Saltmarsh resilience to periodic shifts in tidal channels

Ladd, C. J. T. , Duggan-Edwards, M. F., Pagès, J. F. and Skov, M. W. (2021) Saltmarsh resilience to periodic shifts in tidal channels. Frontiers in Marine Science, 8, 757715. (doi: 10.3389/fmars.2021.757715)

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Resilience of coastal ecosystems to climate change is largely determined by the interaction between plants and the surrounding tidal environment. Research has tended to focus on processes operating at the local scale to explain resilience mechanisms, overlooking potentially important landscape-scale processes and patterns. We show from aerial images spanning 67 years across 3 estuaries that saltmarsh loss was compensated by expansion elsewhere in the estuary when tidal channels shifted position. Compensatory expansion rates were as high as 6 m/yr. This phenomenon of “geomorphic compensation” represents a hitherto overlooked large-scale self-organizing pattern that facilitates the long-term persistence of marshes in estuaries. The geomorphic compensation pattern likely also occurs in other hydrological systems including mangrove forests, and seagrass meadows, and river islands. Compensatory erosion-expansion patterns occurred at the same time as net marsh extent increased by between 120 and 235% across all three estuaries. Marsh expansion mostly occurred in the lower parts of each estuary, where channel migration and compensatory expansion was less evident. Patterns of geomorphic compensation therefore appear to operate at discrete spatio-temporal scales, nested within a hierarchy of coastal morphodynamic processes that govern longer-term patterns of either net marsh gain or loss. Coastal ecosystem resilience can therefore only be fully appreciated when examining erosion and expansion patterns at both local and landscape scales. The intrinsic dynamics of marshes described here have important implications for the long-term delivery of ecosystem services.

Item Type:Articles
Additional Information:This work was supported by the Coleg Cymraeg Cenedlaethol (Ysgoloriaethau Ymchwil), the Welsh Government and Higher Education Funding Council for Wales (Sêr Cymru National Research Network for Low Carbon, Energy and Environment), the Natural Environment Research Council (C-SIDE Project) (Grant No. NE/R010846/1), and the United Kingdom Research and Innovation Global Challenges Research Fund (Living Deltas Research Hub) (Grant No. NE/S008926/1).
Glasgow Author(s) Enlighten ID:Ladd, Dr Cai
Authors: Ladd, C. J. T., Duggan-Edwards, M. F., Pagès, J. F., and Skov, M. W.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Frontiers in Marine Science
Publisher:Frontiers Media
ISSN (Online):2296-7745
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Frontiers in Marine Science
Publisher Policy:Reproduced under a Creative Commons License

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