Functional responses and feeding rates of Mesocyclops pehpeiensis Hu (Copepoda) fed different diets (rotifers, cladocerans, alga and cyanobacteria)

The feeding rates and functional responses of the copepod Mesocyclops pehpeiensis (adult females) were quantified using rotifers (Brachionus rubens, Brachionus havanaensis and Plationus patulus), cladocerans (Moina macrocopa, Ceriodaphnia dubia and Alona glabra), the green alga Chlorella vulgaris and the cyanobacterium Anabaena sp. as food. Mesocyclops pehpeiensis showed preferences for B. havanaensis, B. rubens and M. macrocopa when offered mixed rotifer and cladoceran species. Functional response curves showed increased consumption with increasing density of B. rubens in the medium until about 160 ind. 40 ml(1) of prey, and thereafter reached an asymptote. In general, regardless of water temperature, prey consumption was higher in the absence of algae in the medium. Consumption was highest at 35 degrees C and declined with decreasing temperatures. Ingestion rates of the alga and cyanobacterium showed maxima at 25 degrees C. Our results also indicated that M. pehpeiensis is an omnivore, consuming phytoplankton and zooplankton.