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12.1 Introduction
Wetlands, meeting many crucial needs for life, are an essential fraction of human
civilization. Wetland plays some significant roles in regional ecosystem, such as
regulation of the climate, cleansing of the environment and balancing of the regional
water. The wetland provides a critical habitat to a large number of flora and fauna.
Based on several estimates, the extent of the world’s wetlands is generally thought
to be from 7 to 9 million km
2
or about 4–6% of the land surface of the Earth (Mitsch
and Gosselink 2000). Ramsar Convention has described wetlands as the “regions of
marsh, fen, peat land or water, whether natural or artificial, permanent or temporary
with water that is static or flowing, fresh, brackish or salt, including areas of marine
water the depth of which at low tide does not exceed six meters”.
The wetlands around the world are receiving increased attention since these contribute to a healthy environment in many ways. They hold water during summer
seasons, thus help to maintaining the water table high and relatively stable. However,
during monsoon seasons, they mitigate stream and trap the suspended solids and
associated nutrients. They buffer stormy seas, reduce shoreline erosion and take up
intemperance nutrients, which help to reduce eutrophication and contribute to maintain the condition of mangrove habitat. Mangroves are highly productive components and an excellent natural renewable resource; it also protects coastal areas from
sea erosion and forms the violent effects of cyclones and tropical storms (Kathiresan
2003). It serves as considerable repositories of aquatic biodiversity (Prasad et al.
2002). Most of the coastal finfish and shellfish species spend their early life stages
in mangrove habitats. They provide shelters, foods and nesting sites for migratory
birds and reptiles. Most of the migratory birds have adapted to life in or near mangrove wetlands water in many ways.
12.2 Distribution of Wetlands in India
Almost 86% of the estimated total natural wetland area is found in tropical, subtropical regions and boreal regions of the world. Whereas, temperate zone wetlands
contribute only about 14% of the world’s total natural wetlands. The wetlands in
India are distributed in various ecological regions, totally about 27,000 wetlands are
there of which 4000 are coastal wetlands. The coastal wetlands occupied about
6750 km
2
, and are mainly dominated by mangroves (4461 km
2
). Indian mangroves
make up 3.1% of the total global; it spread alongside the east (59.6%), west (27%)
coasts of India and the Andaman and Nicobar islands (13.3%) respectively.
India, by virtue of its geographical extent, varied geography and climatic conditions, supports a rich diversity of inland and coastal wetland ecosystems. Although,
the significance of wetlands has been known for a long time, their role in maintaining ecological balance is still lesser understood. The Ramsar Convention of IUCN
held during 1971 in Iran raised global awareness of the conservation and management
K. Silambarasan and A. Sundaramanickam
12.1 Introduction
Wetlands, meeting many crucial needs for life, are an essential fraction of human
civilization. Wetland plays some significant roles in regional ecosystem, such as
regulation of the climate, cleansing of the environment and balancing of the regional
water. The wetland provides a critical habitat to a large number of flora and fauna.
Based on several estimates, the extent of the world’s wetlands is generally thought
to be from 7 to 9 million km
2
or about 4–6% of the land surface of the Earth (Mitsch
and Gosselink 2000). Ramsar Convention has described wetlands as the “regions of
marsh, fen, peat land or water, whether natural or artificial, permanent or temporary
with water that is static or flowing, fresh, brackish or salt, including areas of marine
water the depth of which at low tide does not exceed six meters”.
The wetlands around the world are receiving increased attention since these contribute to a healthy environment in many ways. They hold water during summer
seasons, thus help to maintaining the water table high and relatively stable. However,
during monsoon seasons, they mitigate stream and trap the suspended solids and
associated nutrients. They buffer stormy seas, reduce shoreline erosion and take up
intemperance nutrients, which help to reduce eutrophication and contribute to maintain the condition of mangrove habitat. Mangroves are highly productive components and an excellent natural renewable resource; it also protects coastal areas from
sea erosion and forms the violent effects of cyclones and tropical storms (Kathiresan
2003). It serves as considerable repositories of aquatic biodiversity (Prasad et al.
2002). Most of the coastal finfish and shellfish species spend their early life stages
in mangrove habitats. They provide shelters, foods and nesting sites for migratory
birds and reptiles. Most of the migratory birds have adapted to life in or near mangrove wetlands water in many ways.
12.2 Distribution of Wetlands in India
Almost 86% of the estimated total natural wetland area is found in tropical, subtropical regions and boreal regions of the world. Whereas, temperate zone wetlands
contribute only about 14% of the world’s total natural wetlands. The wetlands in
India are distributed in various ecological regions, totally about 27,000 wetlands are
there of which 4000 are coastal wetlands. The coastal wetlands occupied about
6750 km
2
, and are mainly dominated by mangroves (4461 km
2
). Indian mangroves
make up 3.1% of the total global; it spread alongside the east (59.6%), west (27%)
coasts of India and the Andaman and Nicobar islands (13.3%) respectively.
India, by virtue of its geographical extent, varied geography and climatic conditions, supports a rich diversity of inland and coastal wetland ecosystems. Although,
the significance of wetlands has been known for a long time, their role in maintaining ecological balance is still lesser understood. The Ramsar Convention of IUCN
held during 1971 in Iran raised global awareness of the conservation and management
K. Silambarasan and A. Sundaramanickam