A model study of demography and spatial distribution of Calanus finmarchicus at the Norwegian coast

For calanoid copepods living in an advective environment, any predictive li fe history model relies on our comprehension of the significance of advecti on and environmental parameters. To study the propagation of an initial pop ulation of Calanus finmarchicus with respect to spatial distribution and st age development throughout time, we have developed a lagrangian particle-tr acking model. The advection of the population is driven by a physical compo nent, while a biological model describes vertical migration and stage devel opment. The physical model is composed of large- and small-scale current fi elds, while the biological model reflects our current understanding of vert ical migration and spawning behavior resolved spatially. The results indica te that the population is distributed along the major current branches in t he Norwegian Sea, with fractions entering the Barents Sea, West-Spitsbergen and the Norwegian Shelf. A part of the population spends their entire life progression in the oceanic realm, with relatively low rate of advection. T he stage progression shows that C, finmarchicus developing in the oceanic r egion has a late spawning period compared to the fraction of the population residing in the near coastal regions. The life history of Calanus finmarch icus in Norwegian waters is considered to deviate between one and three gen erations per year. In the shelf region, Lofoten is often referred to as the northernmost area where a two-generation cycle occurs. Our two-generation simulations are compared with held data obtained from the OMEX study site, and the results indicate that the two-generation cycle is a very plausible explanation to the obtained data. The spawning regions of G(2) are both oce anic regions in close vicinity to the Norwegian Atlantic Current flowing al ong the shelf break, and the mid-Norwegian shelf. (C) 2000 Elsevier Science Ltd. All rights reserved.