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Climate-driven Avicennia germinans expansion reduces marsh edge erosion in coastal Louisiana (USA)

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Abstract

Subtropical black mangrove (Avicennia germinans) is expanding into higher latitudes and encroaching on existing temperate salt marshes with the potential to alter a variety of ecological processes. In the Mississippi River Delta (Louisiana, U.S.A.), wave-driven marsh edge erosion is on the order of meters per year and accounts for half of the total marsh loss. Here, we show that edge erosion is reduced by 40–60% when colonized by Avicennia as compared to salt marsh dominated by Spartina alterniflora. This reduction is associated with a greater soil shear strength, which in turn is driven by more live belowground biomass and deeper roots. Crucially, Avicennia reduces edge erosion only when well established, i.e., marshes with sparse Avicennia cover had similar edge erosion rates to those with Spartina, likely due to a shallower root biomass. Overall, climate-driven Avicennia expansion will not prevent marsh edge erosion, but can significantly slow it down. Avicennia could be used as a nature-based solution to slow the rate of edge erosion if it is planted inland allowing it 5–10 years to mature before being exposed along the marsh edge.

Data availability

The data analyzed during this study is available in the Dryad repository: https://doi.org/10.5061/dryad.02v6wwqh9. Data is also available upon request by email to the primary author. The primary author is Mike Rabalais.

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Funding

This work was supported by the National Science Foundation under award GEO/EAR 2126167.

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Authors and Affiliations

  1. Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA

    Mike Rabalais, Ethan Elmer, Tracy Elsey Quirk & Giulio Mariotti

  2. Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA

    Giulio Mariotti

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  1. Mike Rabalais
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  2. Ethan Elmer
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  3. Tracy Elsey Quirk
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  4. Giulio Mariotti
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Contributions

MR wrote the main manuscript text and prepared Figs. 1, 3, 4, 5, 6, and 7. EE and GM prepared Table 1 and Fig. 2. MR, TQ, and GM reviewed the manuscript.

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Correspondence to
Mike Rabalais.

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Competing interests

The authors declare no competing interests.

Ethics approval

All applicable international, national, and/or institutional guidelines were followed by the authors. Plant samples were collected from publicly accessible sites. Site access permits needed were obtained, and no threatened or endangered species were collected. Avicennia germinans is listed as an IUCN Red List Species of Least Concern and Spartina alterniflora has no regulations or restrictions for collection.

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Rabalais, M., Elmer, E., Quirk, T.E. et al. Climate-driven Avicennia germinans expansion reduces marsh edge erosion in coastal Louisiana (USA).
Sci Rep (2026). https://doi.org/10.1038/s41598-026-39843-3

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