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Data of Dissertation


Author: Simone Maciel da Costa Gouvea.

Title: Effects of saxitoxins produced by  Cilindrospermopsis raciborskii and other cyanotoxins on cladocerans (Branchiopoda)

Year: 2005.    Full text (in Portuguese)


In the last years, cyanobacterial blooms have been occurred frequently all around in the world, due to the increase in eutrophication processes. In Brazil, Cylindrospermopsis raciborskii produces saxitoxins and is dominant in several Brazilians water bodies. In the present study we investigate the effects of a saxitoxin producer strain (T3) and a non-toxic strain (NPLP-1) of Cylindrospermopsis raciborskii and of the water of the Funil reservoir, with occurrence of C. raciborskii, in the mobility, survivor, reproduction and fecundity of three species of cladocerans. We performed bioassays with different strains of cyanobacteria producers of different toxins, using intact cells and extract of lyophilized cells with the aim of proposing standard protocols to monitor toxins in water public supply impoundments, through bioassays with cladocerans. D. pulex and M. micrura showed an inhibition in their swimming movements when exposed to T3 strain and to Funil reservoir water. Strain NPLP-1 (nontoxic) did not show inhibition on their swimming movements, suggesting that this effect was really caused to saxitoxins. This is the first report on inhibition of swimming movements in cladocerans exposed to saxitoxins. In chronic bioassays, the cladocerans D. pulex e M. micrura were sensitive to T3 strain and were resistant to NPLP-1 strain, while D. gessneri was resistant to strains T3 and sensitive to strain NPLP-1. Bioassays performed with different strains, showed no adverse effect (CYP-030 and ITEP-024), inhibition in swimming movements (T3), until death (NPLJ-4). D. pulex was a good biomonitor to saxitoxins. The present study showed that, in using bioassay to the detection of cyanotoxins, it should be considered the sensitivity of cladocerans to toxins, mechanism of their action (paralysis or death) and accessibility to toxins (intact cells or extracts). In the performed bioassays were observed different sensitivity to cyanobacteria strains and their toxins among the cladocerans.