Climate change alters the egg development dynamics in cold-water adapted coregonids

We tested experimentally how the eggs of coregonid fish from the same parents develop at different incubation temperatures under natural long and climate change induced short winter conditions. The experimental scenarios simulating the water temperature in the spawning areas were constructed using a meteorological model including the climate change scenarios and a thermodynamic water quality model. Northern latitude stocks of vendace (Coregonus albula) and European whitefish (Coregonus lavaretus) had high flexibility in the egg developmental rates: the physiologically distinct temperature-dependent regulation of the ontogenetic steps during incubation caused over 3 months long hatching-to-feeding window to adjust the hatching and start of external feeding in optimal conditions. Survival of embryos and larvae did not differ between scenarios and even in the shortest winter scenario, the survival and growth rate of embryos and larvae was high. An among-family effect on the hatching time of the offspring was also observed. Our results showed that spring warming of the water already under the ice is the key cue to synchronize the hatching of coregonids close to the ice break-up period.