Compelling reasons to protect these habitats have surfaced in recent years as we begin to understand more about mangroves.
Once perceived as ‘swampy wastelands’, mangrove forests are now being lauded for some miraculous feats. From curing disease to buffering coastlines from extreme weather and fighting climate change, there is more to mangroves than meets the eye.
Here are seven facts about mangroves that might surprise you:
1) Mangroves protect coastlines from tsunamis
In 2004, an earthquake in the Indian Ocean triggered a catastrophic tsunami that battered shorelines across India and Southeast Asia. Although there was significant loss of life, with an estimated 227,000 people killed, scientists have since concluded that the tragedy would have been much worse if mangrove forests were absent.
The dense roots and branch networks of the mangroves acted as a buffer and slowed down the monstrous waves, some of which reached almost 100ft high. The damage in villages located behind mangroves was significantly reduced, and subsequent studies suggest that mangroves can reduce casualties in nearby settlements by 8%.
Over the past 15 years, community-based initiatives – such as the Green Coast Project – have encouraged the restoration of mangrove forests that were damaged in the 2004 tsunami in order to reinstate this natural barrier.
2) Mangrove forests help fight climate change
We all know that plants photosynthesise, using up carbon dioxide and emitting oxygen into the atmosphere in order to grow. Yet mangrove forests are specially adapted to storing carbon in soil and dead roots.
Due to their ability to absorb carbon, mangrove forests are known as ‘carbon sinks’ or ‘carbon-rich biomes’. By storing excess carbon, they help reduce global warming as there is less carbon dioxide trapped in the atmosphere. According to research, 14% of coastal carbon sequestration is thanks to mangrove forests.
By destroying mangroves to establish shrimp farms, a practice that has expanded exponentially in the past 30 years, a high volume of gas is released. The carbon that was safely stored away is unleashed into the air.
The tangled roots of mangrove trees reduce erosion by stabilising sediments that would otherwise be lost to the sea. By making the coastline less susceptible to washing away, the biodiversity of the area is maintained.
On top of that, valuable farmland is protected. Landowners are able to continue using their land, and fewer people are forced to move further inland.
The aerating roots of mangroves allow them to grow out of oxygen-poor mudflats. Original photo:Girish Gopi
Erosion of land usually occurs through weathering, such as the constant force of waves breaking or as a result of large storms. The dense roots of the mangrove forest not only protects the coastline from the sea, but also the reverse: seagrass meadows and coral reef habitats are protected from the sediment from the shoreline. This is important since both these ecosystems are vital for many marine species, but are vulnerable to changes in external conditions.
Young fish are vulnerable to predators on the coral reef or in the deep sea. To sustain population numbers, many species take to the safety of the mangroves to spawn, where larger predators are unable to follow them.
Organic matter from the mangrove forest, such as leaves and detritus, form the base of important marine food chains. There is plenty of food in the mangroves for sheltering fish, making it the perfect nursery in which to grow.
Sharks also use mangroves as nurseries for their young. Lemon shark pups instinctively swim away from the mother and towards the mangroves after birth. Here, the juveniles must learn to hunt in order to avoid starvation.
6) Mangroves absorb pollution and protect coral reef populations
Along with absorbing excess carbon, mangrove forests remove pollution from the soil, including toxic heavy metal. Mangrove forests therefore purify the water that flows out to the ocean. Without this process, contaminated water would spill into the sea, affecting the food chains for marine life, which in return could poison humans through consumption.
The shrimp farmers recognised that using chemical fertilisers, pesticides, disinfectants and antibiotics is not the best way to rear the largest yields of shrimp. Instead, a more natural solution is working better.
In addition, the brackish water of the mangroves appears to reduce the acidity of the water. The result is that the structure of the coral reef is more stable, and growth is accelerated. Interestingly, tree-climbing fish, or mudskippers, are seen to be ‘bio-indicators’ for the health of mangrove habitats.
Mudskippers live on mudflats in mangroves and are sensitive to pollution, such as litter, runoff chemicals from the land or wastewater. If mudskipper populations are prolific, it means that there is less pollution in the mangrove as a whole.
Tree-climbing fish, or mudskippers, live on mangrove mudflats.
7) Mangrove forests provide a home to endangered species
With habitat loss and degradation of mangrove forests, the biodiversity of species continues to be threatened, including some of the quirkier animals:
Pygmy three-toed sloths, which only feed on a particular type of mangrove leaves, are estimated to have less than 500 individuals left.
Get involved in a marine conservation project to help protect mangrove forests, hawksbill turtles or lemon sharks. GVI has sustainable projects in Curieuse in the Seychelles, and Phang Nga in Thailand.
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Increasing global temperatures and rising sea levels: the effects of climate change are taking a toll. Contribute to global environmental conservation efforts by joining a GVI wildlife conservation or marine conservation program.