Variations in the advection of Calanus finmarchicus onto the Faroe Shelf

Abstract

The copepod Calanus finmarchicus is a dominant factor in the marine ecosystem on the Faroe Plateau, but its abundance is highly variable. Interannual differences of about one order of magnitude in Calanus abundance were observed on the shelf in spring and summer. In winter, C. finmarchicus is scarcely found on the Faroe Plateau, but during spring and summer it is imported from offshore by advection. Variations in the numbers of imported overwintered C. finmarchicus on the shelf in April are much larger than in the offshore waters feeding the area, and variability in inflow rates is likely the major explanation. Independent estimates of flushing rates for the shelf water exhibit variations of a similar order of magnitude as the interannual variations in the biomass of C. finmarchicus on the shelf. Prolonged windstress, especially from the southwest, increases the flushing rate, and there is some observational evidence of a relationship between C. finmarchicus abundance on the shelf and water inflow. © 2000 International Council for the Exploration of the Sea.