Beware: mangrove forests around the Indo-Pacific areas could be gone for good by 2070. The outlook for many other mangrove forests in the world – even with relatively low rises in sea level – could be as bleak.
This is what international researchers warned in their study published in the journal Nature last Oct. 14.
Mangroves in Thailand, Java, Sumatra, Papua New Guinea, and the Solomon Islands, too, could be submerged within the next 45 years, according to the study.
Catherine Lovelock, lead researcher and biological sciences professor at the University of Queensland, said this loss before the century ends could spell major knock-on effects for fisheries and the local communities.
"Without mangrove forests, fish decline, there's reduced coastal protection, there's reduced coastal carbon sequestration," Lovelock said, asserting that mangroves have a whole range of uses to the ecosystem.
In calculating the predicted submersion of the Indo-Pacific mangroves, the team already considered measures to control greenhouse gas emissions.
Mekong River in Vietnam was singled out due to the dams holding the mangroves back, said Lovelock, warning that in building dams, the sediment supply to the coast will be changed – a downside for coastal systems.
Sediment washing off land was typically trapped in mangroves’ roots, building up soil gradually and helping mangroves keep up with sea level rise caused by climate change. Reduced sediments therefore mean inundated tidal flats that are not favortable for mangroves.
Lovelock reminded that mangroves have a variety of purposes, including serving as nurseries for some fish species and stopping carbon dioxide emissions, where land use change makes up 25 percent of global CO2 emissions.
Australia maintains about a million hectares of coast mangrove habitats, with an estimated $194 billion value in services to the country.
Some areas are better off than others – Lovelock deemed Shark Bay in Western Australia and around Adelaide as specifically vulnerable, while those in places like northwestern Australia can cope even with high rises in sea level.
Mangrove forests with a high sediment supply or tidal range, including eastern Borneo, east Africa, and the Bay of Bengal, are also “relatively resilient,” likely surviving into the second half of the century with up to moderate sea level rise.
The decline in mangrove forests are slowed by a good look at their financial contribution. Their long-term survival, however, are encouraged with careful planning, including continued sediment supply and providing retreat pathways for better response to sea level changes.
Photo: James St. John | Flickr
