Life table demography of the rotifer Lecane Tenuiseta under culture conditions, and various age distributions

Abstract

The rotifer Lecane tenuiseta found contaminating an unpolluted culture water reservoir, was cultured in a dilute baker's yeast suspension using the same water. Ova, cultured individually in 10 µl wells at 20°C, were observed at half day intervals for hatching, daughter ova and death. Data were subjected to life table demographic analyses. With a stable age population of parthenogenic females, laying 6.8 ova per lifetime and increasing at 0.23 per individual day, mean life expectancy of a newly laid ovum was 26 days, generation time was 8.4 days and 11% of the population appeared as developing embryos. With a stationary age population calculated by the Leslie-Ranson method, there would be no change in life expectancy but a decrease in embryos to 9%; a stationary age distribution calculated by the Hummon method would show a decrease in life expectancy to 4.9 days and a increase in embryos to 46%. Calculation by the latter method is more consistent with available field data for species of planktonic rotifers.