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

Abstract

For calanoid copepods living in an advective environment, any predictive life history model relies on our comprehension of the significance of advection and environmental parameters. To study the propagation of an initial population of Calanus finmarchicus with respect to spatial distribution and stage development throughout time, we have developed a lagrangian particle-tracking model. The advection of the population is driven by a physical component, while a biological model describes vertical migration and stage development. The physical model is composed of large- and small-scale current fields, while the biological model reflects our current understanding of vertical migration and spawning behavior resolved spatially. The results indicate that the population is distributed along the major current branches in the 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. The stage progression shows that C. finmarchicus developing in the oceanic region has a late spawning period compared to the fraction of the population residing in the near coastal regions. The life history of Calanus finmarchicus in Norwegian waters is considered to deviate between one and three generations 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 field 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 oceanic regions in close vicinity to the Norwegian Atlantic Current flowing along the shelf break, and the mid-Norwegian shelf.