Effects of the biochemical composition of three microalgae on the life history of the rotifer Brachionus plicatilis (Alvarado strain): an assessment

The biochemical composition of microalgae used as food is essential for aquatic species in commercial production systems, such as rotifers and microcrustaceans. Life table bioassays with the rotifer Brachionus sp. "Alvarado" strain were performed using three microalgae (Nannochloropsis oculata, Dunaliella salina and Isochrysis sp.) as food. Microalgae growth rate, dry weight and biochemical composition (protein, lipid, carbohydrate) and pigments (chlorophyll and carotenoid) were determined. The microalgae showed significant differences in their biochemical composition. N. oculata showed the highest growth rate, while D. salina showed the slowest growth rate, but instead, it displayed a higher content of proteins, lipids, carbohydrates, chlorophyll, and carotenoids per cell. Rotifer life table analysis showed no significant differences among any of the microalgae as food bioassays. However, Isochrysis sp. had a higher effect on the net reproductive rate of the rotifer Brachionus sp. "Alvarado" followed by D. salina, while N. oculata showed a higher effect on life expectancy and generation time. In conclusion, the three microalgae are found to be useful to support rotifer cultures; however, both, D. salina and Isochrysis sp., might improve the rotifer culture due to better growth and reproduction in short time. This information is useful to implement the culture of this tropical strain of Brachionus plicatilis complex in order to obtain high population densities, making rotifers available for several applications such as the establishment of larviculture in hatcheries, bioassays for ecological studies or to assess its sensitivity through toxicity tests.