The power of mangroves
Benefits of a hybrid ecosystem
Of all the ocean ecosystems, from vibrant coral reefs to seagrass meadows, from sprawling saltmarshes to dense kelp forests, none support more biodiversity than mangroves. With roots firmly planted in two worlds, mangrove forests straddle the line between land and sea. They are among the few trees on Earth that can tolerate salt water, and our planet is all the better for it.
Mangrove forests consist of thick, binding trunks twisting around one another to hold fast against the shifting underwater sediment and rolling tides. One of their unique adaptations is how they thrive in saline environments. They have a clever filtration system that keeps out up to 90% of the salt as water enters their roots, while any excess salt is excreted through their waxy leaves. And to cope with regular tides, some mangroves grow pencil-like roots that stick up out of the wet ground, acting like a snorkel.
There are at least 50 types of mangroves around the world, and while some species are well-equipped to handle the regular tidal flooding of the coast, others live in sheltered bays or along riverbanks further inland in drier, less salty soil.
A biodiversity haven
Despite only covering 1% of the planet, these lush, forested swamps are an ideal habitat for a myriad of animals, including 341 threatened species who find sanctuary among the robust roots.
From above, mangrove forests look beautiful, with their emerald foliage rising above crystal blue1 coastal waters. But it’s beneath the canopy where they really come to life. In the clear shallows at the fringes of the forest, juvenile sharks and shoals of tropical fish dart among the roots. Pink sea sponges cling to the trunks underwater, while deeper into the thicket, where the water turns murky with sediment, crocodiles lurk ominously. Up above the water, giant snakes wind around branches, monkeys jump from tree to tree, and hummingbirds flit between branches.
Further inland, spotted and muntjac deer tiptoe over the exposed roots because for all of the safety these forests offer, they also hide predators. In Asia's mangroves, the Bengal tiger hunts, its stripes providing perfect camouflage as it stalks prey through the dense vegetation.
Other benefits of mangroves
If this wealth of biodiversity wasn’t reason enough to protect the world’s mangroves, here are a few more nature-based solutions worth safeguarding:
Carbon sequestration
Mangroves are powerhouses when it comes to carbon storage, locking away up to ten times more in their stems and leaves than terrestrial forests do. Their roots also trap sediment, twigs, leaf litter, and other organic matter, which decays and builds up over thousands of years, creating carbon-rich soils, making mangroves one of the most important carbon stores on the planet.
Coastal protection
As a thick, impenetrable natural buffer between sea and land, the coastal protection mangroves offer is invaluable. They protect against disasters caused by rising sea levels and coastal flooding, acting as a barrier against waves, storm surges, and tsunamis. In fact, mangroves prevent $65 billion in property damages and reduce flood risk to some 15 million people each year.
Livelihoods and food security
These forests are also crucial for local economies, providing food, fuel, shelter, and income. In the Western Indian Ocean region alone, many of the 40 million coastal residents depend on mangroves for their livelihoods. Globally, that number rises to 120 million people. Mangroves support industries such as fishing, beekeeping, and tourism. The benefits extend to food security as well. Healthy mangrove ecosystems connected to coral reefs can double the biomass of some fish species. By providing nurseries and habitats for these fish and crustaceans, mangroves support the fishing industry and thus improve food security for coastal communities.
Water filtration
Mangroves also offer essential natural water filtration. Their dense root systems trap sediment before it reaches the coast, this improves water quality by absorbing nutrients from runoff that would otherwise have led to harmful algal blooms. These purifying abilities also keep water clear and healthy for fragile coral reefs and seagrass meadows, and prevent them from being smothered by the sediment.
Threats
Despite their immense value, mangroves are extremely threatened and are declining at an alarming rate. Aquaculture, particularly shrimp farming, poses one of the biggest threats. This intensive single-species aquaculture can devastate mangrove ecosystems2 as the forests are often cleared to make room for temporary shrimp pools, reducing biodiversity in favour of a more 'controlled' environment. Some farms dig channels to supply ponds with enormous quantities of water, diverting the natural flow that the surrounding mangroves need. Then, when abandoned, these pools leave behind toxic water containing shrimp feed, pesticides, chemicals, and antibiotics. One study in Thailand suggests this approach intentionally removes reliance on original ecosystem services, increasing external inputs. Ultimately, the industry trades long-term ecological benefits for short-term economic gains, often resulting in lasting environmental and social degradation.
Coastal development for tourism, urban expansion, and infrastructure projects also lead to widespread mangrove destruction. Not only does this directly remove mangrove forests, but it also alters the hydrology, sedimentation, and erosion patterns crucial for mangrove survival.
Climate change-induced sea level rise presents another significant challenge. Mangroves require stable sea levels for long-term survival, and while they can potentially move inland with rising waters, coastal developments often block this natural progression.
Solutions
However, there is hope. Organisations like the Mangrove Action Project (MAP) are implementing innovative approaches to conserve and restore mangroves. Their Community-Based Ecological Mangrove Restoration (CBEMR) technique empowers local stakeholders and communities, teaching them to use mangrove ecology and biology to facilitate natural regeneration.
This bottom-up approach has shown success in various locations. In Thailand, MAP has successfully re-established healthy, biodiverse mangrove forests in abandoned shrimp ponds along the Andaman coast. Similar projects in Myanmar, Honduras, and Tanzania are also equipping local communities with the tools to protect mangrove forests and along with it, their own livelihoods.
In Bangladesh, the vast Sundarbans along the southern coast are recognised as crucial shields protecting people and their livelihoods from tropical cyclones and tidal surges. Recent years have seen an increase in mangrove numbers as NGOs and local communities have introduced programs to restore the much-need defence in certain districts.
The key to protecting mangroves lies in recognising their value as vital cross-world connectors providing essential services to the natural world and to human communities. By supporting local people who rely on mangroves for food, work, and safety, facilitating natural regeneration, and addressing the root causes of mangrove loss, we can ensure these remarkable forests continue to thrive and bless the world with their endless benefits.
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Amie 🐋
Mangroves are found in 118 tropical and subtropical countries, with Indonesia boasting the largest coverage at a whopping 23,000 square kilometres, more than twice the size of Jamaica!
Source: The Marine Diaries.
Here in Florida the coastal development and urban sprawl have certainly contributed to mangrove destruction. And it's stupid since this destruction actually removes their buffering effect from hurricanes, allowing more storm damage to coastal infrastructure. I did not know about the impact from shrimp farming...another reason not to eat farm-raised shrimp! Thanks for raising awareness!
Nature is truly miraculous. I remember a friend of mine telling me about mangroves back in my second year of university. She was studying ecology, and I learned so much about the importance of biodiversity from her!