Interactive effects of food and salinity on the reproductive and growth indices of two Brachionus rotifer strains from Iran

Two Iranian strains of Brachionus rotifers were cultured under different food and salinity regimes. The rotifers were fed with five algal types (freshwater and marine Chlorella vulgaris, Nannochloropsis occulata, Isochrysis galbana and Scenedesmus obliquus) at three different salinities (5, 15 and 25 g/L) and their reproductive and growth parameters were assessed. The maximum number of ovigerous females (73 ± 7 ind/mL), population density (354 ± 3 ind/mL) and specific growth rate (0.75 ± 0.01 / day) were obtained for the rotifers fed with freshwater Chlorella. In Zbl strain, minimum growth rate (0.04 ± 0.05/ day) and population density (13 ± 4 ind/mL) were for the rotifers fed with Isochrysis at 25 g/L, while in Ba strain, population growth and density were null after feeding Scenedesmus at 5 g/L. The rotifer strains were differentially affected by salinity of medium, and Zbl and Ba strains had their maximum growth rates and population densities at 5 and 25 g/L, respectively. Analysis of variance showed significant effects of food type, salinity and their combined effects on all the estimated parameters, while rotifer strain and its interaction with food type and salinity significantly affected growth rate and population density of the rotifers (P < 0.05).