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Data of Dissertation

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Author: Aloysio da Silva Ferrão Filho.

Title: Influence of cyanobacterial bloom in populational dynamics of zooplankton in Jacarepaguá Lagoon (RJ): Toxic effects of  Microcystis aeruginosa on cladocerans.

Year: 1998.    Full text (in Portuguese)

Abstract

In this work, we studied the zooplankton communities of Jacarepaguá Lagoon (RJ) and the influences of the Microcystis aeruginosa bloom on cladoceran populations of this coastal lagoon. Sampling work was performed from August/96 to September/97 at tree stations for the analysis of zooplankton community and physical and chemical variables. Several laboratory experiments were performed to test the toxic effects of M aeruginosa strains and natural assemblages of this cyanobacteria on cladoceran species. The experiments consisted of acute and chronic toxicity experiments, weight gain experiments and measures of filtering rates in cladocerans submitted to toxic cyanobacteria. The field data analysis showed a strong influence of temperature and salinity on the zooplankton community dynamics. The highest density of zooplankton organisms occurred in summer and in low salinity conditions. The cladoceran populations showed signals of food limitation during the M aeruginosa bloom, as reduced egg production and appearance of ephypia. The increase in microcystin in the seston, however, has not excerted a clear effect on zooplankton populations. The laboratory experiments showed that M aeruginosa can excert toxic effects on cladoceran populations. These effects were more evident with laboratory strains of cyanobacteria than with natural assemblages, and can be enumerated as reductions in survivorship, fecundity, weight gain and filtering rates. However, the toxic effects of M aeruginosa depend on: toxic cell concentration, colony size, availability of nutritious resources and sensitivity of cladoceran species.

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