1 / 14

Silt dynamics in the WaddenSea

Silt dynamics in the WaddenSea. Action plan - position paper. Wadden Sea. Unesco World heritage site Primary function: nature Exploitation only when the natural system is not negatively affected. System is rich in silt and mud

elaina
Download Presentation

Silt dynamics in the WaddenSea

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Silt dynamics in the WaddenSea Action plan - position paper

  2. Wadden Sea • Unesco World heritage site • Primary function: nature • Exploitation only when the natural system is not negatively affected • System is rich in silt and mud • Large deposits in the bed, large vertical fluxes (bed – water column), large horizontal fluxes (in and out of the tidal basins) Position paper silt Wadden Sea

  3. Muddy waters • System is under anthropogenic pressure • Access • Islands • Harbours (Harlingen, Ems, Elbe) • Tourism • Fishing • Extraction • Gas • Salt • Eutrophication Position paper silt Wadden Sea

  4. Mud dynamics in the Wadden Sea • Tidal basins • most import - export via North Sea • very limited lateral transport of water – for silt, transport across the watersheds between tidal basins may be significant • large differences between Dutch tidal basins • West sandy • East muddy Position paper silt Wadden Sea

  5. Silt within the ecosystem Do we have (a) problem(s) with silt? Is the sediment getting more or less muddy? Has water clarity decreased? How does mud content influence species? Is turbidity a problem for the natural system? You have to identify a problem before you can solve it Position paper silt Wadden Sea

  6. Effects of silt on ecology • In the water column: • Silt reduces light penetration • Primary production is influenced by light, but also by nutrients • Light is limiting for seagrass (submerged Zostera marina) • Silt may interfere with feeding efficiency of filter feeders • In the bed • Silty mudflats have higher benthic primary production than sandy ones • Effects on zoobenthos can be direct (e.g. burrowing) or silt can be a covariable with hydrodynamics Position paper silt Wadden Sea

  7. Knowledge gaps • Knowledge agenda Wadden Academy (Ecology en Geology) • Insight in the sediment fluxes (sand and silt) per tidal basin • Quantify effect of ecosystem engineering species • Required • Integrated monitoring • Integrated modelling Position paper silt Wadden Sea

  8. Average net sedimentation Net input from IJsselmeer Net transport via the Dutch Coast Maximum influence nourishments Harbour dredging and dumping Resuspension from mussel culture plots Filtration by mussels Gross import North Sea Gross exchange North Sea (including Ems) Exchange gullies - flats Resuspension due to tides and waves 0 500 1000 1500 2000 2500 3000 silt flux flux (in 106 m3 / year) Proportions may vary strongly per tidal basin Relevant processes analysis Dutch part Position paper silt Wadden Sea

  9. Plan of Action • Learning by doing • Accept that there is a lot we don’t know, but get started on the basis of “best guess”. • Not doing anything is also a decision • Monitor and learn from current activities • Integrated approach • Sedimentologist – ecologists • Modelling – measuring • Small scale – large scale coupling • Scientists, users, policy makers • Practical approach • Focus on knowledge of processes that can be directly influenced by human intervention • With background knowledge of autonomic and long-term trends Position paper silt Wadden Sea

  10. Where can human activity play a role? Morphology changes flow and wave exposure short term – long term Bed disturbance – feedbacks from ecosystem engineers short term – long term Nutrient loadings – pelagic feedback on particle dynamics / flocculation long term Position paper silt Wadden Sea

  11. Scope • Full Wadden Sea (International) • Including • Ems • Weser • Elbe • More emphasis on Dutch part • Concerning: • Factors influencing silt dynamics (at different spatial and temporal scales) • How human activities influence these factors • How human intervention will improve the ‘natural status of the ecosystem’ Position paper silt Wadden Sea

  12. Monitoring – already running • National initiatives: • Standard monitoring programme (MWTL) is known to have serious short comings regarding silt • WaLTER – assuming it gets the go ahead, will come up with new monitoring strategies by 2014 • International • COSYNA: what can we learn, how can we in future contribute • Other • For our purposes: what do we need to know, vs what do we want to know Position paper silt Wadden Sea

  13. Links with national and international programmes • National Delta Programme • ‘Kustlijnzorg’ (Coastal care programme) • Waddenfonds • ZKO • Interreg • Bi (tri?)lateral Wadden Sea Research Position paper silt Wadden Sea

  14. Position Paper = Concrete action plan • International feedback group • 2 concepts • Regular contact with policy makers – system users • Link with questions in the field (Arjen Bosch et al.) Position paper silt Wadden Sea

More Related