Shelf recruitment of Calanus finmarchicus off the west coast of Norway: role of physical processes and timing of diapause termination
Authored by Geir Huse, Annette Samuelsen, Cecilie Hansen
Date Published: 2009
DOI: 10.3354/meps08060
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Abstract
The copepod Calanus finmarchicus is an important part of the Norwegian
Sea ecosystem because of its dominating abundance and importance as prey
for fish larvae and adult planktivorous fish. The abundance of C.
finmarchicus on the Norwegian shelf is generally low in winter, whereas
in spring the shelf is replenished by individuals that overwinter at
depth, either in fjords or in the deep basins of the Norwegian Sea. In
the present study shelf recruitment is investigated using an
individual-based model for C. finmarchicus coupled to the HYbrid
Coordinate Ocean Model and a biophysical model. The model was set up on
a nested grid along the west coast of Norway and used to study the shelf
recruitment originating from the Norwegian Sea. We investigate the
effect of wind, currents and the timing of Calanus ascent on the shelf
abundance of C. finmarchicus. The most important findings are the
following: (1) periods of large on-shelf transport are connected with
strong westerly winds associated with passing low-pressure systems; (2)
the transport of overwintering adults onto the shelf determines the
total shelf abundance prior to mid-summer; (3) the early spring bloom on
the shelf causes increased shelf population of C. finmarchicus in the
spring and throughout the summer compared to the areas further
off-shore; and (4) the entry routes taken by C. finmarchicus are related
to bathymetry; in particular, the deep trenches around Halten Bank and
the Norwegian trench are favoured places to enter the Norwegian shelf.
Tags
individual-based models
Fish populations
Marine copepod
North-atlantic
Norwegian sea
Reproductive-biology
Overwintering calanus
Nordic seas
1997 spring bloom
Vertical
migration