Bio-conversion rate and optimum harvest intervals for Moina australiensis using digested piggery effluent and Chlorella vulgaris as a food source

The bio-conversion rate of Moina australiensis fed with Chlorella vulgaris grown on digested piggery effluent at three different feeding rates was determined and a 2, 3 and 4-day harvest interval strategy was investigated. This study indicates that C. vulgaris is a suitable food source for M. australiensis. A significant difference (P ⩽ 0.001) in the feeding rate against mean total populations was found among treatments. The increase in the amount of algae fed accelerated the production rate, and the population density peaked faster in the high C. vulgaris fed treatment. The BCR calculated from this experiment indicates that for every 1000 mg of C. vulgaris fed there was an increase of 437.9 mg of M. australiensis biomass produced. A significant difference (P ⩽ 0.001) in biomass production among the different harvest interval treatments was observed. The 2-day harvest interval treatment produced 7.78 g of M. australiensis followed by 6.89 g in the 3 day and 5.01 g in the 4-day harvest interval treatment. This study provides strong evidence that M. australiensis can utilise the bacterial blooms and bio-films associated with digested piggery effluent as a food source.