Thesis (doctoral)--Universidad de Buenos Aires, 1988. / Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 259-272).

Thesis (Ph.D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 259-272) Also available in print.

vii, 162 leaves : ill., photos., maps, tables, graphs ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1979

Not available / text

The biological remains preserved in the sediments of Arctic lakes and ponds in the Canadian High Arctic are important indicators of environmental change, especially as long-term instrumental data are often lacking. Although recent studies have underscored variability amongst these aquatic ecosystems, data are lacking from several key ecosystems. This thesis addresses some of these critical knowledge gaps in the Canadian high Arctic, using diatom-based limnological and paleolimnological techniques. First, I explore the limnology and diatom ecology along a gradient of bioclimatic zones on Melville Island in the western High Arctic. Lakes and ponds located in the most lushly vegetated zone were significantly different from those elsewhere on the island, both in terms of measured limnological variables and in terms of diatom assemblage composition. Diatom species distributions from Melville Island can best be explained by differences in pH and related variables. Secondly, ponds and lakes located in a High Arctic oasis on northern Ellesmere Island, recorded significantly higher specific conductivity, nutrients, and dissolved organic carbon than freshwater bodies from the surrounding polar desert. In Chapter 5, I provide an examination of long-term environmental change from Melville Island, a region of the High Arctic for which no paleolimnological data exist. The timing of diatom shifts in a dated sediment core from a small pond is consistent with the onset of climate warming in the early 20th century. Differences in ice cover have often been invoked to explain differences in the timing and magnitude of diatom shifts in the Arctic, but this hypothesis has not been explicitly tested. In Chapter 6, I compare two adjacent lakes with similar physical characteristics but different ice cover regimes from northern Ellesmere Island. I provide strong evidence that extended ice cover dampens diatom community responses to environmental change. In the final chapters, I determine that marine-derived nutrients significantly affect the limnology of ponds on Cape Vera, Devon Island, and are related to the degree of seabird influence. Although a portion of diatom species distributions can be linked to seabird influence, the most abundant taxa show little relation to the nutrient gradient. In a paleolimnological context, diatoms are not robust indicators of seabirds in High Arctic ponds. / Thesis (Ph.D, Biology) -- Queen's University, 2007-09-13 19:30:46.991

The technique of protein A-gold immunoelectron microscopy was used to determine the distributions of two photosynthetic complexes in the thylakoid membranes of the diatom Phaeodactylum tricornutum. The fucoxanthin-chlorophyll a/c light-harvesting complex, believed to be associated with photosystem II, was found to be equally distributed among appressed and unappressed membranes, whereas photosystem I was slightly more concentrated in the latter. These results suggest that in diatoms, the two photosystems and their associated light-harvesting complexes are essentially equally distributed on the two types of membranes, in marked contrast to the lateral heterogeneity observed in higher plants and green algae. Furthermore, it was expected that in P. tricornutum, the nuclear-coded proteins of the fucoxanthin-chlorophyll a/c light-harvesting complex would be present in the vesicles of the periplastidal reticulum, which were postulated to be involved in protein transport into chloroplasts. Immunolabelling results, however, indicated that these proteins were absent from the periplastidal vesicles.

vii, 162 leaves : ill., photos., maps, tables, graphs ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1979

Thesis (Ph. D. - Renewable Natural Resources)--University of Arizona, 1999. / Includes bibliographical references (leaves 340-346).

Thesis (Ph.D.)--Bowling Green State University, 2006. / Document formatted into pages; contains xvi, 112 p. : ill. (some col.) Includes bibliographical references.