiment was found to be insufficient for definitive assessment of the roles of GCLM and GSH biosynthesis in MeHg toxicity, the work described here may provide pilot data for the design of future experiments. Additional results from such experiments should provide a better understanding of the fundamental processes involved in MeHg-induced developmental toxicity, and suggest public health strategies for protecting developing children from such injury.
ItemThe Role of Suspended Particle Layers in the Biogeochemistry of Monterey Bay, California(University of Hawaii at Manoa, 2014-09-26)Recent evidence suggests that suspended particles may act as anoxic or suboxic (low dissolved molecular oxygen) microzones in oxygenated seawater. In March 2002, the remotely operated vehicle Ventana was used to study layers of such suspended particles in Monterey Bay, California. This new method of water column sampling allowed for water collection with minimal disturbance, yielding detailed chemical analyses of the layers and the surrounding seawater. Although elevated levels of methane were discovered in the water column, they did not correlate with particle concentrations. In addition, it appears that, with the exclusion of 5 extraneous points, concentrations of dissolved silica, alkalinity, nitrogen, phosphorus, methane, oxygen, and N20 showed large changes independent of particle concentration. Comparison of Monterey Bay nutrient data to Pacific open-ocean data indicates possible depletion of particulate C by the time sampled depths in Monterey are reached, thereby limiting the role particles play in the waters. Although this appears to refute the hypothesis that suspended particle layers play an active role in controlling the bulk water column chemistry of the bay, small-scale perturbations may be present but just not discernable from the sampling scale and depths of this research. In September 2001 similar research was done that included methane stable carbon isotope data, indicating future study of this system should include a more detailed look at small-scale changes at, above, and below individual particle layers in addition to mineral analysis of the particles, and methane and N20 stable isotope data.