Previous Abstract | Back to Abstracts Page | Next Abstract
Shelf recruitment of Calanus finmarchicus off the west coast of Norway – the role of physical processes and timing of diapause termination.
Annette Samuelsen, Geir Huse, Cecilie Hansen
Mohn-Sverdrup Center/NERSC
(Abstract received 07/02/2007 for session X)
ABSTRACT
The copepod C. finmarchicus is an important part of the Norwegian Sea ecosystem because it is the main food source for planktivorious fish, such as herring, and larvae of most commercial fish stocks. C. finmarchicus has a one-year life cycle, and the shelf population is recruited from individuals that have over-wintered at depth either in fjords or in the deep basins in the Norwegian Sea. The shelf recruitment of C. finmarchicus was investigated using an individual based model for C. finmarchicus coupled to the HYbrid Coordinate Ocean Model. The model was set up on a 4.5 km grid along the west coast of Norway and used to study the shelf recruitment from the Norwegian Sea population. Here, the focus is on physical mechanisms that contribute to the cross-shelf transport of C. finmarchicus in the spring, before and during reproduction. We investigated the effect of wind, temperature and timing of Calanus ascent on the abundance of the shelf population of C. finmarchicus. Five numerical experiments for the year 1995 were performed, in the three first the mean date of ascent was Julian day 40, 60, and 80 respectively, the fourth we used spatially uniform rather than realistic food fields, and in the fifth the initial fat-reserves of the individuals were reduced. It was found that in 1995 the ‘best’ ascent time in terms of spring shelf recruitment was day 60, mainly because of a large onshore transport event around day 70. In the run with uniform food concentration the absence of an early spring bloom on the shelf lead to a temporary smaller shelf population in the spring, but the shelf populations were equally large later in the summer. Early ascent date lead to more recruitment from outside the small model domain, particularly from the south.
Previous Abstract | Back to Abstracts Page | Next Abstract
2007 LOM Workshop, Bergen, Norway, August 20-22, 2007