http://hdl.handle.net/1957/1339 Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/9171 Title: Cenozoic biogenic silica sedimentation in the Antarctic Ocean, based on two deep sea drilling project sites <br/> <br/>Abstract: The Antarctic Ocean during the Cenozoic experienced four periods of increased surface productivity: the Middle Eocene; the beginning of the Miocene; the Middle Miocene; and near the Miocene-Pliocene boundary. The fourth increase in productivity began five million years ago and has since progressively increased to the present level of intense surface productivity. The major control of Antarctic surface productivity is climate. Opal production in the Neogene increased during glacial times, due to the intensification of upwelling south of the Polar Front, caused from accelerated atmospheric circulation and an increased volume production of Antarctic Bottom Water. Cenozoic variations in surface productivity are also related to the tectonic changes in the Antarctic Ocean basin, which altered the patterns of surface and thermohaline circulation. Antarctic Surface Waters became more conducive to biological productivity with the progressive latitudinal and thermal isolation of Antarctica, The efficiency of surface productivity has progressed to such an extent that much of the global silica supply has been transferred to the Antarctic at the expense of other productive oceanic regions such as the Central Equatorial Pacific. In the Neogene, the preservation or dissolution of calcium carbonate is influenced by the rate of upwelling south of the Polar Front. During glacial times, the upwelling of COB_rich Circumpolar Deep Water accelerates and effectively raises the calcite compensation depth. <br/> <br/>Description: Graduation date: 1977; Presentation date: 1977-04-21 http://hdl.handle.net/1957/9169 Title: The role of stridulation in the behavior of the shore crab Hemigrapsus oregonensis <br/> <br/>Abstract: The claw shuddering display of the shore crab Hemigrapsus oregonensis was explored with acoustic and behavioral observations. Male H. oreqonensis stridulate during claw shuddering display. The stridulatory apparatus is present only on the males. The acoustic signal was of brief duration, showed a general pattern of sound bursts, but varied among individual crabs. The larger crabs produced more intense signals. Because H. oreqonensis live in a turbid water of a mud-rock habitat or in burrows of the estuary, acoustic communication is well suited to their environment. Behavioral observations of H. oregonensis, collected from Yaquina Bay, Oregon, were made in habitat replicas of the mud-rock environment. Stridulation by male crabs was elicited equally by male and female crabs but the amount of stridulation increased when all the crabs were males. The strldulat,ing crab was typically maintaining a territory and did not retreat after signaling. The significance of stridulation in the total repertoire has not been resolved but territoriality as exemplified by burrow defense and communication facilitating ritualization have been indicated, and its importance in sexual behavior has not been demonstrated. <br/> <br/>Description: Graduation date: 1978; Presentation date: 1977-08-25 http://hdl.handle.net/1957/9163 Title: Stakeholder evaluation of market based approaches towards managing the adverse impacts of commercial fishing on the marine environment <br/> <br/>Abstract: Over fishing, by-catch of non-target fish species, marine mammals, seabirds, and damage to benthic habitats remain serious problems in fisheries management. Management methods based on traditional command and control (CAC) approaches may meet with initial successes yet additional progress is often marginal, requiring managers to implement additional regulations to achieve improvements in environmental performance. Market-based instruments (MBI), particularly in the context of rights-based systems, are relatively new and potentially powerful instruments for addressing environmental externalities in the marine environment, yet few policymakers have embraced or actively experimented with them. A comprehensive literature review, a general survey on perceptions and attitudes, and workshops using policy relevant decision support frameworks were used to understand, educate and assist west coast fishery management participants in evaluating the strengths, weaknesses, and trade offs associated with the potential use of MBI compared to traditional CAC regulations in managing the adverse impacts of fishing on marine ecosystems. Survey results suggest that although there were some differences among the various stakeholder groups, fishery management participants are familiar, receptive and perceive MBI as an effective, potential way to manage the adverse environmental impacts of fishing on the west coast. Workshop results indicate that there was little difference among the diverse stakeholder groups in evaluating the different policy approaches towards managing the adverse environmental impacts of fishing on the west coast. An individual transferable bycatch quota of non-commercial fish species is a market-based policy option that had high criteria satisfaction, while managing the essential fish habitat through market based instruments was ranked low and had high uncertainties. The combination of a structured and participatory decision support system and a comparison of the potentials of MBI relative to traditional CAC regulations should assist policy makers and stakeholders in seeking more creative and effective approaches in managing the environmental impacts of fishing activities. <br/> <br/>Description: Graduation date: 2008 http://hdl.handle.net/1957/9124 Title: An investigation into nitrogen uptake by Emilania huxleyi during continuous darkness <br/> <br/>Abstract: Experiments were conducted with two strains of the coccolithophorid Emiliania huxleyi. Previous experiments with CCMP1742 and 372 at a light intensity of 60 µEin/m²-s showed that during five-day periods of continuous darkness, strain 1742 was taking up nitrate from the media while strain 372 was not. The nitrate uptake in strain 1742 was concurrent with an increase in particulate nitrogen. This observation, combined with the fact that carbon-rich alkenones decreased during the same dark period, led to the hypothesis that amino acids were being synthesized during the continuous darkness period in E. huxleyi strain 1742. This thesis presents results from three separate continuous darkness experiments with E. huxleyi strains 1742 and 372, run at a light intensity of 165 µEin/m²-s. These experiments were conducted to determine whether 1) amino acids are synthesized in E. huxleyi strain 1742 during continuous darkness, 2) this strain is physiologically unique in this regard, and 3) any amino acid accumulation is compound-specific. Two separate and independent methods for amino acid determination were utilized: gas chromatography paired with a flame ionization detector (GC-FID) and the ninhydrin method. Alkenones, media nutrients, and particulate organic carbon and particulate nitrogen (PN) were also measured. Results showed that no dark-period nutrient uptake or PN accumulation occurred in strain 372, in agreement with previous findings. No accumulation of amino acids was displayed in this strain during the continuous darkness period. CCMP1742 displayed nitrogen uptake, PN accumulation, and amino acid synthesis during the first experiment, but not the second or third experiments. The argument is presented that the increased light intensity of 165 µEin/m²-s inhibited the above dark-period nitrogen dynamics. This inhibition may have been overcome in the first experiment due to a previous nutrient stress experienced by the cells used to inoculate the experiment culture. Future experiments should utilize ¹⁵NO₃ to track the media nitrogen into cells, and also investigate the effects of light intensity and nutrient stress on dark-period protein production. <br/> <br/>Description: Graduation date: 2009