動物プランクトン利用による微細藻類のバイオマス変換

抄録

Photosynthetic bioreactors using microalgae have been used in the past and are effective in biological oxygen regeneration in the CELSS. However, there is little published data on the utilization of algal biomass. In order to utilize it as food for zooplankton using a Closed Ecological Recirculating Aquaculture System (CERAS), this study examined the optimal food concentration and the algal biomass conversion efficiencies based on dry weight in different feeding levels for water fleas, Moina macrocopa, fed on Chlorella algae, Chlorella vulgaris. In experiment 1, M. macrocopa were cultured for 3 days under five different food concentrations (10^5.0, 10^5.5, 10^6.0, 10^6.5 and 10^7.0 cells/mL) in aerated 2L beakers. Growth rates of M. macrocopa increased with higher concentration of microalgae up to a concentration of 10^6.0 cells/mL. Increasing the concentration above 10^6.5 cells/mL resulted in lower growth rate. The result shows that the growth of M. macrocopa is impeded at the concentration above 10^6.5 cells/mL. In experiment 2, M. macrocopa were fed at a rate of 4 × 10⁵ cells/individual for 1^st day with concentration of cells feed increasing at rates of 1.2, 1.4 and 1.6 times/day up to day 5. The biomass conversion efficiency for the treatments were 0.308 ± 0.039, 0.306 ± 0.015 and 0.287 ± 0.020/day respectively, and the values were not significantly different (p>0.05). The results show that biomass conversion is similar between the different feeding rates. Thus, the population growth of M. macrocopa depends on feeding level and can be controlled by feeding, without changing biomass conversion efficiency.