This WP investigates potential regime shifts and thresholds in various subsystems of the Baltic Sea, i.e. the catchment generating nutrient loads, the marine basins with their temporal and spatial nutrient and oxygen regimes in the water and in the sediments, and the food web as a responsive system to bottom up (salinity, temperature, nutrients, oxygen) and top down (fishery, seabird and seal predation) effects.
Aim of the WP
The main aim is to test for gradual and abrupt changes in this unique collection of time series. We will describe the variables´ behaviour: persistence (permanent or temporary change) and the speed of change (abrupt or gradual). If the change is abrupt we will test for thresholds and several indicators, which could potentially serve as early warning indicators of impending shifts.
In model studies, such indicators have been found to provide early warning of regime shifts and hold much promise for adaptive management as for example the zooplankton species Arcatia spp. as an prerequisite species for cod reproduction. The indicators to be tested include increase in variance, changes in skewness, kurtosis, higher autocorrelation and change in the spectral density ratio.
We will use long-term (>30 years) monitoring data accessible via BNI. The most comprehensive Baltic Environmental Database (BED) includes biogeochemical long-term data from the rivers and the sea; the database used in the HELCOM/ICES working group on integrated assessments of the Baltic Sea (WGIAB), includes food-web data (from phytoplankton to fish) for the entire Baltic Sea. Long-term climate data forcing for runoff and ventilation of the sea basins are available via SMHI.
- Casini, M., T. Blenckner, C. Möllmann, A. Gardmark, M. Lindegren, M. Llope, G. Kornilovs, M. Plikshs, & N. C. Stenseth. 2012. Predator transitory spillover induces trophic cascades in ecological sinks. Proceedings of the National Academy of Sciences of the United States of America 109:8185-8189.
- Lindegren, M. Blenckner, T. & N.C. Stenseth. 2012. Nutrient reduction and climate change cause a potential shift from pelagic to benthic pathways in a eutrophic marine ecosystem. Global Change Biology 18, 3491-3503.
- Nyström, M., A. V. Norström, T. Blenckner, M. la Torre-Castro, J. S. Eklöf, C. Folke, H. Österblom, R. S. Steneck, M. Thyresson, & M. Troell. 2012. Confronting Feedbacks of Degraded Marine Ecosystems. Ecosystems 15:695-710.
- Tomczak, M. T., G. E. Dinesen, E. Hoffmann, M. Maar, and J. G. Støttrup. 2012b. Integrated trend assessment of ecosystem changes in the Limfjord (Denmark): Evidence of a recent regime shift? Estuarine, Coastal and Shelf Science.
A list of additional publications is available here