TRIPLE TROUBLE FOR MANGROVES

The study found that mangrove forests, their large biodiversity and the coastal protection they provide are under pressure from three distinct threats – sea-level rise, lack of mud and squeezed habitats.

The research, conducted by an international team of experts including Dr Barend van Maanen from the University of Exeter, identifies not only how these coastal forests get pushed against their shores, but also what causes the loss of their diversity.

The landwards dams built on the rivers stops the flow of silts into the ocean waters and causing availability of low amount of mud necessary for growth of mangroves. The increase in the sea level due to global warming, is threat to mangroves as they cannot survive under water for long time.

Both mangrove coverage loss and diversity loss go hand in hand when that landward retreat is limited by expanding cities, agriculture or flood protection works. A narrow mangrove zone is much less effective in protecting the coast against storms, or in the worst case loses its protective properties altogether.

New computer simulations show how coastal forests retreat landward under sea-level rise, especially in coastal areas where mud in the water is declining. The simulations include interactions among tides, mud transport and, for the first time, multiple mangrove species.

Increasing landward flooding then seriously reduces biodiversity. Human land use prevents the mangroves ‘escaping’ flooding by migrating inland, narrowing the mangrove zone and further endangering biodiversity. Mangrove ecosystem protects local communities from storms, it protects coastal zones during Tsunamis.

Dr van Maanen, senior lecturer at the University of Exeter and supervisor of the project, said: “Both mangrove coverage loss and diversity loss go hand in hand when that landward retreat is limited by expanding cities, agriculture or flood protection works.”

Source – Environmental Research Letters.