Reproduction rate and microbial load of the rotifer Brachionus calyciflorus (Pallas, 1766) fed on Chlorella sp. cultured on organic media

Abstract An experiment was conducted to evaluate the culture performance and total microbial load of the rotifer Brachionus calyciflorus reared on microalgae Chlorella sp. cultured with a replacement of 50% of the standard Bolds’ Basal Medium (BBM) with poultry manure filtrate (POMF), sheep manure filtrate (SHMF), water hyacinth root compost filtrate (WHRCF), water hyacinth leaf compost filtrate (WHLCF), water hyacinth root and leaf compost filtrate (WHR + LCF) and a control treatment with 100% BBM. The results indicated that the POMF substituted culture of Chlorella sp. gave significantly highest cell density (1.83x10⁸ cells mL⁻ ¹) followed by the 100% BBM culture (1.74x10⁸ cells mL⁻ ¹) supporting 272 ± 6.4 and 122.2 ± 5.53 rotifers mL⁻ ¹ B. calyciflorus population, respectively. The SHMF culture gave the third highest Chlorella sp. density (5.94x10⁷ cells mL⁻ ¹) and supports 83.4 ± 13.78 rotifers mL⁻ ¹ B. calyciflorus population. The three treatments with the compost filtrate of the different parts of water hyacinth gave the least Chlorella sp. cell density and B.calyciflorus population as well. In terms of the total viable bacterial count of B.calyciflorus cultured on the substitution of the different organic media indicated that B.calyciflorus cultured on 100% BBM and 50% POMF- based culture gave significantly lowest total bacterial counts of 6.9x10⁶ ± 9.9x10⁵ and 8.05x10⁶ ± 4.94x10⁵ CFU mL⁻ ¹, respectively while SHMF, WHR + LCF, WHLCF, WHRCF group showed higher total bacterial counts of 1.62x10⁷ ± 2.83x10⁵, 1.09x10⁷ ± 7.78x10⁵, 1.25x10⁷ ± 7.07x10⁴, 1.03x10⁷ ± 7.07x10⁴ CFU mL⁻ ¹, respectively in non-rinsed samples. Therefore, it can be concluded that 50% substitution the standard BBM media for Chlorella sp. culture with organic manures such as POMF can be a sustainable alternative to culture the rotifer B. calyciflorus for larval fish culture.