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Rapid infill of abandoned tidal channels creates hotspots for blue-carbon accumulation in coastal wetlands

Rapid infill of abandoned tidal channels creates hotspots for blue-carbon accumulation in coastal wetlands
Rapid infill of abandoned tidal channels creates hotspots for blue-carbon accumulation in coastal wetlands

Sinuous channel networks dissecting tidal wetlands are highly dynamic and are often abandoned as a result of channel captures and meander cutoffs. However, the effects of channel dynamics on blue carbon fluxes remain unclear. Analyses of abandoned tidal channels in the Venice Lagoon (Italy) demonstrate that they take up organic carbon at significantly faster rates than neighboring marshes. This is because, despite slightly lower sediment carbon density, abandoned tidal channels yield significantly higher rates of sediment vertical accretion owing to topographic accommodation and reduced flow velocities, which facilitate the deposition of particulate matter and debris. We estimate that abandoned tidal channels in Venice capture 17 tons of carbon annually, equivalent to 21 ha of marshes, despite covering only 3.5 ha in total. Hence we argue that abandoned tidal channels serve as hotspots for blue-carbon accumulation and should be considered to improve estimates of carbon fluxes in coastal wetlands.

Venice Lagoon, abandoned tidal channels, blue carbon, coastal wetlands, salt marshes
0094-8276
Puppin, Alice
34bb7877-adbb-4ed6-b386-92cbc6b670e3
Tognin, Davide
258ed2d9-d5cd-495f-9d74-5f4d3de5f5a3
Ghinassi, Massimiliano
0e9a8a6e-e7b8-4419-b410-e267562e9ae9
D'Alpaos, Andrea
9530c7c5-03f1-4a09-9b64-d9b6a9aac950
Lazarus, Eli D.
642a3cdb-0d25-48b1-8ab8-8d1d72daca6e
Gao, Chao
739e2f49-9184-4fb1-a7eb-3907bf0cc3eb
Finotello, Alvise
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Puppin, Alice
34bb7877-adbb-4ed6-b386-92cbc6b670e3
Tognin, Davide
258ed2d9-d5cd-495f-9d74-5f4d3de5f5a3
Ghinassi, Massimiliano
0e9a8a6e-e7b8-4419-b410-e267562e9ae9
D'Alpaos, Andrea
9530c7c5-03f1-4a09-9b64-d9b6a9aac950
Lazarus, Eli D.
642a3cdb-0d25-48b1-8ab8-8d1d72daca6e
Gao, Chao
739e2f49-9184-4fb1-a7eb-3907bf0cc3eb
Finotello, Alvise
517cc559-3779-473f-b477-fc531064f95e

Puppin, Alice, Tognin, Davide, Ghinassi, Massimiliano, D'Alpaos, Andrea, Lazarus, Eli D., Gao, Chao and Finotello, Alvise (2025) Rapid infill of abandoned tidal channels creates hotspots for blue-carbon accumulation in coastal wetlands. Geophysical Research Letters, 52 (7), [e2024GL113705]. (doi:10.1029/2024GL113705).

Record type: Article

Abstract

Sinuous channel networks dissecting tidal wetlands are highly dynamic and are often abandoned as a result of channel captures and meander cutoffs. However, the effects of channel dynamics on blue carbon fluxes remain unclear. Analyses of abandoned tidal channels in the Venice Lagoon (Italy) demonstrate that they take up organic carbon at significantly faster rates than neighboring marshes. This is because, despite slightly lower sediment carbon density, abandoned tidal channels yield significantly higher rates of sediment vertical accretion owing to topographic accommodation and reduced flow velocities, which facilitate the deposition of particulate matter and debris. We estimate that abandoned tidal channels in Venice capture 17 tons of carbon annually, equivalent to 21 ha of marshes, despite covering only 3.5 ha in total. Hence we argue that abandoned tidal channels serve as hotspots for blue-carbon accumulation and should be considered to improve estimates of carbon fluxes in coastal wetlands.

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Geophysical Research Letters - 2025 - Puppin - Rapid Infill of Abandoned Tidal Channels Creates Hotspots for Blue‐Carbon - Version of Record
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Accepted/In Press date: 4 March 2025
e-pub ahead of print date: 7 April 2025
Published date: 7 April 2025
Keywords: Venice Lagoon, abandoned tidal channels, blue carbon, coastal wetlands, salt marshes

Identifiers

Local EPrints ID: 501018
URI: http://eprints.soton.ac.uk/id/eprint/501018
ISSN: 0094-8276
PURE UUID: d101bae0-fb16-437b-aef6-86a6a0dcf543
ORCID for Eli D. Lazarus: ORCID iD orcid.org/0000-0003-2404-9661

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Date deposited: 20 May 2025 17:14
Last modified: 22 Aug 2025 02:18

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Contributors

Author: Alice Puppin
Author: Davide Tognin
Author: Massimiliano Ghinassi
Author: Andrea D'Alpaos
Author: Eli D. Lazarus ORCID iD
Author: Chao Gao
Author: Alvise Finotello

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