The Maketu Estuary is a shallow intertidal estuary (2.3 km2) located in the Bay of Plenty, North Island, New Zealand. The Kaituna River contributes the largest freshwater flow into the estuary through control gates. Lake Rotoiti and indirectly Lake Rotorua supply the base flow to the Kaituna River, with tributaries along the 50 km reach also significantly contributing to the flow. Water quality within the river is affected by elevated nutrients, faecal coliforms, high oxygen demand and algae concentrations derived from the lakes as well as contributions from tributaries and industrial and urban discharge. Through the use of a coupled hydrodynamic-biogeochemical numerical model ELCOM-CAEDYM, this study aims to examine the nutrient, phytoplankton and hydrodynamics of the Maketu Estuary and lower Kaituna River. Water quality and hydrodynamic measurements were sourced from Environment Bay of Plenty's data archives as well as a number of instrument deployments to collect water velocity, tidal elevation and salinity and temperature measurements during the course of this study. Included in the field work was a survey of the lower river and estuary bathymetry. Model simulations predicted that the maximum residence time in the Maketu Estuary is 1.5 days, occurring in the inner western region. Residence time in the lower river (mouth to 8.5 km upstream) is in the order of hours although some variations were predicted near the river mouth. Growth rates of four phytoplankton groups where assessed over a 15 day period in January 2004. In the Kaituna River ELCOM-CAEDYM predicted that the community growth rates were small with the exception of a slight increase in biomass of the two freshwater groups in a semi-detached river bend. The increase in the loop was correlated with an increase of residence time. In the estuary, marine diatoms showed the highest growth rates in the western region which is expected to relate to retention time and available nutrients. Dinoflagellates showed the smallest variation in predicted growth rates, most likely due to their broad salinity tolerance. The two freshwater species showed a reduction in abundance when mixed with marine water. A principle limiting factor to phytoplankton growth in both the river and estuary is the low residence time. A number of scenarios were simulated in the river and estuary by altering the forcing conditions in the model. A simulation of the increased nutrient load associated with the Rotoiti diversion wall revealed that phytoplankton growth in the river and estuary will not be significantly affected. Because of the close proximity of the control gates to the river mouth, a proportion of water drawn through the structure can be marine. By opening the old river channel, model simulations predicted that a reduction in salinity would be possible, however the outcome of complete freshwater is probably not achievable. Increasing the discharge volume from the river into the estuary was also simulated. The results indicated that increasing the freshwater inflow at Fords Cut would reduce the salinity in the estuary while increasing the net (residual) flow towards the estuary mouth. Increasing the flow would also result in a greater range of salinity in regions of the estuary. Changing the inflow location to the historic Papahikahawai Channel also affected the salinity in the estuary. The most significant effect of an inflow at this location was a reduction of the residual currents in the western region of the estuary.

O reservatório do Lobo, localizado no estado de São Paulo, é um sistema dinâmico no qual se desenvolve um ciclo diurno de estratificação e mistura, de modo similar ao que tem sido observado em outros lagos tropicais. Utilizou-se simulação 3D computacional com os softwares ELCOM (Estuary and Lake Computer Model) acoplado ao CAEDYM (Computacional Aquatic Ecosystem Dynamics Model), ambos desenvolvidos pelo CWR (Center for Water Research) da Universidade da Austrália. Foram realizadas cinco simulações: Piloto Primavera baseada em dados reais da estação no ano primavera no reservatório para o ano de 2007; Primavera-P em que as concentrações de fósforo total, fosfato inorgânico e fosfato total dissolvido foram aumentadas em 100% no reservatório (coluna de água e sedimento) e nos rios tributários; Primavera-V na qual a intensidade dos ventos foi aumentada em 50%; Primavera-T onde a temperatura da água (reservatório e tributários) e do ar foram aumentadas em 10C e, Primavera-X, onde a temperatura da água (reservatório e tributários) e do ar sofreu aumento em 10C, as concentrações de fósforo total, fosfato inorgânico e fosfato total dissolvido foram aumentadas em 100% e a velocidade do vento aumentada em 50%. A concentração de clorofila a foi representada pelos grupos cianobactérias e clorofíceas. O espaço de tempo das simulações representou 90 dias. As clorofíceas apresentaram maior desenvolvimento populacional do que as cianobactérias em todas as simulações. No reservatório, a mistura vertical é ocasionada diariamente pelo vento ou por processos convectivos causados pela perda de calor no corpo de água. A oxigenação do reservatório é maior com a ocorrência de ventos e de grupos fotossintéticos. As concentrações totais de fósforo e nitrogênio apresentaram aumento em todas as simulações. / Lobo reservoir is located in the state of São Paulo and it is a dynamic system where happens a diurnal cycle of mix and stratiphication as seen in other tropical lakes. 3D computational simulation where used. ELCOM (Estuary and Lake Computer Model) and CAEDYM (Computacional Aquatic Ecosystem Dynamics Model) both created by CRW (Center for Water Research) from Australia University to simulate biophysicochemicalls conditions in the reservoir. Five simulations had been carried through: Pilot Spring based in real data for the station spring of the year 2007 in the reservoir; Spring-P where the concentrations of total phosphorus, inorganic phosphate and dissolved total phosphate had been increased in 100% in the reservoir (water column and sediment) and in the tributaries rivers; Spring-V in which the intensity of the winds was increased in 50%; Spring-T where the temperature in the water (reservoir and tributaries) and in the air where increased in 10C and, Simulation Spring-X where the concentrations of total phosphorus, inorganic phosphate and dissolved total phosphate had been increased in 100% in the reservoir (water column and sediment) and in the tributaries rivers, the intensity of the winds was increased in 50% and the temperature in the water (reservoir and tributaries) and in the air where increased in 10C. The concentrations of chorophyll a where represented by the groups: cyanobacterias and chllorophyceas. The time space of the simulations represented 90 days. The chllorophyceas presented bigger populational development in all simulations. In the reservoir, a vertical mix happens every day because of the wind or by convective process caused by the lost of temperature in the water. The oxygenation in the reservoir is bigger whit the occurrence of winds and photosynthetic groups. The total concentrations of nitrogen and phosphorus in all simulations presented increasement.

O reservatório do Lobo, localizado no estado de São Paulo, é um sistema dinâmico no qual se desenvolve um ciclo diurno de estratificação e mistura, de modo similar ao que tem sido observado em outros lagos tropicais. Utilizou-se simulação 3D computacional com os softwares ELCOM (Estuary and Lake Computer Model) acoplado ao CAEDYM (Computacional Aquatic Ecosystem Dynamics Model), ambos desenvolvidos pelo CWR (Center for Water Research) da Universidade da Austrália. Foram realizadas cinco simulações: Piloto Primavera baseada em dados reais da estação no ano primavera no reservatório para o ano de 2007; Primavera-P em que as concentrações de fósforo total, fosfato inorgânico e fosfato total dissolvido foram aumentadas em 100% no reservatório (coluna de água e sedimento) e nos rios tributários; Primavera-V na qual a intensidade dos ventos foi aumentada em 50%; Primavera-T onde a temperatura da água (reservatório e tributários) e do ar foram aumentadas em 10C e, Primavera-X, onde a temperatura da água (reservatório e tributários) e do ar sofreu aumento em 10C, as concentrações de fósforo total, fosfato inorgânico e fosfato total dissolvido foram aumentadas em 100% e a velocidade do vento aumentada em 50%. A concentração de clorofila a foi representada pelos grupos cianobactérias e clorofíceas. O espaço de tempo das simulações representou 90 dias. As clorofíceas apresentaram maior desenvolvimento populacional do que as cianobactérias em todas as simulações. No reservatório, a mistura vertical é ocasionada diariamente pelo vento ou por processos convectivos causados pela perda de calor no corpo de água. A oxigenação do reservatório é maior com a ocorrência de ventos e de grupos fotossintéticos. As concentrações totais de fósforo e nitrogênio apresentaram aumento em todas as simulações. / Lobo reservoir is located in the state of São Paulo and it is a dynamic system where happens a diurnal cycle of mix and stratiphication as seen in other tropical lakes. 3D computational simulation where used. ELCOM (Estuary and Lake Computer Model) and CAEDYM (Computacional Aquatic Ecosystem Dynamics Model) both created by CRW (Center for Water Research) from Australia University to simulate biophysicochemicalls conditions in the reservoir. Five simulations had been carried through: Pilot Spring based in real data for the station spring of the year 2007 in the reservoir; Spring-P where the concentrations of total phosphorus, inorganic phosphate and dissolved total phosphate had been increased in 100% in the reservoir (water column and sediment) and in the tributaries rivers; Spring-V in which the intensity of the winds was increased in 50%; Spring-T where the temperature in the water (reservoir and tributaries) and in the air where increased in 10C and, Simulation Spring-X where the concentrations of total phosphorus, inorganic phosphate and dissolved total phosphate had been increased in 100% in the reservoir (water column and sediment) and in the tributaries rivers, the intensity of the winds was increased in 50% and the temperature in the water (reservoir and tributaries) and in the air where increased in 10C. The concentrations of chorophyll a where represented by the groups: cyanobacterias and chllorophyceas. The time space of the simulations represented 90 days. The chllorophyceas presented bigger populational development in all simulations. In the reservoir, a vertical mix happens every day because of the wind or by convective process caused by the lost of temperature in the water. The oxygenation in the reservoir is bigger whit the occurrence of winds and photosynthetic groups. The total concentrations of nitrogen and phosphorus in all simulations presented increasement.

Lake Erie has undergone a substantial amount of ecosystem changes over the past century; including cultural eutrophication and several invasions by industrious exotic species. Simple mass balance models for phosphorus have been useful in guiding policy decisions that led to reduced eutrophication, but new, confounding threats to the ecological health of Lake Erie continue to appear and lake managers continue to need useful tools to better understand the lake. As more complex ecological questions are asked to guide future management decisions, more complex ecological models are developed in an effort to provide some clues. The walleye fishery in Lake Erie is economically very important. Walleye recruitment has been highly variable from year to year since the 1990s. Modelling zooplankton is desired as a diagnostic tool for elucidating the quality of habitat – spatially and temporally – that is available to walleye in their vulnerable larval state. ELCOM-CAEDYM (or ELCD) is a 3-dimensional, coupled hydrodynamic and ecological model, which has been successfully applied to Lake Erie to model the nutrients and phytoplankton. The objectives of this study were to better understand the ELCOM-CAEDYM model of Lake Erie through a sensitivity analysis (SA), which has not been done before, and to explicitly simulate zooplankton in this model. An SA is important for determining which of the uncertain parameters have the greatest impact on the output variables. Due to the complexity of the CAEDYM model and the highly interdependent functions and variables modelled, a local SA (comparing changes in output by perturbing parameters one-at-a-time from some baseline configuration) was not desirable. Local SA’s ignore the possibility of a parameter’s effects being correlated to the status of other parameters. However, quantitative global methods are enormously computationally expensive for a complex model. The Lake Erie ELCD model simulates temperature, mixing, nutrient cycles, and phytoplankton dynamics. Phytoplankton are represented by 5 functional groups. With the explicit inclusion of 2 functional groups of zooplankton (copepods and cladocerans), the model uses over 300 function parameters in addition to requiring meteorological data and river inflow characteristics throughout the simulation. The model is set up with a 2-km grid over 40 layers with a 5-minute timestep from April 11 to September 1. This full simulation takes 6 days to complete. A quantitative global method to evaluate all parameters potentially significant to zooplankton would be impossible. The Morris method was selected for its streamlined global sampling procedure combined with the manageable computational demands of a one-at-a-time analysis. This method provides the relative sensitivity of diagnostic outputs to perturbed parameters. Ninety-one parameters were selected to be evaluated in 3680 simulations for the Morris SA. The selection of which parameters to evaluate and their assigned ranges are critical components in any SA. The ranges for parameters that represent a measurable quantity were assessed based on observed values in Lake Erie and other relevant studies. For some parameters, a measured realistic range was unknown. In these cases, values from relevant published models or judgements based on experience with the ELCD-Erie model were used to choose a suitable range. To assess the sensitivity of CAEDYM variables to parameters, DYRESM was substituted for ELCOM to vastly decrease the computation time of a single run. DYRESM is not suitable to model the entire lake due to the large size and irregular shape of the entire lake. Therefore, only the West Basin was modelled and analysed using DYCD. The West Basin was of special interest for a sensitivity analysis of CAEDYM parameters with respect to zooplankton because it is an important area for walleye larval development. DYCD output profiles for temperature, total chlorophyll a (TChla as a surrogate for total phytoplankton concentration) were similar in magnitudes and seasonal dynamics compared to ELCD outputs in deep West Basin stations. The sensitivity of zooplankton, TChla and TP to each parameter was assessed using two single value diagnostics: the simulated seasonal maximum and the simulated day on which peak maximum was reached. Zooplankton were sensitive to almost all of the zooplankton parameters perturbed in the analysis. This may indicate that modelling zooplankton is extremely complex, relying on many dynamic processes, or that evaluated ranges were not constrained well enough. An example of sensitivity to a poorly known parameter is the messy feeding coefficient. Reducing the uncertainty of this parameter would improve the confidence in the zooplankton assimilation submodel. Other parameters that stood out for being especially significant to zooplankton were: the respiration rate, mortality rate, internal phosphorus to carbon ratio, the temperature multiplier and standard temperature for feeding dynamics, and the half saturation constant. Most of these are easily explained as they directly aid or impede growth or they directly affect zooplankton losses. The most significant phytoplankton parameters on TChla and zooplankton outputs were, not surprisingly, the maximum growth rate and the mortality and respiration coefficient. Some particulate matter parameters proved to be important to outputs as well. More than 2500 of the 3680 parameter configurations resulted in unrealistic zooplankton simulations: peak values that did not much exceed initial conditions on the first day of the simulation. The SA exercise pinpointed a few configurations that resulted in reasonable peak zooplankton values and timing; these runs were used as a starting point for calibrating the ELCD model. Parameters were further manually adjusted by quickly checking their impacts on DYCD before applying them to ELCD. Post SA and minor calibration, the modelled zooplankton results were dramatically better than initial modelling attempts prior to the SA. Zooplankton concentrations throughout the lake were close to measured ranges and in some parts of the lake seasonal patterns were also similar to measured patterns. Modelled zooplankton results were least consistent with observations in the south west area of the lake: zooplankton were overestimated in late June-early July and they subsequently crashed and were underestimated in late July-August. It is supposed that this is due to higher grazing pressure from fish larvae in that area of the lake, which is not explicitly modelled. Although it is not anticipated that the south west seasonal zooplankton patterns will improve through parameter calibration (since predator effects are uniformly characterized throughout the lake by the same mortality factor) , further calibration is needed to improve results in the rest of the lake since copepods are generally overestimated and cladocerans generally underestimated. Phytoplankton groups must also be calibrated simultaneously to ensure that they are still operating within reasonable concentrations given more successful zooplankton simulations.

Lake Erie has undergone a substantial amount of ecosystem changes over the past century; including cultural eutrophication and several invasions by industrious exotic species. Simple mass balance models for phosphorus have been useful in guiding policy decisions that led to reduced eutrophication, but new, confounding threats to the ecological health of Lake Erie continue to appear and lake managers continue to need useful tools to better understand the lake. As more complex ecological questions are asked to guide future management decisions, more complex ecological models are developed in an effort to provide some clues. The walleye fishery in Lake Erie is economically very important. Walleye recruitment has been highly variable from year to year since the 1990s. Modelling zooplankton is desired as a diagnostic tool for elucidating the quality of habitat – spatially and temporally – that is available to walleye in their vulnerable larval state. ELCOM-CAEDYM (or ELCD) is a 3-dimensional, coupled hydrodynamic and ecological model, which has been successfully applied to Lake Erie to model the nutrients and phytoplankton. The objectives of this study were to better understand the ELCOM-CAEDYM model of Lake Erie through a sensitivity analysis (SA), which has not been done before, and to explicitly simulate zooplankton in this model. An SA is important for determining which of the uncertain parameters have the greatest impact on the output variables. Due to the complexity of the CAEDYM model and the highly interdependent functions and variables modelled, a local SA (comparing changes in output by perturbing parameters one-at-a-time from some baseline configuration) was not desirable. Local SA’s ignore the possibility of a parameter’s effects being correlated to the status of other parameters. However, quantitative global methods are enormously computationally expensive for a complex model. The Lake Erie ELCD model simulates temperature, mixing, nutrient cycles, and phytoplankton dynamics. Phytoplankton are represented by 5 functional groups. With the explicit inclusion of 2 functional groups of zooplankton (copepods and cladocerans), the model uses over 300 function parameters in addition to requiring meteorological data and river inflow characteristics throughout the simulation. The model is set up with a 2-km grid over 40 layers with a 5-minute timestep from April 11 to September 1. This full simulation takes 6 days to complete. A quantitative global method to evaluate all parameters potentially significant to zooplankton would be impossible. The Morris method was selected for its streamlined global sampling procedure combined with the manageable computational demands of a one-at-a-time analysis. This method provides the relative sensitivity of diagnostic outputs to perturbed parameters. Ninety-one parameters were selected to be evaluated in 3680 simulations for the Morris SA. The selection of which parameters to evaluate and their assigned ranges are critical components in any SA. The ranges for parameters that represent a measurable quantity were assessed based on observed values in Lake Erie and other relevant studies. For some parameters, a measured realistic range was unknown. In these cases, values from relevant published models or judgements based on experience with the ELCD-Erie model were used to choose a suitable range. To assess the sensitivity of CAEDYM variables to parameters, DYRESM was substituted for ELCOM to vastly decrease the computation time of a single run. DYRESM is not suitable to model the entire lake due to the large size and irregular shape of the entire lake. Therefore, only the West Basin was modelled and analysed using DYCD. The West Basin was of special interest for a sensitivity analysis of CAEDYM parameters with respect to zooplankton because it is an important area for walleye larval development. DYCD output profiles for temperature, total chlorophyll a (TChla as a surrogate for total phytoplankton concentration) were similar in magnitudes and seasonal dynamics compared to ELCD outputs in deep West Basin stations. The sensitivity of zooplankton, TChla and TP to each parameter was assessed using two single value diagnostics: the simulated seasonal maximum and the simulated day on which peak maximum was reached. Zooplankton were sensitive to almost all of the zooplankton parameters perturbed in the analysis. This may indicate that modelling zooplankton is extremely complex, relying on many dynamic processes, or that evaluated ranges were not constrained well enough. An example of sensitivity to a poorly known parameter is the messy feeding coefficient. Reducing the uncertainty of this parameter would improve the confidence in the zooplankton assimilation submodel. Other parameters that stood out for being especially significant to zooplankton were: the respiration rate, mortality rate, internal phosphorus to carbon ratio, the temperature multiplier and standard temperature for feeding dynamics, and the half saturation constant. Most of these are easily explained as they directly aid or impede growth or they directly affect zooplankton losses. The most significant phytoplankton parameters on TChla and zooplankton outputs were, not surprisingly, the maximum growth rate and the mortality and respiration coefficient. Some particulate matter parameters proved to be important to outputs as well. More than 2500 of the 3680 parameter configurations resulted in unrealistic zooplankton simulations: peak values that did not much exceed initial conditions on the first day of the simulation. The SA exercise pinpointed a few configurations that resulted in reasonable peak zooplankton values and timing; these runs were used as a starting point for calibrating the ELCD model. Parameters were further manually adjusted by quickly checking their impacts on DYCD before applying them to ELCD. Post SA and minor calibration, the modelled zooplankton results were dramatically better than initial modelling attempts prior to the SA. Zooplankton concentrations throughout the lake were close to measured ranges and in some parts of the lake seasonal patterns were also similar to measured patterns. Modelled zooplankton results were least consistent with observations in the south west area of the lake: zooplankton were overestimated in late June-early July and they subsequently crashed and were underestimated in late July-August. It is supposed that this is due to higher grazing pressure from fish larvae in that area of the lake, which is not explicitly modelled. Although it is not anticipated that the south west seasonal zooplankton patterns will improve through parameter calibration (since predator effects are uniformly characterized throughout the lake by the same mortality factor) , further calibration is needed to improve results in the rest of the lake since copepods are generally overestimated and cladocerans generally underestimated. Phytoplankton groups must also be calibrated simultaneously to ensure that they are still operating within reasonable concentrations given more successful zooplankton simulations.

Furnas Centrais Elétricas S.A. / A ecologia de reservatórios, que são ecossistemas complexos, dinâmicos e artificiais, vem assumindo destaque no Brasil. O objetivo deste trabalho foi avaliar a viabilidade da aplicação, no reservatório de APM-Manso, de um modelo ecológico tridimensional em estudos sobre a dinâmica fitoplanctônica, simulando a variação temporal do fitoplâncton para cenários distintos de carga de nutrientes. O modelo CAEDYM foi acoplado ao ELCOM e simulação foi realizada em duas etapas: uma hidrodinâmica e outra ecológica. Escolheu-se para as simulações o período de cinco meses, a partir de 1 de setembro de 2005. Foram construídos dois cenários de simulação, o primeiro contendo os valores reais de carga de nutrientes dos principais rios contribuintes medidos em campo, e o segundo com redução na carga nutricional destes rios, simulando um possível processo de substituição de áreas florestadas por áreas de pastagem na bacia do rio Manso. A comunidade fitoplanctônica simulada apresentou rápidas respostas à disponibilidade nutricional do ambiente, e os resultados obtidos corroboraram com diversas teorias sobre as estratégias adaptativas e sobre as dinâmicas algais. Dentre as classes simuladas, Bacillariophyceae e Cryptophyceae se mostraram mais sensíveis às reduções de carga, enquanto Chrolophyceae e Cyanophyceae, apesar de terem suas biomassas reduzidas, sofreram menos com o impacto, sugerindo estarem mais adaptadas à limitação de nutrientes. Os picos chuvosos influenciaram positivamente as taxas de crescimento das Bacillariophyceae apenas no Cenário 1, uma vez que a limitação por nutrientes foi mais decisiva para esta classe no Cenário 2. Observou-se em ambas as simulações uma tendência de substituição na dominância de Cyanophyceae por Chlorophyceae. / The ecology of reservoirs has assumed prominence in Brazil. This study explored the application of a tridimensional ecological modeling on phytoplankton dynamics, in Manso reservoir, simulating the temporal variation of phytoplankton community in two different scenarios of nutrient loading. CAEDYM was coupled to ELCOM, and the simulation was conducted in two stages: one hydrodynamic and other ecological. It was chosen for the simulation the period of five months, from Septemper 1th, 2005. Were constructed two scenarios: the first containing the actual values of nutrient loading of the main river measured in field, and the second with a reduction in nutrient load, simulating a possible replacement process to grazing areas from forested areas in the Manso River basin. The simulation showed rapid responses of phytoplankton to nutritional availability, and the results obtained corroborated with several theories about phytoplankton adaptive strategies and their dynamics. Among the simulated classes, Bacillariophyceae and Cryptophyceae were more sensitive to load reduction, while Chlorophyceae and Cyanophyceae suffered less from the impact, suggesting that they are more adapted to nutrient limitation. Rain positively influenced the growth rates of Bacillariophyceae only in Scenario 1, since the limitation of nutrients was more decisive for this class in Scenario 2. It was observed in both simulations a trend of replacing the dominance of Cyanophyceae with Chlorophyceae.

Furnas Centrais Elétricas S.A. / A ecologia de reservatórios, que são ecossistemas complexos, dinâmicos e artificiais, vem assumindo destaque no Brasil. O objetivo deste trabalho foi avaliar a viabilidade da aplicação, no reservatório de APM-Manso, de um modelo ecológico tridimensional em estudos sobre a dinâmica fitoplanctônica, simulando a variação temporal do fitoplâncton para cenários distintos de carga de nutrientes. O modelo CAEDYM foi acoplado ao ELCOM e simulação foi realizada em duas etapas: uma hidrodinâmica e outra ecológica. Escolheu-se para as simulações o período de cinco meses, a partir de 1 de setembro de 2005. Foram construídos dois cenários de simulação, o primeiro contendo os valores reais de carga de nutrientes dos principais rios contribuintes medidos em campo, e o segundo com redução na carga nutricional destes rios, simulando um possível processo de substituição de áreas florestadas por áreas de pastagem na bacia do rio Manso. A comunidade fitoplanctônica simulada apresentou rápidas respostas à disponibilidade nutricional do ambiente, e os resultados obtidos corroboraram com diversas teorias sobre as estratégias adaptativas e sobre as dinâmicas algais. Dentre as classes simuladas, Bacillariophyceae e Cryptophyceae se mostraram mais sensíveis às reduções de carga, enquanto Chrolophyceae e Cyanophyceae, apesar de terem suas biomassas reduzidas, sofreram menos com o impacto, sugerindo estarem mais adaptadas à limitação de nutrientes. Os picos chuvosos influenciaram positivamente as taxas de crescimento das Bacillariophyceae apenas no Cenário 1, uma vez que a limitação por nutrientes foi mais decisiva para esta classe no Cenário 2. Observou-se em ambas as simulações uma tendência de substituição na dominância de Cyanophyceae por Chlorophyceae. / The ecology of reservoirs has assumed prominence in Brazil. This study explored the application of a tridimensional ecological modeling on phytoplankton dynamics, in Manso reservoir, simulating the temporal variation of phytoplankton community in two different scenarios of nutrient loading. CAEDYM was coupled to ELCOM, and the simulation was conducted in two stages: one hydrodynamic and other ecological. It was chosen for the simulation the period of five months, from Septemper 1th, 2005. Were constructed two scenarios: the first containing the actual values of nutrient loading of the main river measured in field, and the second with a reduction in nutrient load, simulating a possible replacement process to grazing areas from forested areas in the Manso River basin. The simulation showed rapid responses of phytoplankton to nutritional availability, and the results obtained corroborated with several theories about phytoplankton adaptive strategies and their dynamics. Among the simulated classes, Bacillariophyceae and Cryptophyceae were more sensitive to load reduction, while Chlorophyceae and Cyanophyceae suffered less from the impact, suggesting that they are more adapted to nutrient limitation. Rain positively influenced the growth rates of Bacillariophyceae only in Scenario 1, since the limitation of nutrients was more decisive for this class in Scenario 2. It was observed in both simulations a trend of replacing the dominance of Cyanophyceae with Chlorophyceae.

Os gestores de recursos hídricos estão encarregados da gestão de longo prazo, a regulação e a proteção dos recursos hídricos. No entanto, reconhece-se que a estes gestores devem levar em conta a multiplicidade de usos dos recursos hídricos que são apresentadas pelas partes interessadas, tais como agricultores, fornecedores de água e grupos de ambientalistas. Dada a complexidade do sistema hidrológico, o desenvolvimento e a utilização de modelos matemáticos são muitas das vezes necessários. Neste contexto a modelagem ambiental é frequentemente realizada para avaliar os impactos da degradação do ecossistema devido à ação humana. Essa aplicação orientada a investigações proporciona um importante meio pelo qual os cientistas podem interagir e influenciar nas políticas a nível local, regional, nacional e internacional. No Mato Grosso, durante a implantação da hidroelétrica de Aproveitamento Múltiplo de Manso foram adotadas medidas de mitigação dos impactos socioeconômicos causados. Essas medidas geram uma tendência de aumento populacional associado a uma mudança das características sócio-econômicas, para toda a região do entorno do Reservatório, o que agrava o problema de poluição por nutrientes e denota que existe uma necessidade proeminente de estudos do impacto que estas cargas causariam no ecossistema do reservatório. Utilizando o modelo hidrodinâmico e termodinâmico tridimensional ELCOM, associado ao modelo biogeoquímico Caedym, este trabalho tem a finalidade de criar uma modelagem representativa das cargas dos principais nutrientes causadores da eutrofização cultural, sendo eles: a amônia (NH4), o nitrato (NO3) e o Ortofosfato (PO4), com a finalidade de estudar os efeitos das dinâmicas espaciais e temporais destas cargas no estado trófico deste reservatório no em torno dos pontos de lançamento de esgoto e na sua totalidade. / The water managers are responsible for long-term management, regulation and protection of water resources. However, it is recognized that these managers should take into account the multiple uses of water resources that are made by interested parties such as farmers, water suppliers and environmental groups. Given the complexity of the hydrological system, the development and use of mathematical models are often necessary. In this context, environmental modeling is often performed to assess the impacts of ecosystem degradation due to human action. This type of application-oriented research provides an important means by which scientists can interact and influence policies at local, regional, national and international. In the Mato Grosso State during the implementation of the hydropower plant to multiple use, called APM-Manso, measures were taken to mitigate the socioeconomic impacts caused. These measures create a trend of increasing population coupled with a changing socioeconomic characteristics for the entire area surrounding the reservoir, which aggravates the problem of nutrient pollution and indicates that there is a need prominent studies of the impact that the excess nutrients causes in the ecosystem of the reservoir. Using the hydrodynamic and thermodynamic threedimensional model, ELCOM, associated with the biogeochemical model, Caedym, this work aims to create a model representative of the loads of the main nutrients that cause the cultural eutrophication, which are: ammonia (NH4), nitrate (NO3) and orthophosphate (PO4), in order to study the effects of spatial and temporal dynamics of these nutrients in the trophic state of the reservoir around the points of discharge of sewage and in its entirety.

Os gestores de recursos hídricos estão encarregados da gestão de longo prazo, a regulação e a proteção dos recursos hídricos. No entanto, reconhece-se que a estes gestores devem levar em conta a multiplicidade de usos dos recursos hídricos que são apresentadas pelas partes interessadas, tais como agricultores, fornecedores de água e grupos de ambientalistas. Dada a complexidade do sistema hidrológico, o desenvolvimento e a utilização de modelos matemáticos são muitas das vezes necessários. Neste contexto a modelagem ambiental é frequentemente realizada para avaliar os impactos da degradação do ecossistema devido à ação humana. Essa aplicação orientada a investigações proporciona um importante meio pelo qual os cientistas podem interagir e influenciar nas políticas a nível local, regional, nacional e internacional. No Mato Grosso, durante a implantação da hidroelétrica de Aproveitamento Múltiplo de Manso foram adotadas medidas de mitigação dos impactos socioeconômicos causados. Essas medidas geram uma tendência de aumento populacional associado a uma mudança das características sócio-econômicas, para toda a região do entorno do Reservatório, o que agrava o problema de poluição por nutrientes e denota que existe uma necessidade proeminente de estudos do impacto que estas cargas causariam no ecossistema do reservatório. Utilizando o modelo hidrodinâmico e termodinâmico tridimensional ELCOM, associado ao modelo biogeoquímico Caedym, este trabalho tem a finalidade de criar uma modelagem representativa das cargas dos principais nutrientes causadores da eutrofização cultural, sendo eles: a amônia (NH4), o nitrato (NO3) e o Ortofosfato (PO4), com a finalidade de estudar os efeitos das dinâmicas espaciais e temporais destas cargas no estado trófico deste reservatório no em torno dos pontos de lançamento de esgoto e na sua totalidade. / The water managers are responsible for long-term management, regulation and protection of water resources. However, it is recognized that these managers should take into account the multiple uses of water resources that are made by interested parties such as farmers, water suppliers and environmental groups. Given the complexity of the hydrological system, the development and use of mathematical models are often necessary. In this context, environmental modeling is often performed to assess the impacts of ecosystem degradation due to human action. This type of application-oriented research provides an important means by which scientists can interact and influence policies at local, regional, national and international. In the Mato Grosso State during the implementation of the hydropower plant to multiple use, called APM-Manso, measures were taken to mitigate the socioeconomic impacts caused. These measures create a trend of increasing population coupled with a changing socioeconomic characteristics for the entire area surrounding the reservoir, which aggravates the problem of nutrient pollution and indicates that there is a need prominent studies of the impact that the excess nutrients causes in the ecosystem of the reservoir. Using the hydrodynamic and thermodynamic threedimensional model, ELCOM, associated with the biogeochemical model, Caedym, this work aims to create a model representative of the loads of the main nutrients that cause the cultural eutrophication, which are: ammonia (NH4), nitrate (NO3) and orthophosphate (PO4), in order to study the effects of spatial and temporal dynamics of these nutrients in the trophic state of the reservoir around the points of discharge of sewage and in its entirety.

The Lower Karori Reservoir (LKR) is a small, monomictic lake of 2.34 ha situated in the Karori Wildlife Sanctuary (KWS), Wellington. Over the past decade cyanobacterial blooms have become a common occurrence in this water body. In 2005 Anabaena planktonica was detected for the first time in the LKR and this species now forms dense blooms during summer. These blooms are problematic as they reduce aesthetic appeal and have resulted in odour problems for visitors to this high profile wildlife sanctuary. The objectives of this study were to identify key physical, chemical and biological variables influencing phytoplankton dynamics in the LKR and to use ecological models to investigate plausible management options. The key parameters investigated, that may cause bloom formation were; summer stratification, high nutrient levels, and the food web effects of a large population of European perch (Perca fluviatilis). High resolution sampling was carried out every six hours over a 72 hour period during pre-bloom, bloom and post-bloom periods in 2006/7 to elucidate short term temporal and spatial variations in biological and physico-chemical parameters. Quantitative polymerase chain reaction (QPCR) was used to enumerate A. planktonica populations, allowing a large number of samples to be simultaneously evaluated. Algal densities were also estimated using conventional phytoplankton enumeration and chlorophyll a analysis. Water samples were collected for nutrient analysis at discrete depths and profiles were taken for temperature, dissolved oxygen and photosynthetic active radiation. Secchi depth and pH were also measured. Weekly or fortnightly phytoplankton and zooplankton samples and physical variables have been collected at LKR since September 2005 as part of an independent sampling program carried out by the KWS, Waikato University and Cawthron Institute. In this project the 2-year data set was used to assist with analysis of lake processes and for validation of the hydrodynamic-ecological model DYRESM-CAEDYM. Between 12 and 15 February, 2007, electric fishing was undertaken within the LKR. A total of 3,946 P. fluviatilis were removed and the effects on phytoplankton and zooplankton concentrations were investigated. To increase knowledge of the physiology of A. planktonica, laboratory experiments were undertaken using cultures subjected to a range of different light intensities and temperature regimes The phytoplankton assemblage of the LKR shows very distinct temporal variations. Summer stratification occurred in the LKR for ~4 months each summer. During these periods A. planktonica comprised up to 99.9% of the surface phytoplankton population. During isothermy chlorophytes, bacillariophytes and small flagellated dinophytes are co-dominant in the phytoplankton assemblage. The results of the QPCR showed distinct diurnal vertical movement of A. planktonica, with the highest cell concentrations occurring at 1900 hours at the surface. Ammonium (NH4-N) is the dominant species of inorganic nitrogen during periods of stratification, while nitrate (NO3-N) is generally dominant during times of isothermy. Phosphate concentrations at surface and depth remained at low levels throughout the sampling period. The large surface populations of A. planktonica, are probably responsible for the elevated total nitrogen concentrations in surface waters during stratified periods. There appeared to be some short term effects of the P. fluviatilis removal with an increase in large crustaceans (e.g., Daphnia sp.) and a reduction in A. planktonica densities observed in the months following the P. fluviatilis removal. Only a small proportion of the total P. fluviatilis population was removed and it is unlikely that the effects will be long-lasting without subsequent removal steps. However, it seems likely that P. fluviatilis is one of the factors contributing to cyanobacterial blooms and management of this fish species should be considered in future lake restoration plans. Growth experiments indicated A. planktonica grow over a wide range of light intensities and temperatures, although highest growth rates were generally associated with higher temperatures (25 C) and light intensities (60 - 140 μmol m-2 s-1). Ecological and hydrodynamic trends within the LKR over a two year period were simulated with adequate success using the model DYRESM-CAEDYM. Management scenarios simulated using DYRESM-CAEDYM suggest implementation of an artificial destratification system in the LKR may be the most practical and effective means of controlling A. planktonica blooms. The addition of an artificial aeration system emitting air at a rate of approximately 50 l-1 s-1 should result in an isothermal system. Without summer stratification some of the physiological features of A. planktonica (e.g., buoyancy regulation and nitrogen-fixation) that give it a competitive advantage over other phytoplankton species will be reduced.