This study examines the impact of snowmelt runoff on nutrient transfer from the terrestrial to the aquatic (lake) portion of a subarctic catchment 6 km WSW from Schefferville, Quebec. / Statistically significant differences in snow chemistry were recorded among the tundra, woodland and forest snowpacks. Significant overland substantial scouring of nutrients from the organic horizons were recorded in the tundra, woodland and forest. A calculation designed to generate, on a daily basis, 70% of the meltwater from the terrestrial catchment to the lake indicates overland flow is a predominant route of meltwater during the spring. This calculation made possible the determination of daily nutrient mass transfer from land to lake. The daily nutrient mass balance of input and output to Elizabeth Lake during springmelt indicates significant retention of land source nutrients. Deuterium/hydrogen measurements aided in determining mixing of snowmelt and lake water. The data indicate snowmelt water is undistinguishable from lake water at depths greater than 1.0 m. / It is concluded that snowmelt runoff is an important event for nutrient transfer from terrestrial to aquatic systems in this environment.

St. Lucia estuarine lake system has a history of episodic droughts and floods leading to a high variability in physico-chemical characteristics which may influence the community structure of nano- and microplankton that are the main primary energy synthesisers in aquatic systems. Originally, the St. Lucia estuary and the Mfolozi River shared the same mouth with the Mfolozi River acting as the main source of fresh water to the system and as stabiliser of the common inlet. Due to prolonged mouth closure from 2001-2012 and high evaporation rates, severe extended droughts and high salinities were experienced in 2001-2012.This project aimed to characterise community composition and biomass of nano-and microplankton (autotrophic and heterotrophic) under the varying and extreme physico-chemical conditions in order to characterize the energy basis of the planktonic food web in St. Lucia. Its main objectives were to compare and add onto Johnson’s (1977) list of phytoplankton taxa in the system, to estimate the biomass (carbon) of nano- and microplankton from cell counts and biovolume measurements, and lastly to understand and establish trends in the change in community structure of these organisms with the varying physico-chemical characteristics. Nano- and microplankton samples were collected monthly from October 2010 to September 2011 at three different sites: Lister’s Point, Charters Creek and the mouth representing the lakes and estuary Channel. Chlorophyll a and physico-chemical parameters were also measured in situ during collection. In the lab, samples were settled using the Utermöhl method and species were identified to at least genus level, counted and cell measurements taken under an inverted microscope for biovolume calculations and biomass thereof. Abundance in cells per liter and biomass (carbon) in pg/L was then analyzed from the counts. The nano-and microplankton groups recorded in the system were cyanobacteria, chlorophytes, cryptophytes, dinoflagellates, ciliates and diatoms. Seventy eight phytoplankton taxa were identified composed of 56 diatoms, eight green algae, one cryptophyte, seven cyanobacteria and six dinoflagellate taxa. Nineteen ciliate taxa were also found. Only 12 of the diatom taxa identified in this study were listed by Johnson (1977), none of the taxa in the other phytoplankton groups was listed by Johnson (1977). The Johnson (1977) study conducted in the system from 1975-1977 listed the phytoplankton taxa occurring at that time. There was no significant difference in the community composition, biovolume and biomass between seasons hence no seasonal trend however, there were significant differences in the nano- and microplankton community composition, biovolume and biomass at the three different sites of the system. Cyanobacteria were the main taxa in the northern embayments dominating in abundance, biovolume and biomass (biological variables), green algae and cryptophytes dominated in abundance, biovolume and biomass in the Channels while in South Lake, green algae dominated in abundance but diatoms dominated in biovolume and biomass. Ciliate biological variables were higher in the northern regions than in the other parts of the estuary. The absence or limited grazing pressure of ciliate predators in the northern region due to their inability to cope with the extreme salinities compared to the other parts of the system explains why the northern embayments had the highest abundance, biovolume and biomass of ciliates. Ciliates and heterotrophic dinoflagellates were the heterotrophs in this study. Autotrophic:heterotrophic biomass ratio was lowest in the northern regions as heterotrophs had a higher biomass there. This ratio was higher in the South Lake and the Channel. The lack of stratification and generally high turbidity in the system made the system unfavourable for dinoflagellate growth. The higher presence of ciliate predators in the South Lake and Channel probably accounts for the low heterotrophic biomass hence high autotrophic:heterotrophic biomass ratio in South Lake and the Channel. Nutrients were not limiting during this study and salinity was the main physico-chemical characteristic accounting for the differences in nano- and microplankton biological variables. The Cyanothece bloom in the northern region was primarily due to high salinities (>150) which also indicated unfavourable conditions for other plankton types. The high diatom biomass in the southern lake was due to low salinities (<28) which favoured their growth, whereas chlorophytes and cryptophytes dominated in the Channel mainly due to low turbidity (median of 11.4NTU) and fresh water input from the Mfolozi lowering salinities (<5). The South Lake and Channel thus had the highest available energy for higher trophic level organism since 1) diatoms and green algae are the most favoured food source for phytoplankton grazers while the cyanobacteria though most abundant are the least favoured food source leaving the northern lake with smaller energy source for higher trophic level organisms and 2) The low autotrophic:heterotrophic biomass ratio in the northern region leaves the region with a lower net carbon biomass than the other parts of the system with a higher autotrophic: heterotrophic biomass. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.

Thesis (Ph.D.)--University of Western Australia, 2008.

Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-01Bitstream added on 2014-06-13T21:07:55Z : No. of bitstreams: 1 abra_j_dr_botib.pdf: 2675025 bytes, checksum: 56e6c0de805d468df7a29ded156183b4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente estudo foi realizado em três lagoas marginais ao rio Paranapanema, em sua zona de desembocadura na Represa de Jurumirim, e em dez açudes em propriedades rurais na região noroeste paulista. O nosso objetivo principal foi avaliar a estrutura das comunidades de rotíferos e seus principais fatores determinantes de eventuais diferenças em ambientes sujeitos a perturbações e regimes hidrológicos distintos. As coletas foram realizadas em duas estações do ano (em estações seca de 2007 e 2008 e chuvosa de 2008 e 2009), na região litorânea e pelágica dos ambientes. Os seguintes parâmetros físicos e químicos foram analisados: profundidade, temperatura da água, transparência, pH, condutividade elétrica, oxigênio dissolvido, material em suspensão, clorofila a, nitrogênio e fósforo total. Foram analisados os atributos da comunidade de rotíferos: riqueza, diversidade, equitabilidade e abundância de espécies. As variáveis físicas e químicas da água apresentaram diferenças entre os locais e dentro dos ambientes (zona pelágica e litorânea), mas não foi possível elaborar padrões locais e temporais entre as diferenças dos fatores abióticos. As lagoas marginais apresentaram menores variações dos fatores físicos e químicos da água entre estações do ano. Maiores riquezas e diversidades significativas foram associadas à presença de macrófitas aquáticas e maiores abundâncias de espécies foram associadas à trofia dos ambientes. Não houve diferenças temporais significativas entre os atributos da comunidade dos rotíferos, mas houve diferenças entre os locais. Devido ao fato de incluir no estudo a região litorânea, houve uma grande contribuição em número de espécies que tem hábitos litorâneos e também novos registros de espécies para o estado de São Paulo foram feitos. A conectividade... / The present study was carried out at three lakes adjacent to the River Paranapanema in the region of its entrance into the Jurumirim Reservoir and at ten reservoirs on rural properties in the north west of the State of São Paulo. The aim was to evaluate rotifer community structure and the principal factors determining differences in environments subject to distinct perturbations and hydrological regimes. Samples were collected at two periods of the year (the dry seasons of 2007 and 2008 and the rainy seasons of 2008 and 2009) at the littoral and on the limnetic of the environments. The following physical and chemical parameters were determined: depth, water temperature, transparency, pH, electrical conductivity, dissolved oxygen, suspended matter, chlorophyll a, total nitrogen and phosphorus. The following characteristics of rotifer community structures were computed: species richness, diversity, uniformity and abundance. The physical and chemical variables of the water revealed differences between sites and within the two environments (limnetic and littoral zones), but no local and temporal patterns were identified in the differences between abiotic factors. The adjacent lakes presented the lowest seasonal variations with regard to the physical and chemical characteristics of the water. The highest species richness and diversity of species were related to the presence of aquatic macrophytes, and the greatest abundance of species was associated with the trophic conditions of environments. No significant temporal differences between the characteristics of the rotifer community structures were found, but differences between sites were recorded. Due to the fact that the study included the littoral zone, there was a significant contribution in terms of the number of species with littoral habitats, and some... (Complete abstract click electronic access below)

Orientador: Raoul Henry / Coorientador: Maria Stela Maioli Castilho Noli / Banca: Raoul Henry / Banca: Fábio Amodêo Lansac Tôha / Banca: Maria da Graça Gama Melão / Banca: Marcos Gomes Nogueira / Banca: Silvia Maria Caglierani Casanova / Resumo: O presente estudo foi realizado em três lagoas marginais ao rio Paranapanema, em sua zona de desembocadura na Represa de Jurumirim, e em dez açudes em propriedades rurais na região noroeste paulista. O nosso objetivo principal foi avaliar a estrutura das comunidades de rotíferos e seus principais fatores determinantes de eventuais diferenças em ambientes sujeitos a perturbações e regimes hidrológicos distintos. As coletas foram realizadas em duas estações do ano (em estações seca de 2007 e 2008 e chuvosa de 2008 e 2009), na região litorânea e pelágica dos ambientes. Os seguintes parâmetros físicos e químicos foram analisados: profundidade, temperatura da água, transparência, pH, condutividade elétrica, oxigênio dissolvido, material em suspensão, clorofila a, nitrogênio e fósforo total. Foram analisados os atributos da comunidade de rotíferos: riqueza, diversidade, equitabilidade e abundância de espécies. As variáveis físicas e químicas da água apresentaram diferenças entre os locais e dentro dos ambientes (zona pelágica e litorânea), mas não foi possível elaborar padrões locais e temporais entre as diferenças dos fatores abióticos. As lagoas marginais apresentaram menores variações dos fatores físicos e químicos da água entre estações do ano. Maiores riquezas e diversidades significativas foram associadas à presença de macrófitas aquáticas e maiores abundâncias de espécies foram associadas à trofia dos ambientes. Não houve diferenças temporais significativas entre os atributos da comunidade dos rotíferos, mas houve diferenças entre os locais. Devido ao fato de incluir no estudo a região litorânea, houve uma grande contribuição em número de espécies que tem hábitos litorâneos e também novos registros de espécies para o estado de São Paulo foram feitos. A conectividade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study was carried out at three lakes adjacent to the River Paranapanema in the region of its entrance into the Jurumirim Reservoir and at ten reservoirs on rural properties in the north west of the State of São Paulo. The aim was to evaluate rotifer community structure and the principal factors determining differences in environments subject to distinct perturbations and hydrological regimes. Samples were collected at two periods of the year (the dry seasons of 2007 and 2008 and the rainy seasons of 2008 and 2009) at the littoral and on the limnetic of the environments. The following physical and chemical parameters were determined: depth, water temperature, transparency, pH, electrical conductivity, dissolved oxygen, suspended matter, chlorophyll a, total nitrogen and phosphorus. The following characteristics of rotifer community structures were computed: species richness, diversity, uniformity and abundance. The physical and chemical variables of the water revealed differences between sites and within the two environments (limnetic and littoral zones), but no local and temporal patterns were identified in the differences between abiotic factors. The adjacent lakes presented the lowest seasonal variations with regard to the physical and chemical characteristics of the water. The highest species richness and diversity of species were related to the presence of aquatic macrophytes, and the greatest abundance of species was associated with the trophic conditions of environments. No significant temporal differences between the characteristics of the rotifer community structures were found, but differences between sites were recorded. Due to the fact that the study included the littoral zone, there was a significant contribution in terms of the number of species with littoral habitats, and some... (Complete abstract click electronic access below) / Doutor

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"April 2002" Includes bibliographical references and list of the publications and papers submitted. Pt. 1: section 1. Ostracod taxonomy and ecology -- section 2. Limnology of salt lakes -- section 3. Ostracod palaoecology - Quaternary environments -- section 4. Palaolimnology - Quaternary paleoenvironments and geology -- pt. 2: section 5. Geochemistry of ostracod shells -- section 6. Palaeoceanography Contains the majority of the author's scientific publications. Aims at reconstructing Quaternary paleoenvironments, mostly from the Australian region, using the fossil remains of organisms as well as new geochemical techniques.

"April 2002" / Includes bibliographical references and list of the publications and papers submitted. / 2 v. (various pagings) : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Contains the majority of the author's scientific publications. Aims at reconstructing Quaternary paleoenvironments, mostly from the Australian region, using the fossil remains of organisms as well as new geochemical techniques. / Thesis (D.Sc.)--University of Adelaide, Dept. of Geology and Geophysics, 2002