Biomonitoring of an urban lake (Soldati Lake, Argentina): physicochemical analysis of water and ecotoxicological tests using a native species

This work aimed to evaluate the water quality of Soldati Lake (City of Buenos Aires, Argentina) through physicochemical and ecotoxicological studies. Two samplings were performed: one in summer 2023 (sites: S1 and S2) and another in winter 2023 (site: S1). In both of them, physicochemical parameters (water temperature, pH, electrical conductivity, dissolved oxygen, nitrate, nitrite, ammonium, inorganic phosphorus, and chemical oxygen demand), heavy metals (Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb, and Zn), and As were determined. In addition, in winter, Biomphalaria straminea (Dunker 1848) adult gastropods and their egg masses were exposed to water samples (S1) and tap water (TW) as a control. Biochemical (acetylcholinesterase, carboxylesterase, catalase, and glutathione S-transferase activities and protein content) and immunological parameters, oviposition, embryotoxicity, and offspring quality were evaluated. In summer, As and Zn were detected at concentrations lower than the guide levels for aquatic life and recreational use. Electrical conductivity, dissolved oxygen, temperature, and hardness were lower in winter, while chemical oxygen demand and nitrite levels were lower in summer. Ammonium and phosphate concentrations in all samples exceeded the guideline levels, while dissolved oxygen was lower than its guideline level. Biochemical parameters, hemocyte viability and their population proportions, and offspring quality were not modified by the treatment. In snails exposed to water samples, an increase in the percentage of granulocytes with cytoplasmic projections (activation) was observed; 65% in snails exposed to S1 compared to 41% in those exposed to TW. Also, significant alterations in embryonic development occurred, including malformations, arrested and delayed embryos, and a decrease in hatching rate. Embryotoxicity proves to be a sensitive endpoint for aquatic biomonitoring using B. straminea as a biological model.