Effects of temperature, pH, and photoperiod on the performance of a freshwater cladoceran Moina micrura culture enriched with Lysinibacillus fusiformis and Bacillus pocheonensis

The freshwater cladoceran Moina micrura has tremendous potential for mass culture as a live feed for larviculture. This study aimed to evaluate the efficacy of probiotics Lysinibacillus fusiformis A1 and Bacillus pocheonensis S2 in enhancing the population density, growth rate, and production of M. micrura under different environmental conditions. Four different temperatures (15, 20, 25, and 30°C), pH levels (4, 6, 8, and 10), and photoperiods (4L:20D, 6L:18D, 8L:16D, and 12L:12D) were set up. The daily number of individuals incubated under each environmental parameter was monitored for 12 days to determine the population density and growth rate of M. micrura. Meanwhile, the daily number of neonates from five females kept under respective environmental parameters was monitored until they died naturally. Probiotics were added individually at 5×104 CFU mL-1 twice during the first and sixth days of the experiment. M. micrura enriched with B. pocheonensis S2 at 30°C had the highest maximum population density (10 ± 0.2 ind mL-1) and the number of neonates produced (132 ± 6.43 ind), whereas treatment at 20°C had the best growth rate (0.1863 ± 0.006 d-1). M. micrura incubated with B. pocheonensis S2 at a normal photoperiod of 12L:12D had the highest maximum population density (10 ± 0.3 ind mL-1) and the number of neonates produced (129 ± 4.58 ind) while incubation at 8L:16D had the best growth rate (0.2879 ± 0.0007 d-1). M. micrura enriched with L. fusiformis A1 at pH 8 had the highest maximum population density (11 ± 0.8 ind mL-1), growth rate (0.5508 ± 0.04 d-1), and the number of neonates produced (129 ± 4.36 ind). Results recommend that a warmer temperature of 30°C, alkaline pH from 8 to 10, and a normal photoperiod of 12L:12D can be adopted for M. micrura enrichment with B. pocheonensis S2 to maximize its productivity for aquaculture use.