A diffusion model for the primary production of phytoplankton

The ecology model, presented in Svansson (Marine Chemistry, 35 (1991) 347–354) and Larsson and Svansson (Polar Biology, 12 (1992) 183–188) is here applied to the Skagerrak, where nutrients limit the primary production of algae during most of the year. Differences with Antarctic conditions, presented in the two mentioned papers, are discussed. In the Skagerrak not only is the mixing different (much smaller) but the deep phosphate (one third only) and the winter quanta attenuation (2–3 times larger) are different also. Regeneration of nutrients is probably higher in a sea with small mixing. Two model computations illustrate the differences and the difficulties. It is too early to come to a “final solution”. Among the problems, for instance, is that there are too few data for the Skagerrak. This lack is partly offset by information from the Kattegat. More work is needed with the model, especially after further data have been collected.