The effects of <i>Anabaena spiroides</i> (Cyanophyceae) exopolysaccharide on copper toxicity to <i>Simocephalus serrulatus</i> (Cladocera, Daphnidae)

Abstract

Summary 1. This work investigated the consumption of a microalgal ( Anabaena spiroides ) exopolysaccharide by the cladoceran Simocephalus serrulatus (Cladocera, Daphnidae) and its effect on copper toxicity. 2. Total organic carbon concentration was used to quantify the microalgal exopolysaccharide. Both copper‐complexed exopolysaccharides and copper‐free exopolysaccharides were taken up by S. serrulatus . 3. A reduction of free copper ions was obtained in the presence of A. spiroides exopolysaccharide. Copper toxicity (EC 50 ) and zooplankton concentrations were inversely correlated to exopolysaccharide concentration in experimental media. 4. An increase of free copper ions in experimental media was obtained after exopolysaccharide consumption, suggesting that S. serrulatus excreted copper to the surrounding environment.