Nutrient gradients in the wadden sea
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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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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

Western Dutch Wadden Sea: Salinity (Zimmermann, 1976)

July 71

April 72

IJsselmeer influence in Western Dutch Wadden Sea prominent

November 71

June 72

North German Wadden Sea


  • 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)

Cross-shore profiles in the Niedersachsen Wadden Sea

In Niedersachsen, there is no permanent freshwater source!



  • Conclusion:

  • High concentrations in winter after sluice outlet

  • Concentrations in summer smaller

  • Concentrations in winter homogeneous

  • Strong gradient in summer




Linear y-axis (µmol N/L)

Slope of DIN-curves

Slope of DIP-curves

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

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

Nutrient budget: summer


North Sea



Inter-basin exchange


Nutrient budget: inter-basin exchange is small

Stanev et al., 2003

Sluices: Variability of runoff

Sluices: nutrient concentrations

Exchange with North Sea: Time constant

Exchange constant 3 days

Rain (EMEP):

2 mg/L


only in winter

Inter-basin exchange:


North Sea.

3 days exchange



Export of dissolved nutrients

Conceptual model for nutrient dynamics:

depth function

Theoretical profiles:

Essential assumption: mortality of phytoplankton is depth dependent (filter feeders)

Ebenhöh et al., 2004

What is the essential difference between Niedersachsen and the other two regions??

Can we treat the entire Wadden Sea in the same way?

Thanks for your attention!

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