Studies on life history characteristics of Brachionus plicatilis O. F.!Muller (Rotifera) in relation to temperature, salinity and food algae

Effects of temperature (18, 24, and 30 degrees C), salinity (5 - 40 ppt, five intervals) and algal foods (Synechococcus sp., Chlorella pyrenoidosa, Isochrysis zhanjiangensis, Dunaliella salina and Tetraselmis cordiformis) on the life table demography of six geographical Brachionus plicatilis sensu stricto clones, which had been identified according to the prevalent taxonomy and biometric analysis of B. plicatilis sensu lato, were studied. The results showed that temperature, salinity and temperature x salinity significantly influenced the life history parameters. Genotype (clone) had no effect on the population growth rate but did influence the net reproductive rate, generation time and lifespan. All rotifer clones showed the expected increase in population growth rate with increasing temperature. B. plicatilis s. s. attained a higher population growth rate at low-medium salinities (5 - 20 ppt) than at high salinities (25 - 40 ppt). The equivalent spherical diameter (ESD) of food algae, salinity and ESD x salinity had significant effects on the life history parameters. In this case, genotype had no effect on population growth rate, net reproductive rate and generation time but did influence lifespan. The population growth rate of B. plicatilis s. s. evaluated against particle retention spectrum of algae at two salinities resulted in bell-shaped curves. Dunaliella salina with an ESD = 7.7 mu m was considered to be the best food for B. plicatilis s. s. while Synechococcus appeared to be an inadequate food algae.