Evaluation of cyanobacterial blooms in water supply rivers from Joinville city
ABSTRACT The proliferation of cyanobacteria in waters, especially in rivers, is associated with anthropic action, wastewater from industries, agriculture, and the lack of basic sanitation. Many health problems occur due to the cyanotoxins produced by these microorganisms. The present study aimed to evaluate the densities of cyanobacteria and their possible correlations with physical-chemical parameters in waters from supply rivers of the city of Joinville, in order to verify which factors are involved in the growth of these organisms between the years 2015 to 2019. The amount of cyanobacteria cells per milliliter of water were analyzed from the last 5 years of the Cubatão and Piraí rivers, based on the certificates of analysis provided by the current water supply service of Joinville. It was found that the cyanobacteria density values increased in both rivers from the year 2018. The physical-chemical parameters analyzed showed a low correlation with the cyanobacteria density from 2015 to 2019 for the Cubatão and Piraí rivers. To understand this increase in cyanobacteria, other climatic factors such as precipitation and average annual temperature were studied. The expressive increase in precipitation in January 2018, followed by a period of reduced rainfall, in addition to the gradual rising temperature in recent years, might be related to this elevation in the density of cyanobacteria between 2018 and 2019, requiring monitoring of this evolution in the supply rivers of the Joinville city.