Seasonal variations in population dynamics of Calanus finmarchicus in relation to environmental conditions in the southwestern Norwegian Sea

A seasonal study of the life cycle and reproductive biology copepod Calanus finmarchicus – dominant zooplankton species a key link between lower higher trophic levels within southwestern Norwegian Sea - is presented. C. reproduces, feeds accumulates lipids during spring summer surface waters, which enables it to survive overwintering at depth until following spring. An inflow warm saline Atlantic Water (AW) enters from southwest meets cold less subarctic waters (SAW) flowing north west. This confluence establishes dynamic Iceland Faroe Front. The includes seven cruises, conducted July 2013 2014. Ascent occurred earlier over prolonged period in AW compared SAW. peak egg production per capita April (43 eggs female?1 d?1) May (13 SAW AW, respectively. productivity can be explained by larger female size, increased lipid content better feeding conditions. rates were not reflected an abundance young copepodite stages June, potentially due decoupling early ascent late onset bloom. Descent, largely comprised pre-adult stages, depths was already initiated June both regions. coincides with content, being significantly summer. smaller portion individuals remained upper layers spawn second generation August regions, increasing biomass. phenology stage development likely influence competition herring mackerel duration their stay Faroese waters.