Dormant eggs of a calanoid copepod from tropical brackish aquaculture ponds

Many Asian aquaculture farms cultivate copepods as live-feed for aquaculture species, as copepod nutritional and behavioural qualities are usually higher than those of traditional live-feeds (i.e., Artemia and rotifers). The most convenient method to use zooplankton in aquaculture as live feed involves dormant eggs. In this study, to establish whether the copepod species of the tropical Taiwanese ponds exhibit quiescence of their eggs, several sediment samples were collected from the ponds and incubated at low temperature. After 3 months of cold incubation, several nauplii of Acartia bilobata Abraham, 1970 hatched from the sediment at high temperature over several days. Further investigations need to be conducted to understand the origin of the dormancy (i.e., induced originally in the field or in the laboratory). Nevertheless, it is the first reported case of dormant eggs in calanoid copepods in tropical regions. The present study will certainly find some interest in tropical aquaculture as our results showed that long-term storage of tropical calanoid copepod eggs is possible, even if collected directly from the sediment without sorting the eggs.