Combined Effects of Food Level and Temperature on Life Table Demography of Moina macrocopaStraus (Cladocera)

Abstract

AbstractThe combined effects of four levels of temperatures (18 °C, 23 °C, 28 °C and 33 °C) and food densities (0.5 × 106, 1.0 × 106, 2.0 × 106 and 4.0 × 106 cells ml–1 of Chlorella vulgaris) on the life‐table demographic parameters (age‐specific survivorship and fecundity, average lifespan, gross reproductive rate, net reproductive rate, generation time and intrinsic rate of population increase) of a laboratory population of the cladoceran Moina macrocopa were investigated. Both food level and temperature, independently and in interaction, significantly influenced nearly all the parameters. The average lifespan was maximized at 18 °C under 1.0 × 106 cells ml–1 of Chlorella. The reproductive performance was a direct function of the food level, but the magnitude of food‐level effect depended on temperature. Among the algal concentrations used here, 0.5 × 106 – 2.0 × 106 cells ml–1 were suitable for the survival and reproduction of M. macrocopa. Regardless of the food‐level effect, both the gross reproductive rate and the net reproductive rate at 23 °C was higher, and the generation time generally decreased with the rise of temperature. Within the suitable food‐level range, the average value of the intrinsic rate of population increase ascended with the rise of temperature from 0.72 to 2.41 day–1. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)