Longevity of the freshwater anostracan Streptocephalus mackini (Crustacean: Anostraca) in relation to food (Chlorella vulgaris) concentration

SUMMARY 1. Temporary ponds are inhabited by a variety of invertebrates, of which anostracans are an important group. We studied the lifetables of male and female anostracan Streptocephalus mackini at 3 algal concentrations (0.5 × 10 6 , 1.0 × 10 6 and 1.5 × 10 6 cells mL −1 ). 2. Regardless of sex, S. mackini showed better survivorship at lower food levels. The longest average lifespan observed was 85 ± 2 days for males fed Chlorella at 0.5 × 10 6 cells mL −1 . 3. Both net reproductive rate and generation time decreased with increasing food level. The highest net reproductive rate was about 120 cysts per female. The longest generation time of about 40 days, observed at 0.5 × 10 6 cells mL −1 , was more than three times that at 1.5 × 10 6 cells mL −1 . 4. The rate of population increase ( r ) was nearly the same (0.31 ± 0.06) at high (1.5 × 10 6 cells mL −1 ) and intermediate (1.0 × 10 6 cells mL −1 ) food levels. The r ‐value at low food level (0.5 × 10 6 cells mL −1 of Chlorella ) was 0.20 ± 0.01 per day.