Population growth of Daphnia magna cultured in manure-fertilised water under laboratory conditions

Abstract

In developing countries, mass production of Daphnia magna, used as a food in freshwater aquaculture, is a challenge. A fifteen-day laboratory experiment was conducted to examine the population growth and reproductive parameters for D. magna reared in green water fertilised with organic manures, namely cow dung (CD), chicken manure (CM) and baker’s yeast (Y). Mean number of eggs produced per female per day was highest in CD (n = 5.43) compared to Y (n = 3.38) and CM (n = 0.34). Egg development times were 0.36, 0.79 and 1.77 days for CD, Y and CM, respectively. Ages at first reproduction were 8.46 days for CD and 12.03 days for CM. Duplication times were 3.88, 3.96 and 4.09 days for Y, CD and CM, respectively. Adult mortality was lowest in CD (16.7%) but highest in CM (50%) and Y (100% for both adults and offspring). There were no offspring mortalities in CD and CM; however, 50% of adults and 33.3% of offspring in CM entered resting stages. Body length and weight ranged from 0.62 to 5.69 mm and 0.004 to 0.53 mg, respectively. Daphnia magna cultured in CD outperformed those in CM and Y under various parameters, signifying the value of cow dung in D. magna mass production. Further research is required to optimise organic manure applications for large-scale production in outdoor settings.