Annual population development and production by Calanus finmarchicus, C-glacialis and C-hyperboreus in Disko Bay, western Greenland

The populations of the copepod species Calanits finmarchicus, C. glacialis and C. hyperboreus were investigated in Disko Bay during a 14-month period in 1996-1997. The three species were predominant in the copepod community. The biomass reached a maximum at the beginning of June (127 mg C m(-3)). Fr om the end of July until the end of April the following year, the biomass w as <1-6 mg C m-3. All three species showed seasonal ontogenetic migration. The spring ascent for all three species was just prior to or in association with the break-up of sea ice and the development of the spring bloom, wher eas descent occurred over a larger time span during summer. The main overwi ntering stages were CV for C. finmarchicus, CIV and CV for C. glacialis and C. hyperboreus. Peak abundance of juvenile copepodites, representing the n ew generation, was in August for C. finmarchicus, in July for C. glacialis and in May/June for C. hyperboreus. From the timing of reproduction and the population development, the life cycles were deduced to be 1 year for C. f inmarchicus and at least 2 years for C. glacialis and C. hyperboreus. Secon dary production and potential grazing impact of the Calanus community were estimated by two methods based on specific egg-production rates and tempera ture-dependent production. The Calanus community was not able to control th e primary producers during the spring bloom but probably did during postblo om. The estimates also indicated that grazing on ciliates and heterotrophic dinoflagellates contributes as an essential food source in the post-bloom period.