Short-Term Toxicity of Lanthanum to Embryonic and Yolk-Sac Stage Larvae of the Rare Minnow Gobiocypris rarus Ye & Fu, 1983

Abstract

The wide use of rare-earth elements in China for aquacultural purposes and many other applications has resulted in their accumulation in the aquatic environment and has caused concern about their safety. In this study, we tested the toxicity of lanthanum (La (III)) to the early life stages (embryonic and sac-fry stages) of the rare minnow Gobiocypris rarus Ye & Fu, 1983. We exposed fertilized eggs to 0, 0.06, 0.13, 0.25, 0.50, 1.00, and 1.92 mg/L of La (III) until the yolk sac was exhausted in any group (at about 168 h of exposure). Exposure to 1.00 and 1.92 mg/L La (III) had obvious lethal effects on embryos, La (III) exposure also accelerated the development of embryos and had a significant inhibitory effect on the hatching rate after 96 h. As the exposure time increased, the larvae exhibited obvious yolk-sac edema, pericardium edema, spinal curvature, tail bending, and other symptoms of poisoning, including deflated swim-bladder. In general, these results clearly indicate that La pollutants hinder the development of rare minnow embryos and are acutely toxic to rare minnow larvae. Our finding would provide a theoretical basis for further research of relevant feed additive criteria for this fish.