Baltic Sea benthic succession model

From the data of traditional samplings and the experimental results together with imaging techniques like video, sedimentprofiling and fotography it was possible to create a sucssession model specific for the Baltic Sea. The model is based on five degrading stages describing not only the benthos fauna of the southern Baltic but also the redoxproperties of the sediments. It is also applicable on historical datasets and allows a longterm trend analysis. This model is different from other succession models (Pearson, Rosenberg 1978) as this model only shows the succession stages relevant to the Baltic Sea with higher resolution. Initial comparisons with data from 1932 and 1989 show a general degrading of all deep sea floors by one stage.

Stage 1: describes a stable (Climax-) community

• dominated by Bivalves respectivly Echinoderms
• deep settled and long living species
• mixed and oxigenised sediments with a deep redox layer

Stage 2:

describes a heavily fluctuating community (Basic Baltic Sea  community)

• dominated by Bivalves and long living Polychaeta
• biomass is elevated (mainly an effect of eutrophication)
• the redox layer raised already closer to the surface

Stage 3:

describes a community of small polychaets with heavy fluctuations

• fading biomass
• occasionally the community is comletly erased by oxygen depletion
• the redox-layer is already a few millimeters below the sediment surface

Stage 4:

describes a community without any macrofauna

• Beggiatoa meadows
• isolated vagile epifauna (Harmothoe)
• already first lamaelle of sedimentation events can be found

Stage 5:

describes a habitat with extreme living conditions

• on the long run without live
• sediments with lamaelle
• examples are the Landsort deep in the Baltic and the Black Sea