Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 71-79). Also available via the World Wide Web.

Arsenic (As) exposure through water and As contaminated food in rural areas around the world is well documented. While there are accurate, precise, and even robust screening methods for on-site water analysis, the determination of toxic inorganic As (iAs, a class I carcinogen) in foodstuff has been made possible through methods based on mass spectrometry. No screening or field method for iAs in food has been established and, there is also a lack of screening and monitoring methods for human exposure to iAs. The objectives of this thesis were to develop and apply a robust, reliable and well established screening method which is field deployable for the measurement of iAs in rice and seaweed in addition to the total As metabolites in human urine resulting from exposure to inorganic As. Reported in this work is the development and application of optimised field deployable methods based on the Gutzeit reaction with the aid of a field test kit (FTK) for the determination of iAs in rice, rice-based products, edible seaweeds and seaweeds cultivated from their natural habitat. The methods involve simple sample extraction by boiling in nitric acid before analysis with the FTK. Results were obtained in under an hour with the FTK and further validated with speciation analysis by HPLC-ICP-MS (High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry). Analysis of 30 store-bought rice samples with the field method gave good reproducibility (± 12 %) for samples with variable As concentrations. The results were comparable to those obtained by HPLC-ICP-MS with no contribution from organoarsenicals. Screening analysis with the field method based on recent regulations for inorganic arsenic in rice also gave low false positive and false negative rates ( < 10 %) for violations against these regulations, an indication that the method can accurately identify samples that are above or below the recommended maximum contaminant limits for iAs in rice. Similarly, results from the seaweed analysis with the field method were also comparable to those from speciation analysis by HPLC-ICP-MS with limited bias between the set of data from both vii methods. Optimisation of extraction methods using a subset of samples gave 80-95% iAs recovery with no contribution from the organoarsenicals present in the samples. The determination of total As metabolites in urine from the exposure to iAs could not be done directly using the FTK. In this case, the method involved the use of UV photolysis with persulphate and titanium dioxide as oxidizing agents for the conversion of methylated As species (DMA) to the inorganic form before analysis with the FTK. A partial determination of DMA with the FTK in urine matrix was demonstrated but this needs to be studied further for the development of a robust field method for monitoring human exposure to iAs.

Seven species of marine phytoplankters assigned to different taxonomic divisions were tested for toxic responses to two different molecular species of selenium known to be prevalent in seawater, selenite and selenate. Selenate proved to be more toxic than selenite, although severe toxicity was only observed at high concentrations (10⁻² and 10⁻³ M) of both selenate and selenite. At these concentrations, growth was completely or severely inhibited in most species tested. In some of the species that remained viable, both the percentage of motile cells and their swimming speed were drastically reduced. Scanning electron microscopy revealed that, under these circumstances, Dunaliella tertiolecta cells possessed much shorter flagella compared to the controls, while those that became non-motile lacked flagella altogether. Despite these striking alterations in both growth and morphology, cells of Amphidinium carterae, Dunaliella tertiolecta and Pavlova lutheri showed, after prolonged exposures, signs of adaptation to high selenium concentrations. Lower concentrations of selenium were generally non-toxic and frequently even stimulatory to growth. These observations suggest that for meaningful inferences on selenium toxicity both the concentration range and the length of the studies must be considered and the potential for adaptation to high selenium concentrations taken into consideration. The main ultrastructural and physiological changes in cells of Dunaliella tertiolecta, Pavlova lutheri and Amphidinium carterae treated with selenite or selenate involved the cell coat, mitochondria, chloroplasts as well as the respiratory and photosynthetic rates. Other changes were observed in the nucleus, lipids, vacuoles, nitrogen and carbon contents, but these showed greater variability among the microalgae studied. The major alterations suggested that energy transducing systems were severely affected by selenium toxicity. These led to significant decreases or even elimination of storage products which were indicative of severe shortage in energy and produced major reductions in growth. These occurred later upon exposure to the toxicant and coincided with the loss of cell coat material, suggesting that the shedding of cell surface material might play a major role in the detoxification and adaptation of the microalgae to toxic concentrations of selenium. / Science, Faculty of / Botany, Department of / Graduate

This dissertation reports a study of the fungi and 'protists' (Labyrinthulids, Thraustochytrids, Hyalochlorella marina) associated with the intertidal red algae Rhodoglossum affine and Gelidium coulteri. Research focused on laboratory isolations from algal thalli collected from in situ populations. Different isolation techniques and isolation media were employed to evaluate the abundance and diversity of fungi and protists associated with these red algae. Algal tissue surface sterilization and rigorous rinsing procedures were used to remove and/or enumerate surface-associated microbes. The results obtained from the different isolation techniques and algal tissue pretreatment procedures are compared and discussed in terms of their usefulness for each member of the algal-associated microbiota. Natural populations of affine and coulteri support a rich fauna of marine protists. The most prevalent members of this protist fauna were Labyrinthula spp. resembling the "Vishniac Strains" and Thraustochytrium motivum. Schizochytrium aggregatum, a new species of Labyrinthulid designated Labyrinthuloides sp. 1, and Hyalochlorella marina were also common depending upon the isolation method utilized. These protists appear to be associated with the surfaces of the algal thalli, and exist as saprobes and/or perthophytes rather than biotrophic parasites of the algal tissues. Isolations from field-collected algal tissues also yielded actinomycetes, yeasts, and a high diversity of imperfect fungi. Overall isolation frequencies for individual fungal taxa were low. Most of the mycelial fungi isolated are considered to be of terrestrial origin and of questionable 'significance' in the intertidal habitat. Only four, possibly five, are presently considered marine. The mycelial fungi most commonly isolated include: Acremonium sp. 019-78, Cladosporium cladosporioides, Dendryphiella salina, Penicillium spp., Phoma sp. (Group 1), Sigmoidea littoralis sp. nov., and Unidentified hyphomycete 044-78. Certain of these fungi may grow saprobically (as pertho-phytes) on reproductive and/or senescing algal tissues in the intertidal habitat, but their activities appear to be limited. Field-collected thalli of Rhodoglossum affine and Gelidium coulteri were allowed to decompose in mesh bags placed in the intertidal. The succession of higher fungi associated with the decomposing algae was followed by plating representative bimonthly subsamples of the algal tissues onto a Base Mineral Medium. Rhodoglossum affine deteriorated completely after 52 days of exposure, while a small amount of Gelidium coulteri remained after 71 days. Qualitative aspects of the mycobiota associated with the two algal species were similar, however fungi were isolated more frequently from coulteri. A dominant mycobiota was apparent after 36 days of exposure on the beach. Acremonium sp. 019-78, Dendryphiella salina and Sigmoidea littoralis sp. nov. were active colonizers of the decomposing algal tissues, and their isolation frequencies increased as decomposition proceeded. Several species of bacteria capable of utilizing the cell wall polysaccharides of red algae (agar, carrageenan) were also present on the decomposing algae. It is possible that the activities of these bacteria enhanced fungal development. Thraustochytrium motivum, Schizochytrium aggregatum and Ulkenia sp. RC02-80 were placed into sterile seawater cultures with surface-sterilized tissues of Rhodoglossum affine and Gelidium coulteri. After 72 hours of incubation, positive growth associations were examined using scanning electron microscopy. The three Thraustochytrids displayed luxuriant growth on all algal tissue types, and produced extensive ectoplasmic networks on the algal surfaces which functioned in attachment and, presumably, in the absorption of dissolved nutrients. Ectoplasmic net elements were resolved down to 0.02 pm in diameter, but no obvious 'penetration' of the algal tissues could be discerned. All of the protists (Labyrinthulids, Thraustochytrids, Hyalochlore11a marina) isolated from these red algae are described and illustrated. Certain commonly encountered and/or poorly known mycelial fungi are also described, including a new species of marine hyphomycete, Sigmoidea littoralis sp. nov. / Science, Faculty of / Botany, Department of / Graduate

No description available.

No description available.

No description available.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

No abstract available. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004

Choi Li Si. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 156-168). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Contents --- p.v / List of Tables --- p.ix / List of Figures --- p.xi / Chapter Chapter 1: --- General Introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- The distribution and growth of coral and algae in Hong Kong --- p.3 / Chapter 1.3 --- Objectives --- p.6 / Chapter 1.4 --- Study Site --- p.7 / Chapter 1.5 --- Coral species chosen for the experiment --- p.10 / Chapter 1.6 --- Thesis outline --- p.11 / Chapter Chapter 2: --- "General Survey on Changes in Percentage Coverage of Coral and Fleshy Macroalgae in AMW and AYW, Tung Ping Chau, over Time" / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Methods and Materials --- p.26 / Chapter 2.2.1 --- In-situ survey methods --- p.26 / Chapter 2.2.2 --- Comparison of coral cover in the presence or absence of algae --- p.26 / Chapter 2.2.3 --- Environmental parameters --- p.27 / Chapter 2.2.4 --- "Image, data and statistical analysis" --- p.28 / Chapter 2.3 --- Results --- p.28 / Chapter 2.3.1 --- Coral coverage in AMW and AYW --- p.28 / Chapter 2.3.2 --- Percentage algal cover in AMW and AYW --- p.29 / Chapter 2.3.3 --- Dominating fleshy algal species in AMW and AYW --- p.30 / Chapter 2.3.4 --- Comparison of the coral coverage before and after the algal removal --- p.30 / Chapter 2.3.5 --- Water temperature --- p.31 / Chapter 2.3.6 --- Nutrient levels --- p.32 / Chapter 2.3.7 --- Further observation on the health of the corals during fleshy macroalgal bloom --- p.34 / Chapter 2.4 --- Discussion --- p.35 / Chapter Chapter 3 --- "The Effects of Algal-Coral Interactions on the Photosynthetic Ability of the Coral, Porites lobata in AMW and AYW, Tung Ping Chau" / Chapter 3.1 --- Introduction --- p.59 / Chapter 3.2 --- Methods and Materials --- p.66 / Chapter 3.2.1 --- Settings of the permanent corals --- p.66 / Chapter 3.2.2 --- Measurement of the seasonal changes in the photosynthetic ability of the corals --- p.66 / Chapter 3.2.3 --- Measurement of the diurnal changes in the photochemical efficiency of Porites lobata --- p.67 / Chapter 3.2.4 --- Correlation of quantum yield with the zooxanthellae density and the chlorophyll a concentrations --- p.68 / Chapter 3.2.5 --- Evaluation of zooxanthellae and chlorophyll-a densities --- p.68 / Chapter 3.2.6 --- Statistical analysis --- p.69 / Chapter 3.2.6.1 --- Monthly measurement of the photosynthetic ability of the corals --- p.69 / Chapter 3.2.6.2 --- Diurnal measurements of the photosynthetic ability of the corals in May and July2002 --- p.70 / Chapter 3.2.6.3 --- Relationships between quantum yield and zooxanthellae and chlorophyll a concentrations --- p.70 / Chapter 3.3 --- Results --- p.70 / Chapter 3.3.1 --- The photosynthetic activities of corals --- p.70 / Chapter 3.3.2 --- The photochemical quenching (qP) of the corals --- p.72 / Chapter 3.3.3 --- Diurnal fluctuations in the photosynthetic ability of Porites lobata and the Photo synthetically Active Radiation (PAR) --- p.73 / Chapter 3.3.3.1 --- Photosynthetic quantum yield of Porites lobata --- p.74 / Chapter 3.3.3.2 --- Diurnal changes in the Photo synthetically Active Radiation (PAR) --- p.75 / Chapter 3.3.4 --- The relationship between the photosynthetic ability of the corals and their chlorophyll-a and zooxanthellae densities --- p.76 / Chapter 3.3.5 --- Correlation between photosynthetic activities of corals and eenvironmental parameters --- p.76 / Chapter 3.3.5.1 --- Heights of coral colonies --- p.76 / Chapter 3.3.5.2 --- Photosynthetic ability of the corals and the presence of the drifting algae --- p.77 / Chapter 3.3.5.3 --- Photosynthetic ability of the corals and sea water temperature --- p.77 / Chapter 3.4 --- Discussion --- p.78 / Chapter 3.4.1 --- The photosynthetic activities of the corals --- p.78 / Chapter 3.4.2 --- The photochemical quenching of the corals --- p.80 / Chapter 3.4.3 --- Diurnal changes in the photosynthetic efficiencies of the P. lobata --- p.81 / Chapter 3.4.4 --- Relationship between the fluorescence yield and the chlorophyll-a and zooxanthellae densities --- p.82 / Chapter Chapter 4 --- The effects of drifting fleshy macroalgae on the corals: A caging manipulation of their effect on the photosynthetic activities of the corals / Chapter 4.1 --- Introduction --- p.114 / Chapter 4.2 --- Methods and Materials --- p.115 / Chapter 4.2.1 --- Setting up of the cages --- p.115 / Chapter 4.2.2 --- Setting up of the corals --- p.116 / Chapter 4.2.3 --- Measurement of the photosynthetic activities of the corals --- p.117 / Chapter 4.2.4 --- Data and statistical analysis --- p.117 / Chapter 4.3 --- Results --- p.117 / Chapter 4.3.1 --- The photosynthetic ability of the corals under different treatments --- p.117 / Chapter 4.3.2 --- The photosynthetic activities of different regions of the corals in each treatment --- p.119 / Chapter 4.4 --- Discussion --- p.120 / Chapter Chapter 5 --- "Interactions between corals, filamentous algal turf and encrusting coralline algae in Tung Ping Chau" / Chapter 5.1 --- Introduction --- p.135 / Chapter 5.2 --- Methods and Materials --- p.138 / Chapter 5.3 --- Results --- p.139 / Chapter 5.3.1 --- Coral-algal turf interactions --- p.139 / Chapter 5.3.2 --- Coral-coralline algae interactions --- p.140 / Chapter 5.3.3 --- General observations on the growth of the algal turf and the CCA on corals --- p.141 / Chapter 5.4 --- Discussion --- p.141 / Chapter Chapter 6 --- Summary and Perspectives --- p.152 / References --- p.156