Avaliação experimental do crescimento da comunidade fitoplanctônica do reservatório João Leite em diferentes condições de luz e nutrientes
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2013-11-29
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Universidade Federal de Goiás
Resumo
Human activities of natural resources exploration can have negative impacts on lakes
and reservoirs. The increase in the amount of nitrogen and phosphorus in water
cause deterioration in the water quality and eutrophication. Eutrophication by algae
and cyanobacteria may hinder the use of water for several purposes. João Leite’s
reservoir, located in the state of Goiás, is an important water resource for the public
supply; approximately, 2.300.000 inhabitants are in need of its water. The present
work aimed to study the dynamics of variation of a phytoplankton community in João
Leite’s reservoir by a bioreactors board studies in order to evaluate the population
growth of phytoplankton in different conditions of light and nutrients. The experiments
were performed in nine bioreactors with controlled light conditions (22 μmol de
fótons.m-2 .s-1, 44 μmol de fótons.m-2 .s-1,, 67 μmol de fótons.m-2 .s-1) and nutrients (N /
P = 10) (N / P = 16) and (N / P = 20) and according with a factorial experimental
design with two factors at three levels (3 Meters). The bioreactors were submitted to
a photoperiod of 12/12 hours and kept at a temperature of 25 ± 2 ° C. The natural
water samples were collected in 5 sampling campaigns in the months of April, May,
June and July 2013 from João Leite’s reservoir and monitored for five consecutive
days in the laboratory. The results showed a significant positive correlation between
light and nutrients on the growth of algae and cyanobacteria. A principal component
analysis (PCA) indicated light intensity and nitrate as the factors that most influenced
the increase of phytoplankton density. The paired t-test and Tukey tests showed that
the effect of light, however, was more significant than the effect of nutrients. The
growth of algae and cyanobacteria were modeled as logistic model that adjusted well
to the data with R ² value ranging between 0.80 and 0.99. The laboratory experiment
corroborated the data of seasonal variations in the reservoir, in which occurred as the
increase of algae and cyanobacteria density as was the increase in nitrate
concentration and light intensity.
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PINA, Rafaela Wolff de. Avaliação experimental do crescimento da comunidade fitoplanctônica do reservatório João Leite em diferentes condições de luz e nutrientes. 2013. 143 f. Dissertação (Mestrado em Engenharia do Meio Ambiente) - Universidade Federal de Goiás, Goiânia, 2013.