To the uninitiated, mangroves might appear to be merely coastal cousins of inland forests, but these rich ecosystems support the planet and people in unique ways, from providing breeding grounds for fish to carbon storage, to protection against flooding.
Yet despite their importance, mangrove forests are under threat. Over a third have already disappeared, and in regions such as the Americas they are being cleared at a faster rate than tropical rainforests.
Much of that clearance is to reclaim land for agriculture, industrial development and infrastructure projects.
In addition to climate change and pollution, there are also local threats. These include overharvesting of wood for fuel and construction, dams and irrigation that reduce the flow of water reaching the forests, and overfishing causing disruption to food chains and fish communities.
We are destroying a coastal ecosystem that helps sustain life and livelihoods. Here are five of the many reasons we should be doing much more to preserve mangrove forests.
1. They are a natural coastal defence
The sturdy root systems of mangrove trees help form a natural barrier against violent storm surges and floods. River and land sediment is trapped by the roots, which protects coastline areas and slows erosion. This filtering process also prevents harmful sediment reaching coral reefs and seagrass meadows.
In 2017, the UN Ocean Conference estimated that nearly 2.4 billion people live within 100 km of the coast. Mangroves provide valuable protection for communities at risk from sea-level rises and severe weather events caused by climate change.
2. They are carbon sinks
Coastal forests help the fight against global warming by removing carbon dioxide from the atmosphere, most of which is stored within the plant. When mangrove tree roots, branches and leaves die they are usually covered by soil, which is then submerged under tidal water, slowing the breakdown of materials and boosting carbon storage.
Research shows that coastal mangroves outperform most other forests in their capacity to store carbon. An examination of 25 mangrove forests across the Indo-Pacific region found that per hectare, they held up to four times more carbon than other tropical rainforests.
3. They provide livelihoods
Many people living in and around mangroves depend on them for their livelihood. The trees are a reliable source of wood for construction and fuel, which is prized for its hardy resistance to both rot and insects. However, in some areas, the wood has been harvested commercially for pulp, wood chip and charcoal, raising concerns about sustainability.
Plant extracts are collected by locals for their medicinal qualities and the leaves of mangrove trees are often used for animal fodder.
The forest waters provide local fishermen with a rich supply of fish, crabs and shellfish to sell for income.
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4. They encourage ecotourism
Sustainable tourism offers a stimulus to preserve existing mangrove areas, with potential to generate income for local inhabitants.
Often located near to coral reefs and sandy beaches, the forests provide a rich environment for activities like sports fishing, kayaking and birdwatching tours.
Of course, it is important to maintain a balance between visitor numbers and protecting the forests’ delicate ecosystem.
If held at sustainable levels, ecotourism could provide the perfect motivation to protect mangroves, instead of clearing them for mass tourism developments.
5. They are rich in biodiversity
Human activity has caused huge biodiversity loss in land and marine ecosystems around the globe, endangering many plant and animal species.
By filtering coastal waters, mangroves form a nutrient-rich breeding ground for numerous species that thrive above and below the waterline.
A huge variety of wildlife lives or breeds in the mangrove ecosystem, including numerous fish, crab and shrimp species, molluscs, and mammals like sea turtles. The trees are home to an array of nesting, breeding and migratory birds. When mangrove forests are cleared valuable habitat is lost, threatening the survival of myriad species.
But that’s not the whole story. The forests are also a potential source of undiscovered biological materials that could benefit mankind, such as antibacterial compounds and pest-resistant genes, which are also lost when coastal areas are cleared.
Land clearance of mangrove areas and other forests like the Amazon has had a major impact on different species. The International Union for Conservation of Nature’s (IUCN) Red List shows that of 68,574 species of invertebrates, 8,374 were on the brink of extinction.
Protecting natural ecosystems like mangrove forests not only helps preserve biodiversity, it also helps preserve a vital resource for local communities.