Abstrakt
Daphnia egg banks are important reservoirs of dormant stages. Although the hatching is probably of minor importance in water bodies with a permanent population, this may differ after major disturbances.
In 2006, two 500-year floods hit the Vranov Reservoir (Czech Republic), in which we had investigated population of the Daphnia longispina complex in preceding years. In this study we focused on the impact of those floods on the dormant egg bank.
A year after the floods, we did not observe any sediment layer that would be devoid of ephippia, however, we observed a significant increase in the proportion of empty ephippia and a decrease in the proportion of those containing eggs. We attribute these changes to flood disturbance, which caused redistribution of stored ephippia and those detached from the shoreline.
Deposited to shallow parts of reservoir after the floods, dormant eggs could therefore receive and respond to hatching stimuli, and contributed to Daphnia recovery after the flood.