Wetlands - Introduction
Wetlands refer to complex ecosystems encompassing a wide range of inland, coastal and marine habitats such as floods, plains, swamps marshes, tidal marshes etc.
Wetlands are areas with open standing water (that is the water table is at the surface and the ground is saturated with water) with vegetation. Basically, the wetland is a transitional zone where land and water meet. A special soil environment is created due to standing water with little or no oxygen. Therefore, in wetlands, water is the primary factor controlling the environment, the associated plant (Hydrophytes), and animal life.
Wetlands provide suitable habitats for endangered and rare species of birds and animals, endemic plants, insects and invertebrates, besides sustaining migratory birds and waders.
Wetlands can be:
1. Either natural or artificial (examples of man-made wetlands include fish and shrimp ponds, farm ponds, irrigated agricultural land, salt pans, reservoirs, canals etc.).
2. Either temporarily or permanently covered by water.
3. Either static or flowing water
4. Fresh, brackish or salt water (including areas of marine water the depth of which at low tide does not exceed 6 meters)
How much of the earth’s surface is presently composed of wetlands is not known precisely. Wetlands exist in every country and in every climatic zone. As per United Nations Environment Program (UNEP) estimates, their area could be about 570 million hectares. Whereas, some other estimates suggest that their area could be more than 70 million hectares.
Types of Wetland
There are some major wetlands types:
1. Marine Wetlands - Marine wetlands include coastal lagoons, Coastal Lakes, rocky shores and Coral reefs.
Various types of ecosystems are formed in the oceanic environment based upon physical attributes like the presence or absence of sunlight, temperature of ocean waters, salinity and density of ocean waters, nutrient availability, ocean currents etc.
2. Estuarine Wetlands - Estuaries and their surrounding wetlands are bodies of water usually found where fresh water meets the saltwater. Estuaries contain nutrients and sediment from both the land and sea.
Estuaries are home to unique plant and animal habitats that have adapted to brackish water -including deltas, tidal marshes, and mangrove swamps.
They are biologically and physically the most productive and valuable ecosystems in the world.
3. Lacustrine Wetlands - Locus means Lakes. These are the standing water ecosystems like lakes ponds and even man-made reservoirs.
In simple terms, a lake is a water body surrounded by land. They are largely non-riverine or non-channel systems and are not influenced by tidal water.
Generally, the Species diversity is low in lacustrine wetlands. as they are often isolated from one another and from other water sources like rivers and oceans. Primary production in such wetlands depends upon the input of nutrients from land.
4. Riverine Wetlands - These include low-lying depressions like oxbow lakes or may be distributed over floodplains of the rivers. These may be seasonally flooded by river waters and may be dry for most of the growing season.
5. Palustrine Wetlands - These include marshes, fens, swamps, peatlands, bogs, etc.
6. Marshes are wetlands that have predominantly emergent herbaceous vegetation like grasses, reeds, sedges and cattails.
7. Fens are slightly acidic whereas bogs are highly acidic
8. Swamps are the forested wetlands which are dominated by woody vegetation.
9. Peatlands or mires are wetlands that have an accumulation of partially decayed organic matter called peat. These are usually found in regions where temperatures are low. Also, due to anaerobic conditions and low temperature microbial activity is slow. Thus, decomposition of organic matter is slower than its production which leads to accumulation of peat.
These are more commonly found in boreal regions of the Northern Hemisphere. However, a few peatlands also occur in mountainous regions of tropical and sub-tropical latitudes.
Significance of Wetlands -
Wetlands are one of the world’s most important environmental assets, containing a disproportionately high number of plant and animal species compared to other areas of the world. Throughout history, they have been integral to human survival and development.
1. Wetlands are among the world’s most productive environments. They are cradles of biological diversity, providing the water and primary productivity upon which countless species of plants and animals depend for survival. They support high concentrations of birds, mammals, reptiles, amphibians, fish and invertebrate species.
2. Wetlands add moisture to the atmosphere, which could fall back as rain.
3. Wetlands are also essential storehouses of plant genetic material. Rice, for example, which is a common wetland plant, is the staple diet of more than half of humanity.
4. Wetlands can even be used as sewage treatment plants that require little technology or maintenance.
5. Wetlands store carbon by primary production. Carbon is stored in living plants, animals and rich organic soils of wetlands. However, they are also natural emitters of GHGs like methane due to anaerobic conditions.
6. They help in recharging groundwater and in purifying water by wetlands micro-organisms and plant species like cattail and reed which help filter out toxins from polluted water. Thus, they are natural water filters.
7. Wetlands are land surfaces covered or saturated with water for part or whole of the year. They are shallow systems with black and rich sediments and abundant nutrients. They have vegetation adapted to thrive in saturated conditions. These nutrients and chemicals are naturally recycled in wetlands.
8. Wetlands control flooding by holding excess water and releasing it slowly. Coastal wetlands help in shoreline protection and act as a buffer during storm disasters.
9. Wetlands are the major breeding, nesting, and migration staging areas for many birds.
10. Wetlands provide tremendous economic benefits, for example, water supply; fisheries (over two-thirds of the world’s fish harvest is linked to the health of coastal and inland wetland areas); agriculture, through the maintenance of water tables and nutrient retention in floodplains; timber production; energy resources, such as peat and plant matter; wildlife resources; and recreation and tourism opportunities.
Threats to Wetlands -
Even as we realize their importance, however, wetlands are shrinking rapidly all over the world. Some of the main threats to wetlands include:
- Almost half of wetlands have disappeared over the past century and those that remain have been fragmented by development.
- Encroachment and construction over wetlands due to agriculture and urban expansion.
- Water diversion for dams, irrigation canals etc. This causes fragmentation of hydrological regimes and catchment degradation of wetlands.
- Some wetlands have been used as toxic waste dumps and landfills. Pollution due to domestic sewage, solid waste disposal, agriculture run-off and industrial effluents. Pollutants like agricultural and sewage disposal cause eutrophication in wetlands.
- Overharvest of wetland resources like fisheries etc.
Global Conservation Efforts for Wetlands
Wetlands are vital for human survival and therefore international efforts for wetland conservation gain importance.
Ramsar Convention -
The Ramsar Convention is the only global environmental treaty that deals with a particular ecosystem. The treaty was adopted in the Iranian city of Ramsar in 1971 and the Convention’s member countries cover all geographic regions of the planet. It entered into force in 1975. The Ramsar Convention is the only global environment treaty dealing with a particular ecosystem.
There are 168 countries (called Contracting Parties) as part of the Ramsar Convention with more than 2000 wetlands as wetlands of international importance.
The Ramsar Convention on Wetlands was developed as a means to call international attention to the rate at which wetland habitats were disappearing, in part due to a lack of understanding of their important functions, values, goods and services. Governments that join the Convention are expressing their willingness to make a commitment to helping to reverse that history of wetland loss and degradation.
Major obligations of countries which are party to the Convention are:
- Designate wetlands for inclusion in the list of ‘Wetlands of International Importance’.
- Promote, as far as possible, the wise use of wetlands in their territory.
- Promote international cooperation especially with regard to transboundary wetlands (lying across the boundaries of two or more countries), shared water systems, and shared species.
- Create wetland reserves.
The ‘Wise Use’ Concept - The parties of the Ramsar Convention have agreed to the conservation and management of wetlands based on the ‘wise use’ principle. ‘Wise use of wetlands is the maintenance of their ecological character, achieved through the implementation of ecosystem approaches, within the context of sustainable development.’
The Convention defines a wetland 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.’
The Montreux Record (MR) -
Montreux Record is the list of Ramsar Sites where the change in ecological character has occurred, is occurring, or is likely to occur as a result of technological development, pollution, or other human interference.
Montreux record sites require priority national and international conservation attention and receive preference for application of the Ramsar Advisory Mission.
Montreux Record was established by Recommendation 4.8 of the Conference of the Contracting Parties (1990). Resolution 5.4 of the Conference (1993) determined that the Montreux Record should be employed to identify priority sites for positive national and international conservation attention. Sites may be added to and removed from the Record only with the approval of the Contracting Parties in which they lie. As of August 2021, 48 sites are listed in the Montreux Record.
Wetlands International South Asia Society - It is a non-governmental organisation with a mission to sustain and restore wetlands, their resources and biodiversity. It was established in 1996 as part of Wetlands International with a mandate to promote Wetland COnservation and wise use in the South Asia region.
World Wetland Day -
World Wetland Day which is celebrated each year on 2nd February, marks the date of the adoption of the Convention on Wetlands on 2nd February 1971, in the Iranian city of Ramsar on the shores of the Caspian Sea. World Wetlands Day was celebrated for the first time on February 2, 1997, on the sixteenth anniversary of the Ramsar Convention.
Each Year since 1997, government agencies, non-governmental organizations, and groups of citizens at all levels of the community have taken advantage of the opportunity to undertake actions aimed at raising public awareness of wetland values and benefits in general and the Ramsar Convention in Particular.
Frequently Asked Questions (FAQs)
Question - What is a Wetland?
Answer - A wetland is a transitional zone where land and water meet. These are the areas with open-standing water with vegetation.
In wetlands, water is the primary factor controlling the environment, the associated salt-tolerant plants (Hydrophytes), and animal life.
Question - How many types of wetlands are there?
Answer - There are five major wetlands types: Marine, estuarine, lacustrine, palustrine and riverine wetlands.
Question - What is the significance of Wetlands?
Answer- Wetlands control flooding by holding excess water and releasing it slowly. They help in recharging groundwater and in purifying water by trapping and holding pollutants in the soil. They are the major breeding, nesting, and migration staging areas for many birds.
Wetlands add moisture to the atmosphere, which could fall back as rain. They can even be used as sewage treatment plants that require little technology or maintenance. If they are managed well, they will not breed mosquitoes because of the presence of fish, insects, and birds.
Question - Why are Estuaries and Coastal Wetlands Important?
Answer - Estuaries and coastal wetlands include river mouths, bays, mangrove forests, and salt marshes. Seawater mixes with fresh water and nutrients from rivers, streams, and runoffs. These ecosystems experience, daily and seasonally, wide fluctuations in temperatures and salinity levels because of tidal rhythms, variations in freshwater inflow from land and river, and the impact of storms,
The organisms in these ecosystems have to adapt to changing conditions. Yet, these ecotones are among the most fertile ecosystems, often more productive than the adjacent ocean or river.
Coastal saltwater wetlands are the ocean’s nurseries, where many fish species spend the first part of their lives. These wetlands also protect coastlines from erosion and reduce damage from storms and cyclones.
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