Resumen

AVALOS DE ENCISO, Claudia Raquel et al. Evaluation of Cyanobacteria concentration in the beaches of San Bernardino, Ypacaraí, and Areguá of Lake Ypacaraí during the period 2022-2024. Rep. cient. FACEN [online]. 2024, vol.15, n.2, pp.55-66. ISSN 2222-145X.  https://doi.org/10.18004/rcfacen.2024.15.2.055.

Lake Ypacaraí, a significant aquatic ecosystem in Paraguay, has been the subject of research due to the proliferation of cyanobacteria during certain times of the year, which poses significant risks to public health and biodiversity. The aim of this study was to evaluate the concentration of cyanobacteria at the Municipal Beaches of San Bernardino, Ypacaraí, and Areguá during the summer seasons, which see higher visitor numbers, over a three-year period (2022-2024). Fifteen monitoring campaigns were conducted, where in situ parameters such as pH, conductivity, dissolved oxygen, and temperature were measured. Surface water samples were analyzed at CEMIT to determine cyanobacteria concentrations, total phosphorus, and total nitrogen. Significant variations in cyanobacteria were observed across the three beaches, with the most common genera being Microcystis, Pseudanabaena, and Dolichospermum. The results of the Kruskal-Wallis analysis indicated significant differences over time (p less than 0.05) in cyanobacteria concentrations (0 - 38,883 cells/mL). Spearman's correlation coefficient revealed a significant positive correlation between cyanobacteria and conductivity (r=0.55), suggesting that a higher presence of dissolved ions and nutrients may have favored their proliferation. Meanwhile, the negative correlation with total Kjeldahl nitrogen (r=-0.52) highlighted the increase in biomass due to the ability of some cyanobacteria to fix atmospheric nitrogen under conditions of nitrogen deficiency. These findings reflect the complex interaction between cyanobacteria and the physicochemical conditions of the water, emphasizing the importance of environmental and human factors in the dynamics of these microorganisms in Lake Ypacaraí.

Palabras clave : eutrophication; water quality; nutrients; environmental variables.

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