The Wadden Sea Ecosystem

1 Introduction.- 2 ELAWAT: Goals and Conceptual Framework.- 3 Study Area: The Backbarrier Tidal Flats of Spiekeroog.- 3.1 Description of the Spiekeroog Backbarrier System.- 3.2 Meteorological Conditions in the East Frisian Wadden Sea from 1994-1996.- 3.3 Hydrographic Conditions in the Spiekeroog Backbarrier System.- 3.4 Morphology and Sedimentology of the Spiekeroog Backbarrier System.- 3.4.1 Origin of the Wadden Sea.- 3.4.2 History of the Coastal Evolution.- 3.4.3 Morphology and Morphodynamics.- 3.4.4 Sedimentology.- 3.5 Biofacies in the Spiekeroog Backbarrier Tidal Flats.- 3.5.1 Introduction.- 3.5.2 Horizontal and Vertical Aspects of Biofacies.- 3.5.3 Case Study Mytilus Bed.- 3.5.4 Effects of Ice Winters.- 3.6 Ecosystem Engineers: Mytilus edulis and Lanice conchilega.- 3.6.1 Mytilus edulis.- 3.6.2 Lanice conchilega.- 4 Statistical Models and Techniques for the Analysis of Conditions of an Ecological System.- 4.1 Introduction.- 4.2 Terminology.- 4.3 Statistical Methods for the Description and Measurement of Stability Properties.- 4.3.1 Description of Patterns and Processes.- 4.3.2 Analysis of Relations.- 4.3.3 Tests for Statistical Distinction Between States of a System.- 4.4 Statistics in ELAWAT.- 5 Spatial and Temporal Distribution Patterns and Their Underlying Causes.- 5.1 Distribution of Nutrients, Algae and Zooplankton in the Spiekeroog Backbarrier System.- 5.1.1 Introduction.- 5.1.2 Material and Methods.- 5.1.3 Tidal Variations.- 5.1.4 Seasonal Variability.- 5.1.5 Interannual Variability.- 5.1.6 Relations Between Phytoplankton and Copepods.- 5.1.7 Relations Between Phytoplankton and Meroplanktonic Larvae.- 5.1.8 Resuspension of Benthic Algae.- 5.2 Biogeochemical Processes in Tidal Flat Sediments and Mutual Interactions with Macrobenthos.- 5.2.1 Microbial and Geochemical Processes.- 5.2.2 Distribution of Macrofauna Along the Transect.- 5.2.3 Discussion.- 5.2.4 Conclusions.- 5.3 Settlement, Secondary Dispersal and Turnover Rate of Benthic Macrofauna.- 5.3.1 Introduction.- 5.3.2 What Determines Year-Class Strength in Intertidal Soft Bottom Benthic Macrofauna?.- 5.3.3 Development of Spatial And Temporal Patterns by Initial Settlement and Secondary Dispersal.- 5.3.4 In situ Turnover Rates of Juvenile Macrofauna in Soft Sediments.- 5.3.5 Small-Scale Temporal Variability in Benthos Distribution Patterns: Patchiness vs. Mobility.- 5.3.6 Lanice conchilega.- 5.4 Modelling the Spatial and Temporal Distribution of Lanice conchilega.- 5.5 Biotic Interactions in a Lanice conchilega-Dominated Tidal Flat.- 5.5.1 Introduction.- 5.5.2 Methods.- 5.5.3 Species Composition and Macrobenthos Abundances.- 5.5.4 Lanice conchilega: Density and Distribution.- 5.5.5 Benthos Associated with Lanice conchilega.- 5.5.6 Discussion.- 5.6 Size Frequency, Distribution and Colour Variation of Carcinus maenas in the Spiekeroog Backbarrier System.- 5.6.1 Introduction.- 5.6.2 Material and Methods.- 5.6.3 Results.- 5.6.4 Discussion.- 6 Recolonization of Tidal Flats After Disturbance.- 6.1 Introduction.- 6.2 Material and Methods.- 6.3 Recolonization After Experimental Disturbances.- 6.3.1 The Course of Recolonization.- 6.3.2 Mode of Recolonization.- 6.4 Recolonization Following the Ice Winter 1995/96.- 6.5 Discussion.- 6.5.1 Recolonization in Dependence of the Sediment Chemistry.- 6.5.2 Temporal Development of Recolonization.- 6.5.3 Comparison of Recolonization After the Ice Winter and After Experimental Disturbances.- 7 Effects of the Ice Winter 1995/96.- 7.1 Introduction.- 7.2 The "Disturbing" Effects of the Ice Winter 1995/96.- 7.2.1 Mechanical Effects.- 7.2.2 Direct Effects of Low Temperatures.- 7.3 The Seasonal Development 1996 (Regeneration).- 7.3.1 The Pelagic System.- 7.3.2 The Benthic System.- 7.4 The "Black Area Event" 1996.- 7.5 Comparison of Ice Winter Effects in Different Parts of the Wadden Sea.- 8 Grid-Based Modelling of Macrozoobenthos in the Intertidal of the Wadden Sea: Potentials and Limitations.- 8.1 Introduction.- 8.1.1 Theoretical Background.- 8.1.2 Empirical Background.- 8.2 The First Model: A Demonstration.- 8.2.1 Results of the First Model.- 8.3 Problems When Applying the Grid-Based Approach in the Wadden Sea.- 8.4 A Grid-Based Approach Tailored to the Wadden Sea: TOPOGRID.- 8.4.1 Typical Results of TOPOGRID.- 8.5 Methodological Conclusions.- 8.6 Ecological Conclusions.- 9 Stability Properties in the Wadden Sea.- 9.1 Introduction.- 9.2 The Conceptual Framework: A Glossary.- 9.3 A Canon of Questions.- 9.4 The Abiotic Ingredients of the Wadden Sea.- 9.4.1 Meteorological Boundary Conditions and Disturbance Regime.- 9.4.2 Hydrography, Morphology and Sediments.- 9.4.3 Chemistry of the Sediments.- 9.4.4 Summary: Abiotic Ingredients of the Wadden Sea.- 9.5 The Biotic Ingredients of the Wadden Sea.- 9.5.1 Bacteria.- 9.5.2 Microphytobenthos and Phytoplankton.- 9.5.3 Macrozoobenthos.- 9.5.4 Migratory Birds.- 9.5.5 Summary: Biotic Ingredients of the Wadden Sea.- 9.6 Conclusions.- 10 Assessing Stability Properties: How Suitable is this Approach for Ecosystem Research in the Wadden Sea?.- 11 Joint Research Projects: Experiences and Recommendations.- 11.1 Realization of ELAWAT.- 11.2 Problems and Potentials of Joint Projects.- 11.3 Gaps of Knowledge and Research Recommendations.- 11.4 Recommendations for the Realization of Joint Projects.- 12 Protection of Processes in the Wadden Sea.- 12.1 What is Protection of Processes?.- 12.2 Protection of Processes in the Wadden Sea.- 12.3 Arguments from ELAWAT for the Protection of Processes.- 12.4. Outlook.- 13 Summary.