Effect of Algal Food on Animal Prey Consumption Rates in the Omnivorous Copepod, Mesocyclops thermocyclopoides

We measured the food consumption rates in the omnivorous copepod Mesocyclops thermocyclopoides on different animal prey types in the presence of, and in the absence of one of the algal food types, the small, nonmotile Chlorella , or the large, motile Chlorogonium. Animal prey tested included different zooplankton species covering a size range of 88 to 1446 μm. The number of animal prey consumed was inversely proportional, but the total weight consumed was directly proportional, to the body size and dry weight of the prey item. There was a significant reduction in animal prey consumption in the presence of algae, being higher with cladoceran prey than with ciliates and rotifers, and in the presence of Chlorogonium than in the presence of Chlorella. Cannibalism in M. thermocyclopoides was low when algal food was available.