Modelling hydrography and algal production in a poll in western Norway

A heliothermic poll is modelled in terms of a physical-chemical-biological (PCB) model. The poll was used as a food production system and thermal source for a bivalve culture system. Physical, chemical and biological variables were monitored during April–October 1989, when the poll was not manipulated, and in 1990 when the poll was manipulated in order to enhance bivalve production capacity. The manipulations involved input of nutrients and turbulent energy to the poll. Nitrogen input increased seven-fold while bivalve production increased six-fold in the culture system. P modelling was successful both years. CB modelling with a parameter set developed for a mesocosmos system was successful in 1990 concerning chlorophyll and silicate, but less successful in the 1989 season. The model gives increased understanding of PCB processes in the poll which is needed in developing management configurations of such culture systems.