Limnology of rearing ponds for Australian fish larvae: Relationships among water quality, phytoplankton, zooplankton, and the growth of larval fish

Abstract

Fertilization of earthen ponds used to rear the larvae of golden perch, Macquaria ambigua, and silver perch, Bidyanus bidyanus, resulted in phytoplankton blooms dominated by the cyanobacterium Anabaena possibly because of a low N:P ratio. There was a zooplankton succession of rotifers (mostly Brachionus), Moina, Boeckella and Mesocyclops, and then Daphnia. An increase in Daphnia correlated with a decline in Anabaena, suggesting grazing on that cyanobacterium. Golden perch larvae included copepods in their diet whereas silver perch did not, and this was reflected in lower Boeckella numbers in the golden perch ponds. There was sufficient zooplankton forage, supplemented by chironomid larvae in the later stages of the rearing ponds, for fish growth. The limnological conditions and zooplankton communities in these ponds provide a model for evaluating nursery grounds for these fish.