All the major aspects of the Baltic Sea ecosystem, such as eutrophication, food web dynamics, fishery, susceptibility to pollutants and biodiversity, as well as their responses to climate changes, are both affected by- and reflected in the nutrient biogeochemical cycles.

As a tool for studying these problems, BALTSEM has been under development since the 1990s  and is now freely available for both hindcast and forecast simulations via the Baltic Nest system.

Simulates the ecosystem

BALTSEM simulates seasonal ecosystem dynamics driven by all the major transport mechanisms and nutrient biogeochemical fluxes in the Baltic Sea, which is presented as a chain of 13 highly vertically resolved but horizontally averaged water columns and underlying sediments. 

Detail formulations of BALTSEM and model-data comparisons are presented here:  BALTSEM - a marine model for decision support within the Baltic Sea region (1888 Kb)  (pdf).

Scientific tool

BALTSEM has been used as the major scientific tool for development of the HELCOM Baltic Sea Action Plan.  Other examples of the BALTSEM implementation include simulation of the long-term development of the Baltic eutrophication since 1850, as well as its participation in the ensemble modelling of the climate change projections.

Furthermore, BALTSEM has also been used as a generator of the input data for benthic and food-web modelling.

BNI Sweden has developed two expansions to BALTSEM; BALTSEM-C and BALTSEM-POP to describe the carbon cycle and dynamics of persistent organic pollutants in the Baltic Sea.