In order to assess the impact of climatic changes on the living Barents Sea, the Nansen Legacy is using the end-to-end ecosystem model NORWECOM, and contributes to its further improvement with an Individual Based Model for a Arctic key copepod species.

NORWECOM.E2E is an ecosystem model where ocean circulation, phytoplankton, zooplankton and fish are coupled to investigate ecosystem dynamics and trophic interactions. The model has also a module for ocean acidification, thus possible effects of changes in pH can also be investigated. The model operates on a fine scale in both time and space (typical 10km and 1 hour) and can therefore give a very detailed picture of both the ocean state and the biological processes.

While some organisms (e.g. phytoplankton) are modelled using functional groups, where many different species are modelled as a bulk, Individual Based Models (IBM) are used for selected species. In an IBM, the full life cycle of an individual (birth, growth, feeding, reproduction, migration and death) is simulated in great detail, using all existing knowledge of the species from laboratory and field studies.

The main zooplankton species in the Nordic and Barents Seas are Calanus finmarchicus, Calanus hyperboreus and Calanus glacialis. One of the main differences between them are their preferred water temperature, with C. finmarchicus being an Atlantic species and the two other Arctic species. With climate change it is belived that the distribution of these three species will change, which again may impact on pelagic fish for which zooplankton are imprtant prey.

NORWECOM.E2E already has IBMs for C. finmarchicus and C. hyperboreus. As part of the Nansen Legacy an IBM for C. glacialis is now being developed. Using results from climate models, distribution, interactions and stock biomass of these threet zooplankton species are investigated to better understand the consequences of climate change.