Scientific Reports (Nov 2024)

Sea-level rise and extreme Indian Ocean Dipole explain mangrove dieback in the Maldives

  • Lucy Carruthers,
  • Vasile Ersek,
  • Damien Maher,
  • Christian Sanders,
  • Douglas Tait,
  • Juliano Soares,
  • Matthew Floyd,
  • Aminath Shaha Hashim,
  • Stephanie Helber,
  • Mark Garnett,
  • Holly East,
  • Jamie A. Johnson,
  • Gheorghe Ponta,
  • James Z. Sippo

DOI
https://doi.org/10.1038/s41598-024-73776-z
Journal volume & issue
Vol. 14, no. 1
pp. 1 – 10

Abstract

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Abstract Mangrove forests enhance Small Island Developing States’ resilience to climate change, yet in 2020, a mangrove dieback impacted ~ 25% of mangrove-containing islands in the Maldives. Using remote sensing, dendrology and sediment geochemistry, we document a significant decrease in mangrove health post-2020 (NDVI: 0.75 ± 0.09) compared to pre-2020 (0.85 ± 0.04; P < 0.0001). Dead trees showed reduced stomatal conductance (δ 13C: − 26.21 ± 0.11 ‰) relative to living ones (− 27.66 ± 0.14 ‰), indicating salinity stress. Critically, sea-level rise (30.50 ± 23.30 mm/year) outpaced mangrove sediment accretion (6.40 ± 0.69 mm/year) five-fold between 2017 and 2020. We attribute this dieback to salinity stress driven by record-high sea levels in 2020, linked to an extreme positive Indian Ocean Dipole event. These findings reveal the vulnerability of mangrove ecosystems to rapid sea-level rise and highlights the urgent need for adaptive conservation strategies in Small Island Developing States.