Reproduction of the zooplankton, Daphnia carinata and Moina australiensis: implications as live food for aquaculture and utilization of nutrient loads in effluent.

At present, recycle of resources from agricultural waste is in priority. In order to mitigate impacts cause by the high nutrient loads (N and P) in the agricultural effluent, the utilization of nutrient loads from the effluent is essential. Two South Australian species of zooplankton, Daphnia carinata and Moina australiensis are commonly found in agricultural effluent ponds in the Roseworthy district of South Australia. These studies compared the ability of both zooplankton species to utilise nutrients when cultured in anaerobically digested piggery effluent and their subsequent suitability for use as live feed for aquaculture. In order to understand the start-up and maintenance of both species in culture, their reproduction was investigated. The study was carried out from Mar 2007 to Dec 2009 and designed to; a. determine the optimal culture conditions for asexual reproduction, based on nutrient tolerance (LC50 of un-ionized ammonia level), optimal culture temperature and photoperiod effects; b. identify conditions suited for sexual reproduction by focusing on stimuli to induce and hatch ephippia (resting egg), storage conditions for ephippia, sex ratio and embryonic development of the resting egg; c. determine the nutrient utilization efficacy of both zooplankton species; and d. quantify the nutritional profile of both species raised on effluentgrown algae to used be as live feed in aquaculture. M. australiensis had greater (P<0.05) tolerance at higher levels of un-ionized ammonia (NH₃-N) than D. carinata. Moreover, older neonates (