Toxicidade de Microcystis aeruginosa (Cyanobacteria) produtora de microcistinas em cladóceros tropicais : investigação sob diferentes vias de exposição

Abstract

Cyanobacteria can produce various toxic metabolites such as bioactive alkaloids and peptides. Among these, the microcystins are the most reported, and may interfere with the quality of the water body, causing ecological damages such as changes in the food chain, local biodiversity decline, and impacts on public health. Microcystins may be retained within the cell or be released by cell lysis in the senescence phase of flowering in the aquatic environment where the animals are exposed to these two routes of exposure in the environment. Therefore, the toxicity of intact cells and crude aqueous extract of microcystin-LR-producing cells Microcystis aeruginosa NPLJ-4 on cladocerans was estimated. The effects on mortality, age of first reproduction, mean fecundity, total neonates, survival, somatic and population growth of Ceriodaphnia cornuta and Macrothrix spinosa were evaluated. The animals were more sensitive to intact cells. The two routes of exposure affected the population parameters of cladocerans, but the intact cells were more toxic. The somatic growth rate of the animals was not affected by the crude extract, and there were no significant differences between treatments and control. These results show that intake of intact cells is more toxic to cladocerans than exposure to toxins released into the water. With this study, it is hoped to contribute to the knowledge of the interactions between zooplankton and toxic cyanobacteria, especially under blooming events.