The development and reproductive output of three species of Cladocera (Crustacea, Branchiopoda) with different size spectra as the result of vertebrate and invertebrate predation impact

Abstract

Seasonal changes in development and reproduction of three species of Cladocera, Bosmina longirostris, Bosmina coregoni and Diaphanosoma brachyurum, were studied in regard to impact of vertebrate (planktivorous fish) and invertebrate (cladoceran Leptodora kindtii and cyclopoid copepods Mesocyclops leuckarti and Thermocyclops oithonoides) predators. Each of the cladocerans represented a different prey type. The population of the largest body-sized D. brachyurum was not affected by predators suggesting unidentified mechanisms of predation-avoidance. Diaphanosoma displayed low reproductive output coinciding with high density. Medium-sized B. coregoni, influenced by planktivorous fish, invested in reproduction and carried large egg-clutches resulting in gradual increase in population density. The population of small body-sized B. longirostris, that was influenced by invertebrate predators, displayed high density and reproductive effort in spring, followed by extreme collapse in abundance and reproduction during summer months. The results suggest that invertebrate predators may suppress populations of some Cladocera more strongly than planktivorous fish.