سروه قادرپور

Despite the positive role of rotifers in many hatcheries for feeding the early stages of aquatic larvae, the lower mineral content of zinc (Zn) is one of the disadvantages of rotifer compared to copepods. Therefore, it is necessary to increase its amounts through enrichment. For this purpose, in the present study, a combination of algae Isochrysis aff. galbana and Nannochloropsis oculata were enriched with zinc sulfate for 1 and 3 hours. Due to obtaining better results in 1 hour, its effects on the growth and enrichment of rotifer were surveyed. The 1: 1 alga composition was enriched with zinc sulfate at concentrations (45, 90, and 135 mg/l). The highest amount of zinc was observed in the mixed algal enriched with 90 mg/l for 1 h, which had the highest copper amount and there was no significant difference with the control group. Also, the manganese amount was higher than the other treatments except for the control group. After feeding the rotifers with enriched algae for 1 hour, the best treatment was 45 mg/l, which also contained the second level of zinc and the first level of manganese, copper, potassium, and sodium. On the other hand, this treatment had the highest number of eggs on the peak day of reproduction treatments (third day) and its population density in the last days was not significantly different from the control group (p <0.05). Zn-enriched rotifers can be used to feed marine fish to meet the nutritional needs of aquatic larvae.

Despite the positive role of rotifers in many hatcheries for feeding the early stages of fish larvae and crustaceans, the lower content of minerals such as selenium (Se, 30 times) and zinc (Zn, 5 times) is considered as one of the disadvantages of this live prey compared to copepods. Therefore, increasing the amount of these nutrients through enrichment is essential. To this end, the present study investigated the effects of the combination of 2 algae Isochrysis aff. galbana and Nannochloropsis oculata enriched with sodium selenite and zinc sulfate on growth and mineral content of rotifer. First, the 1:1 composition of the algae was enriched with a mixture of zinc and selenium salts (each with concentrations of 20, 40 and 80 mg L-1 in algal enrichment medium). The highest number of rotifers (339 ± 11.06 ind mL-1), SGR (± 0.48 ± 0.008 day-1), and the lowest doubling time without any significant difference observed in rotifers fed with algae enriched with 40 mg L-1 of both minerals (p>0.05). However, the highest amount of Zn and Se were observed in those fed with 80 mg L-1 of both minerals. In conclusion, feeding rotifers with Se and Zn enriched algae increased Se and Zn in the rotifers. Thus, microalgae enriched with Se and Zn can be used to feed marine rotifer to meet the nutritional requirements.

This research was performed to introduce a standard protocol for enrichment of Artemia urmian with Canola oil. Artemia urmiana nauplii were enriched at three densities (50000، 100000 and 200000 nauplii L-1) and three concentrations of Canola oil (0. 1، 0. 2 and 0. 3 g L-1). Their effects were evaluated on survival، total length and profile of fatty acids at 6، 9، 12، 15 and 18 hours after the onset of enrichment. Cysts of A. urmiana were hatched according to the standard method. A. urmiana nauplii were stocked at above densities in 7 L cylindrical containers. Canola oil emulsion was added at concentrations of 0. 1، 0. 2 and 0. 3 g L-1 at the beginning and 12 hours after the onset of enrichment. The results of analysis showed that enrichment of A. urmiana with 0. 3 g L-1 Canola oil at 100000 nauplii L-1 for 18 hours was considered as the best treatment. Artemia nauplii enriched in this treatment had significantly higher levels of (n-3) PUFA and survival and minimum total length comparing to other treatments. The treatment had significantly higher levels of (n-6) PUFA than all treatments except treatment with a density of 50،000 nauplii L-1 with 0. 1 g L-1 Canola oil for 18 hours.

In this study¡ the effects of enriching Artemia franciscana nauplii with three concentrations of Canola oil at three density levels were evaluated on survival¡ total length and fatty acids of Artemia franciscana nauplii to determine the optimum concentration oil¡ density of nauplii and optimum time for maximum survival rate and fatty acids and minimum total length of nauplii. Cysts of Artemia franciscana were hatched according to the standard method (Sorgeloos¡ 1986). Artemia franciscana nauplii were then stocked at densities of 50000¡ 100000 and 200000 nauplii L-1 in 7 L cylindrical containers. Canola oil emulsion was added at concentrations of 0.1¡ 0.2 and 0.3 g L-1 at the beginning and 12 hours after the onset of enrichment. Nauplii were sampled at 6¡ 12 and 18 h after onset of enrichment for measuring the survival¡ total length and the concentration of fatty acid. The results of analysis showed that enrichment of Artemia with 0.3 g L-1 Canola oil at 50000 nauplii L-1 for 18 hours was considered as best treatment. Artemia nauplii enriched in this treatment had maximum linoleic and linoleic acids¡ highest survival and minimum total length.