Successional patterns of attached estuarine diatoms were investigated using laboratory model ecosystems. Artificial substrates of acrylic plastic were exposed to 0, 4, and 10 hours of desiccation per day. Diatom assemblages that developed under temperatures normal for Yaquina Bay, Oregon (control ecosystem) were compared to assemblages that developed at temperatures elevated 10 C (heated ecosystem). Continuously submerged substrates were quickly invaded by solitary, motile and attached diatoms. By the end of the experiment, filamentous and tube dwelling colonial diatoms had become established with many motile and epiphytic diatoms interspersed among the colonies. However, planktonic taxa were the first to settle on the substrates exposed to 4 and 10 hours of desiccation. These taxa were gradually replaced in prominence by solitary, motile and attached taxa that had previously colonized the continuously submerged substrates and by several species that were tolerant of desiccation and high air temperatures. Again, filamentous and tube dwelling forms began to establish colonies at the end of the experiment. A total of 21,569 diatoms was counted in 42 samples, and 136 species were identified. The most abundant diatoms found in the control ecosystem included Navicula directa, Thalassiosira no. 1, Thalassionema nitzschioides, Nitzschia no. 2, and Navicula diserta. Thalassiosira no. 1, Thalassionema nitzschioides, Nitzschia aerophila, Nitzschia sigma, and Navicula no. 2 were the most abundant species in the heated ecosystem. Of these taxa, Navicula directa and Thalassionema nitzschioides were the most evenly distributed over the samples. Species diversity was higher in the heated ecosystem than in the control ecosystem. / Graduation date: 1973

Graduation date: 1975

A chemostatic system was developed for the long term studies of population dynamics of chain forming diatoms. Vessel volume rather than flow rate was varied in these systems to obtain different growth rates at steady state in systems with an equal capacity to produce. Population level responses to high dilution rates were examined for Skeletonema costatum both in long term steady state and under non-steady state conditions. Development of populations were observed from small innocula through steady state dilution rates approaching the maximum growth rate of the population. Populations were characterized in terms of particulate carbon and nitrogen, particle numbers and volumes, particle size distributions, and the relationship of production and specific growth rate to biomass. Qualitative observations were made on cell dimensions, morphology, and bouyancy. Four phases of growth were identified in some or all of the systems: selection phase in which population concentrations declined, but significant changes in population characteristics occurred; exponential phase in which populations increased in a uniform and density-independent fashion; transition phase in which adjustments were made in population characteristics; and, finally, steady state in which populations were stable. Selection phase was observed when small innocula were placed in high dilution rate systems or when steady state cultures were transfered to higher dilution rates. Those cultures experiencing selection phase showed changes in physical cell dimensions and in nutrient cell size. Physical cell dimensions and nutrient cell size and their relationship to growth rate are discussed. The work of Caperon (1968) is examined for similar selectional effects. A method using curves of nutrient per cell versus residence time of a particle in a chemostat is suggested to separate selection and dilution rate effects in dynamic systems. A model summarizing the ides of nutrient reservoirs is suggested. / Graduation date: 1975

Thesis (Ph. D.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 118-127). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

No description available.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1990.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 123-131).

The changes in the infra-red absorption frequency of three diatomic molecules, HCl, HBr and CO, on the transition between the gaseous and the solution phase have been investigated experimentally. The magnitude of this shift has been predicted using a purely electrostatic interaction. The experimental values and predicted values for HCl agree within 17%. The experimental and predicted values for HBr and CO agree within an order of magnitude. The investigation provides a method for independently checking the variation of the dipole moment of these molecules with internuclear distance against values previously determined by infra-red intensity measurements. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 92-110).