Abstract
Wetlands are home to numerous species of fish, birds, and reptiles. The enormous roots of the mangrove trees act as shelter to small fish, reptiles, and amphibians. Pesticides and agro-chemical fertilizers have been playing a very pivotal role in the degradation of the land and the water bodies. The different herbicides that are present in wetlands are Dicamba, Endothall, MCPA, Triallate, Trifluralin, 2, 4-D, and insecticides Carbaryl, Carbofuran, Fenvalerate, Malathion, Parathion, and Terbufos. These pesticides have been provided with the aim of catering to the security of the crops which are highly vulnerable to the pests. However, harmful effects of pesticides on wetland species have been a concern for long time. Wetlands constitute one such habitat threatened by the pesticides. But there has been a lack of comprehensive research in this direction. The chapter will identify the gaps in the current research and will review the status of Indian wetlands with special reference to pesticides and their impact.
TopIntroduction
Wetlands are the precious life-sustaining water resources in India. Besides playing a vital role in the hydrological cycle, wetlands are the most productive ecosystems of the world and a potential source of carbon sequestration, although they covers about 4% of the earth’s ice-free land surface (Prigent et al., 2001). Ramsar Convention on Wetlands, which is an international treaty signed in 1971 for national action and international cooperation for the conservation and wise use of wetlands and their resources, defines wetlands as “areas of marsh, fen, peatland 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 metres”.
Globally, the areal extent of wetland ecosystems ranges from 917 million hectares (Lehner and Doll, 2004) to more than 1275 m ha (Finlayson and Spiers, 1999). One of the first widely used wetland classifications systems (devised by Cowardin et al., 1979) categorized wetlands into marine (coastal wetlands), estuarine (including deltas, tidal marshes, and mangrove swamps), lacustarine (lakes), riverine (along rivers and streams), and palustarine (‘marshy’– marshes, swamps and bogs) based on their hydrological, ecological and geological characteristics.
The Ramsar Classification is exhaustive, given under three broad groups as Marine/Coastal wetlands, Inland wetlands and Human-made wetlands. There are twelve categories under Marine/Coastal wetlands, twenty categories under Inland wetlands and ten categories under Human-made wetlands, as given below:
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Marine/Coastal wetlands
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Inland wetlands
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Human-made wetlands
Wetlands are ecologically sensitive and adaptive systems (Turner et al., 2000). Wetlands exhibit enormous diversity according to their genesis, geographical location, water regime and chemistry, dominant species, and soil and sediment characteristics (Space Applications Centre, 2011). However, many wetlands which perform potentially valuable functions are continued to be ignored in the policy process. As a result many freshwater wetland ecosystems are threatened and many are already degraded and lost due to urbanization, population growth, and increased economic activities (Central Pollution Control Board, 2008) (Figure 1). Wetlands being dynamic and influenced by both natural and man-made activities, need frequent monitoring. Regular updation of the status of the wetlands is all the more significant in view of the accelerating pressure on the very existence of these resources due to developmental activities and population pressure being witnessed currently.
TopStatus Of Wetlands In India
India with its annual rainfall of over 1,300 mm, varying topography and climatic regimes, supports diverse and unique wetland habitats (Prasad et al., 2002). The available estimates about the area extent of wetlands in India vary widely from a lowest of 1% to a highest of 5% of geographical area (Space Applications Centre, 2011).
Key Terms in this Chapter
Contamination: Is the presence of an unwanted constituent, contaminant or impurity in a material, physical body, natural environment, workplace, etc. Contaminants are biological, chemical, physical, or radiological substances.
Herbicide: A herbicide is a chemical substance used to control or manipulate undesirable vegetation, especially weeds. Herbicides are extensively used in gardening, farming, and landscape turf management.
Eutrophication: Is the enrichment of a water body with nutrients, usually with an excess amount of nutrients. This process induces growth of plants and algae and due to the biomass load, may result in oxygen depletion of the water body.
Biota: Biota is defined as the animal and plant life of a particular region, habitat, or geological period.
Food Chain: A food chain is a linear network of links in a food web starting from producer organisms (such as grass or trees which use radiation from the sun to make their food) and ending at apex predator species (like grizzly bears or killer whales), detritivores (like earthworms or woodlice), or decomposer species (such as fungi or bacteria).
Ecosystem: An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (like air, water, and mineral soil), interacting as a system.
Pesticide: A pesticide is a chemical that is used to control a pest. A pest can be an insect, weed, bacteria, fungus, rodent, fish, or any other troublesome organism.
Pollution: Pollution is the introduction of contaminants into the natural environment that causes adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat, or light.