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Morten D. Skogen

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

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Morten D. Skogen

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

  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. 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. 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. 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 inputof nutrients by 50 % between 1985 and 1995 forthose areas where nutrientcause, 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. Reductions in North Sea nitrogen and phosphorous loads 1985-2000 (source approach)

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

  8. Assessment criteria based on the OSPAR Common procedure Areas categorised as problem area, potential problem area or non-problem area

  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. EcoQO for phyto-plankton ChlA EQO: maximum and mean chlorophyllAconc. during the growingseason should remain below elevated levels, defined as conc. > 50% above the spatial (offshore) and/orhistorical backgroundconc.

  11. NORWECOMThe 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. 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 environmental status, eutrophication issues, what-if scenarios, climate/fish relations,….. offline version coupled to Bergen Climate Model for paleo studies – potential oil fields

  13. 2 types of phytoplankton (diatoms, flagellates) • 3 nutrients (N, P, Si) • Dead organic matter (DetN, DetP, diatom skeletals) • Oxygen • (IBM Calanus finm.) • 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) • Primary production • Respiration • Algae death • Regeneration • Self shading • Turbidity • Sedimentation • Resuspension • Denitrification NORWECOM

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

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

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

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

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

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

  22. GO2 GC1 X X 90% 50% Realistic Fixed 1985 Effects of reduced N and P to oxygen minimum value O2, annual minimum value • almost no effect • trend towards lower oxygen values (consistent with increased temperatures)

  23. Assessment summary:

  24. What controls inter annual variability??

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

  26. 23 North Sea and Baltic subareas:

  27. Cost function:

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

  29. Integrated assessment:

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

  31. 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.

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

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

  34. 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.

  35. Winter DIN Winter DIP Annual primary prod. 101 gC/m2/y 1985 103 gC/m2/y 2002

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