ROTIFER Brachionus plicatilis PRODUCTION OTIMIZATION USING DIFERENTS STOCKING DENSITIES AND DIFERENTS MICROALGAE Nannochloropsis oceanica CONCENTRATIONS
The e stablishing of dietary protocols for the Brachionus plicatilis, using different food options and optimal stocking conditions, are important to diversify their production protocols . Therefore, t he use of the microalga Nannochloropsis oceanica in different stocking of rotifers are the aims of the present study.
The experiment was delineated from the factorial statistical model of Central Composite Rotatable Design. The rotifers were stocked at different densities (59, 100, 200, 300 and 341 rot mL-1 ) and fed with different concentrations of N. oceanica (59, 100, 200, 300 and 341 × 109 cell rot-1 day-1) for 72 hours in 11 experimental containers. This statistical model allowed the creation of different production scenario s for rotifers production, such as Optimized Scenario (O . S.), Maintenance Scenario (M . S.) and Production Scenario (P . S.).
The results are shown in Table 1 and suggests that the highest population growth rate (0.53), can be found using N. oceanica concentration of 300 × 10⁹ cell 10⁶ rot-1 day-1 and a rotifer stocking density of 100 rot mL-1 in the PS. However, the maintenance of the rotifers production (M. S.) with reduced cost ($ 0.39) , it is possible to obtain a population growth rate of 0.32. In addition, it has been shown that although population growth rate of rotifers is more closely related to the amount of food supplied, there is a correlation between reproduction rate and stocking density.
As conclusion, in order to obtain a maximized population growth rate of the rotifer B. plicatilis it is recommended to use a N. oceanica concentration of 300 × 10⁹ cell 10⁶ rot-1 day-1 and a rotifer stocking density of 100 rot mL-1. Though, the best configuration for rotifers production, including all the responses obtained, was using a concentration of 270 × 10⁹ cell 10⁶ rot-1 day-1 and a rotifer stocking density of 69 rot mL-1.
