EFFECTS OF TEMPERATURE, FOOD CONCENTRATION, AND INITIAL ROTIFER DENSITY ON THE INTERSPECIFIC COMPETITION BETWEEN TWO ROTIFER SPECIES

There is often intense competition among species in an environment with limited resources and space, leading to the exclusion of inferior competitors, reduced species diversity, and changes in zooplankton communities.This study investigated the interspecific competition between two dominant rotifer species in the Pearl River Basin, Brachionus calyciflorus and Keratella valga, through laboratory experiments at different temperatures, food concentrations, and initial rotifer densities.In separate cultures, the population growth of both rotifer species was affected by changes in temperature, food density, and initial density.In mixed cultures, B. calyciflorus was inhibited by competition, leading to an overall decrease in its population growth rate and maximum population density.K. valga was also affected by competition, leading to an increase in its population growth rate and maximum population density at 20 ℃ or at an initial density of 1.0 × 10 6 cells/mL.B. calyciflorus was excluded by K. valga at low and medium food concentrations (0.5 × 10 6 and 1.0 × 10 6 cells/mL), whereas the opposite was found at high food concentration (3.0 × 10 6 cells/mL).Food concentration is obviously the main factor affecting outcome.Temperature, initial density, and interactions between the three factors also have an effect on it.