857 resultados para São Francisco River
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Foi investigada a correlação entre nível hidrológico, pluviosidade e temperatura e reprodução de peixes num trecho lótico do rio Grande, abaixo da barragem de Volta Grande. Para a captura, realizada com redes de espera, foram feitas seis amostragens bimestrais de abril de 1998 a fevereiro de 1999. As gônadas foram classificadas de acordo com o estádio de maturação e aquelas maduras ou esgotadas foram correlacionadas com as variáveis ambientais. A maioria das espécies apresentou reprodução sazonal, entre outubro e fevereiro. A freqüência relativa bimestral de gônadas maduras ou esgotadas de todos os exemplares agrupados foi correlacionada significativamente com pluviosidade (Spearman r = 0,94, p = 0,005) e temperatura do ar (r = 0,84, p = 0,036), mostrando a importância destes fatores no controle do ciclo reprodutivo dos peixes. Devido à barragem, o nível hidrológico pouco variou e não foi encontrada correlação significativa entre reprodução e nível hidrológico (r = -0,43, p = 0,396).
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The distribution and physiological condition of 116 Caiman crocodilus yacare was assessed over one year in the Southern Pantanal. Body mass and intermediary plasma metabolites were measured at three different time periods, representing large differences in the abundance of surface water. During the wet season the study site was completely submerged under water and C. c. yacare were distributed evenly throughout. High levels of [glucose] and [triglyceride] in the plasma indicated regular feeding. As the dry season progressed C. c. yacare became increasingly crowded around the remaining ponds. They showed a reduction in plasma [glucose] and [triglyceride], and an increase in plasma [beta-hydroxy-butyrate], signifying that they were feeding less and utilising fat reserves. At this sampling period, similar to 40% of the male C. c. yacare that were > 10 years old inhabited dry grassland and did not have access to water. These animals were significantly lighter than males of a similar length that had immediate water access, and plasma [uric acid] indicated that they had not fed for a long time and were metabolising tissue proteins. Essentially, the adult male C. c. yacare that inhabited dry grassland were in a state of energy deficiency. This was so severe in some animals that recovery seemed unlikely. The study suggests that fluctuations in the abundance of surface ground water may influence the size and structure of the C. c. yacare population in the Pantanal.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The main purpose of this research was to measure the condition of the fish species Hoplias aff. malabaricus collected in Aguapeu River (black waters) and Branco River (white waters), which belong to Itanhaem River basin, a coastal watershed in São Paulo state, Brazil. Individuals of Hoplias aff. malabaricus were sampled by using gill nets, monthly from March 2001 to February 2002. The Condition Factor was obtained through the length-weight relationship, assuming that the higher the mass for a given length, the better the condition of the fish. The Condition Factor was compared among fishes from both rivers, resulting that Branco River individuals have significantly lower condition. Limnological aspects were studied from May 2001 to November 2002 and some show significant differences between Aguapeu River and Branco River. These were salinity, do and total organic N, which the higher values being observed in Branco River propably due to estuarine waters influence. However, the lower condition of the Branco River fishes should also be an effect of a disturbance due to the sand mining in this river, since this activity cause important alterations to the environment, affecting the whole biota, included aquatic macrophytes, invertebrates and fishes.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Determinations of Al and Mn concentrations in the tissues (gills, hepatopancreas and muscle) of the freshwater crab Trichodactylus fluviatilis and water samples, both collected from sites on tributaries of the Corumbatai River (São Paulo, Brazil) were performed. The Bioaccumulation Factor (BAF), calculated for different sites with respect to the water concentration, ranged from 173-555 for Al and from 636 - 921 for Mn. Dissolved concentrations of Al and Mn in water samples (collected in different sites) were related to the accumulation of these metals in crabs, suggesting that T. fluviatilis is good biomonitor for Al and Mn pollution in aquatic ecosystem.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Mercury Redox Chemistry in the Negro River Basin, Amazon: The Role of Organic Matter and Solar Light
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In this manuscript, seasonal and spatial trends of water collected from two sampling places in the Preto River in the Turvo-Grande watershed were evaluated. Water samples were collected during June/07 to July/08 and parameters sulphate, total organic carbon, ammonia, conductivity, dissolved oxygen, temperature, dissolved total solids and nitrate were quantified. Seasonal trend indicated sanitary effluents as a point source of contamination in both sampling points. Vertical trends demonstrated that the Municipal Dam was not stratified and received a diffuse source of pollutants from flooding and agriculture runoffs. It was also verified that there is relatively fast ammonia consumption kinetics having a half-life time of 1.43 h which can explain the low ammonia concentrations found in these aquatic bodies.