High toxicity of agro‐industrial wastewater on aquatic fauna of a South American stream: Mortality of aquatic turtles and amphibian tadpoles as bioindicators of environmental health

CUZZIOL BOCCIONI, ANA P.; PELTZER, PAOLA M.; ATTADEMO, ANDRÉS M.; LEIVA, LEONARDO; COLUSSI, CARLINA L.; REPETTI, MARÍA R.; RUSSELL?WHITE, KAREN; DI CONZA, NOELIA; LAJMANOVICH, RAFAEL C.

WATER ENVIRONMENT RESEARCH

WATER ENVIRONMENT FEDERATION

Año: 2024 vol. 96

1061-4303

The aim of this study was to characterize an aquatic system of Santa Fe prov-ince (Argentina) receiving wastewater from agro-industrial activities (mainlydairy) by in situ assessment (fauna mortality, physicochemical, microbiologi-cal, and pesticide residues measurement), and ecotoxicity bioassays onamphibian tadpoles. Water and sediment samples were obtained from the LosTroncos Stream (LTS), previous to the confluence with the “San Carlos” drain-age channel (SCC), and from the SCC. Biological parameters (mortality andsublethal biomarkers) were used to evaluate ecotoxicity during 10-day expo-sure of Rhinella arenarum tadpoles to LTS and SCC samples. Nine pesticideswere detected in both LTS and SCC. Chemical and biochemical oxygendemand, ammonia, and coliform count recorded in SCC greatly exceededlimits for aquatic life protection. At SCC and LTS after the confluence withSCC, numerous dying and dead aquatic turtles (Phrynops hilarii) wererecorded. In the ecotoxicity assessment, no mortality of tadpoles was observedin LTS treatment, whereas total mortality (100%) was observed in SCC treat-ments in dilution higher than 50% of water and sediment. For SCC, medianlethal concentration and the 95% confidence limits was 18.30% (14.71–22.77) at24 h; lowest-observed and no-observed effect concentrations were 12.5% and6.25%, respectively. Oxidative stress and neurotoxicity were observed in tad-poles exposed to 25% SCC dilution treatment. In addition, there was a largegenotoxic effect (micronuclei test) in all sublethal SCC dilution treatments(6.25%, 12.5%, and 25%). These results alert about the high environmentalquality deterioration and high ecotoxicity for aquatic fauna of aquatic ecosys-tems affected by agro-industrial wastewater