The importance of wetlands to society, both in their fundamental value and as an essential constituent of the ecosystem, has long been acknowledged by biologists and other natural scientists. Wetlands are responsible for many intricate ecological processes as well as for their prosperous flora and fauna. The important functions of wetlands are water shortage, storm protection and flood migration, shoreline stabilization, ground water recharge and discharge, water purification, retention of sediments, nutrients and pollutants and stabilization of local climate, particularly temperature and rain. Attributes of wetlands embrace the safeguarding of biological diversity by supporting bird fauna(like waterfowls and migrant birds) fish, reptiles, mammals and invertebrate species like shrimps, many plant species and a range of micro organisms including plankton.
Wetlands have been under peril of degradation due to anthropogenic activities. Major threats to the wetlands and their biota are
2)Aqua culture development
4)Weed infestation which in turn lead to the decrease in biological diversity, deterioration of water quality, sedimentation and shrinkage in areas under wetlands, decrease in migratory bird population, decrease in fish productivity and abundant growth of unwanted aquatic biota.
Wetlands despite their remarkable ecological and economic prospective are considered as lands of low value or just waste lands and they have been encroached for urban development as well as for agricultural purposes. Wetlands are taken by many as mear dumping sites of domestic sewage, solid waste, industrial effluents and pesticide fertilizer run off from nearby agricultural lands. Pollution leads to eutrophication which in turn reduces dissolved oxygen and increases the biological oxygen demand leading to the mass mortality and depletion of stock of fish and other aquatic organisms. The eutrophication process further creates conditions favourable for the weeds to flourish in the wetlands. In the case of India infustation aquatic species like eichornia crassipes and ipomea aquatica is a wide spread problem which interfere with the ecological functions of wetlands. Another major threat to the environmental quality of the wetlands is their haphazard utilization for aqua culture. Intensive use of fish and prawn feed and the consequent draining of the nutrients rich water into the neighbouring sea or river ecosystem result in the degradation of wetlands. Siltation as a natural geological process has its own natural pace in aquatic ecosystem including wetlands. But Siltation together with anthropogenic activities would pilot to the reduction and loss of wetland habitats as well as the modification in their faunal and floral composition.