Contains copies of 43 author's publications and introductory statement / Includes bibliographies / 44 pts : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D. Sc.)--University of Adelaide, 1986

Macroalgae are abundant on shallow temperate reef environments, often forming complex communities that comprise several strata. In southern Australia, these assemblages are dominated by large canopy forming taxa from the Orders Laminariales and Fucales. The presence of subtidal fucoid macroalgae differentiates these communities from that elsewhere, and emphasises the need for local studies rather than relying on generalisations made elsewhere. Like most natural systems, temperate reefs are often threatened by human activity with degradation reported from many locations in close proximity to urban settlements. The work presented in this thesis involves an examination of the temporal and spatial variability in the structure of macroalgal communities from reefs along the Adelaide (South Australia) metropolitan coast. The work looked specifically at the effects of a dispersed sediment plume, resulting from the 1997 beach sand-replenishment dredging program, on shallow sub-tidal reef systems. An examination of the structure of canopy forming phaeophycean macroalgae in Gulf St Vincent (South Australia), noted large amounts of both spatial and temporal heterogeneity. Notwithstanding, this variation was not random, but demonstrated considerable structure that could be linked to a number of important underlying processes. In particular, macroalgal assemblages appeared as a mosaic of patches, each of which comprised a high-density state clearly dominated by a single genus (Cystophora, Sargassum, or Ecklonia), or alternatively a lower density mixed assemblage (Variable Low Abundance, VLA). Macroalgal community structure appeared to be driven by biotic interactions at small scales (metres), such that patches comprised of different species of algae in high density states rarely abutted one another. Instead, VLA assemblages frequently formed a buffer being situated between these mono generic patches. In terms of successional processes, the high-density states appeared to be relatively stable whereas the VLA state, at least in some systems, was transitory. This finding was supported by the absence of intermediary high- density states (e.g. a mix of Cystophora and Ecklonia) implying that state changes must occur via the VLA state following some form of disturbance. Larger scale patterns appeared to be driven by environmental variation, with factors such as wave exposure influencing habitat suitability for individual species and thereby affecting community composition. These phenomena were examined in terms of life history strategies that tend to promote stability, and which are common in late successional taxa. The importance of properties enhancing stability and the role of disturbance was investigated experimentally using a dispersed sediment plume, which entirely engulfed two reefs, as a pulse impact. This disturbance was of particular relevance given that degradation of macroalgal communities in close proximity to the City of Adelaide has been, at least in part, attributed to the effects of elevated levels of sediment. Follow up surveys revealed that the sedimentation from the plume had primarily affected newly recruiting individuals, with few juveniles surviving to one year of age. Over the following few years, the effect of this recruitment failure cascaded into the adult stand. In broader terms, unfavourable climatic conditions prior to the start of the study, including a particularly severe El Nino event, had a widespread effect on local assemblages, causing high levels of both adult and juvenile mortality. As such, at the commencement of the study, macroalgal communities across the study area were in the process of recovery. This was observed at control sites over the duration of the study. In contrast, recruitment failure at the sediment-affected sites retarded the recovery process, exacerbating the problems associated with prior unfavourable climatic events and leaving them in a degraded state. This study demonstrated that macroalgal assemblages are equipped (under natural conditions) to handle 'normal' environmental fluctuations (such as inter-annual variability). However, the additional stress associated with certain anthropogenic impacts has the potential to push them over the limit, causing degradation. The loss of canopy macroalgae reduces the structural complexity of the system, leading to a concomitant reduction in their ability to recover. As such, these findings are of particular relevance to those charged with the responsibility for managing near-shore marine environments. The plume was created accidentally during a dredging operation for beach sand replenishment of Adelaide's eroding shoreline. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.

Graduation date: 1997

The Feldmannia sp. virus is a large icosahedral virus that persistently infects marine brown alga Feldmannia sp.. So far, there is no information available about viral genome replication, gene structure and gene expression in this unique viral-host system. The purpose of this study was to characterize the general features of viral transcripts in the virus producing sporophyte plants. Northern analysis, using four cosmid clones that cover the entire viral genome, showed that there were six major transcripts and at least eighteen minor transcripts in the virus producing sporophyte plants. These transcripts are not evenly distributed in the viral genome. A 5.7 kb BamHI fragment-R was found to encode a 1.5 kb and a 0.9 kb major transcript, and those two major transcripts were chosen for detailed sequence analysis. The 1.5 kb transcript was identified as the putative major capsid protein (MCP) gene. The FsV MCP has significant similarity with the major capsid protein of Chlorella virus-PBCV-1 and with iridoviruses, fish lymphocystis disease virus, frog virus 3, and with African swine fever virus. / Graduation date: 1996

Graduation date: 1995

Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, June 1997. / Includes bibliographical references. Also available on the Internet.

Harmful algal blooms (HABs) in the Gulf of Mexico are primarily caused by dense aggregations of the dinoflagellate species, Karenia brevis. Karenia brevis produces a highly toxic neurotoxin, brevetoxin which has been shown to cause Neurotoxic Shellfish Poisoning (NSP) and respiratory distress in humans in addition to a wide range of negative impacts upon natural ecosystems. Karenia mikimotoi is a co-existing species present during K. brevis blooms. K. mikimotoi has caused major HAB events in other parts of the ocean, but has not been recognized as a major contributor to toxicity of blooms in the Gulf of Mexico. K. brevis and K. mikimotoi have both been associated with the presence of unidentified hemolytic toxins. Production of hemolysins has not previously been investigated for either species to date in the Gulf of Mexico. Presence of hemolysins may affect toxicity and the overall impact of HABs. Therefore, detection of hemolysins is imperative for accurate identification of potential harmful impacts of such blooms. The primary goal of this research is to define whether either species is capable of producing hemolytic activity independent of brevetoxin activity; and to identify if there is significant differentiation between a variety of clonal isolates regarding toxicity and growth rate when subjected to variable experimental conditions.

Process variables of electrolytic technology to reduce the energy consumption of harvesting Nonnocloropsis salina were investigated including electro-coagulation, electro-floatation, and electro-flocculation. Electro-coagulation and electro-flocculation showed significant cost savings, however electro-floatation did not. The objectives were to determine the effects of electrode material, pH adjustment and electro-polymer addition for electro-coagulation and determine the performance characteristics for electro-coagulation and electro-flocculation. Both treatments proved to be competitive with the energy consumption of a centrifuge. The best electrolytic treatments were electro-coagulation with aluminum and nickel electrodes. Energy requirements at optimum conditions were 239 and 344 kWh/ton. The best treatment combination using electro-flocculation was 432 kWh/ton with no electrode consumption, which could lead to potential cost savings.

<p>Sammandrag på engelska.</p>

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