Calanus helgolandicus egg production time-series

copepod egg photos

Calanus helgolandicus egg production rates (EPR) have been recorded from station L4 in the Western English Channel off Plymouth since 1992. This long series of high-frequency observations of Calanus helgolandicus reproduction is unique. The data set provides an important opportunity to advance zooplankton seasonal succession modelling, and investigations of inter-annual variability at higher trophic levels. In a laboratory female Calanus sp are picked from a live sample collected mid-morning at L4. Five replicates each containing five females are incubated in filtered seawater for 24 hours at ambient L4 temperature. The eggs produced are collected and counted. Females are verified for Calanus helgolandicus. Data is presented as average EPR per female per day. Although the weekly experiments are conducted using a standard methodology throughout, the original data set itself has not been recorded in a completely standard way. Checks have been made to ensure the quality and integrity of the electronic data and some deductions have had to be made. Therefore, users are encouraged to contact the originators for advice and should read the metadata.

Enquiries can be directed to Andrea McEvoy ( or Angus Atkinson (

Egg production data

The WCO is a partnership between Plymouth Marine Laboratory and The Marine Biological Association.

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Project funded by:

Research council’s National capability funding.