Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 123-137). Also available via the Internet.

Thesis (M. Soc. Sc.)--University of Hong Kong, 2003. / Also available in print.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Charles E. Epifanio, College of Marine and Earth Studies. Includes bibliographical references.

Thesis (M.S.)--University of North Carolina at Wilmington, 2006. / Includes bibliographical references (leaves: 111-117)

This thesis examines the causes and consequences of habitat selection and timing of breeding of the Great Blue Heron (Ardea herodias). My general hypothesis was that the duration of low tides and seasonal abundance of prey strongly influenced the location of colony-sites; timing of the breeding season; habitat shifts; and the use of space by foraging herons of different age- and sex-classes. I studied Great Blue Herons along the Pacific coast of Canada for five breeding seasons and four winters. Breeding herons were studied at a colony of 85 to 100 pairs on Sidney Island near the town of Sidney, and periodic visits were made to about 40 other colonies around the Strait of Georgia, British Columbia. At Sidney, I studied the foraging behaviour, food availability, habitat use and reproductive success in detail. At other colonies, I recorded the reproductive success of herons, located their main feeding areas and searched for nests of a predator, the Bald Eagle. In the non-breeding season, I investigated the foraging behaviour, dispersion pattern and habitat shifts of juvenile and post-breeding adult herons in the Fraser River delta. I hypothesized that heron colony-sites were located near food supplies or away from predators. Twenty-nine of 33 colony-sites were located within 6 km of their main feeding site. The number of heron pairs was slightly greater where eagles nested in high abundance than where eagle abundance was low, contrary to the hypothesis that breeding herons avoid areas with active eagle nests. I hypothesized that herons began breeding in spring shortly after females acquired enough food energy to make eggs, or so chicks were in nests when food was most plentiful to their parents. Egg-laying began about 9 days after a female's daily food intake crossed an energy threshold of 1715 kJ/day, whereas the peak availability of food energy to adults occurred about 35 days before the peak food demands of their chicks. Food intake rates by adults increased gradually in March and April with the increasing duration of low tides and the inshore movement of fishes. Adult food intake rates reached a peak in May when sea perch were most abundant, and diminished through June and July. Most juvenile and adult female herons foraged on beaches from February to October and in marshlands and grasslands from November to January. Some males returned to territories along riverbanks in August and remained there until the start of the next breeding season in March. I tested the hypothesis that herons leave foraging habitats in autumn when they can no longer catch enough food or when interference from conspecifics reduced foraging intake rates below a threshold required to maintain their energy balance. In October and November adults moved to marshlands and juveniles moved to grasslands when they could no longer maintain daily energy balance on beaches as a result of declining duration of low tides and food intake rates. Interference competition was too infrequent to explain habitat shifts by adult or juvenile herons in autumn. / Science, Faculty of / Zoology, Department of / Graduate

Visible blue light wavelengths in the 400-470-nm range have been observed to have antimicrobial properties. The purpose of this review article is to delineate the mechanism of action, optimizing conditions, and public health and clinical applications of antimicrobial blue light (aBL) as characterized by the current literature. A widely accepted hypothesis for the mechanism of bacterial inactivation by aBL is that the light causes photoexcitation of endogenous photosensitizers, porphyrins and flavins, which leads to the release of reactive oxygen species that subsequently lead to cell toxicity. Factors that have been observed to be associated with enhanced antimicrobial action include increased duration of exposure, pre-treatment with quinine hydrochloride, and exposure of target bacteria to sub-lethal stress conditions. Studies examining the effect of repetitive exposure to sub-lethal levels of aBL on bacteria show no significant evidence of development of resistance. Additionally, aBL has exhibited the ability to inactivate multidrug-resistant (MDR) bacteria. While studies have also observed aBL to have efficacy in inactivating fungal and viral pathogens, there is a need for further research to elucidate the mechanisms of photoinactivation of fungi and viruses by aBL. Multiple studies have shown that aBL is effective in causing significant CFU reduction in biofilms, an observation that supports the application of aBL for decontamination of surfaces and treatment of localized infections. aBL has demonstrated efficacy in eliminating foodborne pathogens found on food surfaces and exposed surfaces in the food processing environment. Studies applying aBL to decontamination of surfaces in the clinical environment have concluded that it is a viable decontamination practice that shows promise for helping to minimize the spread of healthcare-associated infections (HAIs). Existing literature provides evidence in favor of the application of aBL in clinical contexts such as the treatment of gonococcal infections, eye infections, and otitis media, and in the decontamination of stored platelets and plasma. Studies investigating these clinical applications have demonstrated the efficacy of aBL for inactivating the clinically relevant pathogens, as well as the preservation of normal human cells upon exposure to the doses of light that are lethal to the pathogens. / 2022-11-18T00:00:00Z

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A culture collection of clonal, axenic cultures of 35 Arthrospira strains and five strains, which were duplicate subcultures of the original isolates, was established. In addition, eight morphological mutants were isolated from cultures of these strains. All strains are different from those belonging to the genus Spirulina as concluded from TEM and PyMS studies. All Arthrospira strains, duplicates and different morphotypes were screened for variation in morphological, ultrastructural, physiological and biochemical characters for taxonomic purposes. Special emphasis was put on the analysis of factors which influence the morphology of the trichome helix, as this is the feature most characteristic forArthrospira strains. For example, the orientation of coiling was found to be influenced by genetic drift or the growth temperature, but can also be reversed by mechanical impact. Studies were also made on the ability to utilize sugars for growth. None of the strains grew on sucrose, but many grew on glucose and/or fructose. Growth in the presence of sucrose under photoheterotrophic conditions required an adaptation process, though sucrose is not being utilized for growth. Analysis of fatty acid composition of all strains revealed quantitative differences between strains, most markedly in the unsaturated fatty acid fraction. Repeat experiments showed the same results each time, indicating the value of this approach for identification purposes. Similarly, lectin-binding to cell surface structures proved to be a useful approach for differentiation between strains. Analysis of the whole cell composition by pyrolysis mass spectrometry (PyMS) did not confirm the clusters based on other phenotypic characters, but showed that there is a high similarity between duplicate strains or different morphotypes derived from the same stock. Numerical analysis of the data for 28 characters resolved the helical strains in two phenotypic clusters which show a high correlation to the two molecular clusters based on ARDRA of the ITS of the same set of strains. The helical trichome morphology of the strains showed the highest correlation to either of the clusters. Comparison of species descriptions and morphological characters of the strains, as determined in the presented work, indicate, that phenotypic cluster I is composed of Arthrospira maxima, A. fusiformis and A. indica, while A. platensis forms phenotypic cluster II

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