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Nutrient gradients in the Wadden Sea

Nutrient gradients in the Wadden Sea. Götz Flöser, GKSS Research Centre TMAP-Workshop, Hamburg, 29.11.2004. Monitoring in the North Sea. Measuring stations in Niedersachsen not near the mainland. Nutrient budget? Philippart & Cadée, 2000.

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Nutrient gradients in the Wadden Sea

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  1. Nutrient gradients in the Wadden Sea Götz Flöser, GKSS Research Centre TMAP-Workshop, Hamburg, 29.11.2004

  2. Monitoring in the North Sea Measuring stations in Niedersachsen not near the mainland

  3. Nutrient budget? Philippart & Cadée, 2000 Western Dutch Wadden Sea: Salinity (Zimmermann, 1976) July 71 April 72 IJsselmeer influence in Western Dutch Wadden Sea prominent November 71 June 72

  4. North German Wadden Sea TRANSWATT • The gradients found in Schleswig-Holstein can be attributed to: • freshwater input from polders, • influence of the Elbe at westerly wind conditions • Generally, mixing is the main process (N-S-diagrams)

  5. Cross-shore profiles in the Niedersachsen Wadden Sea In Niedersachsen, there is no permanent freshwater source!

  6. DIN-Profil µMol/L • Conclusion: • High concentrations in winter after sluice outlet • Concentrations in summer smaller • Concentrations in winter homogeneous • Strong gradient in summer Langeoog

  7. µMol/L Langeoog

  8. Linear y-axis (µmol N/L)

  9. Slope of DIN-curves Slope of DIP-curves

  10. Nutrient measurements in the Wadden Sea: Correlation with salinity. • Two different findings: • Winter: mixing of sluice waters with Wadden Sea • Sommer: no correlation with salinity

  11. Consequence: winter concentrations of NH4+NO2 double the values near the islands

  12. Nutrient budget: summer Rain North Sea DIN-inventary Sluices Inter-basin exchange Sediment

  13. Nutrient budget: inter-basin exchange is small Stanev et al., 2003

  14. Sluices: Variability of runoff

  15. Sluices: nutrient concentrations

  16. Exchange with North Sea: Time constant Exchange constant 3 days

  17. Rain (EMEP): 2 mg/L Sluices: only in winter Inter-basin exchange: small North Sea. 3 days exchange DIN-inventary Sediment

  18. Export of dissolved nutrients Conceptual model for nutrient dynamics:

  19. depth function Theoretical profiles: Essential assumption: mortality of phytoplankton is depth dependent (filter feeders) Ebenhöh et al., 2004

  20. What is the essential difference between Niedersachsen and the other two regions?? Can we treat the entire Wadden Sea in the same way?

  21. Thanks for your attention!

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