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Ongoing environmental changes and increasing pressure on freshwater habitat require that we understand the ecological quality of freshwater ecosystems across a wide range of habitat types. This Ph.D. thesis addresses the utility of fish as ecological indicators in heterogeneous reservoir ecosystems. In the first section, I develop suitable indices and calculate ecological potential in two case studies, one using common fish guilds and traits at a large continental scale and another using species-specific indicators for a country-specific dataset. In the second section, I compare the assessment of fish communities across a large geographical region and identify anthropogenic stressors with the highest impact on fish communities. In the third section, I discuss the issue of optimal gillnet sampling design for reliable fish indicator values to increase the utility of assessment methodologies and to reduce sampling effort and fish mortality required to obtain reliable data. In the fourth section, I compare estimates of fish recruitment based on different sampling methods and develop a novel statistical approach to analyse factors affecting fish recruitment. This work provides an initial step towards the improvement of ecological quality of freshwater reservoirs.

Agricultural runoff is a major non-point source pollutant in the Midwest and has been documented as a significant contributor to nutrient loads in the Mississippi River and subsequent hypoxic conditions in the Gulf of Mexico. In an attempt to minimize eutrophication, researchers have been collaborating with farmers to improve best management practices targeting nutrient retention. Over the past four decades riparian buffers have proven effective in retaining nutrients and sediment from agricultural runoff. We hypothesize that the addition of biochar to vegetated buffers can further improve nutrient attenuation by enhancing nutrient adsorption and cycling soil physical, chemical, and biological properties. In June 2012, fifteen flumes were established adjacent to fifteen existing flumes that were installed in 2008 for a related study at Southern Illinois University's farms. Each flume was either vegetated and/or amended with one of ten treatments and replicated three times: 1) giant cane (Arundinaria gigantea (Walt.) Muhl) established in 2008; 2) Kentucky bluegrass (Poa pratensis L.); 3) orchardgrass (Dactylis glomerata L.); 4) giant cane and compost (i.e., horse manure and mushroom compost); 5) biochar (i.e., pine and oak feedstock pyrolyzed between 450 °C and 650 °C.); 6) biochar and giant cane; 7) biochar, giant cane, and compost; 8) corn; 9) volunteer herbaceous species; and 10) a non-amended, non-vegetated control. Soil samples were collected prior to the application of soil amendments and nutrients were assessed annually. Surface runoff samples were collected from significant rain events (i.e., precipitation > 2.5 cm) and analyzed for nutrient and sediment levels. Data indicate that various combinations of biochar, compost, and giant cane were successful at reducing the frequency of surface runoff events as well as reducing concentrations of NO3- and NH4+ in agricultural surface runoff. Concentrations of dissolved reactive phosphorus (DRP) were greatly reduced when biochar and giant cane were present in the buffer without the addition of compost. Total phosphorus (TP) concentrations were lowest for the established giant cane treatment. There were no significant differences in the concentrations of total suspended solids (TSS) among the various buffer treatments. Data from this study are promising for the incorporation of biochar, compost, and giant cane into vegetated buffers to reduce the concentration of nutrients in agricultural surface runoff.

Orientador: Edmir Daniel Carvalho / Banca: Katharina Eichbaum Esteves / Banca: Gianmarco Silva David / Resumo: O presente trabalho teve como objetivo estudar o regime alimentar de Oreochromis niloticus (Linnaeus, 1758) e Tilapia rendalli (Boulenger, 1897) na represa de Barra Bonita, Médio Rio Tietê, SP, utilizando-se duas abordagens: i) caracterização das dietas de O. niloticus e T. rendalli, e possíveis relações com a aceleração do processo de eutrofização e ii) variação ontogenética e padrões sazonais do regime alimentar dessas espécies. As amostragens foram realizadas mensalmente (março de 2007 a fevereiro de 2008) no município de Anhembi (SP). Os peixes foram obtidos do desembarque da pesca artesanal e paralelamente, foi realizada a pesca experimental com uso de tarrafas de malha 3 cm entrenós não adjacentes, visando amostrar exemplares de pequeno porte. Foram coletados ainda fatores abióticos da água (oxigênio dissolvido, temperatura da água, pH e condutividade elétrica, transparência da água e clorofila-a total). Outros dados como cota altimétrica da represa e pluviosidade mensal foram compilados da concessionária AES - Tietê. De todos os exemplares de peixes foram obtidos dados biométricos (comprimento padrão e peso total). Os estômagos foram transferidos para frascos etiquetados contendo solução de formaldeído 10%. O conteúdo estomacal foi analisado pelos métodos de freqüência de ocorrência e volumétrico, combinados no Índice alimentar. Para avaliar as possíveis variações ontogenéticas e sazonais, foram analisadas as dietas dos exemplares de cada espécie agrupados em classes de tamanho e por estação seca e chuvosa. Na dieta das duas espécies foram observados 26 itens alimentares agrupados em sete categorias (fragmentos vegetais, algas, detritos, peixes, microcrustáceos, macroinvertebrados e insetos aquáticos). A espécie O. niloticus, consumiu 24 itens, e foi considerada detritívora, enquanto que T. rendalli, consumiu... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present work aimed to study the food habits of niloticus (Linnaeus, 1758) and Tilapia rendalli (Boulenger, 1897) in the Barra Bonita reservoir, São Paulo State, by using two approaches: i) characterization of O. niloticus e T. rendalli feeding habits and to find any possible relationship with the reservoir's eutrophication process and ii) analyze seasonal and ontogenetic variation with regard to the diet of these species. Samples were collected monthly, from March 2007 to February 2008, in Anhembi, São Paulo State. The fishes were obtained of artisanal fish landing and fishing was done using casting net (3cm between-knot mesh size), to get small individuals. Some physico-chemical variables of water samples were collected (dissolved oxygen, water temperature, pH and electric conductivity, water transparency and chlorophyll a). Another data such as reservoir altimeter quota and monthly rainfall were gathered from the AES - Tietê. Biometric data (standard length and total weight) were obtained from all individuals. The stomachs were transferred to labeled bottle with formaldehyde 10%. The stomach content was analyzed by frequency of occurrence and volume, combined on the food index. To evaluate possible seasonal and ontogenetic variation, it was analyzed the diet of each species grouped in size class and by dry and wet season. In the diet of both species were observed 26 different food items grouped into seven categories: vegetables fragments, algae, detritus, fishes, micro crustaceans, macro invertebrates and aquatic insects). O. niloticus consumed 24 items, and was considered detritivorous, whereas T. rendalli consumed 23 items, and was considered omnivorous, because it used animal and vegetal resources without dominance of any no category. With regard to a possible relationship with the reservoir's eutrophication process, this could be mitigated by species, given that the feed... (Complete abstract click electronic access below) / Mestre

RESUMO A Ãgua constitui o recurso de maior importÃncia para o homem, no entanto parece nÃo existir nenhuma preocupaÃÃo do ser humano em preservÃ-la, uma vez que as atividades diÃrias estÃo prejudicando cada vez mais, a qualidade deste recurso. Este trabalho teve por objetivo analisar a estrutura da comunidade fitoplanctÃnica e a qualidade da Ãgua de ecossistemas aquÃticos do Estado do Cearà (Brasil). Foram realizadas coletas mensais nas estaÃÃes chuvosa e seca, entre 2004 e 2007, nos seguintes ecossistemas: estuÃrios dos rios CauÃpe, MundaÃ, Cearà e Malcozinhado; lagoas de Jijoca, PecÃm, Uruaà e Maraponga; bicas do Ipu e das AndrÃas e aÃudes Favelas, da Corte e Campus do Itaperi. Os resultados mostraram mudanÃa significativa na estrutura da comunidade fitoplanctÃnica, influenciada principalmente pelos nÃveis de precipitaÃÃes pluviomÃtricas. As Bacillariophyceae foram predominantes nos ecossistemas analisados, exceto nos aÃudes Favelas, da Corte e do Campus do Itaperi, que apresentaram elevados nÃveis de eutrofizaÃÃo, com dominÃncia de Cyanophyceae, Zygnematophyceae e Chlorophyceae, respectivamente. As espÃcies raras, a grande maioria, formaram um grupo totalmente isolado daquelas consideradas dominantes, abundantes e pouco abundantes, constituÃdas por um nÃmero reduzido de espÃcies, confirmando a grande influÃncia sazonal da regiÃo, sobre a comunidade fitoplanctÃnica. Os ecossistemas apresentaram grande variaÃÃo na diversidade, riqueza e equitabilidade das espÃcies, no entanto a diversidade foi maior durante a estaÃÃo chuvosa. Com base nos teores de O2 e CO2 dissolvidos, amÃnia total, nitrito, fosfato, bem como, nos Ãndices do estado trÃfico do fosfato e/ou da transparÃncia da Ãgua e na presenÃa de bioindicadores, os estuÃrios dos rios MundaÃ, CauÃpe e CearÃ, a lagoa da Maraponga e os aÃudes Favelas, da Corte e Campus do Itaperi foram classificados como ambientes eutrÃficos; o estuÃrio do Rio Malcozinhado e as lagoas do PecÃm e de Uruaà como mesotrÃficos; e a lagoa de Jijoca e as bicas do Ipu e das AndrÃas como oligotrÃficos. Foram registrados diversos bioindicadores de Ãguas eutrofizadas e/ou poluÃdas, destacando-se a presenÃa de Cyanophyceae potencialmente tÃxicas nos diversos ecossistemas, com blooms no estuÃrio do Rio Cearà e no aÃude Favelas, nÃo sendo registrada uma biomassa significativa nos outros ambientes, mesmo naqueles que apresentaram elevado estado trÃfico, como o aÃude do Campus do Itaperi, com ocorrÃncia de bloom de Chlorophyceae e, no aÃude da Corte, cujo bloom foi de Zygnematophyceae, mostrando que na anÃlise de sanidade dos ecossistemas aquÃticos, a anÃlise conjunta dos parÃmetros biolÃgicos e fÃsico-quÃmicos do ecossistema à de suma importÃncia para um parecer ambiental adequado. / Water is the most important resource for humans, though it s eems there is no concern of human beings in preserving it, because daily activities increasingly under mine the quality of this resource. This study aimed to analyze the phytoplankton community structure and water quality in aquatic ecosystems of Cearà State (Brazil). Monthly collections were made during the rainy and dry seasons between 2004 and 2007 in the following ecosystems: the CauÃpe, MundaÃ, Cearà and Malcozinhado river estuarie s; the Jijoca, PecÃm, Uruaà and Maraponga lakes; the Ipu and Andreas waterspouts and the Favelas, Corte and Campus do Itaperi dams. The results showed significant changes in phytoplankton community structure, mainly influenced by levels of rainfall. The Bacillariophyceae were predominant in the ecosystems studied, except in the Favelas, Corte and Campus do Itaperi dams, which showed high levels of eutrophication, with dominance of Cyanophyceae, Zygnematophyceae and Chlorophyceae, respectively. Rare species, the great majorit y, formed a group totally isolated from those considered dominant, abundant and little abundant, consisting of a small number of species, confirming the major seasonal influence of the region's on the phytoplankton community. Ecosystems showed great variation in diversity, richness and evenness of species, however, diversity was highest during the rainy season. The following environments were classified according to the concentration of dissolved O 2 and CO2, total ammonia, nitrite, phosphate, as well as on trophic status indices of phosphate and/or water transparency and on the presence of bioindicators: the MundaÃ, CauÃpe and Cearà river estuaries, Maraponga lake and the Favelas, Corte and Campus do Itaperi dams as eutrophic environments; the Malcozinhado river estuary and PecÃm and Uruaà lakes as mesotrophic environments; and Jijoca lake and the Ipu and AndrÃas waterspouts as oligotrophic environment. Several bioindicators of eutrophic and/or polluted waters were recorded, in partic ular the presence of potentially toxic cyanobacteria in various ecosystems, with blooms in the Cearà river estuary and Favelas dam, while significant biomass was not recorded in other environments, even those showing a high trophic status, such as the Campus do Itaperi dam, with a Chlorophyceae bloom, and the Corte dam, with a Zygnematophyceae bloom, showing that the joint analysis of biological and physicochemical parameters of the ecosystem is of paramount importance for an appropriate environmental assessment of the health of aquatic cosystems.

>Magister Scientiae - MSc / In the Otjozondjupa Region, Namibia, water is transferred from Swakoppoort and Omatako Dams into Von Bach Dam to limit evaporation losses and bring water closer to the purification plant. There is a gap in the knowledge about the effects on water quality in Von Bach Dam due to water transfer from Swakoppoort and Omatako Dams, as previous studies on such aspects in the area do not exist. The study objective was to; (a) characterise water quality of the three dams, (b) determine whether water transfers affect the water quality of Von Bach Dam, (c) determine if the treatment of water abstracted from Von Bach Dam for potable water supply has been influenced by water quality changes arising from water transfers. Four sampling locations were established in Von Bach Dam, one in Swakoppoort Dam, and one in Omatako Dam. Water samples were collected in these three dams weekly. Two senior officers responsible for water treatment were interviewed about possible water treatment problems arising from the water transfer. Descriptive statistics, ANOVA and correlation were carried out to analyse the data. The results showed that, secchi disk depths, total phosphorus, orthophosphate, ammonia, dissolved organic carbon, chlorophyll a and microcystis were statistically different in the three dams at a 5% significance level. Upstream land uses, geology of the catchment and water stratification are likely to influence the water quality in the three dams. During water transfers into Von Bach Dam, secchi disk depths, turbidity, dissolved oxygen, iron, total phosphorus, ammonia (NH₄-N) and chlorophyll a were statistically different at a 5% significance level at all the four sampling locations within this dam. These differences are due to the influence of water transfers. The influence of water transfers on water quality was localised at the discharge points SL4 (at the inflow of Von Bach Dam) and SL1 (at the outflow of Von Bach Dam). Water treatment problems due to high ammonia, dissolved organic carbon, and turbidity in the water abstracted from Von Bach Dam occurred during water transfers and runoff from the catchment. This view was supported by the study findings.

No abstract available Please read the resumé in the section 08back of this document / Thesis (PhD)--University of Pretoria, 2009. / Microbiology and Plant Pathology / unrestricted

Phosphorus is recognized as a key nutrient in the cultural eutro-phication of lakes. A simulation model of the phosphorus cycle in eutro-phic Skaha Lake shows total phosphorus to be a useful indicator for the prediction of trophic states. Difference equations and a daily time scale are used in a mass balance model which accounts for the dynamic stratification regime of the lake. Total phosphorus movement between epilimnion, hypolimnion, and sediments is detailed in a series of submodels. An eddy diffusion submodel predicts loading from the hypolimnion to the epilimnion which can equal external loading for short periods of the summer. A phosphorus sedimentation submodel predicts organic sedimentation on the basis of primary production and inorganic sedimentation from adsorption considerations. A regeneration submodel considers the temperature-dependent decomposition rates of sedimented phosphorus. A primary production submodel accounts for temperature, light and phosphorus dependency, as well as respiration, grazing, sinking and advection losses. Based on known phosphorus loading and three years of limnological data, reasonable agreement was found between real and simulated total phosphorus concentration, phytoplankton biomass, and hypolimnetic dissolved oxygen. Results show that three to four times more phosphorus apparently returns to the lake from deep-water sediments than possible by bacterial decomposition alone. Improved simulation of phytoplankton production could probably be achieved with the inclusion of a zooplankton submodel and exten sion to include the specific growth dynamics of more than one algal group. The Michaelis-Menton half-saturation constant appears to be the most sensitive coefficient in the primary production submodel. The probable effects of four phosphorus management policies are assessed using 20 years of hydrologic data (1949-69) and the eutrophic conditions of 1970 as a starting point. While no attempt is made to predict the trophic status of the lake for the next 20 years, definite trends are apparent. With no phosphorus removal and no increase in loading over the hypothetical 20-year period, phytoplankton blooms increase in intensity and hypolimnetic dissolved oxygen approaches zero. With 60 per cent removal of municipal phosphorus and conditions of either low or high economic growth in the Penticton region, the eutrophic conditions of 1970 are reached within 12 to 14 years. Algal blooms and hypolimnetic dissolved oxygen deficits are particularly serious during dry years. With 100 per cent municipal phosphorus removal, trophic conditions appear to improve significantly, with the possibility of minor algal blooms during only dry years. These results indicate that complete removal of the phosphorus from municipal sources appears to be the most rational long-range management policy. These conclusions demonstrate that a theoretical model to predict trophic indicators in a lake can be useful as both a research tool and a practical planning aid for decision-making. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The importance of resource supply and herbivory in driving competitive interactions among species has been an important but contentious issue within ecology. These variables exhibit different effects on species competition when manipulated in isolation but interact when manipulated together. I tested the direct and interactive effects of nutrient addition and simulated grazing (clipping) on the competitive performance of primary producers and community structure of a seagrass bed in South Florida. One square meter experimental plots were established in a mixed seagrass meadow from August 2007 to July 2009. The experiment was a 3 x 3 factorial experiment: 3 fertility treatments: control, medium (2.4 mg N d-1 and 80 µg P day-1) and high (4.8 mg N d-1 and 160 µg P day-1) x 3 clipping intensities (0, 25% and 50 % biomass removal (G)) x 5 replicates for each treatment = 45 plots). Nutrient additions and simulated grazing were done every two months. Fertilization and simulated grazing decreased sexual reproduction in S. filiforme. Fertilization increased competitive dominance within the primary producers while simulated grazing counteracted this effect by removal of the dominant species. Fertilization ameliorated the negative impacts of simulated grazing while simulated grazing prevented competitive exclusion in the fertilized plots. Nutrient addition and simulated grazing both exerted strong control on plant performance and community structure. Neither bottom up nor top down influences was eliminated in treatments where both factors where present. The effects of fertilization on plant performance were marked under all clipping intensities indicating that the system is regulated by nutrient availability both in the presence or absence of grazers. Clipping effects were strong under both fertilized and unfertilized conditions indicating that the seagrass bed can be simultaneously under top-down control by grazers.

Estuaries are valuable economic resources to humans. However, changes in these ecosystems, such as alteration in nutrient availability, can impose eutrophic pressures. Traditionally, estuaries have been monitored through chemical analyses that measure factors such as sediment oxygen demand (SOD) and reduced forms of Fe(II), Mn(II), and H2S. These methods are time consuming and have been proven to be unreliable. This study was conducted to determine if using T-RFLP analysis could be used as a proxy for some of the current methods used to monitor eutrophication. Using SPSS to perform a principle component analysis, it was determined that connections can be made between the genetic fingerprints of microbial communities in estuaries and the biogeochemical markers that are currently used to monitor eutrophication. This method can potentially replace the current methods by allowing scientists to measure more sites rapidly and with reproducibility.