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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 2.3°C 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. |
