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Vol. 6 No. 4 - October 2000

Mangroves - In A Mangled Mess

Shakila Khan and Jabeen Abidi

When Darwin proclaimed "Survival of the fittest", a fragile but unique wetland ecosystem stood up to the challenge- the mangroves. Derived from Portuguese "mangue" (meaning the tree bush), they are one of the very few habitats to have been crafted from such extreme hostility. Where the river meets the sea and the land is covered by a muddy ooze which is inundated twice each day by tides, the mangroves have made their niche adapting to such environmental aggressions as the rise and fall of tides and hostile saline conditions. In the process, they have become so specialized that they can live nowhere else on earth.

A mangrove creek is a beautiful self conditioned macrocosm, a rich ecosphere packed with myriad life forms contained macrocosm, a rich ecosphere packed with myriad life forms, each more fascinating, more unique, more precious than the next. This exclusivity, which was once its bulwark has now become a major threat to its very existence. The biggest predator - the man, who in the quest for development has reclaimed the land for housing, poisoned the water with effluents, cut the trees for fuel and consumed the green fodder for livestock.

Unable to adapt to such rapid fire assault mangroves are fast disappearing from coastal belts all around the world. In India, particularly, mangroves have disappeared faster before scientists could document their worth. Before putting their lives in peril, no one perhaps paused to realize their importance or their contribution to the quality of human life.

The total area under Mangroves in India had been estimated at 356,500 ha nearly eighty five percent of which is found in West Bengal (Sunderbans) and Andaman and Nicobar Islands. The Indian Mangroves comprise approximately 59 species belonging to 41 genera and 29 families. Species like Sonneratia caseolaris, Suaeda fruticosa, Urochondara setuloisa etc are unique to this region. Heritiera fomes locally known as "Sundri" after which the Sunderbans are named is restricted to the Gangetic Sunderbans and Andaman Islands.

This ecosystem is the only one which has developed special mechanisms to adapt to the frequent changes in the soil like dilution of salts in rainy season concentration in the summer months and it is this adaptability, which enables them to withstand a variety of environmental stresses ranging from high salinity at one extreme to a complete lack of it or near freshwater conditions at the other.

As and when the psamatic (clay loam) deposition resulted in new lands on the saline waters, the first herb species to appear was Protersia coarctata. The tidal water flow carried other halophytic seeds as well as seedlings which settled down on the soft clay soil, which started anchoring with deep root system like "pneumatophores" and kenn roots. Along with "Protersia" sp., other mangrove species also started growing to form dense ridge forests within 2-3 years. The first Europeans travelling to the tropics were amazed at the impossible sight of trees growing in the sea and frightened by forests that were the abode of all sorts of pests and wild animals from rare insects to crocodiles and incredible animals like the dugong and they kept away from areas which were often used as refuges by pirates.

Mangroves are a bridge between the aquatic and terrestrial ecosystems and confer numerous benefits for humankind including the promotion of sustainable fisheries. Endowed with rich and diverse living resources, apart from their direct resource potential in forestry and fishery production, indirectly they help in protection of coastlines and maintenance of ecological balance. At the 2nd World Climate Conference held at Geneva in 1990, experts agreed that changes in temperature and sea levels of the following order could occur by 2090. For the temperature rise by 4, 3, and 2.3C there would be a rise in the sea level by 60, 40 and 35 cms, respectively. Mangroves are last frontiers in our defense against the adverse consequence of changes in the sea level.

This complex but fragile ecosystem if lost, can never be retained to its pristine status. Any interference with free- flow of tidal water and freshwater from land-ward side may alter the character sometimes destroy the animals or vegetation of the mangroves. It is, therefore, unfortunate that many of the coastal ecosystems comprising coral reefs, sea grasses and mangroves are being destroyed for short-term gains such as extension of tourism or aqua-culture. Industrial pollution, wood for domestic use as fuel and raw material for industries are also seriously damaging our biological wealth.

Recent advances in biotechnology have envisaged moving genes across sexual barriers. It may, thus, be possible to isolate from the mangrove species, genetic material conferring tolerance to seawater intrusion and transfer them to other plants growing near coastal areas. Thus, the conservation of mangroves, coral reefs,, wild grasses and other coastal plant material becomes imperative both for the immediate purpose of protecting coastal areas from the adverse impact of storms and cyclones and for meeting the long term need for suitable donors of genes for sea water tolerance, since the loss of every gene or species limits our options for the future. Therefore, an increase, in research interest and eco-restoration of damaged mangrove ecosystems should be an immediate priority. As they say of the earth, also holds true for all of nature's bounties, which, in the words of Mostafa K. Tolba "We have not inherited from our ancestors, but borrowed from our children".

Ms Shakila Khan is a Scientist and Ms jabeen Abidi is a former Project Fellow at National Environmental Engineering Research Institute, Nagpur 440 020, India.


This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.


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