Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 176-192). Also available on the World Wide Web.

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.

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.

Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004. / "March 2004" Bibliography: leaves 115-141.

Thesis (M.S.)--Western Washington University, 2010. / Includes bibliographical references (leaves 70-73). Also issued online.

Few previous studies of zooxanthellae have considered temperate Anthozoan symbioses. The present study investigates how the characteristics of zooxanthellae symbiotic with temperate Anthozoa vary in response to natural variations in environmental parameters. Variations in the number (density), division rate, size and ultrastructure of zooxanthellae from the temperate anemones Anemonia viridis (Forskal) and Anthopleura ballii (Cocks) were examined in response to season, water depth and artificial irradiance (A. viridis in aquaria). In addition, variations in chlorophyll concentrations were considered in intertidal and laboratorymaintained A. viridis. Zooxanthellae from both intertidal and shallow subtidal A. viridis showed variations which correlated with seasonal variations in environmental parameters. Zooxanthella density in intertidal A. viridis showed an inverse relationship with temperature, daylength and sunshine. Higher zooxanthella density was observed in A. viridis from a shallow, subtidal habitat during February 1998 (2.06 ± 0.11 x 108 cells g"' wet weight) than during July 1998 (1.01 ± 0.09 x 108 cells g'' wet weight; T= 7.67, p< 0.001). Stereological analysis of transmission electron micrographs showed that zooxanthellae in intertidal A. viridis had significantly higher chloroplast volume fraction during February (32.1 ± 1.5 %) than July (21.8 ± 2.1 %; T= 4.07, p<0.05). The proportion of chlorophyll a per zooxanthella was significantly higher in December than all other months except January (ANOVA, F= 5.62 p<0.05). The zooxanthellae of A. viridis may thus photoadapt to low winter irradiances by increasing zooxanthellae density, chloroplast volume and the proportion of chlorophyll a per cell. By contrast, zooxanthellae from A. viridis maintained in artificial irradiances in the laboratory of 4 µmol m=2 s' and 20 pmol m2 s' showed no variation in density or ultrastructure, due either to the low irradiances used or a lack of variation in other physical parameters compared to the field. A. ballii zooxanthella density responded to both depth and season and was lower at 6m during summer than at 6m during winter and at 18 m during both summer and winter. Chloroplast volume fractions in A. ballii was not affected by depth during winter, nor by season at 18 in. Starch and lipid stores in zooxanthellae from both A. viridis and A. ballii responded to seasonal fluctuations. Lipid was present in zooxanthellae during summer (intertidal A. viridis, volume fraction 19.8 ± 3.4 %) and absent during winter, and starch volume was significantly higher from zooxanthellae in A. ballii at 6 in in winter (14.3 ± 4.2 %) than 18 min winter (4.7 ± 1.6 %) or summer (4.7 ± 1.1 %; ANOVA, F= 6.04 p< 0.05). It is concluded that the zooxanthellae of the temperate anemones A. viridis and A. ballfi show variations in zooxanthellae characteristics which correspond to variations in dayto-day weather, season and water depth.

Thesis (M.S.)--University of North Carolina Wilmington, 2008. / Title from PDF title page (October 20, 2008) Includes bibliographical references (p. 40-47)

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Edward C. Theriot and Judith C. Lang. Vita. Includes bibliographical references.

Thesis (doctoral)--Rijksuniversiteit te Leiden, 1998. / Acknowledgements and foreword inserted. Includes bibliographical references (p. 173-196).

Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 73-80.