Shelf sea systems of the Northeastern Atlantic Ocean

Shelf sea ecosystems are known to exhibit natural fluctuations. They suffer from global indirect anthropogenic stressors such as CO2-induced warming, ocean acidification and nutrient transport via the atmosphere. Additionally they suffer from direct regional or local impacts like eutrophication, invasion of new species, and overexploitation of fish stocks. External controls like climate variations and internal controls of the food web are dynamically balanced within unstressed ecosystems, but this balance changes with increasing variations of external forcing. As a consequence, multiple drivers interact to reorganize the structure of entire ecosystems, manifested in so-called "ecosystem regime shifts" (Möllmann et al., 2009).

The figure shows the annual amount of nitrogen per drainage area from rivers (Gmol N 10-6 km-2 yr-1). The central northern European continent exhibits the highest number (red) indicating very high population density and intensive agriculture.

Central Questions

  • What changes in biogeochemical cycles and foodwebs of shelf seas are to be expected from climate forcing in the next decades?
  • Which combinations of natural variability of the external forcing, long term trends in the global environment and additional stress by direct human intervention promote interannual and decadal variability of material cycles and food webs in shelf sea ecosystems?

Questions to be tackled in detail

  • Will oxygen deficiency situations increase?
  • Will the acidification of shelf seas accelerate?
  • Will the continental carbon shelf pump efficieny further decrease?
  • Will sedimentation at the coast balance the sea level rise?
  • Is a shift from phytoplankton diatoms to other species to be expected?

CliSAP topic B3 will combine the existing modeling and experimental expertise to understand and to predict possible responses of marine systems to cyclical and secular changes in external forcing and random pertubations.