Investigations into the Food Selectivity of the Planktic Crustaceans Daphnia hyalina, Eudiaptomus gracilis and Cyclops vicinus

The food selectivity of Daphnia hyalina, Eudiaptomus gracilis and Cyclops vicinus was investigated in laboratory experiments using algae of different sizes and at different concentrations as food sources. Vanderploeg and Scavia's (1979a, b) coefficient, which is most suitable for characterising selectivity, was selected from the literature and used to analyze the results. None of the three species was found to feed selectivity, however. The results show, on the other hand, that the leaky‐sieve model can be used to describe the feeding patterns of these species. There were clear differences between the particle size ranges consumed by our experimental species, and these showed that, during the experiments, Daphnia hyalina acted as a microfilter‐feeder, whereas Eudiaptomus gracilis and Cyclops vicinus acted as macrofilter‐feeders.