Variation in life history responses of Daphnia to toxic Microcystis aeruginosa

Three clones of Daphnia pulex and two clones of Daphnia longispina were exposed to toxic Microcystis aeruginosa for 21 days in a lifetable experiment. The growth and reproduction of individual daphnids were followed daily to study the long-term effects of toxic Microcystis. Exposure to Microcystis increased mortality, decreased growth, delayed maturation and decreased offspring production, indicating nutritional deficiency and toxic effects. We found variation in life history responses between species and among clones. Our results suggest that toxic cyanobacteria may act as a modifying agent in zooplankton communities at both the species and clonal level.