EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Burrowing fauna mediate alternative stable states in the redox cycling of salt marsh sediments

Sebastiaan van de Velde1, Gilad Antler2,3, and Filip Meysman4,5
Sebastiaan van de Velde et al.
  • 1Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, United States of America (
  • 2Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
  • 3The Interuniversity Institute for Marine Sciences, Eilat, Israel
  • 4Department of Biology, Universiteit Antwerpen, 2610 Wilrijk, Belgium
  • 5Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands

The East Anglian salt marsh system (UK) has recently generated intriguing data with respect to sediment biogeochemistry. Neighbouring ponds in these salt marshes show two distinct regimes of redox cycling: the sediments are either iron-rich and bioturbated, or they are sulphide-rich and unbioturbated. No conclusive explanation has yet been given for this remarkable spatial co-occurrence.  Using pore-water analysis and solid-phase speciation, I will demonstrate that differences in solid-phase carbon and iron inputs are likely small between pond types, so these cannot act as the direct driver of the observed redox dichotomy. Instead, the results suggest that the presence of bioturbation is the driving force behind the transition from sulphur-dominated to iron-dominated sediments. The presence of burrowing fauna in marine sediments stimulates the mineralisation of organic matter, increases the iron cycling and limits the build-up of free sulphide. Subsequent early diagenetic modelling confirms that the observed regimes in pond geochemistry are caused by negligible differences in solid-phase inputs, which are amplified by positive feedbacks resulting from the impact of bioturbation on iron and sulphur cycling.

How to cite: van de Velde, S., Antler, G., and Meysman, F.: Burrowing fauna mediate alternative stable states in the redox cycling of salt marsh sediments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3840,, 2020


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