Faunal Diversity in Indian Wetlands

Wetlands are transitional areas between dry terrestrial and permanent aquatic ecosystems. In recent years, more particularly during the last three decades of the twentieth century, wetlands are recognised as a highly productive ecosystem and their importance in socio-economical frontiers has also been increasingly felt.

Wetlands include 22 habitat types (IUCN, 1989) and in India they can be categorised under following predominant wetland types:

Extent of Indian Wetlands

Estimates of total wetlands area in India as shown in the Directory of Asian Wetlands (IUCN, 1989) are presented in Table 1.

According to the estimate of the Ministry of Environment & Forests, India possesses about 4.1 million ha wetlands (excluding paddy fields and mangroves), of which 1.5 million ha are natural and 2.6 million ha man-made. Using space borne remotely sensed data from IRS 1A/1B, Space Application Centre (ISRO), Ahmedabad (1998) estimated total Indian wetland areas to be about 7.6 million ha excluding paddy fields, rivers and canals, out of which 3.6 million ha are inland and 4 million ha are coastal.

India being a signatory to the Ramsar convention (1971), so far designated six wetlands viz. Chilka (Orissa), Keoladeo Ghana National Park (Rajasthan), Sambhar (Rajasthan), Wular (Jammu & Kashmir), Loktak (Manipur) and Harike (Punjab) as Ramsar sites, the wetlands of international importance. At the national level, 22 national wetlands and 11 national lakes have been identified for intensive conservation and management purposes to restore these wetlands as waterfowl habitats and rich resources of genetic diversity.

Faunal Diversity

An appreciable amount of information is available on the fauna of Indian wetlands. During 1990’s, serious attempts have been made to census waterfowl populations in India. Of 1,421 sites counted in India, 34 sites covered during the Asian waterfowl census 1994-1996 qualify as sites of international importance. Of these, the Chilka Lake topped the national list harbouring a total of 1,484,l86 waterbirds of 85 species in 1996. Chilka Lake hosts over 729 species of wetland fauna including 227 species of fishes and 156 species of birds (ZSI, 1995). Avifaunal diversity in Keoladeo Ghana National park, the most famous wetland sanctuary in India is very rich, hosting at least 332 avian species including endangered Siberian White Crane, Grus leucogeranus. Pulicat Lake is another important wetland for resident and migratory waterfowl, notably pelicans, flamingos, ducks, storks, herons, egrets, gulls, terns and other shore birds. The largest concentrations of Greater Flamingos, Phoenicopterus ruber occur in Andhra Pradesh in part of Pulicat Lake Sanctuary.

Besides waterbirds, fish and other vertebrates, wetlands also support a rich invertebrate fauna including many annelids, coelenterates, crustaceans, molluscs and echinoderms as shown in Table 2.

Endemicity

Endemism in wetland fauna is poorly known. Among vertebrates, one species mammals, namely, the Marsh Mongoose Herpestes palustris reported as new species from Salt Lake swamp, 44 species of water birds, one species of Himalayan Newt Pleurodeles verrucosus and 223 species of fish are known to be endemic in Indian wetlands.

Threatened species

Single species of dragon-fly, Epiophlebia laidlawi inhabiting hill streams of Darjeeling district, West Bengal, one species of salamander Pleurodeles verrucosus, 14 species of reptiles belonging to crocodiles, turtles, varanus and pythons, 17 species of wetland birds of Pelecaniformes, Ciconiformes, Anseriformes, Gruiformes and Charadriiformes and 10 species of mammals are recognised as ‘threatened’ or ‘endangered’ species occurring in wetland ecosystems.

Introduced species

Introduction of exotic animal species in Indian wetlands has been made mainly for commercial purpose. Such exotic species include several species of fishes, viz., tilapias, silver carp, grass carp, cyprinus carp, gouramy. English trout, bighead carp, etc., which are introduced in the Indian waters from Africa, Europe and other parts of the world.

Culturable species

Besides a large number of fishes (more than 50 species), both endogenous and exotic, there are about 10 species of molluscs and 15 species of crustaceans inhabiting inland wetlands that are being cultured and harvested in India. Of these, the tiger prawn. Penaeus mondon, the mud crab, Scylla serrata, etc., are exported frozen, canned or alive from India.

The degradation of wetland environment as well as loss of biodiversity in various wetland types is alarming. It is imperative that adequate attention is needed to prevent loss of biodiversity from wetlands in India. Though various conservation measures are taken to conserve this ecosystem, it is essential to create awareness among local communities and involve them in conservation and management activities. 

JRB Alfred & NC Nandi

Zoological Survey of India

M-Block, New Alipore,

Calcutta – 700 053

TABLE 2

Estimated number of animal species occurring in wetlands in India