Cianobactérias planctônicas do reservatório do ribeirão João Leite (Goiás) durante a fase de enchimento: florística e floração
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2014-03-21
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Universidade Federal de Goiás
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Ribeirão Leite is considered as one of the main sources of public water supply for the city of Goiânia and its metropolitan region. The soil in the watershed is principally used for agro-pastoral activities that may favor the supply of nutrients such as phosphorus and nitrogen for the water reservoir and consequently for the formation of blooms of microalgae and cyanobacteria. No floristic studies of cyanobacteria have been carried out for this reservoir, which is recently formed, however there has been pre-dominance of potentially toxic planktonic cyanobacteria during the filling of this reservoir, which reflects the limnological conditions of the Ribeirão Leite basin. The present study aims to identify and characterize the morphospecies of cyanobacteria and evaluate structure and dynamics of populations. The sample period comprised the date from January 2010 to January 2011, which was filling stage, with the collection of phytoplankton and limnologicals carried out twice a week until the first half of May 2010, and from this date, it was repeated weekly. Physicochemical and also qualitative and quantitative analyzes of phytoplankton were performed in water analysis laboratory of Saneago. Specimens of cyanobacteria were analyzed with microscopy “Zeiss Axiostar plus”, and micro-photographed with image capture system “Axiocam ERc5s” and also with imaging system “Axiovision”. The initial phase of filling of the reservoir demonstrated the greatest efficiency on rainy period of the year, nevertheless, the intermediate phase, which was on dry period, showed lower efficiency. The blooms were observed as characteristics of rainy periods of the year. In the first period, there was the dominance of Geitlerinema amphibium and Cylindrospermopsis raciborskii and in the second period, Aphanocapsa delicatissima was observed as dominant. It was monitored that during the filling phase, there was predominance of filamentous cyanobacteria and in the final phase, dominance was of the colonial organisms. The PCA indicated that the explanatory variables of the system were turbidity, total phosphorus and Secchi disk depth extinction coefficient (axis 1 to 31.7%). In Canonical Correspondence Analysis (CCA), sampling units were influenced on the 1º axis by the dominance of G. amphibium at the stage of filling, when the turbidity was high and Secchi depth (axis 1 to 14.8%, p <0.05; environment correlation of species 0.806) was lower. The Detrended Correspondence Analysis confirmed the distribution of taxa among different climatic periods. For the state of Goiás, 28 taxa were mentioned for the first time
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CARMO, Elaine Jacob da Silva Carmo. Cianobactérias planctônicas do reservatório do ribeirão João Leite (Goiás) durante a fase de enchimento: florística e floração. 2014. 103 f. Dissertação (Mestrado em Biodiversidade Vegetal) - Universidade Federal de Goiás, Goiânia, 2014.