Interannual variability of Calanus helgolandicus in the English Channel

Seasonal and interannual variability in environmental variables, egg production rates and abundance of Calanus helgolandicus at a station in the English Channel have been analysed. The results show a mismatch between the timing of maximum egg production and timing of the abundance peaks. However, except for the year 1996, there was a significant relationship between the initiation of the thermocline and the timing of the maximum female abundance. We advance advection and egg mortality because of sinking as the main factors controlling the timing of the C. helgolandicus abundance peaks in the English Channel.