Toxicity of Copper to the Green Alga, Chlamydomonas reinhardtii (Chlorophyceae), as Affected by Humic Substances of Terrestrial and Freshwater

The influence of humic substances on the toxicity of copper to the green alga Chlamydomonas reinhardtii was determined by measurement of population growth, encystment, and flagella loss among a population exposed to Cu and humic substances. Cu concentrations of 6.7 25.4 mu g/l induced deflagellation. Aqueous fulvic acid had no effect on Cu toxicity; terrestrial humic acid had the largest effect on Cu toxicity. Cu concentrations did not affect algal population growth. The wide variations found in humic substances make it impossible to generalize about their potential effects on Cu toxicity in fresh water.