No description available.

Two marine algae, Isochrysis galbana and Dunaliella tertiolecta, were grown in the presence of arsenate, arsenite, monomethylarsonate (MMA), and dimethylarsinate (DMA). Cell growth was monitored by using in vivo fluorescence and cell density measurements. The effects of different levels of arsenicals on the arsenic uptake were examined using Hydride Generation Atomic Absorption (HGAA) Spectrometry and Graphite Furnace Atomic Absorption (GFAA) Spectrometry. The spin-echo ¹H NMR spectra of these algae are reported. Significant arsenic uptake and incorporation occurred when both algae were subjected to elevated levels of arsenicals. I. galbana was most affected by arsenite at the range of concentrations tested (2 - 8 ppm). Total incorporation is also the highest in this medium. The alga seems to be able to adapt to high arsenate concentrations. D. tertiolecta was most affected by elevated levels of arsenate (10.7 ppm). Water soluble extracts of algal cells grown in this medium contain at least four arsenicals which possibly include arsenate and arsenite. Growth of both algae was not affected by DMA at the levels examined. Growth enhancement is observed in all MMA treated cultures. Arsenic speciation of the residual media showed that both algae can reduce arsenate to arsenite. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

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

The term "interaction" in evolutionary biology and ecology describes the relationships among variables in two classes of causal models. In the first, "interaction" refers to the influence of a single putatively causal variable on a variable of interest. In the second class of models, the term applies when a third variable mediates the relationship between two variables in the first class of models. The development of multi-factor causal models in evolutionary biology and ecology represents a stage in the construction of theory that usually follows from complexities discovered in single-factor analyses. In this thesis, I present three cases that illustrate how results of simple single-factor models in the population genetics and community ecology of seaweeds may be affected by incorporation of a second causal factor. In Chapter II, we consider how the effect of natural selection on genetic variability in seaweeds and other plants may be mediated by life history variation. Many seaweeds have haplodiplontic life histories in which haploid and diploid stages alternate. Our theoretical analysis and review of the electrophoretic literature show that the level of genetic polymorphism in haplodiplonts is not necessarily reduced relative to that in diploids. In Chapter III, I take an experimental approach to understanding how herbivory may mediate the effect of desiccation on the upper intertidal limit of a red alga, Iridaea cornucopiae. Iridaea appears to be grazer-limited in dry, but grazer-dependent in moist environments, suggesting that a third factor may mediate the interaction of desiccation and herbivory. Finally, in Chapter IV, we consider research strategies for studying how the outcome of competitive interactions is affected by seaweed traits. Some of the problems that arise in applying simple models of competition to plants suggest the need for theory that explicitly incorporates plant traits in two- (or more) factor models of interspecific competition. In particular, we note that unique traits of seaweeds require development of new approaches to understanding competition. Single-factor causal models represent an indispensable stage in the development of evolutionary and ecological theory. Properly conceived theoretical and empirical studies focus attention on the assumptions under which such models will hold and suggest lines of inquiry that ultimately lead to the integration of additional causal factors in conceptual models of natural processes. Identifying the circumstances under which simple models will suffice remains one of the most important challenges of evolutionary and ecological scholarship. / Graduation date: 1993

Thesis (D.Sc.) -- University of Adelaide, 1959. / "Adelaide, Dec. 1959." Includes bibliographical references. Also available in electronic format.

Thesis (doctoral)--Rijksuniversiteit Groningen, 1995. / Includes bibliographical references (p. 151-163).

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

Thesis (M. Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 59-62).

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes appendixes. Includes bibliographical references (leaves: 63-67)