Influence of Different Water Sources on Population density, Intrinsic Growth Rate and Culture Performance of Daphnia pulex and Moina micrura

Abstract

Water quality is a critical factor influencing the mass culture of freshwater cladocerans used as live feed in aquaculture. The present study evaluated the effects of three water sources such as borewell water, rainwater and reverse osmosis (RO) water on the population growth of Daphnia pulex and Moina micrura cultured under laboratory conditions using dried baker's yeast as the sole feed. Triplicate cultures were maintained for 10 days, and population density was determined daily using a Sedgwick–Rafter counting chamber. The intrinsic population growth rate (r) was calculated during the exponential growth phase, while one-way and two-way ANOVA were performed to evaluate the effects of water source and culture duration. Rainwater consistently supported the highest population density in both species. Daphnia pulex attained a maximum population density of 107.0 ± 6.48 ind. mL⁻¹ on Day 6, whereas Moina micrura reached 119.0 ± 2.33 ind. mL⁻¹ on Day 7. RO water produced the second-highest population densities, while borewell water consistently resulted in the lowest production. The intrinsic population growth rate of D. pulex was highest in rainwater (0.480 ± 0.055 day⁻¹), whereas M. micrura exhibited the highest growth rate in RO water (0.410 ± 0.041 day⁻¹). One-way ANOVA revealed significant differences in mean population density among water sources for both D. pulex (F₂, ₂₇ = 6.365, P = 0.005) and M. micrura (F₂, ₂₇ = 4.740., P = 0.017). Two-way ANOVA further demonstrated that culture day, water source and their interaction significantly affected population density (P < 0.001) in both species. The findings indicate that rainwater is the most suitable water source for the laboratory culture of D. pulex and M. micrura, while RO water represents a practical alternative where rainwater is unavailable. These results provide useful baseline information for optimizing freshwater cladoceran production as live feed for aquaculture.