"January 2003" / Amendments in pocket inside back cover. / Bibliography: leaves 212-229. / xi, 229 leaves : ill. (some col.), map, plates (col.) ; 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, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2003

Thesis (M.S.) in Zoology--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 97-110).

Harmful algal blooms (HABs) are becoming more prevalent throughout the world’s aquatic systems. These blooms have been the subjects of numerous studies because they can cause human health issues and economic impact through fish kills, contaminated shellfish and decreased tourism. Much research has focused on the “bottom-up” aspect of these blooms; namely, the potential role of increased nutrient input into coastal waters from anthropogenic sources causing increased growth in harmful algal species. However, there are also potential “top-down” controls affecting the rate at which harmful algal species are consumed by grazers. The aim of this project was to determine protozoan grazer population fluctuations and their grazing impact on HAB species through field monitoring and laboratory grazing experiments. Protozoan grazers were chosen because their growth rates could potentially keep up with those of HAB species. Declines in grazer populations before the onset of a bloom could be indicative of a release of the HAB from a “top-down” grazing control. Field samples taken during bloom and non-bloom events helped elucidate any microplankton community changes. After establishing that there appear to be changes to the grazer population before and after a bloom, ingestion experiments including direct epifluorescence microscopy and DNA analyses were conducted to determine if it is possible that a chosen protozoan grazer can ingest a HAB species. Finally, experiments were conducted to determine whether the HAB species was a favorable food source for the grazer. Population growth experiments in which grazers are fed a HAB species, 50:50 mixture, or normal culture food source were used to determine the survival and growth rate of the grazer. Although certain ciliates and heterotrophic dinoflagellates were found to feed on HAB species in the lab and in natural bloom samples, the HAB species as a food source produces lower grazer growth rates than on control food. Protozoan grazers may be a more effective control during bloom initiation than after the bloom has been established. / text

The responses of Chlamydomonas reinhardtii CW15+ (a wall-less mutant) to freezing stress have been examined: Tests following freezing of bulk (0.5ml) samples reveal the existence of an optimum cooling rate f o r preservation of viability, close to l*C min-1. Direct observation of cells during freezing and thawing on a cryo light microscope have allowed different forms of injury to be classified. At suboptimal cooling rates, reduction in surface area during shrinkage can be achieved by severe distortion or by the formation of layered stacks of membrane. Lethal injury is not evident until thawing takes place. The manifestation of injury depends upon the severity of the freezing treatment. The first symptom of injury is membrane blebbing at the cell surface, leading to swelling of the entire cell, followed by collapse. The membrane involved in the swelling might originate i n the mitochondrion and chloroplast envelope. Regions of fusion between membrane of these organelles and the plasma membrane have been observed during rewarming by electron microscopy. Fluorescent markers of the mitochondrial membrane have been detected i n the membrane involved in blebbing. Further damage during slow cooling contributes to rapid lysis on re-expansion. If the freezing treatment is still more severe, osmotic unresponsiveness will result. At supraoptimal cooling rates loss inviability is associated with intra cellular freezing. These responses have been examined in the light of available data regarding the freeze-thaw responses of higher plant protoplasts . The first symptom of damage seen in 'C reinhardtii ie. that of blebbing and massive swelling, is not common to both systems. Thus general rules concerning the responses of plant cells to freezing stresses cannot be made by using either of these protoplasts as a model system, although each may be useful for study of particular aspects of higher plant and algal cell freezing as separate investigations.

The biology of the sub-aquatic lichen, Dermatocarpon luridum, was investigated. This lichen is sparsely distributed within the temperate climatic zones around the world, colonizing rock along watercourses that regularly experience water level fluctuations. Specimens collected from Canada and Austria were cultured using standard growth media. Brightfield microscopy was used for algal species identification, while fungal ITS, algal ITS and algal actin gene sequences were used for phylogenetic and population genetic evaluation. Results were: 1) axenic cultures of the photobiont were successful, while those of the mycobiont were not successful; 2) Diplosphaera chodatii is the photobiont associated with D. luridum var. luridum and allies, suggesting algal sharing between mycobiont species; 3) genetic diversity is high, and gene flow was high within local populations, but low between continental populations. Diplosphaera chodatii may be a keystone species contributing to the survival of D. luridum var. luridum along with other sub-aquatic, aquatic and terrestrial lichens.

The biology of the sub-aquatic lichen, Dermatocarpon luridum, was investigated. This lichen is sparsely distributed within the temperate climatic zones around the world, colonizing rock along watercourses that regularly experience water level fluctuations. Specimens collected from Canada and Austria were cultured using standard growth media. Brightfield microscopy was used for algal species identification, while fungal ITS, algal ITS and algal actin gene sequences were used for phylogenetic and population genetic evaluation. Results were: 1) axenic cultures of the photobiont were successful, while those of the mycobiont were not successful; 2) Diplosphaera chodatii is the photobiont associated with D. luridum var. luridum and allies, suggesting algal sharing between mycobiont species; 3) genetic diversity is high, and gene flow was high within local populations, but low between continental populations. Diplosphaera chodatii may be a keystone species contributing to the survival of D. luridum var. luridum along with other sub-aquatic, aquatic and terrestrial lichens.

No description available.

Surface waters subject to algal blooms have a high rate of fouling water treatment filtration membrane. These waters typically contain high concentrations of hydrophilic organic carbon compounds such as proteins and polysaccharides. These compounds have been found to contribute greatly to membrane fouling. In this study the fouling propensity, and the components of the fouling layer, for microfiltration (MF) and ultrafiltration (UF) membranes, were characterised for samples taken from a wastewater treatment plant with lagoons prone to algal blooms and a blue-green algae culture (Anabaena circinalis). It was found that the organic carbon compounds released during the growth phase (EOM) of Anabaena circinalis have a similar fouling propensity for UF than those released during the lysis phase (AOM), and a slightly higher fouling propensity for MF. However, due to the presence of higher UV-absorbing hydrophilic compounds, higher concentration of intracellular proteins and/or humic acid-like matter in the AOM, irreversible fouling was significantly higher during the lysis phase.

Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2002. / Includes bibliographical references (leaves 235-258).

Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 155-163).