scholarly journals Spatial patterns of surface blooms and recruitment dynamics of Calanus finmarchicus in the NE Norwegian Sea

2006 ◽  
Vol 28 (12) ◽  
pp. 1181-1190 ◽  
Author(s):  
S. L. Basedow ◽  
A. Edvardsen ◽  
K. S. Tande
2009 ◽  
Vol 66 (9) ◽  
pp. 1942-1958 ◽  
Author(s):  
Stéphane Plourde ◽  
Pierre Pepin ◽  
Erica J. H. Head

Abstract Plourde, S., Pepin, P., and Head, E. J. H. 2009. Long-term seasonal and spatial patterns in mortality and survival of Calanus finmarchicus across the Atlantic Zone Monitoring Programme region, Northwest Atlantic. – ICES Journal of Marine Science, 66: 1942–1958. The vertical life table method was used to estimate stage-specific daily mortality rates and survival from 1999 to 2006 for Calanus finmarchicus sampled in the Canadian Atlantic Zone Monitoring Programme, which covers the Newfoundland–Labrador Shelf (NLS), Gulf of St Lawrence (GSL), and Scotian Shelf (SS). Stage-specific mortality rates and survival showed significant regional and seasonal differences, with the largest signal associated with variations in temperature. Density-dependent mortality, associated with the abundance of C6 females, was the main factor influencing mortality in the egg–C1 transition during the period of population growth in spring on the SS, and in summer in the GSL and on the NLS. In autumn, mortality in egg–C1 was positively related to temperature and negatively related to phytoplankton biomass, with particularly high mortality rates on the SS. The integration of our results into stage-specific recruitment rates from egg to C5 revealed that C. finmarchicus populations experience their greatest loss (mortality) during the egg–C1 transition. Loss during development to C1 was greater in the GSL than in the other regions during the period of population growth, resulting in lower recruitment success in the GSL. In autumn, C. finmarchicus showed low stage-specific daily recruitment rates on the SS at high temperatures, and low phytoplankton biomass compared with those in the GSL and on the NLS. Our findings reinforce the necessity of describing regional and seasonal patterns in mortality and survival to understand factors controlling the population dynamics of C. finmarchicus.


2016 ◽  
Vol 160 ◽  
pp. 81-93 ◽  
Author(s):  
Morten Omholt Alver ◽  
Ole Jacob Broch ◽  
Webjørn Melle ◽  
Espen Bagøien ◽  
Dag Slagstad

2006 ◽  
Vol 63 (1) ◽  
pp. 117-127 ◽  
Author(s):  
Irina Prokopchuk ◽  
Evgeniy Sentyabov

Abstract Diets of Norwegian spring-spawning herring, mackerel, and blue whiting in the Norwegian Sea are investigated in relation to the distribution of plankton and hydrographic conditions. Fish stomachs and zooplankton samples were collected during summer (June and July) cruises in 2001 and 2002. Calanus finmarchicus was the principal prey of mackerel, accounting for 53–98% of total stomach content by weight. The diet composition of herring varied depending on feeding area and availability of food under various environmental conditions. C. finmarchicus was important prey for herring only in July 2001 (about 77% by weight) in the central part of the sea and in June 2002 (about 82% by weight) near the Lofotens. In July 2002 appendicularians (Oikopleura spp.), amphipods (mainly Parathemisto abissorum), and euphausiids were important in the diet of herring, and at some stations cannibalism was observed. The main prey of blue whiting were amphipods (10–34% by weight), appendicularians (11–34%), and euphausiids (8–47%), as they usually feed deep in the water column, though C. finmarchicus was important, particularly in June 2002, when blue whiting were caught in the upper layers of the sea. Higher water temperatures indirectly affect pelagic fish through accelerated development of their prey and favourable conditions for migration farther north.


2006 ◽  
Vol 3 (2) ◽  
pp. 25-53 ◽  
Author(s):  
A. Edvardsen ◽  
J. M. Pedersen ◽  
D. Slagstad ◽  
T. Semenova ◽  
A. Timonin

Abstract. During winter 2003 and 2004, zooplankton and hydrographic data were collected in the northern parts of the Norwegian Sea (68–72° N, 8–17° E) west of the Norwegian shelf break at depths down to 1800 m. The results cover both inter and intra annual changes of hydrography and distribution of Calanus spp. For the whole survey area, average seawater temperature down to 1000 m was higher in 2004 than in the same period in 2003. For the upper 500 m the difference was ca. 1°C. Calanus finmarchicus dominated at ca. 75% of the total copepod abundance. Typical abundance of C. finmarchicus in the survey area was 30 000–40 000 m−2. C. hyperboreus was found deeper than C. finmarchicus while other copepods were found at the depth of C. finmarchicus or shallower. From January to February 2004, the peak of abundance of C. finmarchicus and C. hyperboreus shifted ca. 300 m upwards indicating that ascent from overwintering depth took place at a speed of 10 m d−1 during this period. In general, high abundance of copepods was found adjacent to the shelf slope while oceanic areas had low and intermediate abundance. In the southern part of the survey area, location of high and low copepod abundance shifted both between and within years. In the northern part of the survey area where the shelf slope is less steep, copepods was present at intermediate and high abundance during all surveys.


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