EFFECT OF FOOD CONCENTRATION ON GROWTH, REPRODUCTION AND SURVIVORSHIP OF BOSMINA-LONGIROSTRIS (CLADOCERA) - AN EXPERIMENTAL-STUDY

1. Body growth, reproduction and survivorship of Bosmina longirostris were monitored at four food concentrations (0.05, 0.10, 0.25 and 2.50 mg C l-1) to examine the extent to which food concentration affects these life-history parameters. 2. Food concentration had a significant effect on growth, and most of the reproductive parameters (size and age at maturation, brood size, instar duration and egg development time). More than 60% of animals died before maturation at the lowest food concentration, although most animals survived until maturation at other food concentrations. 3. Change in life-history parameters resulted in a decrease in rate of population growth (r) from 0.310 to 0.020 day-1 with decreasing food concentration, showing that this cladoceran is highly food-limited in many lakes. 4. Importance of the effect of food concentration on egg development time was emphasized in relation to analysis of natural populations.