Abstract
Systematic studies on the biogeochemistry of Fe and Mo are necessary to be able to understand primary production in the Baltic Sea. Especially, field studies on the physicochemical speciation of Fe, in relation to variations in plankton production, are important. The bioavailability of Fe to phytoplankton is influenced by its physico-chemical speciation. However, data on physico-chemical speciation of trace metals during blooms in coastal areas are scarce. In this study will state of the art techniques, ultrafiltration and Field Flow Fractionation, be used for the physico-chemical speciation of Fe. Furthermore, the importance of siderophores for the speciation of Fe will be studied in the laboaraotory and in the field. Species-specific internal Fe:C, Mo:C and P:C quotas will be determined in hand-picked Aphanizomenon and Nodularia, and related to the physicochemical speciation of Fe in the surface water. There is very little information on trace metal:C ratios in field populations of phytoplankton. This information is vital to make links between laboratory-based culture studies and marine ecosystem dynamics. There is a urgent need to bridge the gap between the relatively constrained and simple laboratory experiments and the situation in the real marine ecosystem, i.e. the gap between the physiological responses of single organisms to Fe in model systems and that of populations of organisms within the natural ecosystem. This project can contribute in bridging this gap.
Sweden