1. 1 1 Morten D. Skogen North Sea eutrophication assessment OpNet, Geilo, 27-28/5-2009

2. 2 2 References: Skogen, M.D. & Mathisen, L.R. (2009). Long term effects of reduced nutrient inputs to the North Sea. Estuarine, Coastal and Shelf Science, 82:433-442. Almroth, E. & Skogen, M.D. A North Sea and Baltic Sea model ensemble Eutrophication Assessment. Accepted for publication in Ambio.

3. 3 3 Eutrophication : an increase in chemical nutrients -- typically compounds containing nitrogen or phosphorus -- in an ecosystem. Results often in an increase in the ecosystem's primary productivity – i.e. excessive plant growth and decay -- and even further impacts, including lack of oxygen and severe reductions in water quality and in fish and other animal populations.

4. 4 4 Eutrophication (first report) : “By this you will know that I am the Lord: I am going to strike the water of the Nile with the staff that is in my hand, and it will be turned into blood. Fish in the Nile will die, the Nile will stink, and the Egyptians will be unable to drink water from the Nile.” 2.Moses 7:17-18

5. 5 5 North Sea agreement: At the 2nd. International conference on the protection of the North Sea (London 1987), all countries around the North Sea agreed on reducing the input of nutrients by 50 % between 1985 and 1995 for those areas where nutrient cause, or are likely to cause, pollution, in order to combat eutrophication (PARCOM 88/2). OSPAR further developed the Common procedure for the Identification of the Eutrophication Status of the Maritime Areas of the Oslo and Paris Convention in 1997, with an update in 2005. Contracting partners to report on total loads of DIN and DIP in their rivers.

6. 6 6 Reductions in North Sea nitrogen and phosphorous loads 1985-2000 (source approach)

7. 7 7 Reductions in North Sea nitrogen and phosphorous 1985-2000 measured from both sources and loads Toxic Chrysochromulina sp. bloom

8. 8 8 Assessment criteria based on the OSPAR Common procedure Areas categorised as problem area, potential problem area or non-problem area CategoryAssessment criteria I: Degree of nutrient enrichment Riverine inputs and direct discharges (area-specific) Nutrient concentrations (area-specific) N:P-ratio (area-specific) II: Direct effects (during growing season) Chlorophyll A concentration (area specific) Phytoplankton indicator species (area specific) Macrophytes including macroalgae (area specific) III: Indirect effects (during growing season) Oxygen deficiencies Zoobenthos and fish Organic carbon/organic matter (area specific) IV: Other possible effects (during growing season) Algal toxins

9. 9 9 EcoQO for winter nutrients (DIN and/or DIP) concentration EQO: winter DIN and/or DIP should remain below elevated levels, defined as concentrations >50% above salinityrelated and/or region-specific natural background concentrations.

10. 10 EcoQO for phyto- plankton Chl A EQO: maximum and mean chlorophyll A conc. during the growing season should remain below elevated levels, defined as conc. > 50% above the spatial (offshore) and/or historical background conc.

11. 11 NORWECOM The NORWegian ECOlogical Model system http://www.imr.no/~morten/norwecom A coupled physical-chemical-biological model system applied to study primary production and dispersion of particles (e.g. fish larvae and/or pollution) Main partners: Institute of Marine Research Dept. of Fisheries and Marine Biology, Univ. of Bergen Dept. of Mathematics, Univ of Bergen The Norwegian Meteorological institute

12. 12 NORWECOM (2) first coupled physical-chemical-biological model for the whole North Sea North Sea, North Atlantic, Benguela, Hardangerfjorden physics based on POM or ROMS runs operational (7 days forecast) at met.no http://moncoze.met.no http://moncoze.met.no environmental status, eutrophication issues, what-if scenarios, climate/fish relations,….. offline version coupled to Bergen Climate Model for paleo studies – potential oil fields

13. 13 2 types of phytoplankton (diatoms, flagellates) 3 nutrients (N, P, Si) Dead organic matter (DetN, DetP, diatom skeletals) Oxygen (IBM Calanus finm.) Primary production Respiration Algae death Regeneration Self shading Turbidity Sedimentation Resuspension Denitrification ECMWF: Wind and Pressure SeaSurfaceRadiation Surface heat flux Precipitation Evaporation Tides (M2, S2, K1, O1) Freshwater (rivers) River nutrients Atmospheric N Waves (WINCH) Offline (U,V,S,T,ETA,SSR,wind) NORWECOM

14. 14 North Sea primary production model Period 1985-2008 Spin-up: 4 x 1985 Horisontal 10x10km Vertical 21 σ-layers References: –Skogen & Mathisen(2009) –Almroth & Skogen (accepted) 10 km horisontal resolution, 21  -layers

15. 15 Longterm changes of winter DIN and DIP at Noordwijk 10km station Elevated levels

16. 16 Longterm changes of winter DIN and DIP at Noordwijk 70km station

17. 17 Model validation at Noordwijk 10 and 70, Longterm winter DIN and DIP

18. 18 OSPAR ICG-EMO: Target areas, GC1, GO2, NLC2, NLC3 and NLO2 for model statistics to perform a eutrophication assessment based on the OSPAR common procedure Eutrophication in Potomac river

19. 19 Assessment simulations: realistic simulation 1985 fixed values (fixed 1985, 10% reduced) fixed 1985, 50% reduced fixed 1985, 90% reduced Caspian sea from orbit

20. 20 GC1 DIN DIP NLC2 X X Effects of reduced N and P to winter DIN and DIP Fixed 1985 90% 50% Realistic 2-3 years for full effect 50% reduction not sufficient!!

21. 21 NLC3 Chl A Chl A, mean value through the growing season NLO2 X X Effects of reduced N and P to Chl A mean value Fixed 1985 90% 50% Realistic offshore gradient immediate effect lower response than winter nutrients

22. 22 GC1 O 2, annual minimum value GO2 X X Effects of reduced N and P to oxygen minimum value Fixed 1985 90% 50% Realistic almost no effect trend towards lower oxygen values (consistent with increased temperatures)

23. 23 Assessment summary:

24. 24 What controls inter annual variability??

25. 25 A North Sea and Baltic Sea model ensemble Eutrophication Assessment

26. 26 23 North Sea and Baltic subareas:

27. 27 Cost function:

28. 28

29. 29 Modelled winter DIP: Also done for: winter DIN DIN/DIP Chlorophyll Oxygen

30. 30 Integrated assessment:

31. 31 Integrated assessment: Model mean:Weighted model mean:

32. 32 References: Skogen, M.D. & Mathisen, L.R. (2009). Long term effects of reduced nutrient inputs to the North Sea. Estuarine, Coastal and Shelf Science, 82:433-442. Almroth, E. & Skogen, M.D. A North Sea and Baltic Sea model ensemble Eutrophication Assessment. Accepted for publication in Ambio.

33. 33 THANK YOU FOR YOUR ATTENTION Bergen seen from Mt. Ulriken

34. 34

35. 35 Reductions of winter DIN at Helgoland (5-years mean) vs. NAO (J.Aure, IMR, pers.comm)

36. 36 Eutrophication : an increase in chemical nutrients -- typically compounds containing nitrogen or phosphorus -- in an ecosystem. Results often in an increase in the ecosystem's primary productivity – i.e. excessive plant growth and decay -- and even further impacts, including lack of oxygen and severe reductions in water quality and in fish and other animal populations.

37. 37 Winter DINWinter DIP 101 gC/m 2 /y 103 gC/m 2 /y Annual primary prod. 1985 2002