Levels of nutrient enrichment determine the emergence of zooplankton from resting egg banks

We studied the effects of varying levels of nitrogen (N), phosphorus (P), and nitrogen and phosphorus mixture (NP) enrichment on the hatching of resting eggs to determine whether nutrient enrichment levels affect the emergence of zooplankton from resting eggs. We treated resting eggs with six different nutrient concentrations and returned them to the in situ water environment to simulate the restoration of a favourable environment after eutrophication. Low nutrient concentrations had a lesser impact on egg hatching compared with high concentrations, and P had a lesser impact on egg hatching than N and NP. Resting eggs were able to maintain their vitality even in unfavourable environments during the enrichment phase, and they hatched in large numbers when favourable conditions arose. High concentrations of N and NP had a significant effect on the community structure of hatched zooplankton, mainly affecting the emergence of copepod nauplii from resting eggs. The findings suggest that levels of nutrient enrichment determine the emergence of zooplankton from resting egg banks. This study provides a reference for the potential replenishment of active populations by resting egg banks in eutrophic river environments.