Potential recruitment into planktonic population and influencing factors on the hatching of copepod resting eggs in ponds.

Abstract

The formation of resting eggs is an important survival strategy for copepods. The abundance of resting eggs in sediment is of great significance to the recruitment of copepod population in aquatic environment. Desiccation is an important approach of aquaculture management in ponds, which has great influences on pond ecosystem. Surface sediments of aquaculture ponds in Nansha, Guangzhou were sampled before (15th Feberary 2014) and after (2nd March 2014) the desiccation separately to explore the potential recruitment of resting eggs into planktonic copepod population, and environmental factors influencing the hatching success of copepod resting eggs. Results showed that without desiccation and cooling, the highest potential recruitment and immediate hatching rates of resting eggs were observed at the salinity of 20 experimental group, while after cooling to 4 ℃ for four weeks, the hatching rate was highest at the salinity of 15. When exposed to desiccation, the highest potential immediate recruitment and hatching rate of resting eggs were observed at the salinity of 15, while after cooling to 4 ℃ for four weeks, the highest hatching rates were observed at the salinity of 20. It was concluded that desiccation reduced the potential recruitment of resting eggs in sediment significantly (P＜0.05), and desiccation had a negative impact on their hatching duration.