Abstract: The resting egg phase is an important survival strategy of copepoda in the environment, and also an important potential recruitment for copepod population in the water. Surface sediments of Nansha in the Pearl River Estuary were collected to examine the effect of salinity and refrigeration on the hatching of copepod resting eggs. Our results showed that the hatching number and hatching rate of resting eggs incubated were higher at the salinity of 5 and 20 compared to those at other salinity levels (P<0.05). Two sizes of resting eggs in the sediment were separated by a 50 μm mesh size screen and the hatching number of resting eggs was significantly higher in the <50 μm sediment than in the >50 μm sediment (P<0.05). The hatching number of refrigerated resting eggs was significantly higher than that of roomtemperature stored resting eggs (P<0.05). The resting eggs hatched before refrigeration were mainly quiescence eggs and diapause eggs, which had passed the refractory phase in the sediment, and the resting eggs hatched after refrigeration (30 days) were mainly diapause eggs, which did not pass the refractory phase in the sediment, indicating that the resting eggs in the sediment of <50 μm were mainly diapause eggs. The results provide a better understanding of potential recruitment of copepods from resting eggs, and have important implications for further revealing the succession mechanism of copepod species in the estuarine water.

Key words: water source, Eucalyptus urophylla ×E. grandis, drought stress, water use efficient