CONTAMINANTS OF EMERGING CONCERN AFFECT BIOCHEMICAL BIOMARKERS IN NEOTROPICAL FISH FROM AN INTERNATIONAL RIVER IN SOUTHERN BRAZIL

Resumo

Water resources contamination by contaminants of emerging concern (CECs) occurs as a result of the disorderly conversion of natural areas for agricultural and urbanization purposes, and poses an important threat to biodiversity. Thus, biomonitoring is an effective tool for assessing the effects of contamination on exposed organisms, through the analysis of chemical and biological variables. The aim of this study is to evaluate the presence of CECs, such as pesticides, human and veterinary medicines and hormones, in the Uruguay River, southern Brazil, and the possible effects on biochemical biomarkers of Astyanax spp. fish. Three sampling sites were determined: DMC, SB, and URU. Surface water samples for pesticide and drug analysis were collected monthly for a year (2022 – 2023). While water samples for physicochemical and microbiological analysis, sediment for pesticide analysis and fish for biochemical biomarker analysis and pesticide bioaccumulation were collected seasonally. Seventeen pesticides, thirteen drugs and one hormone were detected in the surface water samples. Four pesticides were detected in the sediment and three in the fish muscle. The site with the highest number of pesticides in the water and sediment and drugs was the URU. The biochemical biomarkers showed significant differences between the collection sites; however, seasonality was the main factor contributing to the biomarker responses. The redundancy analyses showed that pH and water temperature were the variables with the greatest influence on the biomarkers, followed by the pesticides thiamethoxam, carbendazim and tebuconazole. The Venn diagram showed that the joint analysis of these variables (pH, temperature, thiamethoxam, carbendazim and tebuconazole) has a synergistic effect on the biomarkers in Astyanax spp. The Uruguay River is contaminated with different classes of CECs (pesticides, medicines and hormones) and that the association of contaminants with natural seasonal fluctuations can potentiate the adverse effects on organisms.