FATORES ABIÓTICOS E O CRESCIMENTO DE CIANOBACTÉRIAS EM RESERVATÓRIOS DE ÁGUA SUPERFICIAIS DO ESTADO DE PERNAMBUCO

Abstract

The degradation of water bodies caused by the release of domestic and industrial effluents without proper treatment, or without any type of treatment, silting, salinization processes and eutrophication of water sources, leads to loss of water quality. As a consequence of this degradation, eutrophication, the presence of nutrients and the climate in the state of Pernambuco have favored the bloom of cyanobacteria in reservoirs used for public supply. With the problem of eutrophic springs of anthropogenic action, what is the influence of the different abiotic variables on the appearance of cyanobacterial blooms in lentic environments, an example of reservoirs? Thus, the present work aimed to analyze the relationship between the abiotic physicochemical variables of water and climatic factors with the occurrence of genera of cyanobacteria that form blooms in shallow water reservoirs used for public supply. The study was carried out from samples collected in four eutrophic freshwater reservoirs in the State of Pernambuco, among the period from 2010 to 2020. The results were treated in the statistical software R (version 4.0.2) and the Relative Abundance calculation was adapted de Lobo & Leighton (1986), with genera of cyanobacteria classified in the following categories: dominant (with density of cyanobacteria> 50% of the total density of the samples) and abundant (density higher than the average density, depending on the total number of cyanobacteria present in the sample). We concluded that Raphidiopsis / Cylindrospermopsis was the most frequent genus and was found in all reservoirs in abundant condition, and that the increase in color, turbidity and pH were positively correlated with the presence of the genera Microcystis and Raphidiopsis / Cylindrospermopsis, and correlated negatively to the increase in hardness. As well as a positive correlation was observed between hardness (calcium and magnesium) and increased density of the genus Planktothrix. Thus, the fruit of this work will serve as a guideline for the public supply service, for the management of surface water reservoirs with blooms, offering the necessary tools to understand which abiotic conditions influence the growth of cyanobacteria in order to outline mitigation or control strategies at Water Treatment Plants.