1.The deep soft seabeds of the Baltic Sea Area offer a wide range of ecological niches for invertebrates (zoobenthos), from the high-diversity marine regions characterised by large and long-lived organisms in the Skagerrak to the species-poor, almost limnic, systems in the inner reaches of the Bothnian Bay and the Gulf of Finland.
2. The zoobenthos processes nutrients and organic matter in the sediments, oxygenates the sediments through bioturbation and bioventilation, affects nutrient fluxes at the sediment/water interface, and acts as a link in both bottom-up and top-down control of the entire Baltic Sea ecosystem.
3. The steep spatial and seasonal gradients of the Baltic Sea structure the zoobenthic communities and shape their functional roles in the food webs as well as in benthic-pelagic coupling.
4. Eutrophication and widespread hypoxia and anoxia are major factors that shape the taxonomic composition, functionality and successional patterns of the zoobenthic communities.
5. As the zoobenthos still recovers from the last glaciation through an on-going succession, there are plenty of vacant niches available in the Baltic Sea for the introduction and establishment of non-indigenous species, and these species may have profound impacts on the whole ecosystem.
6. Due to the sensitivity of the zoobenthos to environmental change and its relative longevity, zoobenthos abundance, biomass and community composition are used as indicators of ecosystem health.
7. Modern science combines field surveys with experiments and advanced mathematical modelling, linking physical and chemical drivers with food web processes. Flux measurements and broad functional analyses, in combination with molecular studies, provide information on processes that reshape our understanding of ecosystem functioning.