Impact of algae and their concentrations on the reproduction and longevity of cladocerans

Cladocerans are used in a wide range of applications (aquatic toxicology, experimental hydrobiology, and aquaculture). Although known to be successfully cultivated with microalgal food sources, cladoceran demographic parameters tend to be different, depending on the kind of cladoceran and concentration of food supplied. For most species, finding precise instructions on culture conditions and expected outcomes is difficult. The aim of this study was to determine the most favorable feeding conditions for the development of three cladoceran species frequently used as test organisms in aquatic toxicology. For this purpose, Ceriodaphnia dubia, Daphnia pulex, and Simocephalus mixtus were fed three concentrations (6, 12, and 18 mg L^-1 dry weight) of the green microalgae Ankistrodesmus convolutus, Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum), and Scenedesmus incrassatulus. Reproduction and survival were evaluated during the entire life cycle. For C. dubia, the P. subcapitata and S. incrassatulus diets produced the best reproductive results. For D. pulex, the best overall results were obtained with S. incrassatulus at 6 mg L^-1 and results with P. subcapitata were similar at all concentrations. For S. mixtus fed P. subcapitata, results were similar at all concentrations. With S. incrassatulus, a decrease in longevity and an increase in fecundity occurred as the amount of food increased; the best reproductive response was achieved with the highest (18 mg L^-1) concentration. The lowest reproduction and survival in the three cladocerans were recorded with A. convolutus. For the cladoceran species tested, the same microalga produced different reproductive and survival results, depending on the concentration; some of the tested foods did not support adequate cladoceran development, because they were nutritionally deficient, despite the similar conditions used for their production. Feeding and culture conditions here described could be useful for a controlled propagation of these cladocerans.