Resting eggs of zooplankton (Copepoda and Cladocera) from the Kiel Bay and adjacent waters (southwestern Baltic)

Resting eggs of four species of calanoid copepods and three species of cladocerans were collected from sediments up to 5 cm depth from the Kiel Bay and adjacent waters in the southwestern Baltic Sea during April-May 1994. All but one species of cladoceran was successfully hatched/reared in the laboratory. In the Kiel Bay, egg abundances varied from 1.8 x 10(5) to 7.4 x 10(5) m(-2). Hatching success of copepod eggs collected from all depths was high (49 to 94%), but was 0 to 79% for cladoceran eggs; Darkness did not seem to affect hatching. Eggs found in the 4 to 5 cm layer of sediment were estimated to be about 15 yr old, showing the presence of an ''egg bank'' in the Baltic. Formation of resting eggs may be a genetic trait acquired during the ice ages.