BENEFITS FROM WETLANDS
Ecosystem functions of wetlands are distinguished on the basis of services and benefits they provide. They are a boon for the man kind and other living beings. The rewards of these wetlands are assessed by Ramsar convention and United Nations Millennium Ecosystem Assessment (MEA) agencies that rank them as wetlands of ecological significance and of societal importance.
The benefits offered by wetlands are as follows:
1. Storage reservoir and Flood control
Floodplains formed by major downstream rivers act as natural storage reservoirs. It distributes the excess water over a wider area and thus reduces its speed and depth by slowing it down.
Wetlands near the headstreams can slow down the sudden rainwater runoff and snowmelt and restrain it to run directly into the land thus, preventing sudden damages by flood streams.
Wet grasslands and peatlands act like sponges alongside the river basins that absorb the rainfall and its direct flow into the streams and rivers. When the peats become inundated with water, meadows and forests help to slow down the flow of runoff. Although draining of peatlands may cause flash floods.
2. Groundwater recharge (replenishment)
The surface water represents only a portion of the water cycle of wetland and it also incorporates the atmospheric precipitation and moisture, and groundwater. Porous sediments allow water to filter through the soil and rocks into the aquifers (source of drinking water). When the water table is low, the wetland recharges the groundwater while it discharges the water in case of presence of excess of water.
Example: Karst ecosystems are connected underground rivers which are influenced by precipitation.
3. Shoreline stabilisation and storm protection
Wetland tidal and inter tidal systems offer protection and stabilization to the coastal zones by reducing the height and speed of the floodwaters.
Example: coral reefs act as barriers towards the storms at the shoreline whereas mangroves confer stabilization of the coastal zone from inside and migrate with respect to the shoreline.
4. Water purification
Wetlands act as biofilters for the purification of water. Hydrophytes and other organisms also help in the purification as they have the capacity to remove the toxic substances (by uptake) such as industrial effluents, mining pollutants and pesticides.
Example: in east Kolkata wetland, the wetland waters are used to treat the sewage effluents in a natural way where the nutrient helps in the sustenance of the fish farms (aquaculture) and provides economic benefits to the farmers.
Some plants as well as some faunal species have a natural ability to absorb and filter heavy metals and toxins such as:
S.No. FLORA/FAUNA HEAVY METAL/TOXINS
1. Eichhornia crassipes (water hyacinth), Lemna (duckweed) and Azolla (water fern) Help in storage of iron and copper (from waste water)
2. Oyster Filters more than 200litres of water per day
5. Reservoirs of biodiversity
The rich biodiversity of flora and fauna is the basis for its identification as a Ramsar site under the International treaty guidelines. Nearly 200 new species are discovered each year. Wetands consist of:
• Biodiverse river basins: the fresh water species differ with respect to their nursery grounds and their spawning grounds.
• Productive intertidal zones: the rich diversity of invertebrates in the intertidal mudflats even with low species number is the basic attraction and source of food for migratory waterfowl species.
• Critical life-stage habitat: salt marshes, mangroves and coral reefs are rich spots for productivity and species diversity as they provide important breeding grounds for the commercial fish stocks.
• Genetic diversity: the diversity arises probably due to long isolation periods of wetlands from other aquatic sources. Thus, it acts as a hotspot for various non threatened, endemic, and endangered species.
6. Wetland products
Wetlands produce an array of ecological products that can be harvested and used for personal and commercial benefits. They provide us with agricultural lands and fish aquaculture systems.
The products and services so obtained are: Fresh and saltwater fishes, food (Rice, sago palm), salt, textile fibers, fodder, medicines, dyes and tannins.
7. Wetlands and climate change
Wetlands help in climate mitigation through carbon sinking and storage of water. They have the ability to store about 44.6 Tg C y−1 globally. Salt marshes sequester about 201 g CO2 m−2 y−1 carbon and peatlands sequester about 20-30g CO2 m−2 y−1 carbon. This has lead to blue carbon initiatives.
8. Aquaculture
Natural waterways are used to harvest the fishes using aquaculture farming in some wetlands such as EKW and this has raised concerns towards their consumption. Although this practice has lead to decrease in the pollutant and toxin content in the water bodies, it has much negative effect on the downstream waterways that affects the developing island states.
9. Cultural value
Wetlands are significant and have religious, historical and archaeological value in various cultures for people as they provide us with food and shelter.
10. Materials and Medicines
Wetlands provide valuable sources such as thatching materials, timber and fuelwood, fibers for textiles, food and fodder, medicines, raw paper making materials, and much more benefits.
Medicines are obtained from the bark, leaves and roots of the plant and apart from that it also provides tannins and dyes extensively used in leather making industries.
11. Recreation areas
Wetlands furnish various leisure facilities-not just scenic beauties but also canoeing, camping, bird watching, swimming, shell collection, hunting and sailing.
12. Vital habitat
Wetlands support a high number of endemic, threatened and endangered species and thus their protection is of utmost important. It also acts as a nursery habitat and breeding ground for various commercially important fish species.
13. A refuge for migrating birds
During the unfavorable conditions and winter seasons, a large flock of birds and extra ordinary mass movements of diverse living creatures takes place from one area to another. They are like pit stops for these creatures which offer them food and protection as they continue to migrate to their final destinations.
Note: Nitrous oxide production from wetland soils
Coastal wetlands like marshes and mangroves are not only the carbon sink grounds but are also emitters of nitrous oxide (N2O) which is a greenhouse gas that can cause global warming up to 300 times that of CO2 and reduce the ozone layer. Excess nutrients also increase N2O fluxes through nitrification and denitrification processes.
To replace the wetland benefits and services, massive amounts of money need to be spent on water filtration and storage, aquaculture and agricultural farm lands, food, fodder, fiber and timber production along with the measures to control the storms and floods.