Response of Lemna minor to sodium chloride and a statistical analysis of continuous measurements for EC50 and 95% confidence limits calculation

Sodium chloride was evaluated as a reference toxicant for bioassays using duckweed, Lemna minor, and a statistical procedure for analyzing the measurements from toxicity tests was determined. Dry weight was the measurement selected on which to base the point estimate, while the criteria used to evaluate NaCl were the concentration dependent response, and a reciprocal response between growth and concentration. The study protocol and the regression analyses used are detailed. A highly significant regression effect was found, indicating a linear relationship between arcsin of dry weight of L. minor and the log of the concentration of NaCl. Stable variance was found to be inversely proportional to the concentration of NaCl.