The Diatom/Dinoflagellate Index as an Indicator of Ecosystem Changes in the Baltic Sea 1. Principle and Handling Instruction

摘要: An ecosystem shift in the Baltic Proper at end of 1980s could be identified by a decreasing springtime diatom/dinoflagellate ratio. Therefore suggested index (Dia/Dino index) was developed as descriptive indicator changes for applications pertaining to Marine Strategy Framework Directive (MSFD). Changes dominance these two phytoplankton classes impact food web because both their quality source grazers and periods occurrence differ, which may lead mismatch zooplankton growth. The rapid sinking diatoms results high Dia/Dino index, indicative low-level availability but high-level delivery zoobenthos. Consequently, can used follow pathway (Descriptor 4 MSFD: “food web”). Moreover, low indicate silicate limitation caused eutrophication, whereas supports mitigated strong sedimentation nutrients removes them from water deposits sediment 5 “eutrophication”). Diatom dominance, thus is typical historical data therefore assumed reflect good environmental status (GES). principles are explained herein using examples very different regimes, Eastern Gotland Basin Kiel Bay. In assessment bodies, GES boundaries 0.5 0.75, respectively, suggested. conditions calculating described limitations advantages this discussed.