Ocorrência de cianobactérias e avaliação toxicogenética de rio tropical do semiárido no nordeste brasileiro sobre influência antropogênica (PI, Brasil).

Abstract

The quality of water is an important factor in the diagnosis of watersheds and acts as a parameter indicator of the impacts caused by the anthropogenic use and occupation of their margins. Semiarid tropical rivers occur in regions of small annual temperature range. Hydrological periods have a short full water duration and long-term droughts. Shallow semi-arid tropical lotic environment may have lentic characteristics because the damming of water in your mouth, with higher riverbed, which enables their physical and chemical stratification. Moreover, these environments may become eutrophic with increased nutrient charge and metal components, favoring the development of Toxic cyanobacteria, and raise the toxigenic potential of water. Based on this, this paper proposed to evaluate the influence of environmental conditions on the biomass of cyanobacteria, as well as evaluating the toxigenic potential water, in association with the concentration of metallic components due to urban contamination in a river in the Brazilian semiarid region. For this, cyanobacterial samples were obtained at surface and bottom of three sampling points of the Poti river, as well as some limnological variables. The genotoxicity was evaluated in Oreochromis niloticus, and toxicity, cytotoxicity and mutagenicity in Allium cepa, exposed to the river water. Analyses revealed the dominance of Planktothrix agardhii, an opportunistic species favored by the heavy load of nutrients coming from anthropogenic action. The presence of this species is a cianotoxic risk to the local biota and the population that use this water, because microcystins produced by this species has hepatotoxic and carcinogenic potential. Significant DNA damage in blood cells of O. niloticus were observed and associated with metal ions Fe, Al, Cu, Cr and Zn. Association between Fe and cytotoxicity, and Al with mutagenicity were found. The river Poti is contaminated with chemicals, including metals of anthropogenic origin that can cause toxicogenic damages to ecosystem species and human health.