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Unlock This CourseMangroves are some of the most amazing coastal ecosystems on Earth! These special forests grow where the land meets the sea, creating a unique environment that's part land, part water. They're found in tropical and subtropical regions around the world, forming a bridge between marine and terrestrial ecosystems.
What makes mangroves so special is their incredible ability to survive in conditions that would kill most other plants - they live in salty water, deal with changing tides twice a day and grow in muddy, low-oxygen soils. It's like they're the superheroes of the plant world!
Key Definitions:
Mangroves are found in over 100 countries, mainly between 30°N and 30°S latitude. The largest mangrove forests are in Asia (particularly Indonesia and Malaysia), followed by Africa and the Americas. They need warm temperatures (above 20°C), regular rainfall and sheltered coastlines to thrive.
Mangrove trees have developed some incredible features to survive in their challenging environment. These adaptations help them deal with salt, changing water levels and muddy conditions that would be impossible for most plants.
The most striking feature of mangroves is their amazing root systems. Unlike normal trees that hide their roots underground, mangroves show off their roots above the surface and each type serves a special purpose.
These are like natural stilts that grow from the trunk and branches down into the water. They spread out widely to anchor the tree firmly in the soft mud and help it stay upright against strong tides and storms.
Also called "breathing roots," these stick up from the mud like snorkels. They have special pores that let oxygen reach the underwater roots, which is essential because the muddy soil has very little oxygen.
These grow horizontally just under the mud surface, spreading out to collect nutrients and provide extra stability. They can extend far from the tree to maximise the area for nutrient collection.
Living in saltwater would kill most plants, but mangroves have developed clever ways to deal with salt. They use a combination of exclusion, secretion and storage techniques to survive.
Many mangroves can filter out salt at their roots, only allowing fresh water to enter the plant. This happens through special membranes that act like tiny filters, keeping the salt out whilst letting water through.
Some mangrove species have special salt glands on their leaves that excrete excess salt. You can sometimes see white salt crystals on the leaf surfaces where the salt has been pushed out and dried.
Different species of mangroves grow in different zones from the sea towards the land, creating distinct bands or zones. This zonation happens because each species has different tolerances for salt, flooding and wave action.
Closest to the sea, these mangroves face the full force of tides and waves. Red mangroves (Rhizophora species) dominate here with their distinctive prop root systems. They can handle being underwater for long periods and cope with the highest salt levels.
In the middle area, black mangroves (Avicennia species) are common. They're famous for their pneumatophores that stick up from the mud like thousands of pencils. They have excellent salt secretion abilities and can handle moderate flooding.
Furthest from the sea, white mangroves (Laguncularia racemosa) grow where flooding is less frequent. They have the lowest salt tolerance but can survive in areas that are only occasionally flooded by the highest tides.
Mangroves have developed unique ways to reproduce in their watery environment. Many species are viviparous, meaning their seeds start growing whilst still attached to the parent tree.
Baby mangroves, called propagules, develop on the parent tree and can photosynthesize before they even leave home! When ready, they drop into the water and can float for weeks or months until they find a suitable place to take root.
Mangroves cover about 150,000 square kilometres worldwide, but their distribution is quite specific due to their environmental requirements.
Home to about 35% of the world's mangroves. Indonesia has the largest area, followed by Australia and Malaysia. The Sundarbans (Bangladesh/India) is the world's largest single mangrove forest.
About 20% of global mangroves, mainly along the west coast. Nigeria has extensive mangrove forests in the Niger Delta, whilst Madagascar has unique species found nowhere else.
About 15% of global mangroves. The Everglades in Florida and the Amazon Delta in Brazil are major examples. Central America and the Caribbean also have significant mangrove areas.
The Sundarbans mangrove forest spans Bangladesh and India, covering about 10,000 square kilometres. It's famous for being home to the Bengal tiger and demonstrates perfect mangrove zonation. The forest shows all three main zones clearly, with Rhizophora species dominating the seaward areas, Avicennia in the middle zones and various other species towards the land. The Sundarbans also shows how mangroves can protect coastlines - the dense root systems help prevent erosion and provide a natural barrier against cyclones and tsunamis.
Mangroves punch well above their weight when it comes to environmental benefits. Despite covering less than 1% of tropical forests, they provide crucial ecosystem services.
Mangrove roots act like natural sea walls, absorbing wave energy and preventing coastal erosion. They can reduce wave heights by up to 70% and provide crucial protection during storms and tsunamis.
Mangroves support incredible biodiversity, providing nursery areas for fish, nesting sites for birds and habitat for numerous species. Many commercially important fish species depend on mangroves for part of their life cycle.
Unfortunately, mangroves are disappearing faster than almost any other ecosystem. We're losing about 1-2% of mangrove forests each year, which is a serious problem given their importance.
The biggest threats to mangroves include coastal development for tourism and housing, conversion to aquaculture (especially shrimp farming), pollution from agriculture and industry and climate change effects like sea level rise and changing rainfall patterns.
In Thailand, local communities have successfully restored thousands of hectares of mangrove forest. After losing 60% of their mangroves to shrimp farming, communities realised the importance of these ecosystems and began replanting programmes. They now combine sustainable fishing with mangrove conservation, showing how people and nature can work together.