Acute Cu toxicity, metal bioaccumulation and ion loss in the Neotropical cyprinodontiform Jenynsia multidentata

Abstract

The acute toxicity of Cu, metal bioaccumulation and ion loss in the cyprinodontiform Jenynsia multidentata, a highly eurihaline Neotropical freshwater fish of wide distribution in the Río de la Plata basin, was established during a 96 h static exposure. The median lethal concentration at 96 h was 229 µg Cu l^-1. The effect of CuSO₄5H₂O was tested in natural freshwater in two-liter Pyrex glass chambers at controlled temperature, with natural light and artificial aeration. During the first hours of exposure to concentrations above 130 µg Cu l^-1, an increase in aquatic surface respiration, air gulping and erratic swimming were observed, showing evidence of the affection of the respiratory system. The concentration of Cu, Na and K in the whole body burden at the end of each experiment showed by correlation analysis Cu bioaccumulation and loss of Na⁺ and K⁺. The concentration of Cu in water was positively correlated with its bioaccumulation (r=0.79, p=0.06), and negatively correlated with the whole body burden of K⁺ (r=-0.84, p=0.037). K⁺ loss was positively correlated with Na⁺ loss (r=0.88, p=0.02). Cu LC50 for this cyprinodontiform seems rather low when compared to fishes often utilized in toxicity tests