published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

This work explores the relationship between nutrient loading and changes in water quality in a sub-tropical, above-ground, off-stream municipal water supply reservoir, the C.W. Bill Young Regional Reservoir. The three source waters for the reservoir have varied but high levels of nutrients such as phosphorus and nitrogen. In other reservoirs, these nutrients have been linked to deterioration of water quality and increased expense in water treatment. The need to minimize excess nutrients results led to the primary research question: what allocation of withdrawals from the three sources will minimize the deterioration of water quality? To answer this question, the relationship between nutrient and other water quality data, such as temperature,phosphorus, chlorophyll a, Secchi depth, and trophic state indices were explored. Results indicate that temperature had a correlation with observed water quality. 27.9% of the variability in trophic state index as a function of Chlorophyll a was correlated with average temperature at one foot below water level. Correlation and regression models were developed using available time-series of linear and log-transformed water quality data to predict Chlorophyll a response. The parameters used in the model were selected from correlation matrices and from the P value in the multiple regression. The models developed were significant at P < 0.05. In the developed models, temperature was found to have greater predictive strength than nutrients indicating that this reservoir may be more strongly influenced by season and light than by nutrient limitation. Lastly, the US Army Corps of Engineers' eutrophication model, BATHTUB, was used to simulate different loading conditions and trophic response. The model results indicate that use of water the middle pool or lower pool of the Tampa Bypass Canal yield similar trophic states with the middle pool slightly lower. Use of water from the Alafia River yielded the highest trophic state and would be expected to have negative impacts on water quality.

This dissertation includes molecular and phytochemical investigations of the harmful, bloom-forming alga, Prymnesium parvum, including analysis of known polyketide metabolites as a function of salinity and growth. Initially, the development of molecular and phytochemical tools was necessary for the detection and quantification of P. parvum and its associated toxins. Suites of oligonucleotides and molecular beacons were designed for conventional and quantitative multiplex PCR to amplify four species- and gene-specific products simultaneously that were used for the detection and quantitation of P. parvum. This built-in redundancy provided increased confidence in reactions with the positive confirmation of four discrete products. Techniques were also developed for the chemical enrichment of toxins produced by P. parvum. Until now, isolation of “prymnesins” has never been reproduced. Polyketide prymnesins possess unique spectral properties that were used to generate an LC-MS fingerprint that comprised 13 ion species. Preliminary investigations using chemifluorimetric methods were also capable of detecting prymnesins in the pico- and nano-molar range. Environmental samples were tested as an independent assessment of these methods. Lastly, the roles of polyketide prymnesins were analyzed with respect to total hemolytic activity (HA) as a function of culture age and salinity. Variation in HA of supernatants was statistically significant relative to both variables (p << 0.05). Salinity was inversely related to HA wherein cultures growing in 5-25 psu were 150-200% more hemolytic. Total HA was inversely related to culture age during the first three weeks, but positively related to it during the next three weeks. Interestingly, no hemolysis was detected in fractions containing prymnesins from culture supernatants and the majority of hemolysins remained in the aqueous phase. Prymnesins extracted from cells varied significantly over the 6-week observation period (p << 0.05); HA was positively correlated during the first half and inversely related during the last half of the study. Salinity was directly related to HA from cell extracts, but these effects were not significantly different until the last three weeks. These investigations suggest that polyketide prymnesins are present at much lower quantities than previously believed, and they may not be the key compounds associated with hemolysis due to P. parvum. / text

I developed a 1D coupled sea ice-ocean-biological (including ice algae) model to study the controlling effect of sea ice on primary and biogenic particle export production in the western Arctic and the impacts of climate change (reduction in sea ice cover duration and thickness, and in surface freshwater fluxes) on these productions. The model was developed in two steps to maximize validation of model results with as much data as possible. I first developed a coupled snow-ice-ice algae model for bottom landfast ice in Resolute (Canadian Archipelago). Next, I developed and coupled a pelagic component (NPZD type) to the ice algal model. The coupled model was implemented on the Mackenzie shelf in the Canadian Beaufort Sea. And finally, I used simulations of future climate change from the Canadian Global Climate Model (CGCM2) to force the 1D model and obtain projections of future primary production on the Beaufort Sea shelf for two 18-year periods (2042-2059, and 2082-2099). The model results show that ice algae are light limited at the beginning of the bloom, then fluctuate between light and nutrient limitation, to finally remain nutrient limited toward the end of the bloom. The bottom ice melt rate regulates the maximum biomass attained in Resolute, while biomass accumulation remains low in the Beaufort Sea due to nutrient iv limitation. The termination of the bloom is triggered by melting of the snow cover and results from (i) increased ice algal losses due to high bottom ice melt rate and (ii) decreased ice algal growth due to nutrient limitation caused by the formation of a meltwater lens below the ice. The snow and sea ice cover melt and/or break-up also controls the timing of the phytoplankton bloom. However, primary producers on the Beaufort Sea outer shelf are essentially nutrient limited and total annual primary production is controlled in part by nutrient “pre-conditioning” in the previous fall and winter and by the depth of winter convective mixing, that are controlled in part by the supply of fresh water from runoff and ice melt. The spring bloom sometimes represents an important fraction of the total annual primary production, which occurs in great part at the base of the mixed layer. Future projections show an increase in average annual primary production of 6% between the periods 1975-1992 and 2042-2059, and of 9% between 1975-1992 and 2082-2099. The relative contribution of the ice algal and spring phytoplankton blooms to annual primary production is reduced in the future runs due to a reduction in the length of the ice algal growth season (resulting from earlier snow and ice melt) and to a reduction in the replenishment of nutrient to the mixed layer in winter. The duration of the summer subsurface phytoplankton bloom increases, which favours the development of the main copepod species and leads to an increase in export production (16% between 1975-1992 and 2082-2099) that is greater than the increase in primary production. This leads to an increase in averaged simulated e-ratio of 10% between the first and last period.

Abstract: The use of earth observing satellites can be an effective supplement or alternative to traditional field sampling. The Landsat series of satellites have been particularity useful in assessing water quality in lakes, oceans, and reservoirs. This study utilized Landsat 5 and 7 imagery to model Secchi disk depth (SDD) and chlorophyll-a concentrations (Chl-a) at Lake Diefenbaker, Saskatchewan. I used data from these Landsat satellites to answer the following questions: First, can models that predict water quality (SDD and Chl-a concentration) be developed for Lake Diefenbaker using Landsat imagery? Second, can these models identify trends that have taken place at the reservoir from 1984-2012? Third, can I determine if ephemeral events like algal blooms or flooding have an effect on the reservoir? Novel models were developed from data collected in 2011 and 2012 that could predict SDD and Chl-a concentrations in the reservoir (linear regression, model I). These models explain less variation than comparable studies, but the loss in explanatory power is made up by their ability to predict data from any Landsat image of the reservoir. My study showed that predicted SDD and Chl-a concentration were positively related, an atypical relationship in freshwater systems. During the archive study period (1984-2012), both mean seasonal SDD and mean seasonal Chl-a have significantly decreased throughout the reservoir (p<0.05, regime-shift analysis). Spatially, the greatest decrease in SDD was closest to the major inflow the SSR, while downstream areas in the reservoir have decreased minimally. There was a decline in Chl-a concentrations that was spatially consistent throughout the reservoir. There was a significant negative relationship between flow rate and both water clarity and Chl-a concentrations (P<0.05, model II linear regression). Algal blooms occurred sporadically throughout the study period. There were blooms in 9% of images analyzed. Blooms typically occurred in the Qu’Appelle arm of the reservoir in the late summer and fall. The water quality data extracted by this study can be useful to many future studies, as historical data is absent for much of the reservoir’s history.

Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, Discipline of Ecology and Evolutionary Biology, 2008. / "December 2007" Bibliography: pages 172-185. Also available in print form.

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 19, 2010) Includes bibliographical references (p. 32-33)

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 120-136). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38772

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references.

A eutrofização de ambientes aquáticos continentais é um processo lento e natural, mas que tem se intensificado sobremaneira devido a influência das atividades antrópicas. Uma das consequências da eutrofização artificial são florações de algas cada vez mais frequentes e intensas. Alguns grupos de algas, como as cianobactérias, podem produzir toxinas que representam um risco para o homem e para a biota aquática e, por isso, sua floração merece atenção especial. O Lago Guaíba é um importante corpo hídrico do Estado do Rio Grande do Sul e o principal manancial do município de Porto Alegre. A sua bacia hidrográfica ocupa cerca de 30% da área do estado e os principais rios - Jacuí, Caí, Sinos e Gravataí - drenam áreas de intenso uso agrícola e industrial. No Lago Guaíba, as florações têm sido frequentes, principalmente na última década e representam um sério desafio ambiental. Neste contexto, o objetivo da presente pesquisa foi avaliar o potencial de identificação dos episódios de floração de algas no Lago Guaíba a partir da integração de dados radiométricos in situ adquiridos simultaneamente a dados limnológicos (clorofila-a, total de sólidos em suspensão, transparência da água, entre outros) e imagens de satélite. Para a obtenção dos espectros de reflectância foi utilizado o espectrorradiômetro portátil FieldSpec® HandHeld, com coleta em 16 pontos amostrais definidos a priori. Os trabalhos de campo ocorreram em março de 2012, maio de 2013 e abril de 2014. Os espectros foram correlacionados com medidas de variáveis limnológicas obtidas simultaneamente. Para a análise espaço-temporal das florações foram selecionadas 10 imagens produzidas pelos satélites Landsat 5 e 7 (sensores TM e ETM+) disponibilizadas pelo Serviço Geológico dos Estados Unidos (USGS), corrigidas para os efeitos da atmosfera e convertidas em reflectância de superfície. Estas imagens foram obtidas nos meses de verão e outono, entre os anos de 2005 e 2012, e coincidiram com as datas das florações identificadas pelo Departamento Municipal de Água e Esgotos (DMAE) do município de Porto Alegre. Três rotinas de processamento foram aplicadas às imagens: 1) o Índice de Vegetação por Diferença Normalizada (NDVI); 2) o Modelo Linear de Mistura Espectral (MLME) e 3) a Análise por Componentes Principais (ACP). Durante a coleta dos espectros em campo não houve florações, mas, ainda assim, estes permitiram identificar padrões de reflectância do lago em diferentes áreas e situações climáticas, bem como a influência da clorofila-a e dos sólidos em suspensão na resposta espectral da água. Os principais resultados do processamento das imagens de satélite foram: a) o NDVI é adequado para o mapeamento da abrangência e intensidade das florações e que resultados superiores a -0,2 indicam áreas de floração; b) o MLME apresentou limitações para o mapeamento das florações relacionadas à dificuldade de obtenção de bons espectros de referência diretamente sobre as imagens, mas permitiu avaliar as variações espaciais das características da água; c) a técnica da ACP ampliou as correlações dos dados das imagens com a Chl-a e as cianobactérias em comparação ao NDVI, e a classificação nãosupervisionada das principais componentes permitiu identificar as áreas (clusters) de floração, assim como áreas onde outros componentes atuavam. Os fatores que contribuíram para o estabelecimento de florações no lago foram: menor velocidade do fluxo da água, menor profundidade da coluna d´água, menor velocidade do vento e menores índices de precipitação pluviométrica, associados à maior disponibilidade de luminosidade e oferta de nutrientes. Concluí-se que as técnicas empregadas foram adequadas para o mapeamento de florações e que análises que utilizam dados de diferentes naturezas podem incrementar as metodologias existentes e abrir novas possibilidades de identificação e monitoramento de algas. / The eutrophication of freshwater ecosystems is a slow and natural process, but that has intensified greatly because of the influence of human activity. One of the consequences of artificial eutrophication are increasingly frequent and intense algae blooms. Some genera groups of algae, and cyanobacteria can produce toxins that pose a risk to humans and aquatic biota and therefore blooms deserve special attention. The Guaiba Lake is an important water body in the State of Rio Grande do Sul and the main source of Porto Alegre city. Its basin covers about 30% of the state area and major rivers - Jacuí, Caí, Sinos and Gravataí - drain areas of intense agricultural and industrial use. In the Guaiba Lake, blooms have been frequent, especially in the last decade and represent a serious environmental challenge. In this context, the objective of this study was to evaluate the potential for identification of episodes of algal bloom in the Guaiba Lake from the integration of radiometric data in situ simultaneously acquired with limnology data (chlorophyll-a, suspended solids total, water transparency, etc.) and satellite images. To obtain the reflectance spectra a portable spectroradiometer FieldSpec® HandHeld was used, with a collection of 16 sampling points defined a priori. The fieldwork took place in March 2012, May 2013 and April 2014. The spectra were correlated with limnological variables obtained simultaneously. For the spatio-temporal analysis of the blooms 10 images produced by Landsat satellites 5 and 7 (TM and ETM+ sensors) were selected and provided by United States Geological Survey (USGS), adjusted for the effects of the atmosphere and converted to surface reflectance. These images were produced in the months of summer and fall, between the years 2005 and 2012, and coincided with the dates of the blooms identified by the Municipal Department of Water and Sewerage (DMAE) in the city of Porto Alegre. Three processing routines were applied to images: 1) Normalized Difference Vegetation Index (NDVI); 2) Linear Spectral Mixture Model (LSMM) and 3) the Analysis by Principal Component (ACP). During the collection of spectra in the field no bloom was identified, but even so it was possible to identificaty reflectance standards in different areas and climatic conditions in the Lake as well as the influence of chlorophyll-a and suspended solids in the spectral response of the water. The main results of the satellite images processing were: a) the NDVI is suitable for mapping the scope and intensity of blooms and results greater than -0.2 indicate flowering areas; b) the LSMM presented limitations for mapping the blooms related to the difficulty of obtaining good reference spectra directly on the images but allowed the evaluation of spatial variations of water features; c) the technique of ACP increased correlations of image data with Chl-a and cyanobacteria compared to NDVI, and non-supervised classification of the principal component identified in the flowering cluster areas as well as areas where other components were at play. Factors that contributed to the establishment of blooms in the lake were slower rate of water flow, the less depth of the water column, lower wind speed and lower levels of rainfall, combined with the greater availability of light and nutrient supply. It was concluded that the techniques used were suitable for mapping blooms and the analysis using data from different natures can improve existing methodologies and open new possibilities for identification and monitoring of algae.