Top-down or bottom-up – The role of birds in the Wadden Sea food web


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sabine.horn [ at ] awi.de

Abstract

The Wadden Sea at the western coasts of Germany, Denmark and the Netherlands is one of the globally most important foraging areas for breeding and migrating birds acting as indicators for the ecological condition of the ecosystem. However, little is known about how the intense predation pressure of birds influences the Wadden Sea food web. The aim of the interdisciplinary project STopP is to determine the food web structure in terms of the interaction between the basis of the food web and birds as top predators. Studied habitat types included the most important foraging areas of birds; mussel banks, cockle beds, sand flats, mud flats, seagrass meadows and beds of the immigrant razor clam Ensis directus a recently preferred prey item of several bird species. Data were analysed using the Ecological Network Analysis (ENA) that reflects trophic structures within the systems and reveals direct and indirect relations between the lower and the upper trophic levels. Preliminary results show that bird predation increases the complexity of the food web due to an increase in connections and a higher total system throughput. On the other hand the predation has also a destabilizing effect due to a high demand of system’s carbon stocks and increased exports out of the tidal system. Furthermore, analyses show considerable indirect dependencies of birds to lower trophic levels such as sediment POC and phytoplankton. Future scenarios modelled with ENA shall show how changes within the lower trophic levels would affect foraging birds due to anthropogenic or natural impacts.



Item Type
Conference (Talk)
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Primary Division
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
50th European Marine Biology Symposium��, 21 Sep 2015 - 25 Sep 2015, Helgoland.
Eprint ID
40185
Cite as
Horn, S. , Asmus, R. , Enners, L. , Garthe, S. , Schwemmer, P. and Asmus, H. , Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung, Wattenmeerstation Sylt, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung, Wattenmeerstation Sylt, Forschungs- und Technologiezentrum Westküste der Christian-Albrechts-Universität zu Kiel, Forschungs- und Technologiezentrum Westküste der Christian-Albrechts-Universität zu Kiel, Forschungs- und Technologiezentrum Westküste der Christian-Albrechts-Universität zu Kiel, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung, Wattenmeerstation Sylt (2015): Top-down or bottom-up – The role of birds in the Wadden Sea food web , 50th European Marine Biology Symposium��, Helgoland, 21 September 2015 - 25 September 2015 .


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