Building with nature: The use of ecosystem engineers for coastal protection
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Globally flooding and coastal erosion represent serious threats along many coastlines, and will become more serious as a consequence of human-induced changes and accelerated sea-level rise. In case of the Oosterschelde, tidal areas are disappearing at a fast rate after the realization of the Delta works.
The natural dynamic cycle of accretion and erosion changed into a continuous erosion process. Reduction in tidal flat area and elevation results in a loss of valuable habitats, impacting biodiversity including bird populations and seals. It also poses threats to coastal defence as dikes become less protected from waves and currents because of loss of tidal flats and salt marshes in front of the dikes. |
Natural oyster reef in the Oosterschelde |
Testing of artificial substrates in the Oosterschelde |
To adequately deal with these threats require innovative, cost-efficient and sustainable methods for conservation of estuarine tidal habitats and coastal defense.
Ecosystem engineering (= modification of the abiotic environment due to biological activity) is an important mechanism in shaping ecosystems. Ecosystem engineers such as oyster reefs or mussel beds are conspicuous habitats that can influence tidal flow and wave action within estuaries and, in doing so, modify patterns of sediment deposition, consolidation, and stabilization. Therefore, the concept of ecosystem-engineering offers promising possibilities for a sustainable coastal protection. |
Goal
This research project uses the concept of ecosystem engineering to investigate the potential use of biogenic reefs in the lower intertidal zone for consolidation and stabilization of tidal flats in the Oosterschelde. The project will provide the means to evaluate the effectiveness and impacts of an innovative and sustainable approach to reduce erosion of intertidal areas.
Approach
We will set up field experiments at a scale that allows us to really monitor the effectiveness and impact of biogenic reefs for the stabilization of tidal flats and for their (local-scale) ecomorphological impact. For this purpose we follow different steps that allow us to successfully design such pilot experiments:
- initial conditions for settlement and development of oyster reefs (habitat analysis);
- development of suitable substrates (e.g. shells of mussels/oysters) for creating optimal conditions for biogenic reef development in tidal areas;
- large-scale pilot to investigate possibilities to create biogenic reefs in the Oosterschelde and evaluate their effectiveness for consolidation and stabilization of tidal flats;
- monitor pilot sites to determine their effect on the environment (physical, biological);
- develop (predictive) tools/models to evaluate the use of biogenic reefs.
To realize this project a multidisciplinary project team is set up with scientists from IMARES, Deltares, NIOO and Van Oord.
Results
The project is now in its start up phase. A habitat suitability model (developed in cooperation with the project “WINN Biobouwers”) is available that generates prediction maps where potential habitats are situated for setting up biogenic reefs. Testing of artificial substrates at a small scale is running and a first pilot experiment at the slikken of Viaenen is foreseen in the spring of 2009. A large-scale pilot will then be executed in 2010.
Follow up
The ecosystem engineer concept offers promising opportunities for ecodynamic design, but has yet to be formally and explicitly applied. Identifying and managing probable engineering species and responsive ecosystems should be a key priority for a sustainable conservation and management and this will necessitate a shift to a process based understanding of the functioning of whole systems, which is a large and important step toward ecosystem-based management. This pilot experiment will enhance our understanding about the use of ecosystem engineers in this ecodynamic design.
Funding & funded by
This project is part of the innovation program “Building with Nature”, managed and administered by the foundation EcoShape. The program aims at developing new design concepts for the layout and sustainable exploitation of river, coastal and delta areas.
Contact
Martin Baptist, Business Card, martin.baptist@wur.nl