The word “mangrove” refers to approximately 75 species of shrubs or trees (ranging in height from 6-35 feet/2-11m).
These trees grow on the coasts in tropical and subtropical environments worldwide (in 118 countries) but the greatest species diversity is in Southeast Asia.
Mangroves are salt-tolerant trees, adapted to live in salty or brackish water and low oxygen conditions found in muddy areas.
Mangroves can be recognized by their exposed roots; sticking up out of the muddy water as if the tree is on stilts! These roots are densely intertwined which allows the mangroves to adapt to the rise and fall of tides and to hold the sediment in place creating the watery coastline.
Mangrove ecosystems are essential to healthy coastal ecosystems for many reasons.
These forest wetlands support a massive diversity of wildlife. They act as fish nurseries, nesting and feeding grounds for birds, refuges for land and marine mammals, and many insects and reptiles. The Global Mangrove Alliance, reports that mangrove forests provide shelter as well as feeding and breeding space for 174 marine megafauna species, including dugongs, manatees, dolphins, porpoises, sea turtles, sharks and rays.
Mangrove ecosystems improve water quality by filtering sediment and pollutants that enter the ocean from land sources. This water filtration supports the health and productivity of surrounding coral reef and seagrass ecosystems by holding back sediment and nutrients that could otherwise smother the underwater systems.
Mangrove Ecosystems are carbon storage champions. They are up to 10 times more efficient than terrestrial ecosystems at absorbing and storing carbon long term, making them a critical partner in the fight against climate change.
Similarly, since they can store large amounts of carbon, the destruction of mangroves releases carbon dioxide into the atmosphere (from their biomass and the surrounding soil) which further contributes to global warming.
Protect Coasts from Storms
Mangroves absorb the force of storms to protect the coastline. They cause waves to break before they hit the shore reducing both the force and height of the wave. They are able to absorb between 70-90% of the energy from a normal wave. In fact, after the southeast Asian 2004 tsunami, the International Union for the Conservation of Nature (IUCN) compared the death toll from two villages; one with dense mangrove forest and one without. Two people died in the first village compared to 6000 in the second. Healthy mangrove ecosystems are natural barriers. Mangroves not only save property and lives, but money as well. One study found that for coastal protection, natural habitats (such as mangrove and coral reef ecosystems) are 2-5 times more cost-effective than man-made structures.
Prevent Shoreline Erosion
The stability mangroves provide is essential for preventing shoreline erosion. Mangroves’ extensive root system helps to stabilize land elevation by trapping sediment, preventing it from washing downstream.
Learn more about the importance of Mangrove Ecosystems.
Approximately 15 million hectares (58,000 square miles) of mangrove ecosystems remain — less than half the world’s original area. Thailand has lost 84 percent of its mangroves, the highest rate of any nation. The Ivory Coast, Guinea-Bissau, Tanzania, Mexico, Panama, Malaysia, Myanmar, Pakistan, and the Philippines have each lost more than 60 percent of their mangrove forests.
Human activity bears the responsibility for much of the mangrove loss largely due to a lack of knowledge of the importance of these ecosystems. They have traditionally been classified as swamps or wastelands without environmental importance. With this mistaken view, it is much easier to exploit these forests in a variety of ways.
Shrimp Aquaculture Industry
As much as 50% percent of mangrove ecosystem destruction in recent years has been due to clear cutting for shrimp farms. Hundreds of thousands of acres of wetlands have been cleared for artificial ponds that are densely stocked with shrimp. This doesn’t only affect the cleared area, but the surrounding mangroves as well; the chemicals, antibiotics, and waste from the farms contaminate the surrounding fresh and coastal waters. Sadly, the average shrimp farm in Asia survives no more than 5 years, leaving a devastated coastline behind.
Unregulated and unsustainable developments are also responsible for large areas of cleared forests and wetlands. Whether for ports and beautiful coastal roads or to build large tourist resorts, golf courses and marinas, humans prefer a clear view of the ocean. But as streams and wetlands are filled by roads and concrete, they can no longer process natural chemicals. Pollutants that accompany development can damage trees or whole forests of mangroves. Of course people, traffic, garbage, and noise, also affect previously untouched coastal ecosystems.
It’s not just urban and vacation areas responsible for clear cutting these forests; agriculture, oil exploration and extraction as well as logging and charcoal production are also threats to healthy mangrove ecosystems.
Mangroves also are vulnerable to sea-level rise resulting from global warming. Mangrove roots trap sediment, building up the soil in a process known as accretion that can create entire islands. A recent study predicts that mangroves will be unable to keep up with global sea-level rise and in as soon as 30 years mangrove forests could begin to drown.
Now that the importance of mangrove ecosystems are better understood, our species must prioritize protecting remaining mangroves and restoring those that have been lost.
Fortunately, scientists know a lot about restoring mangroves. “We are better at restoring mangroves than any other coastal habitat,” said Michael Beck, research professor at the UCSC Institute of Marine Sciences.
There are a number of organizations doing great work in protecting remaining mangrove forests and restoring essential mangrove ecosystems to areas where they were formerly abundant.
Learn more about these organizations and the importance of mangroves by clicking below
There are many hopeful stories of successful mangrove ecosystem education, protection, and restoration. Here are a few to provide inspiration:
In this coastal town, seawater was slowly rising and mixing with the village’s drinking water and onto farmland. People and animals began to get sick and crops began to perish. To protect their homes and livelihood, the villagers decided to reforest 250 hectares of coastal mangroves to act as a barrier against the ocean flooding. Within three years, they already see results: the water is drinkable, the livestock is healthy, the soil is fertile and species are returning to the shallow coastal waters!
Demak Coastline, Java, Indonesia
The eroding coastline of Demak in North Java is recovering by converting degraded fishponds into sedimentation basins to restore mangrove ecosystems. In this case, by making healthy changes to the environment, mangroves can recover naturally, without any planting involved, and quickly, seeing results in less than 2 years! Within one year after a pond was converted, the sedimentation increased by 10 centimetres and mangroves had naturally grown up to 50 cm high. Within several years, the mangroves have reached a height of about 2-3 meters!
Marvelous Mangroves, Bangladesh
Mangrove education is critical to ensure local protection and the support of future generations. Mangrove Action Project has conducted Marvelous Mangroves education programs in 15 countries with over 250,000 students! In 2013, MAP conducted workshops in six rural schools in Khulna, Bangladesh. Two days learning “on land” and three days aboard a boat into the mangroves themselves. All six schools have since established after-school Mangrove Science Clubs to continue to teach their fellow students and teachers as asll as increasing knowledge of sustainable methods of living with mangrove forests, into the communities.
Mikoko Pamoja, Kenya
Mikoko Pamoja means “mangroves together” and is a project in southeastern Kenya to fund mangrove conservation through the sale of carbon credits. Income raised through the protection of the mangroves funds not only further reforestation but also clean water for the community, books for the schools and other local initiatives. Since 2014 the community has protected 117 hectares of mangrove ecosystems and reforested an additional 10 hectares! This model has been such a success, they are starting a second site with a forest 4 times larger!
Community- Based Ecological Mangrove Restoration
With proper research and planning, mangrove ecosystems can be successfully restored and many times, even self repair! If both physical and socioeconomic conditions are restored then nature can take over. Mangrove Action Project conducts community-based ecological mangrove restoration which involves local stakeholders from the outset. After studying each site and local stressors, they facilitate natural regeneration whenever possible. MAP has done training in 15 countries including 12 sites in Thailand converting abandoned shrimp farms into mangrove restoration sites!