A high frequency time series at Weathership M, Norwegian Sea, during the 1997 spring bloom:the reproductive biology of Calanus finmarchicus

Abstract

The reproductive biology of Calanus finmarchjcus was investigated at a permanent station in the Norwegian Sea (Weathership Stn M, 66" N, 2" E) during a time series between March and June 1997 The temporal development of female abundance, egg production rate and gonad development stage in relation to the phytoplankton production cycle is described Abundance of females, copepodite stage 5 and males as well as female gonad morphology were examlned from MrP2 net samples taken daily from the upper 100 m. Daily egg production rate and number of spawn.ing females we]-e determined from 50 individual females placed in multiwells or beakers. Once a week a multinet haul from 1000-500-250-100-50-0 m was performed to study the depth d~stribution of females and gonad development stages. Results show that the reproductive period of C. finmarchicusin the Atlantic rcqion of the Norwegian Sea can be subdivided in 3 periods in relation to phytoplankton devrlopmt,nt.