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چکیده
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Two native rotifer species, Brachionus plicatilis (B. pli) and B. rotundiformis (B. rot) sampled from northwest and south Iran were subjected to an experimental culture in order to evaluate their cultural capabilities at different densities. Each rotifer species was cultured at three salinities of 5, 20 and 30 ppt in triplicate. All the animals were fed with Chlorella vulgaris, and water temperature was 25 ºC and density was 500 ind./ml for all the treatments and replica. The maximum mean ratio of uneggedfemale (UF) to egged females (EF), mean number of mictic females (MF) and mean number of mictic eggs (ME) (per mL) were observed in B. rot at 20ppt. While, maximum average number of males (M) was in B. pli at 20ppt. The highest number of produced resting eggs (RE) was is B. pli at 30ppt and maximum mean number of parthenogenetic eggs (PF) was in B. rot at 5ppt. ANOVA showed significant differences (P<0.05) in the values of the measured parameters among different treatments. Duncan's test revealed that there was significant difference in UF/EF ratio between B. rot at 5 and 20 ppt, between B. rot at 20 ppt and each of the other treatments, and between B. pli at 20 and 30 ppt. There also were significant differences in the number of mictic females of each rotifer species at different salinities and between the two species. However, number of mictic eggs, males, resting and parthenogenetic eggs were not different among B. pli cultured at different salinities. In occlusion, salinity had a significant effect on the life-table and cultural traits of the examined rotifers and both rotifer species showed positive growth responses at lower salinities.
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