Taux de reproduction en fonction de la concentration en nourriture et de la température chez trois espèces du genreBrachionus(Rotifères)

The influence of various algal (Chlorella) concentrations (from 5.10(3) to 1.10(7) cells mL(-1)) on the population dynamic is stu died at two temperatures (16 & 24 degrees C) in three species, Brachionus angularis, B. calyciflorus (with two clones) and B. plicatilis. By observing about fifteen isolated females, the net reproduction rate, R(0), the intrinsic population growth rate, r(m), the threshold, food level (for which r(m)=0), S-0, and the algal concentration, Ks, supporting the maximum population growth rate (or one-half) are determined. The values of these variables are compared with each others and with the literature data. The low values observed in the B. plicatilis strain are conspicuous. This peculiarity is related to the metabolism of the species adapted to various salinity and food conditions.