Drowning mangroves in Maldives signal global coastal risk

Drowning mangroves in Maldives signal global coastal risk
by Sophie Jenkins
London, UK (SPX) Nov 13, 2024

Mangrove forests in the Maldives are facing a severe threat as they succumb to rising sea levels and climate changes, according to a new study led by Northumbria University researchers and published in *Scientific Reports*.

The study highlights that the Maldives, known for its low-lying islands, experienced significant mangrove dieback since 2020 due to rapid sea-level rise and the effects of the Indian Ocean Dipole. This phenomenon resulted in a loss of more than half of mangrove coverage on some islands.

Between 2017 and 2020, sea levels in the Maldives rose by over 30mm annually, significantly outpacing the natural sediment accumulation rate of mangroves. The most severe dieback was observed following the Indian Ocean Dipole's intense phase, which elevated sea levels and temperatures in the Western Indian Ocean.

Research revealed that mangrove roots were increasingly stressed by heightened salinity levels, leading to tree death. Satellite imagery confirmed that mangroves on both inhabited and remote islands experienced extensive damage. The natural sediment-building process was overwhelmed, preventing the trees from staying above water as seawater flooded their environment.

Dr. Vasile Ersek from Northumbria University commented, "Dieback was first observed in the central, low-lying basin areas before expanding outwards. Limited tidal flushing allowed the rising sea to inundate forests, increasing soil salinity beyond what even salt-tolerant mangroves could withstand."

The findings underscore the broader implications for global coastal ecosystems. Mangroves act as natural shields against storms and flooding and are crucial for biodiversity, serving as nurseries for marine life and supporting food security and local economies. Additionally, they are significant carbon sinks, storing three to five times more carbon per area than tropical rainforests. Losses of these forests risk releasing stored carbon, potentially accelerating climate change.

Lucy Carruthers, who led the project during her tenure at Northumbria and now works at East Carolina University, noted, "Sea level in the region peaked in 2020, coinciding with an extreme Indian Ocean Dipole phase. With ongoing global warming, such events are likely to increase, making mangrove die-offs more frequent."

The study's findings align with reports of similar die-offs in Seychelles and Madagascar during the same period. Carruthers stressed, "Our work emphasizes the vulnerability of mangrove ecosystems to rapid sea-level rise. This isn't just a regional issue; it serves as a warning for coastal zones worldwide. The Maldives' experience may be a harbinger of wider environmental challenges."

The researchers advocate for urgent conservation and adaptive strategies for small island nations to help mitigate these risks.

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