Distribution of overwintering Calanus in the North Norwegian Sea

[摘要] During winter 2003 and 2004, zooplankton and hydrographic data werecollected in the northern parts of the Norwegian Sea(68–72° N, 8–17° E) west of the Norwegian shelf break atdepths down to 1800 m. The results cover both inter and intra annualchanges of hydrography and distribution of Calanus spp. For thewhole survey area,average seawater temperature down to 1000 m was higher in 2004 thanin the same period in 2003. For the upper 500 m the difference wasca. 1°C. Calanus finmarchicus dominated at ca. 75% ofthe totalcopepod abundance.Typical abundance of C. finmarchicus in thesurvey area was 30 000–40 000 m⁻².C. hyperboreus was found deeperthan C. finmarchicus while other copepods were found at the depthof C. finmarchicus or shallower. From January to February 2004,the peak of abundance of C. finmarchicus andC. hyperboreus shifted approximately 300 m upwards indicating thatascent from overwintering depth took place at a speed of 10 m d⁻¹during this period. Ingeneral, high abundance of copepods was found adjacent to the shelfslope while oceanic areas had low and intermediate abundance. In thesouthern part of the survey area, location of high and low copepodabundance shifted both between and within years. In the northern part ofthe survey area where the shelf slope is less steep, copepodswas present at intermediate and high abundance during all surveys.

[学科分类] 海洋学与技术