promote longer lifespan of crustaceans such as Daphnia (MacArthur & Baillie, 1929; Dudycha, 2001). Additionally, at higher food concentrations most cladocerans spend much of their energy for cleaning the appendages from algal clogging which causes reduced food intake and increased respiratory loss (Dodson & Frey, 2001). In the present study, we did not quantify algal food consumed by test anostracans nor their respiration. However, the reduced lifespan of S. mackini with increasing algal concentration observed could be because of the above factors.