Dinâmica espaço-temporal de variáveis limnológicas em uma área alagada localizada no Vale do Ribeira do Iguape (São Paulo, Brasil) em diferentes períodos hidrológicos

AIM: The main goal of this research was to investigate the influence of the hydrological pulses on the space-temporal dynamics of physical and chemical variables in a wetland adjacent to Jacupiranguinha River (São Paulo, Brazil); METHODS: Eleven sampling points were distributed among the wetland, a tributary by its left side and the adjacent river. Four samplings were carried out, covering the rainy and the dry periods. Measures of pH, dissolved oxygen, electrical conductivity and redox potential were taken in regular intervals of the water column using a multiparametric probe. Water samples were collected for the nitrogen and total phosphorus analysis, as well as their dissolved fractions (dissolved inorganic phosphorus, total dissolved phosphorus, ammoniacal nitrogen and nitrate). Total alkalinity and suspended solids were also quantified; RESULTS: The Multivariate Analysis of Variance showed the influence of the seasonality on the variability of the investigated variables, while the Principal Component Analysis gave rise in two statistical significant axes, which delimited two groups representative of the rainy and dry periods. Hydrological pulses from Jacupiranguinha River, besides contributing to the inputs of nutrients and sediments during the period of connectivity, accounted for the decrease in spatial gradients in the wetland. This "homogenization effect" was evidenced by the Cluster Analysis. The research also showed an industrial raw effluent as the main point source of phosphorus to the Jacupiranguinha River and, indirectly, to the wetland; CONCLUSIONS: Therefore, considering the scarcity of information about the wetlands in the study area, this research, besides contributing to the understanding of the influence of hydrological pulses on the investigated environmental variables, showed the need for adoption of conservation policies of these ecosystems face the increase anthropic pressures that they have been submitted, which may result in lack of their ecological, social and economic functions

Contribution to limnological knowledge of brazilian semi-arid reservoir that supply Fortaleza\'s metropolitan region: Pacajus and Gavião dams (Ceará, Brazil)

O principal objetivo deste estudo foi investigar a influência das alterações nas condições climáticas e hidrodinâmicas sobre a estabilidade física, a disponibilidade de recursos, a estrutura da comunidade zooplanctônica e os padrões de heterogeneidade espacial dos açudes Pacajus e Gavião, amostrados bimestralmente entre nov. 1988 e dez. 1998. Nos dois reservatórios os pontos foram distribuídos ao longo dos respectivos eixos longitudinais principais, sendo 06 no açude Pacajus e 05 no Gavião. As medidas de temperatura da água, condutividade elétrica, turbidez, pH e oxigênio dissolvido (OD) foram realizadas em intervalos regulares da coluna d\'água com o uso de sonda multiparamétrica (HORIBA U-10). Amostras para determinação de alcalinidade total, nutrientes inorgânicos dissolvidos e fósforo total foram coletadas em profundidades correspondentes à superfície, meio e fundo da coluna d´água. A determinação de clorofila a foi realizada em amostras de superfície. A estrutura vertical dacoluna d\'água dos reservatórios foi caracterizada por pequenos gradientes térmicos e salinos, especialmente durante o segundo semestre, quando o vento atuou como principal forçante indutora de mistura turbulenta. Nessa época do ano as concentrações de OD foram típicas de supersaturação nos dois reservatórios. A dinâmica de nutrientes nos açudes Pacajus e Gavião dependeu das contribuições alóctones durante o período chuvoso e dos processos de regeneração e carga interna durante o período de estiagem. O maior grau de enriquecimento e biomassa algal observados no açude Pacajus classificou-o como eutrófico-hipereutrófico, enquanto que o açude Gavião foi classificado como meso-eutrófico. A heterogeneidade espacial dos reservatórios foi condicionada pelo regime hidrológico do rio barrado, no caso do açude Pacajus, pelos gradientes hidráulicos ao longo ) do eixo longitudinal, pela influência dos procedimentos de transferências hídricas internas, especialmente no açude Gavião, e pela irregularidade na distribuição espacial do fitoplâncton, acompanhando gradientes tróficos. De modo geral, pode-se afirmar que as espécies do zooplâncton identificadas nos açude Pacajus e Gavião são bem representativas da fauna de microinvertebrados planctônicos Neotropical, com amplo espectro de distribuição geográfica no Brasil. A dominância dos Rotifera no açude Pacajus em dez. 1998 foi indicativo das condições hipereutróficas da maioria dos pontos amostrados. Espacialmente, os organismos desse grupo, representados principalmente por espécies dos gêneros Brachionus e Keratella, indicadores de ambientes nutriente-enriquecidos, foram mais abundantes nos compartimentos com estado trófico superior. Comportamento similar foi observado para o Copepoda Cyclopoida Thermocyclops decipiens, espécie indicadora de condições eutróficas, a qual colonizou, preferencialmente, regiões com maior concentração de nutrientes. Ao contrário, organismos dos grupos Copepoda e Cladocera foram mais abundantes nas regiões menos enriquecidas dos reservatórios, apresentando gradientes longitudinais inversos em relação àqueles dos Rotifera e Cyclopoida. Portanto, a distribuição e os padrões de dominância do zooplâncton nos açudes Pacajus e Gavião foram condicionadas, principalmente, pela variabilidade espaço-temporal dos gradientes tróficos.The main aim of this research was to investigate the influence of climatic and hydrodynamics\' alterations about physical stability, resources availability, zooplankton community structure and spatial heterogeneity standard of Pacajus and Gavião dams, collected at two-month period between Nov. 1988 and Dec. 1998. In the reservoirs, the sample stations were distributed along the main longitudinal axis, being six on Pacajus dam and five on Gavião dam. Water temperature, electric conductivity, turbidity, pH and dissolved oxygen were measured in regular intervals in water column using a multiparametric probe (HORIBA U-10). Sample for total alkalinity, inorganic dissolved nutrients and total phosphorous determination were collected in the corresponding depth in water column (surface, middle and deep). Chlorophyll a determination was measured in surface samples. Vertical structure of water column in reservoirs was characterized by little thermal and saline gradients, especially duringsecond semester, when wind was the main induced force of turbulent mixture. At this same period dissolved oxygen concentrations were typical supersaturated on both reservoirs. Nutrients dynamic on both dams were dependent on allocthonous contributions during rainy season and on regeneration processes and internal load during dry season. The greatest rank of enrichment and algal biomass measured in Pacajus\' dam classified it as eutrophic or hipereutrophic while Gavião\'s dam was mesotrophic or eutrophic. Spatial heterogeneity of reservoirs was controlled by hydrological regime of the dammed river in case of Pacajus\' dam, by hydraulic gradients along main axis and the influence of internal hydraulic transferences proceedings in the case of Gavião\'s dam and by irregularity on phytoplankton spatial distribution according to trophic gradients. In general, it can be said that zooplankton species ) identified on both dams are representative of Neotropical plankton micro invertebrate fauna, with large geographic distribution in Brazil. The dominance of rotifers in Pacajus\' dam on Dec. 1998 was favored by hipereutrophic conditions in most of sample stations. Especially, this group of organisms, represented mainly by Brachionus and Keratella, indicators of nutrient enriched environments, were abundant in segments with higher trophic state. Similar behavior was observed to the copepod Thermocyclops decipiens, an indicator of eutrophic conditions, which has colonized regions with higher nutrient concentrations. On the other hand, Copepoda and Cladocera were more abundant on poorer nutrient compartiments of reservoirs, presenting inverse longitudinal gradients in relation with those of Rotifera and Cyclopoida. Therefore, distribution and patterns of zooplankton dominance in Pacajus and Gavião dams were conditioned mainly by spatial-temporal variability of trophic gradients

Contribution to limnological knowledge of brazilian semi-arid reservoir that supply Fortaleza\'s metropolitan region: Pacajus and Gavião dams (Ceará, Brazil)

O principal objetivo deste estudo foi investigar a influência das alterações nas condições climáticas e hidrodinâmicas sobre a estabilidade física, a disponibilidade de recursos, a estrutura da comunidade zooplanctônica e os padrões de heterogeneidade espacial dos açudes Pacajus e Gavião, amostrados bimestralmente entre nov. 1988 e dez. 1998. Nos dois reservatórios os pontos foram distribuídos ao longo dos respectivos eixos longitudinais principais, sendo 06 no açude Pacajus e 05 no Gavião. As medidas de temperatura da água, condutividade elétrica, turbidez, pH e oxigênio dissolvido (OD) foram realizadas em intervalos regulares da coluna d\'água com o uso de sonda multiparamétrica (HORIBA U-10). Amostras para determinação de alcalinidade total, nutrientes inorgânicos dissolvidos e fósforo total foram coletadas em profundidades correspondentes à superfície, meio e fundo da coluna d´água. A determinação de clorofila a foi realizada em amostras de superfície. A estrutura vertical dacoluna d\'água dos reservatórios foi caracterizada por pequenos gradientes térmicos e salinos, especialmente durante o segundo semestre, quando o vento atuou como principal forçante indutora de mistura turbulenta. Nessa época do ano as concentrações de OD foram típicas de supersaturação nos dois reservatórios. A dinâmica de nutrientes nos açudes Pacajus e Gavião dependeu das contribuições alóctones durante o período chuvoso e dos processos de regeneração e carga interna durante o período de estiagem. O maior grau de enriquecimento e biomassa algal observados no açude Pacajus classificou-o como eutrófico-hipereutrófico, enquanto que o açude Gavião foi classificado como meso-eutrófico. A heterogeneidade espacial dos reservatórios foi condicionada pelo regime hidrológico do rio barrado, no caso do açude Pacajus, pelos gradientes hidráulicos ao longo ) do eixo longitudinal, pela influência dos procedimentos de transferências hídricas internas, especialmente no açude Gavião, e pela irregularidade na distribuição espacial do fitoplâncton, acompanhando gradientes tróficos. De modo geral, pode-se afirmar que as espécies do zooplâncton identificadas nos açude Pacajus e Gavião são bem representativas da fauna de microinvertebrados planctônicos Neotropical, com amplo espectro de distribuição geográfica no Brasil. A dominância dos Rotifera no açude Pacajus em dez. 1998 foi indicativo das condições hipereutróficas da maioria dos pontos amostrados. Espacialmente, os organismos desse grupo, representados principalmente por espécies dos gêneros Brachionus e Keratella, indicadores de ambientes nutriente-enriquecidos, foram mais abundantes nos compartimentos com estado trófico superior. Comportamento similar foi observado para o Copepoda Cyclopoida Thermocyclops decipiens, espécie indicadora de condições eutróficas, a qual colonizou, preferencialmente, regiões com maior concentração de nutrientes. Ao contrário, organismos dos grupos Copepoda e Cladocera foram mais abundantes nas regiões menos enriquecidas dos reservatórios, apresentando gradientes longitudinais inversos em relação àqueles dos Rotifera e Cyclopoida. Portanto, a distribuição e os padrões de dominância do zooplâncton nos açudes Pacajus e Gavião foram condicionadas, principalmente, pela variabilidade espaço-temporal dos gradientes tróficos.The main aim of this research was to investigate the influence of climatic and hydrodynamics\' alterations about physical stability, resources availability, zooplankton community structure and spatial heterogeneity standard of Pacajus and Gavião dams, collected at two-month period between Nov. 1988 and Dec. 1998. In the reservoirs, the sample stations were distributed along the main longitudinal axis, being six on Pacajus dam and five on Gavião dam. Water temperature, electric conductivity, turbidity, pH and dissolved oxygen were measured in regular intervals in water column using a multiparametric probe (HORIBA U-10). Sample for total alkalinity, inorganic dissolved nutrients and total phosphorous determination were collected in the corresponding depth in water column (surface, middle and deep). Chlorophyll a determination was measured in surface samples. Vertical structure of water column in reservoirs was characterized by little thermal and saline gradients, especially duringsecond semester, when wind was the main induced force of turbulent mixture. At this same period dissolved oxygen concentrations were typical supersaturated on both reservoirs. Nutrients dynamic on both dams were dependent on allocthonous contributions during rainy season and on regeneration processes and internal load during dry season. The greatest rank of enrichment and algal biomass measured in Pacajus\' dam classified it as eutrophic or hipereutrophic while Gavião\'s dam was mesotrophic or eutrophic. Spatial heterogeneity of reservoirs was controlled by hydrological regime of the dammed river in case of Pacajus\' dam, by hydraulic gradients along main axis and the influence of internal hydraulic transferences proceedings in the case of Gavião\'s dam and by irregularity on phytoplankton spatial distribution according to trophic gradients. In general, it can be said that zooplankton species ) identified on both dams are representative of Neotropical plankton micro invertebrate fauna, with large geographic distribution in Brazil. The dominance of rotifers in Pacajus\' dam on Dec. 1998 was favored by hipereutrophic conditions in most of sample stations. Especially, this group of organisms, represented mainly by Brachionus and Keratella, indicators of nutrient enriched environments, were abundant in segments with higher trophic state. Similar behavior was observed to the copepod Thermocyclops decipiens, an indicator of eutrophic conditions, which has colonized regions with higher nutrient concentrations. On the other hand, Copepoda and Cladocera were more abundant on poorer nutrient compartiments of reservoirs, presenting inverse longitudinal gradients in relation with those of Rotifera and Cyclopoida. Therefore, distribution and patterns of zooplankton dominance in Pacajus and Gavião dams were conditioned mainly by spatial-temporal variability of trophic gradients

Nitrogen and phosphorus in cascade multi-system tropical reservoirs: water and sediment

The aim of this research was to analyze the horizontal spatial heterogeneity of both water and superficial sediment quality among and within the reservoirs of the Cantareira System (CS), focusing on concentrations of N and P, attributed to the dumping of raw domestic sewage into water bodies, which is the main cause of water pollution in São Paulo State (Brazil). The CS is a multi-system complex composed of five interconnected reservoirs, with water transported by gravity through 48 km of tunnels and channels. From the last reservoir of the CS, with an output of 33 m3 s−1, the water is conducted to a water treatment plant, producing half of the water consumed by 19 million people inhabiting São Paulo city. The upstream reservoirs are more eutrophic than the downstream ones. Data also suggest that the low phytoplankton biomass (ranging from 0.9 to 14.4 μg dm−3) is regulated by the low nutrient availability, mainly of phosphorus (TP ranging from below the detection limit, <9.0 μg dm−3, to 47.3 μg dm−3). For water, the DIN/TP ratios values range from 19 to 380. The upstream reservoirs function as nutrient accumulators and the sediment is the main compartment in which P and N are stored. Although the reservoirs are located in different river basins and are not in sequence along the same river, the results suggest a marked gradient between the reservoirs, with features similar to those of cascade reservoirs. The large volumes flowing through the canals and tunnels could explain the observed pattern. The CS reservoirs can therefore be considered multi-system reservoirs in cascade, constituting a particular case of multi-system reservoirs