A particular role in Baltic ecology is assigned to those microalgae, whose sinking connects pelagic and  benthic cycles of matter. This process forms the first step of  material transfer from the pelagic food web of the surface waters to the sediments, which are characterized by geological interactions. The analysis of sinking species of algae and the resulting transfer of elements to the sediment allows conclusions on the recent external loading of the Baltic ecosystem and helps to reconstruct past environmental conditons of this sea. A comparison between algae, abundant in surface waters, and sedimenting species reveals the special importance of certain algal species or groups for the formation of sediments.
 

These analyses are performed since 1997 at a central spot in the Baltic, the Gotland Sea, where sinking matter is continuously collected by means of large funnel-shaped divices (sediment trapsPicture). The saisonal succession of algal groups ,important in this process, as well as a collection of  light- and SEM-microphotopgraphs of algae from samples of surface water and sediment traps, is presented for the period 1997-1999.                                                  Deployment of sediment  traps

The saisonal succession of algal groups ,important in this process, as well as a collection of  light- and SEM-microphotopgraphs of algae from samples of surface water and sediment traps, is presented for the period 1997-1999.