A sequence of autonomous underwater glider deployments were used to characterize the spatial-temporal variability of the region over an eight month period from late September to May. Strongly stratified system was found in early fall with significant gradients in both temperature (T) and salinity (S), during winter T < 23°C and minimum S of 40.3 psu was observed and resulting in weakened stratification that enables deep convective mixing and upwelling of deep water by cyclonic circulations in the region leading to significant biomass increase. Throughout the entire observational period the slope of the 28 and 28.5 kg/m3 isopycnals remained sloping downward from offshore toward the coast reflected a persistent northward geostrophic flow. The depth of the 180 μmol/kg isopleth of oxygen, indicative of the top of the nutricline, paralleled the depth of the 28 kg/m3, but remained slightly deeper than the isopycnal. The deep winter mixing did not penetrate the nutricline where the mixed layer was deeper near the coast. However, because of the cyclonic signature the 28 kg/m3 rose to the surface offshore, injecting nutrients into the surface layer and promoting increased biomass in the central Red Sea. With the presence of cyclonic eddies, there was evidence of subduction associated with the cross-eddy circulation. This subducted flow was toward the coast within the domain of the glider observations. During this period, increases in the particulate backscatter were associated with increased chlorophyll indicating that the suspended particles were primarily phytoplankton particles. Within the mean northward flow there is a cross-basin flow wherein water is upwelled near the center of the Red Sea, there is a eastward component to the northward flow, and subsequent downwelling near the coasts. Within the surface flow subductive processes lead not only to a horizontal flow, but also a downward component toward the coast. Overall transport is very 3-dimensional in the northern Red Sea, such that northward transport and its associated embedded circulations are northward, while southward transport occurs on the western side of the Red Sea, in contrast to some of the descriptions of flow provided in earlier papers.

Made available in DSpace on 2014-12-17T15:03:22Z (GMT). No. of bitstreams: 1 FaranciscoRSF_restricoes.pdf: 1206510 bytes, checksum: bdf6c5d3c8390b9e1ea63d1d4080d1ed (MD5) Previous issue date: 2008-12-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Eutrophication has been listed as one of the main problems of water pollution on a global level. In the Brazilian semi-arid areas this problem takes even greater proportions due to characteristical water scarcity of the region. It is extremely important to the predictive eutrophication models development and to the reservoirs management in the semi-arid region, studies that promotes understanding of the mechanisms responsible for the expansion and control of algae blooms, essential for improving the water quality of these environments. The present study had as its main aims, evaluate the temporal pattern of trophic state, considering the influence of nutrients (N and P) and the light availability in the water column in the development of phytoplankton biomass, and perform the mathematical modelling of changes in phosphorus and chlorophyll a concentrations in the Cruzeta man-made lake located on Serid?, a typical semi-arid region of Rio Grande do Norte. To this, a fortnightly monitoring was performed in the reservoir in 05 stations over the months of March 2007 to May 2008. Were measured the concentrations of total phosphorus, total organic nitrogen, chlorophyll a, total, fixed and volatile suspended solids, as well as the measure of transparency (Secchi) and the profiles of photosynthetic active radiation (PAR), temperature, pH, dissolved oxygen and electrical conductivity in the water column. Measurements of vertical profiles have shown some periods of chemical and thermal stratification, especially in the rainy season, due to increased water column depth, however, the reservoir can be classified as warm polimitic. During the study period the reservoir was characterized as eutrophic considering the concentrations of phosphorus and most of the time as mesotrophic, based on the concentrations of chlorophyll a, according to the Thornton & Rast (1993) classification. The N:P relations suggest N limitation, conversely, significant linear relationship between the algae biomass and nutrients (N and P) were not observed in our study. However, a relevant event was the negative and significant correlation presented by Kt and chlorophyll a (r ? = 0.83) at the end of the drought of 2007 and the rainy season of 2008, and the algal biomass collapse observed at the end of the drought season (Dec/07). The equation used to simulate the change in the total phosphorus was not satisfactory, being necessary inclusion of parameters able to increase the power of the model prediction. The chlorophyll a simulation presented a good adjustment trend, however there is a need to check the calibrated model parameters and subsequent equation validation / A eutrofiza??o tem se apresentado como um dos principais problemas de polui??o aqu?tica a n?vel global. No semi-?rido brasileiro este problema toma propor??es ainda maiores devido a escassez de ?gua caracter?stica da regi?o. Torna-se extremamente relevante para o desenvolvimento do modelos preditivos de eutrofiza??o e para a gest?o dos reservat?rios da regi?o semi-?rida, a realiza??o de estudos que propiciem a compreens?o dos mecanismos respons?veis pela expans?o e controle de flora??es de algas, fundamentais para a melhoria da qualidade da ?gua desses ambientes. Diante disso, o presente estudo teve como objetivos principais, avaliar o padr?o temporal do estado tr?fico, considerando a influ?ncia dos nutrientes (N e P) e a disponibilidade de luz na coluna d ?gua no desenvolvimento da biomassa fitoplanct?nica, e realizar a modelagem matem?tica da varia??o das concentra??es de f?sforo e clorofila a no a?ude Cruzeta localizado na regi?o do Serid?, regi?o t?pica do semi-?rido do Rio Grande do Norte. Para tanto, foi realizado o monitoramento do reservat?rio com amostragens de ?gua quinzenais em 05 pontos de coleta ao longo dos meses de mar?o de 2007 a maio de 2008, sendo determinadas as concentra??es de f?sforo total, nitrog?nio org?nico total, clorofila a, e s?lidos suspensos totais, fixos e vol?teis, al?m da medida de transpar?ncia (Secchi) e dos perfis de radia??o fotossinteticamente ativa (RFA), temperatura, pH, oxig?nio dissolvido e condutividade el?trica na coluna d ?gua. As medi??es dos perfis verticais realizados evidenciaram alguns per?odos de estratifica??o t?rmica e qu?mica, notadamente no per?odo chuvoso, devido a maior profundidade da coluna d ?gua, no entanto o reservat?rio pode ser classificado como pol?mitico quente. Durante o per?odo estudado o reservat?rio caracterizou-se como eutr?fico considerando-se as concentra??es de f?sforo e mesotr?fico na maior parte do tempo, com base nas concentra??es de clorofila a, segundo a classifica??o de Thornton & Rast (1993). As raz?es N:P observadas sugerem limita??o por N, opostamente, rela??es lineares significativas entre a biomassa de algas e os nutrientes (N e P) n?o foram observadas no nosso estudo. Entretanto, chamou aten??o a rela??o negativa e significativa apresentada pelo Kt e clorofila a (r?=0.83) no final do per?odo de estiagem de 2007 e per?odo chuvoso de 2008, e do colapso da biomassa algal observado no final do per?odo de estiagem (dez/07). A equa??o utilizada para simular a varia??o do f?sforo total n?o apresentou ajuste satisfat?rio, sendo necess?rio portanto, inser??o de par?metros capazes de elevar o poder de predi??o do modelo. A simula??o para clorofila a apresentou uma boa tend?ncia de ajuste, entretanto h? necessidade de verifica??o dos par?metros calibrados no modelo e posterior valida??o da equa??o

A biomassa e a produtividade primária fitoplanctônica da costa sudeste foram estimadas através de sensoriamento remoto da cor do oceano e dados in situ. Foram realizados quatro cruzeiros hidrográficos sazonais de mesoescala nas regiões de plataforma e talude continental durante os verões e invernos de 2001 e 2002. Com a descrição das características hidrográficas e distribuições de nutrientes inorgânicos dissolvidos, complementada pela análise de imagens orbitais (AVHRR e SeaWiFS), foi possível determinar os padrões de circulação da Corrente do Brasil, monitorar ressurgências costeiras e de quebra de plataforma, meandramentos e vórtices de mesoescala, assim como, a intrusão de águas frias, menos salinas e ricas em nutrientes vindas de sul sobre a plataforma continental, no inverno. A área de estudo foi dividida nos domínios de plataforma, talude-verão e talude-inverno, baseados em análises estatísticas da biomassa e produção primária fitoplanctônica integradas na zona eufótica. O domínio de plataforma não apresentou diferença sazonal devido ao processo de intrusão da ACAS sobre a plataforma. Este foi apontado como o principal processo de fertilização da zona eufótica nas águas de plataforma e talude tanto no verão como no inverno. Imagens da produtividade primária oceânica foram geradas pela primeira vez para a costa brasileira a partir de imagens da cor do oceano (SeaWiFS), utilizando-se um algoritmo semi-analítico não espectral, verticalmente homogêneo e dados fotossintéticos in situ obtidos simultaneamente. O avanço científico decorrente do presente trabalho é significativo, pois as estimativas de biomassa e produtividade primária fitoplanctônica através de imagens da cor do oceano e dados in situ coletados simultaneamente, ainda não haviam sido realizados na Zona Econômica Exclusiva brasileira. Comparações entre temperaturas da superfície do mar obtidas pelo AVHRR e medidas in situ (CTD) mostraram diferenças menores que 0,5ºC. O algoritmo OC4 apresentou o melhor desempenho entre os algoritmos testados (OC2, GSM01 e NN) para estimar a concentração de clorofila a, a partir de dados SeaWiFS, em relação às medidas fluorimétricas in situ, subestimando as concentrações mais baixas e superestimando as mais altas. Os algoritmos semi-analíticos de produção primária por satélite testados concordaram com as estimativas in situ (14C) por um fator de 2, nos melhores casos. As análises de regressão múltipla mostraram uma relação linear entre a produção primária e a biomassa fitoplanctônica integradas na coluna d’água. Uma abordagem alternativa baseada em uma rede neural artificial multicamada perceptron (12-5-1) foi testada como um modelo não linear para estimar a produção primária integrada na coluna d’água. A produção primária média para o período 2001-2002 foi estimada a partir de dados SeaWiFS em 386 gC m-2 a-1 e a produção primária potencial para a plataforma continental sudeste brasileira (PCSE) foi estimada em 0,06 Gt C a-1. O limite superior da produção pesqueira foi estimado considerando-se uma cadeia trófica com 2,8 níveis e uma eficiência trófica média de 10%. O resultado obtido foi cerca de 90 vezes maior que a captura média entre 1991 e 2000. Porém, se a produção pesqueira estimada for um limite superior que será reduzido a 10% ou 20% devido à acessibilidade ambiental, os recursos pesqueiros estariam limitados por alimento na PCSE. / The phytoplankton biomass and primary production of the Southeastern Brazilian coast are estimated using ocean color remote sensing and in situ data. This study is based on four seasonal hydrographic cruises carried out during the summer and winter of 2001 and 2002, along the continental shelf and slope waters. The hydrographic and dissolved inorganic nutrients in situ measurements were complemented by the sea surface temperature from the Advanced Very High Resolution Radiometer (AVHRR) sensor and chlorophyll a estimates from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) sensor to identify relevant features of the Brazil Current (BC) circulation related to the biological dynamics of this oceanic region. Several meanders and vortices were observed throughout the period along the inshore frontal zone of the BC in association with break shelf upwelling. Coastal upwelling events were observed to encompass a region larger than normally indicated in the literature and anomalous upwelling events were observed during the winter. Cold, less saline, and nutrient rich waters were observed flowing northward over the shelf during the winter. Based on statistical analysis of water column integrated chlorophyll and primary production the study area was divided into 3 domains: shelf, summer-slope, and winter-slope. The shelf domain did not present a significant seasonal difference due to the intrusion of South Atlantic Central Water over the shelf. This intrusion is the main process for the euphotic zone productivity enhancement in the shelf and slope waters during the summer and winter. A non-spectral and vertically homogeneous semi-analytical algorithm was applied to the SeaWiFS ocean color data, which incorporate simultaneously measured in situ photosynthetic parameters. This is the first time that the phytoplankton primary production and biomass estimation over the Brazilian Economic Exclusive Zone were done through remote sensed ocean colour and simultaneously acquired in situ data. Comparisons between in situ measurements and AVHRR based estimates of sea surface temperature have shown differences lower than 0.5ºC. The OC4 algorithm performed better then other chlorophyll retrieval algorithms (OC2, GSM01 and NN) when compared with in situ fluorometric data. However, it overestimates chlorophyll a at higher concentrations and underestimates at lower concentration. The best performing ocean color remote sensing primary productivity algorithms tested agreed with the 14C-based estimates within a factor of 2. A multiple regression analysis showed linear relation between the water column integrated primary production and the integrated chlorophyll. An alternative approach based on a backpropagation multilayer perceptron artificial neural network (12-5-1) was tested to estimate the water column integrated primary production for non-linear phytoplankton production modeling. The mean primary production for the 2 year period in the South Brazilian Bight (SBB) estimated from SeaWiFS is 386 gC m-2 yr-1, and the potential primary production is 0.06 Gt C yr-1. The upper bound for sustainable fish yield was estimated using a food chain of 2.8 links and an average trophic efficiency of 10%. The result was ~90 times larger than the observed fish catch from 1991 through 2000. If this fish yield is an upper bound that will be decreased to 10% or 20% by environmental accessibility, the fishery resources in the SBB are likely to be food-limited.

A biomassa e a produtividade primária fitoplanctônica da costa sudeste foram estimadas através de sensoriamento remoto da cor do oceano e dados in situ. Foram realizados quatro cruzeiros hidrográficos sazonais de mesoescala nas regiões de plataforma e talude continental durante os verões e invernos de 2001 e 2002. Com a descrição das características hidrográficas e distribuições de nutrientes inorgânicos dissolvidos, complementada pela análise de imagens orbitais (AVHRR e SeaWiFS), foi possível determinar os padrões de circulação da Corrente do Brasil, monitorar ressurgências costeiras e de quebra de plataforma, meandramentos e vórtices de mesoescala, assim como, a intrusão de águas frias, menos salinas e ricas em nutrientes vindas de sul sobre a plataforma continental, no inverno. A área de estudo foi dividida nos domínios de plataforma, talude-verão e talude-inverno, baseados em análises estatísticas da biomassa e produção primária fitoplanctônica integradas na zona eufótica. O domínio de plataforma não apresentou diferença sazonal devido ao processo de intrusão da ACAS sobre a plataforma. Este foi apontado como o principal processo de fertilização da zona eufótica nas águas de plataforma e talude tanto no verão como no inverno. Imagens da produtividade primária oceânica foram geradas pela primeira vez para a costa brasileira a partir de imagens da cor do oceano (SeaWiFS), utilizando-se um algoritmo semi-analítico não espectral, verticalmente homogêneo e dados fotossintéticos in situ obtidos simultaneamente. O avanço científico decorrente do presente trabalho é significativo, pois as estimativas de biomassa e produtividade primária fitoplanctônica através de imagens da cor do oceano e dados in situ coletados simultaneamente, ainda não haviam sido realizados na Zona Econômica Exclusiva brasileira. Comparações entre temperaturas da superfície do mar obtidas pelo AVHRR e medidas in situ (CTD) mostraram diferenças menores que 0,5ºC. O algoritmo OC4 apresentou o melhor desempenho entre os algoritmos testados (OC2, GSM01 e NN) para estimar a concentração de clorofila a, a partir de dados SeaWiFS, em relação às medidas fluorimétricas in situ, subestimando as concentrações mais baixas e superestimando as mais altas. Os algoritmos semi-analíticos de produção primária por satélite testados concordaram com as estimativas in situ (14C) por um fator de 2, nos melhores casos. As análises de regressão múltipla mostraram uma relação linear entre a produção primária e a biomassa fitoplanctônica integradas na coluna d’água. Uma abordagem alternativa baseada em uma rede neural artificial multicamada perceptron (12-5-1) foi testada como um modelo não linear para estimar a produção primária integrada na coluna d’água. A produção primária média para o período 2001-2002 foi estimada a partir de dados SeaWiFS em 386 gC m-2 a-1 e a produção primária potencial para a plataforma continental sudeste brasileira (PCSE) foi estimada em 0,06 Gt C a-1. O limite superior da produção pesqueira foi estimado considerando-se uma cadeia trófica com 2,8 níveis e uma eficiência trófica média de 10%. O resultado obtido foi cerca de 90 vezes maior que a captura média entre 1991 e 2000. Porém, se a produção pesqueira estimada for um limite superior que será reduzido a 10% ou 20% devido à acessibilidade ambiental, os recursos pesqueiros estariam limitados por alimento na PCSE. / The phytoplankton biomass and primary production of the Southeastern Brazilian coast are estimated using ocean color remote sensing and in situ data. This study is based on four seasonal hydrographic cruises carried out during the summer and winter of 2001 and 2002, along the continental shelf and slope waters. The hydrographic and dissolved inorganic nutrients in situ measurements were complemented by the sea surface temperature from the Advanced Very High Resolution Radiometer (AVHRR) sensor and chlorophyll a estimates from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) sensor to identify relevant features of the Brazil Current (BC) circulation related to the biological dynamics of this oceanic region. Several meanders and vortices were observed throughout the period along the inshore frontal zone of the BC in association with break shelf upwelling. Coastal upwelling events were observed to encompass a region larger than normally indicated in the literature and anomalous upwelling events were observed during the winter. Cold, less saline, and nutrient rich waters were observed flowing northward over the shelf during the winter. Based on statistical analysis of water column integrated chlorophyll and primary production the study area was divided into 3 domains: shelf, summer-slope, and winter-slope. The shelf domain did not present a significant seasonal difference due to the intrusion of South Atlantic Central Water over the shelf. This intrusion is the main process for the euphotic zone productivity enhancement in the shelf and slope waters during the summer and winter. A non-spectral and vertically homogeneous semi-analytical algorithm was applied to the SeaWiFS ocean color data, which incorporate simultaneously measured in situ photosynthetic parameters. This is the first time that the phytoplankton primary production and biomass estimation over the Brazilian Economic Exclusive Zone were done through remote sensed ocean colour and simultaneously acquired in situ data. Comparisons between in situ measurements and AVHRR based estimates of sea surface temperature have shown differences lower than 0.5ºC. The OC4 algorithm performed better then other chlorophyll retrieval algorithms (OC2, GSM01 and NN) when compared with in situ fluorometric data. However, it overestimates chlorophyll a at higher concentrations and underestimates at lower concentration. The best performing ocean color remote sensing primary productivity algorithms tested agreed with the 14C-based estimates within a factor of 2. A multiple regression analysis showed linear relation between the water column integrated primary production and the integrated chlorophyll. An alternative approach based on a backpropagation multilayer perceptron artificial neural network (12-5-1) was tested to estimate the water column integrated primary production for non-linear phytoplankton production modeling. The mean primary production for the 2 year period in the South Brazilian Bight (SBB) estimated from SeaWiFS is 386 gC m-2 yr-1, and the potential primary production is 0.06 Gt C yr-1. The upper bound for sustainable fish yield was estimated using a food chain of 2.8 links and an average trophic efficiency of 10%. The result was ~90 times larger than the observed fish catch from 1991 through 2000. If this fish yield is an upper bound that will be decreased to 10% or 20% by environmental accessibility, the fishery resources in the SBB are likely to be food-limited.

O conhecimento da estrutura da comunidade fitoplanctônica depende de estimativas robustas de biomassa e de como variam suas taxas de absorção de luz. Assim, é essencial descrever a relação entre grupos taxonômicos e seus morfotipos. Este trabalho investigou a influência da forma do fitoplâncton, por meio de sua razão S/V no coeficiente de absorção de luz. Comunidades fitoplanctônica de plataforma continental foram detalhadas taxonomicamente e categorizada como morfotipos para o cálculo de biomassa fitoplanctônica, razão S/V e tamanho médio, e relações com o coeficiente de absorção de luz foram exploradas. A razão Carbono:Clorofila-a variou entre a superfície e máximo de fluorescência, enquanto a biomassa permaneceu constante, sendo diatomáceas e dinoflagelados os principais grupos formadores de biomassa. Observamos morfotipos exclusivos a um dado grupo taxonômico, contudo, os intervalos de S/V são compartilhados entre grupos taxonômicos e entre morfotipos. A conversão entre biovolume e biomassa deve incorporar informações taxonômicas. A S/V média da comunidade não mostrou relação com a magnitude da absorção de luz pelo fitoplâncton. Os resultados puderam comprovar a baixa performance de modelos para a determinação de tamanho do fitoplâncton por pigmentos e sugerem que a fotoaclimatação deve ser incorporada para a discriminação bio-ótica do fitoplâncton marinho / Acurate descriptions of phytoplankton community structures depends on reliable estimation of biomass and on the understanding of light absorption. It is crucial to trace relationships between taxonomic groups and geometrical morphotypes. We investigated the influence of phytoplankton shapes in the light absorption coefficient by investigating surface/volume (S/V) ratios. Phytoplankton communities from the continental shelf were detailed taxonomicaly and also categorized in geometrical morphotypes in order to calculate phytoplankton biomass, S/V ratios and size to explore relatioships with spectral light absorption coefficients. The Carbon-to-Chlorophyll ratio varied between surface and the chlorophyll maximum deph while biomass remain fairly constant, and both diatoms and dinoflagellates were the main groups present in high biomass. Exclusive morfotypes were observed for some taxonomic groups, however, S/V ratios ranges were shared by distinct taxonomic groups and morphotypes. The conversion between biovolume and biomass must take taxonomic composition into account. The mean S/V for a community show no relatioship with the magnitude of ligth absorption. The results show a low performance of pigment-based models for description of fitoplankton size classes and highlight the importance of incorporating photooaclimation for bio-optical discrimination of marine phytoplankton communities

O conhecimento da estrutura da comunidade fitoplanctônica depende de estimativas robustas de biomassa e de como variam suas taxas de absorção de luz. Assim, é essencial descrever a relação entre grupos taxonômicos e seus morfotipos. Este trabalho investigou a influência da forma do fitoplâncton, por meio de sua razão S/V no coeficiente de absorção de luz. Comunidades fitoplanctônica de plataforma continental foram detalhadas taxonomicamente e categorizada como morfotipos para o cálculo de biomassa fitoplanctônica, razão S/V e tamanho médio, e relações com o coeficiente de absorção de luz foram exploradas. A razão Carbono:Clorofila-a variou entre a superfície e máximo de fluorescência, enquanto a biomassa permaneceu constante, sendo diatomáceas e dinoflagelados os principais grupos formadores de biomassa. Observamos morfotipos exclusivos a um dado grupo taxonômico, contudo, os intervalos de S/V são compartilhados entre grupos taxonômicos e entre morfotipos. A conversão entre biovolume e biomassa deve incorporar informações taxonômicas. A S/V média da comunidade não mostrou relação com a magnitude da absorção de luz pelo fitoplâncton. Os resultados puderam comprovar a baixa performance de modelos para a determinação de tamanho do fitoplâncton por pigmentos e sugerem que a fotoaclimatação deve ser incorporada para a discriminação bio-ótica do fitoplâncton marinho / Acurate descriptions of phytoplankton community structures depends on reliable estimation of biomass and on the understanding of light absorption. It is crucial to trace relationships between taxonomic groups and geometrical morphotypes. We investigated the influence of phytoplankton shapes in the light absorption coefficient by investigating surface/volume (S/V) ratios. Phytoplankton communities from the continental shelf were detailed taxonomicaly and also categorized in geometrical morphotypes in order to calculate phytoplankton biomass, S/V ratios and size to explore relatioships with spectral light absorption coefficients. The Carbon-to-Chlorophyll ratio varied between surface and the chlorophyll maximum deph while biomass remain fairly constant, and both diatoms and dinoflagellates were the main groups present in high biomass. Exclusive morfotypes were observed for some taxonomic groups, however, S/V ratios ranges were shared by distinct taxonomic groups and morphotypes. The conversion between biovolume and biomass must take taxonomic composition into account. The mean S/V for a community show no relatioship with the magnitude of ligth absorption. The results show a low performance of pigment-based models for description of fitoplankton size classes and highlight the importance of incorporating photooaclimation for bio-optical discrimination of marine phytoplankton communities

In light of increasing harmful algal blooms and the need to protect human health and aquatic resources, proactive management approaches merit further study. For this purpose I conducted field samplings to characterize plankton community composition and laboratory experiments to test some approaches to new management schemes in the lower Rincon Delta. On site measurements and microscopic analysis showed that environmental parameters and plankton community composition varied considerably among sampling stations and sampling dates. A recent modeling study suggested that manipulation of freshwater inflow to estuaries might prevent phytoplankton blooms and enhance secondary productivity. To test this theory I conducted three semi-continuous design and flow-through incubation design experiments using natural plankton assemblages. I investigated the effect of two different pulsing regimes of inflow and nutrient loading on zooplankton densities, and phytoplankton biomass and diversity. Despite differences in zooplankton structure and phytoplankton community composition between the two experiment designs, the results confirmed that pulsed inflows might alter plankton dynamics. My findings showed that 3-day pulse treatments consistently supported greater zooplankton densities and higher phytoplankton species diversity when compared to 1-day pulse treatments. In addition, accumulation of phytoplankton biovolume remained low during 3-day pulse treatments. Differences in zooplankton performance between 3-day pulse and 1-day pulse inflow treatments were likely due to the ability of phytoplankton to uptake and store greater amounts of nutrients under conditions of 3-day pulse inflow. This resulted in food of higher quality for zooplankton, and might have supported greater zooplankton population growth rates. Additionally, in an attempt to understand the mechanisms leading to high biodiversity in aquatic ecosystems, I built a resource-storage model and studied the effects of resource-storage on competition of multiple phytoplankton species on multiple abiotic resources. I compared this model with a well-established multi-species competition model. My results showed that for certain species combinations a resource-storage-based model can generate dissimilar outcomes when compared to a model without resource-storage.

In light of increasing harmful algal blooms and the need to protect human health and aquatic resources, proactive management approaches merit further study. For this purpose I conducted field samplings to characterize plankton community composition and laboratory experiments to test some approaches to new management schemes in the lower Rincon Delta. On site measurements and microscopic analysis showed that environmental parameters and plankton community composition varied considerably among sampling stations and sampling dates. A recent modeling study suggested that manipulation of freshwater inflow to estuaries might prevent phytoplankton blooms and enhance secondary productivity. To test this theory I conducted three semi-continuous design and flow-through incubation design experiments using natural plankton assemblages. I investigated the effect of two different pulsing regimes of inflow and nutrient loading on zooplankton densities, and phytoplankton biomass and diversity. Despite differences in zooplankton structure and phytoplankton community composition between the two experiment designs, the results confirmed that pulsed inflows might alter plankton dynamics. My findings showed that 3-day pulse treatments consistently supported greater zooplankton densities and higher phytoplankton species diversity when compared to 1-day pulse treatments. In addition, accumulation of phytoplankton biovolume remained low during 3-day pulse treatments. Differences in zooplankton performance between 3-day pulse and 1-day pulse inflow treatments were likely due to the ability of phytoplankton to uptake and store greater amounts of nutrients under conditions of 3-day pulse inflow. This resulted in food of higher quality for zooplankton, and might have supported greater zooplankton population growth rates. Additionally, in an attempt to understand the mechanisms leading to high biodiversity in aquatic ecosystems, I built a resource-storage model and studied the effects of resource-storage on competition of multiple phytoplankton species on multiple abiotic resources. I compared this model with a well-established multi-species competition model. My results showed that for certain species combinations a resource-storage-based model can generate dissimilar outcomes when compared to a model without resource-storage.