LIFE-HISTORY RESPONSES OF DAPHNIA CLONES TO TOXIC MICROCYSTIS AT DIFFERENT FOOD LEVELS

We examined how the amount of food of good quality, Scenedesmus obtusi usculus, influenced the toxic effects of the cyanobacterium Microcysti s aeruginosa on Daphnia pulex in a 21 day life table experiment. Our r esults show that all life history traits studied, i.e. longevity, grow th and reproduction, of D. pulex were negatively affected by toxic Mic rocystis, The detrimental effects on these life history traits were le ss pronounced at increasing food levels. In addition, D. pulex clones differed in their life history responses to toxic Microcystis, suggest ing that the presence of toxic cyanobacteria may modify the outcome am ong D. pulex clones.