Mangroves, the distinctive trees found in intertidal regions along the world’s tropical and subtropical coastlines, have many rare qualities. These trees play an important role and are now under serious threat. Understand the significance of mangroves.
If you visit the intertidal regions of the world’s tropical and subtropical coastlines, you will notice distinctive trees that rise from a tangle of roots wriggling out of the mud. These are mangroves --- the only species of trees that can tolerate salt water. Mangrove ecosystems have evolved over the years to bridge life between the land and sea.
WHAT & HOW?
Mangroves are extremely productive ecosystems which consist of diverse salt-tolerant plant species — ranging in size from small bushes to the 60-metre giants found in Ecuador. Botanists believe that mangroves originated in the Southeast Asian region and eventually set shop around the world as the seeds and seedlings travelled to fresher, brackish water — ideal conditions for their growth. Within 10 years, as the seeds took root. As these roots spread and sprouted, a single seedling gave rise to a thicket.
WHERE ARE THEY FOUND?
Usually they exist between 32 degrees north and 38 degrees south of the equator, in sheltered, intertidal areas that receive a high annual rainfall. The most extensive area of mangroves is found in Asia, followed by Africa & South America. The Sunderban mangroves of India and Bangladesh are the largest in the world.
HOW DO THEY SURVIVE?
Mangrove trees have a dense root system which give them support in the soft, water-logged land on which they grow. A common feature is that roots protrude above the soil to absorb oxygen from the air, as the sediments are poor in oxygen. Some other species develop ‘aerial roots’ — or root systems that arch high over the water. Some others develop stilt roots that branch and loop off the trunk and lower branches.
WHY SO IMPORTANT?
Mangroves are extremely important to coastal ecosystems they inhabit. They serve as a buffer between marine and terrestrial communities and protect shorelines from damaging winds, waves and floods. Mangrove forests move CO2 from the atmosphere into long-term storage in greater quantities than other forests, making them “among the planet’s best carbon scrubbers.” Besides, they serve as nurseries for many coral reef and important fish species.
THE FOOD CHAIN
Begins with production of carbohydrates and carbon by plants through photosynthesis
Leaf litter is then fragmented by the grazing action of amphipods and crabs
Decomposition continues through microbial and fungal decay of leaf detritus and use and re-use of detrital particles by very small-sized invertebrates like meiofauna and species like worms, molluscs, prawns and crabs
These detritivores are in turn preyed upon by lower carnivores
The food chain ends with higher carnivores such as large fish, birds of prey, wild cats or man himself.
THREATS
Clearing: Mangrove forests, often seen as unproductive and smelly, are cleared to make room for agricultural land, human settlements etc..
Overharvesting: In some parts of the world it is no longer sustainable so it threatening the future of ecosystem.
Changes in rivers: Dams and irrigation reduce the amount of water reaching mangrove forests, changing the level of salinity in the water. If salinity is very high, the mangroves cannot survive. If it is very low, it can lead to mangroves drying out.
Increased erosion: Land deforestation can massively increase the amount of sediment in rivers. This can overcome the mangrove forest’s filtering ability.
Overfishing: Global overfishing crisis impacts the balance of food chains and mangrove fish communities.
Destruction of coral reefs: When coral reefs are destroyed, the stronger waves and currents reaching the coast can undermine the fine sediment in which the mangroves grow.
Pollution: Fertilisers, pesticides, and other toxic man-made chemicals carried by river systems from sources upstream can kill animals in mangrove forests.
Climate change: Mangroves require stable sea levels for long-term survival. They are therefore extremely sensitive to current rising sea levels caused by global warming and climate change.