Science Fair Project on Wetlands | Ecology

Do you want to make an amazing science fair project on wetlands ? You are in the right place. Read the below given article to get a complete idea on wetlands:- 1. Meaning of Wetlands 2. Types of Wetlands 3. Convention 4. Classification 5. Importance 6. Functions 7. Researches.

Contents:

1. Science Fair Project on the Meaning of Wetlands
2. Science Fair Project on the Types of Wetlands
3. Science Fair Project on the Convention of Wetlands
4. Science Fair Project on the Classification of Wetlands
5. Science Fair Project on the Importance of Wetlands
6. Science Fair Project on the Functions of Wetlands
7. Science Fair Project on the Researches on Indian Wetlands

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Science Fair Project # 1. Meaning of Wetlands:

Wetlands, as the name signify, are wet ground, rather than standing water (aquatic habitat). Wetlands develop an organic soil profile with waterlogged soil. The saturation of soil with water, possess a problem for plants as anaerobic conditions are produced with little or no oxygen availability.

This alters the community structure. Wetlands have been described by Smith (1980) as “a halfway world between terrestrial and aqua­tic ecosystems”. So, they range from very nearly aquatic to almost dry. Several wet­lands totally dry out during dry seasons in the year and are very difficult to identify.

The definition of wetland according to the Fish and Wildlife Service of U.S. is — “Wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the type of plant and animal communities living in the soil and on its surface. Wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water”

According to Ramsar Convention (1971) wetlands are “areas of marsh, fen, peat-land 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 meters.”

Wetlands occupy about two percent of the surface area of earth and contain 10 to 14 percent of the carbon. The soils of wetland, such as histosols, contain about 20 percent carbon by weight. The peats are even more carboniferous. The aerobic-anaerobic stratification of wetland sediments (Fig. 4.57) plays a part in the global cycling of sulfur, nitrogen, phosphorus and also carbon.

Indian wetlands cover an area of about 58.2 million hectare. The wet­lands in India are disappearing gradually because of various threats like settlement, agricultural encroachment, and pollution, over-exploitation of fisheries and forest resources and siltation. All these lead to unsustainable harvesting of wetlands.

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Science Fair Project # 2. Types of Wetlands:

The enormous variety of wetland ecosys­tems had led to a large number of descriptive names for wetland types. As water is very important than climate, there exist similar types of wetland in many regions; with often different types of species in the community although having similar basic structure.

Wetlands are divided according to the source and nature of the water which maintains it and thus can be broadly divided into the fol­lowing four types:

i. Marine wetland ecosystems

ii. Flood land ecosystems

iii. Swamp and marsh ecosystems

iv. Bog ecosystems.

i. Marine Wetland Ecosystems:

a. Mangrove swamps:

Mangrove swamps are found along the coastlines in the tropical and subtropical regions. This area is flooded during every high tide, with marine or brackish waters. These coastal wetlands are densely vegetated with thickets of man­grove trees. About 70 species of mangroves are found all over the world.

The most important genera being Rhizophora, Sonneratia and Avicennia. Mangrove vegetations are well-adapted to the salty conditions of the intertidal zone as they have mechanisms to prevent high concentrations of salt from entering the roots and can excrete the excess salt from their leaves and even can drop their leaves.

Mangrove swamps are influenced strongly by the tides as incoming tides import nutritions to the system. Tides are also responsible for dispersing seeds. These seeds germinate before falling to the ground. They grow a thick spear-like hypocotyl, which gets embedded in the mud and then grows anchoring roots.

The mangrove trees have a number of aerial roots arising from the trunk and grow down into the mud beneath. These stilt roots provide support for the trees and lessen the action of the waves of -incoming tides. The trees also show stick-like structure protru­ding out from the mud called pneumatophores (Fig. 4.58). The stilt root and pneumatophores are provided with minute pores that are capable of taking in aerial oxygen.

A number of animal life has been wit­nessed within the mangrove such as fiddler crabs (Uca sp.), mudskippers (Periophthalamus sp.). A number of fishes are washed into this area by the tides which attract a number of birds. There are many detritivores and some major carnivores like alligators, crocodiles, tigers (Panthera tigris) etc.

b. Salt marshes:

Mangrove forests do not grow in higher latitudes, as the trees cannot tolerate cold weather. In such places, salt marshes grow. The salt marshes like the mangrove swamps are under the influence of sea, where salt water enters at the time of high tide. Salt marshes (Fig. 4.59) are made up of patches of low vegetation separated by tidal creeks and tend to develop in sheltered intertidal regions where wave action is not too strong.

The vegetation in salt marshes is domi­nated by grasses such as Spartma and rushes (juncus sp.). The lower lying areas where pools have formed, having high salt concen­tration, a very succulent plant, called glass wort (Salicornia europaea) grows. During high rainfall, the salt are washed away from the marsh areas and are colonised by different types of plant species such as sea lavender (Limonium sp.) and arrow grass (Triglochin sp.).

The soils of salt marshes are low in nitro­gen and high in phosphates. This may limit plant growth. If sulphur from sea water collects in these marshes, the soil will become toxic for plants. When the soil drys out, sulphuric acid may form, thus lowering the pH of the soil.

In such marshes 70% of net productivity is due to chemosynthetic bac­teria which utilizes the sulphur. Mats of cyanobacteria form on the mud and they are important as fixers of light energy. Much of the organic matter produced are, however, washed away by the retreating tide waters.

ii. Flood-Land Ecosystems:

This group of wetland ecosystem obtains their water from rivers. During rainy season, the river overflows its banks and the flood-lands are flooded deeply with water. Being seasonal they may dry out during summer. Flood-lands occur in lowland flat-bottomed valley through which a river meanders (Fig. 4.60).

Normally a mature river follows a channel through which the river flow builds up at the side into sandy banks called levees (Fig. 4.60). The valley gets flooded when the river overflows. There are permanent wet­land areas which form when the river takes a new path on the valley floor, called oxbow lake (Fig. 4.60). A flood plain may have seve­ral oxbow lakes in various stages of infill.

As the river floods the valley, clay, silt and mineral are carried and deposited on the flood plain. The larger particles settles on the bank to form levees, while the smaller parti­cles are carried further away and are left behind as the water recedes. This makes the soil of the flooded plain rich in nutrient.

The bank of the river having such enriched soil makes it ideal for irrigation. Many such areas around larger rivers of India are valuable for cultivation. These areas, in temperate zones, also form rich grazing land.

In temperate flood-land the natural vege­tation is mixed deciduous forest. In tempe­rate North America, the areas flood all year round, have small number of specialized swamp trees like swamp cypress (Taxodium distichum) and by tupels (Nyssa aquatica).

In areas where the river water floods for more than half the year, the above species along with specialist oaks (Quercus sp.) and ashes (Fraxinus sp.) are found. In areas where flooding occurs less than 50%, the swamp species disappears and larger variety of oaks and elms (Ulmus sp.) take their place. These mixed woodlands are invaded by rich fauna of amphibians, reptiles, birds and mammals.

iii. Swamp and Marsh Ecosystems:

These wetlands are found in areas where water runs off the surrounding land or drains and collects or where ground water lies close to the surface or where such areas are fed by rivers and streams. Such areas are flooded all-round the year and are variable in size and form, depth of soil and plant community structure. In those areas where trees are the dominant vegetation, it forms swamps, while those which have large open areas of grasses and reeds form marshes.

a. Swamps:

Swamps are wooded wet­lands, dominated by trees that are similar to those found in the very wettest areas of floo­ded river valleys. The most famous swamp areas occur in Florida (USA). The dominant free species are the swamp cypress (Taxodium sp.) and water tupelo. Several species in the swamp have knee roots that protrude out of the water (Fig. 4.61).

These pneumatophores may act just like the ones present in man­grove swamps. Carbon dioxide has been reported to leave these knee roots. However, there is no report that oxygen is taken in. Swamp trees produce seeds but unlike the mangrove trees, they germinate and grow in dry conditions only. This means that vege­tation of swamp trees can only take place when the swamp temporarily dries.

Several types of swamps have been recognised, which include:

(i) Northern Conifer Swamps:

Here the forest is composed of tamarack, black spruce or white cedar.

(ii) Hardwood Swamps:

These are wet­land forests of elms, ashes, red maple and birches. It also contains oaks and hickories.

(iii) Cypress Swamps:

These Swamps are dominated by cypress and gum. Swamps near rivers include bald cypress and tupelo gum (Nyssa aquatica) and swamps away from rivers include pond cypress (Taxodium ascendens) and water gum (Nyssa biflora).

The density and diversity of vertebrate communities are usually high in swamps. A number of birds such as the warblers, waders etc. are common in swamps. Breeding colo­nies of many large waders, such as great blue herons, are generally located in swamp forests.

b. Marshes:

Marsh is dominated by graminoids (grass like plants) that include not only grasses (Poaceae) but may also be cattails, sedges (Cyperaceae), rushes or other plants with more or less grass like leaves. Marshes are common in temperate zones and may occur around a lake or pond or along­side a river or away from any water bodies in areas areas where the water table is high.

The movement of ground water runoff and the addition of stream water makes the marshes nutrient rich and the pH is usually near neutral to slightly alkaline. The depth of the standing water in marshes may be up to a couple of metres or generally lesser. At greater water depths only floating leaved or sub­merged vegetations are found.

The species which live in marshes often have sharp-edged or tough leaves (Cladium, Phragmites etc.). These tough leaves have probably evolved to deter large herbivores like swamp rhinoceros and straight tusked elephants in the Pliocene and Pleistocene.

These animals have become extinct but the tough grass species have been left relatively untouched. In marshes where the soil surface becomes dry by the middle of summer, the types of vegetation generally found are the sedges in the genus Carex.

Marshes are important breeding sites for frogs and toads. Bird populations are high about 300 to 400 pairs per 40 hectare. Some important species are rails, bitterns, ducks, marsh wren, red-winged black bird and swamp sparrow. Sand hill cranes feeds in drier areas but build their nest in marshes. The mammalian fauna includes musk rat and mink.

Leaf matters falls on the surface of wet marshes and is attacked by decomposers. These leaf litters form the base of the food web in may marshes. Successional processes lead marshes to be replaced by shrubcarr and eventually by swamp forest.

iv. Bog Ecosystems:

Bog are wetlands that receive water only from rainfall (not from streams, rivers or ground-waters) and this sole source of water greatly affects its nutrient content. Unlike river and ground water, rainwater has very little nutrients. Moreover, whatever nutrients may be present get leached as water is drained through the soil profile.

Bog is characterised by the accumulation of peat. Peat filled depressions are common. The dominant species in bogs are mosses in the genus Sphagnum (Fig. 4.62). Different species of Sphagnum are found in bogs, each with slightly different water requirements.

Sphagnum bog develops where rainfall is high and temperature is cool. Bogs generally occur in the temperate and boreal regions. The bog may slowly grow up to form a huge dome of peat called raised bog (Fig. 4.62). In areas where rainfall is high (about 1,000 mm a year), blanket bog develops.

It can develop even on shallow slopes. In blanket bog, the peat can develop to several metres in thick­ness. Often the peat gets eroded (Fig. 4.63) as the surface vegetation gets damaged due to trampling, grazing or pollution. The high rainfall also aids this process.

Bog Succession:

The succession of a typical bog begins around the margin of a lake or pond. Fig. 4.64 shows successive stages in the development of a bog in a ket­tle lake. This takes some hundreds or thou­sands of years. At the time of formation a plant grows out over the water as a floating mat, which is generally a hairy-fruited sedge or water willow. The mat is then invaded by the Sphagnun moss and other plants (Table 4.12).

The biomass of these plants accumulates as peat which then begins to fill in the basin and the floating mat extends further toward the centre. The encroaching mat may take several years to spread and, eventually, may meet itself in the middle, enclosing the pond beneath. Subsequently, bog shrub and trees spread onto the mat. The basin eventually gets filled with peat and trees such as tama­rack or black spruce may extend all along the shore.

Characteristic of Bogs:

Due to the activities of Sphagnum, the plants growing on the bog mat live in an acidic medium (Table 4.13).

Two activities of Sphagnum are most important:

(i) Sphagnum adsorbs cations, such as calcium (Table 4.13).

(ii) It relea­ses hydrogen. Dissociation of organic acids (poly-galacturonic acid) leads also to the release of hydrogen. The pH within the bog is very low, often about 3.0 to 4.0, caused due to formation of humic acid and sulphuric acid, when organic sulphur is oxidised.

Another important fact is that living Sphagnum and peat can absorb 15 to 20 times its own weight in water. The soil of bogs is continuously water-logged. Due to the high water content and high specific heat of water, temperature changes in bogs are slow. Thus, low temperature acidic nature and the water-logged character and, hence, oxy­gen-poor soil, all discourage decomposition and inhibit microbial activity that would result in nitrogen fixation.

Nutrient input in bogs is mainly atmo­spheric and is referred to as ombrotrophic (rain fed). Even this little amount of nutrient is not available to most plants due to the ten­dency of Sphagnum to absorb cations. Some amount of nitrogen do enter the system through lightning and by the activity of blue- green algae. But in general the bog habitat is nitrate poor.

Few plant species (Table 4.12) other than Sphagnum mosses can grow in such condi­tions and they have evolved methods of increasing their nutrient intake. Some are carnivorous plants who lure insects into traps or have sticky leaves. The sundews (Drosera sp) have sticky material secreted by hair on their leaves to catch insects. (Fig. 4.62). Pitcher plants (Sarracenia sp.) digest insects in the pitcher which is a specialised, hollow, water-filled leaf.

The pitcher in same species also helps to catch rain-borne nutri­ents ahead of the Sphagnum. Other plants like the bog myrtle (Myrica gale) can gain extra nutrients from nitrogen fixing bacteria pre­sent in root nodules. Bladderworts grow in surface water at the edges of the bog. It catch­es aquatic invertebrates in small bladders that expand when touched. The animal is sucked in and closed with a trapdoor.

The pitcher of pitcher plants not only acts a burial chamber for some insects, but also harbours some invertebrates. Wyeomeia smithii, a mosquito, undergoes its larval development within the water of the pitcher plant. In this water of the pitcher plant lives a variety of ciliates and flagellates, rotifers and other invertebrates.

Primary productivity in the bog is low. Other than the above mentioned animals some herbivores such as hares and bog lem­mings and a few predators such as spiders and owls may be present. Larger herbivores and predators like deer, caribou and bears may sometimes enter bogs.

Fen:

Fen is an “alkaline bog”, with a pH which is slightly alkaline (Table 4.13). So fens are mineral-rich peat-land. Fens usually occur at the base of slopes and are minerotrophic (mineral fed).

Fens do not have Sphagnum, although other bog plants like pitcher plant may be prominent. Sedges are usually common and the flora is rich in bogs. Some characteristic fen plants are swamp milkweed, marsh bell- flower, Kalm’s lobelia, grass-of-parnassus, Ridell’s goldenrod, dwarf birch and shrubby cinquefoil.

Sometimes tamarck invades fen and may be replaced by white cedar. Cedar swamps have few distinctive bird species and are a favoured winter habitat for white-tailed deer.

Shrubcarr:

Shrubcarrs are shrubby vegetation that may invade marshes, fens or bogs. The most common kind of shrubs in marshes are dogwoods, willows, buttonbush and birches. The development of dense shrub-carr colonies lead to the disappearance of many characteristic plants.

Several kinds of vines are characteristic of the shrubcarr stage and they remain in the following swamp forest. Grape, poison ivy and Virginia creeper are common in shrubcarr, while virgin’s bower, wild cucumber and moon-seed are of limited occurrence

Many of the bird species listed for marshes are also found in the shrubcarr, if it adjoins marshes. A few added species of birds may be found in shrubcarrs, which includes song sparrow, American goldfinch, gray catbird, alder or willow flycatcher, yellow warbler and common yellow throat. The total density of birds in shrubcarr may be 500 or more pairs per 40 hectare.

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Science Fair Project # 3. Convention of Wetlands:

The convention on Wetlands of International Importance especially as Waterfowl habitat often known as the Ramsar Convention from its place of adoption in Iran in 1971—is an intergovernmental treaty which provides the framework for international cooperation for the conservation of wetlands.

By 2002, more than 133 countries had joined the Convention, thereby agreeing to accept a number of obligations, including the following:

1. To designate wetlands of international importance for inclusion in a list of so called Ramsar Sites’.

2. To maintain the ecological character of their listed Ramsar Sites.

3. To recognise their planning so as to achieve the wise use of all the wetlands on their territory.

4. To designate wetlands as nature reserves.

Already more than 1201 wetland sites have been added to the Ramsar list, covering more than 105.8 million hectares of wetland habitat. India joined the convention in 1982 and till November 2010 had designated 25 wetlands as Ramsar sites.

A list of selected Ramsar wetlands of India with their importance and threat is given in the Table 8.2:

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Science Fair Project # 4. Classification of Wetlands:

1. Saltwater:

a. Marine:

i. Subtidal:

(i) Permanent unvegetated shallow water less than 6 m depth at low tide, including sea bays, straits.

(ii) Subtidal aquatic vegetation, including kelp beds, sea grasses, tropical marine meadows.

(iii) Coral reefs.

ii. Intertidal:

(i) Rocky marine shores, including cliffs and rocky shores.

(ii) Shores of mobile stones and shingle.

(iii) Intertidal mobile unvegetated mud, sand or salt flats.

(iv) Intertidal vegetated sediments, including salt marshes and man­ groves, on sheltered coasts.

b. Estuarine:

i. Subtidal:

(i) Estuarine waters; permanent waters of estuaries and estuarine systems of deltas.

ii. Intertidal:

(i) Intertidal mud, sand or salt flats, with limited vegetation.

(ii) Intertidal marshes, including salt-marshes, salt meadows, saltings, raised salt marshes, tidal brackish and freshwater marshes.

(iii) Intertidal forested wetlands, including mangrove swamp, Nipa swamp, tidal freshwater swamp forest.

c. Lagoonar:

(i) Brackish to saline lagoons with one or more relatively narrow connections with the sea.

d. Salt lake:

(i) Permanent and seasonal, brackish, saline or alkaline lakes, flats and marshes.

2. Freshwater:

a. Riverine:

i. Perennial:

(i) Permanent rivers and streams, including waterfalls.

(ii) Inland deltas.

ii. Temporary:

(i) Seasonal and irregular rivers and streams.

(ii) Riverine floodplains, including river flats, flooded river basins, seasonally flooded grassland.

b. Lacustrine:

i. Permanent:

(i) Permanent freshwater lakes (8 ha), including shores subject to seasonal or irregular inundation.

(ii) Permanent freshwater ponds (8 ha).

ii. Seasonal:

(i) Seasonal freshwater lakes (8 ha), including floodplain lakes.

c. Palustrine:

i. Emergent:

(i) Permanent freshwater marshes and swamps on inorganic soils, with emergent vegetation whose bases lie below the water table for at least most of the growing season.

(ii) Permanent peat-forming freshwater swamps, including tropical upland valley swamps dominated by Papyrus or Typha.

(iii) Seasonal freshwater marshes on inorganic soil, including sloughs, potholes, seasonally flooded meadows, sedge marshes, and dambos.

(iv) Peatlands, including acdophilous, ombrogenous, or soligenous mires covered by moss, herbs or dwarf shrub vegetation, and ferns of all types.

(v) Alpine and polar wetlands, including seasonally flooded mead­ows moistened by temporary waters from snowmelt.

(vi) Freshwater springs and oases with surrounding vegetation.

(vii) Volcanic fumaroles continually moistened by emerging and condensing water vapour.

ii. Forested:

(i) Shrub swamps, including shrub-dominated freshwater marsh, shrub carr and thickets, on inorganic soils.

(ii) Freshwater swamp forest, including seasonally flooded forest, wooded swamps on inorganic soils.

(iii) Forested peatlands, including peat swamp forest.

3. Man-Made Wetlands:

a. Aquacuiture/Mariculture:

(i) Aquaculture ponds, including fish ponds and shrimp ponds.

b. Agriculture:

(i) Ponds, including farm ponds, stock ponds, small tanks.

(ii) Irrigated land and irrigation channels, including rice fields, canals and ditches.

(iii) Seasonally flooded arable land.

c. Salt Exploitation:

(i) Salt pans and salines.

d. Urban/Industrial:

(i) Excavations, including gravel pits, borrow pits and mining pools.

(ii) Wastewater treatment areas, including sewage farms, settling ponds and oxidation basins.

e. Water-storage areas:

(i) Reservoirs holding water for irrigation and/or human consumption with a pattern of gradual, seasonal, draw down of water level.

(ii) Hydro-dams with regular fluctuations in water level on a weekly or monthly basis.

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Science Fair Project # 5. Importance of Wetlands:

Although wetlands are among the most diverse and productive resources, they have often been considered as essential wasteland and useful dumping ground of household wastes. It is, therefore, of utmost importance that the enhancement and preservation of wetland resources should be undertaken as they serve multitude of functions and should be undertaken as they serve multitude of functions and should be considered as highly dynamic ecosystems.

Wetland ecosystems are physical links between terrestrial and aquatic resources. As has been shown in Fig. 4.65, wetlands receives and contributes energies and mate­rials, to the other two, and play important roles in dynamics of each type of ecosystem.

Wetlands have played a crucial role in human history, major stages in the evolution of life itself probably took place in nutrient-rich coastal waters.

Some of the first prehistoric cultures-such as those of the early Mesolithic settlements around the post-glacial lake margins and coastal of Europe and those of the coastal Indian communities in North America-were dependent on wetlands for food and materials for building, shelter and clothing.

1. Among the many vital functions of wetlands, flood control is one of the most important. Wetlands act like sponges, storing and slowly releasing rainfall and runoff, thus reducing flood peak. This can reduce the need for expensive dams and other engineering structures.

2. The binding effect of their vegetation is another important aspect of wetlands; it helps in the stabilisation of banks and shores. Not only that-in some cases it helps in the accretion of sediment, thus counteracting forces of erosion, subsidence and sea level rise. Both these functions are vital.

3. Wetlands have a further key role to play in what is known as groundwater recharge and discharge Recharge occurs when water moves from the wetland into the underground aquifer- rock, such as sandstone, which holds water. The wetland acts as a filter for certain kinds of waste and soluble contaminants.

The process is important for controlling storm water run-off for replenishing supplies of water for human consumption and also in maintaining the flow of groundwater which may support other wetlands at the point of discharge. Discharge of wetland stored groundwater may be important in sustaining the agricultural production of surrounding land.

4. Regular deposition of nutrient rich silt contributed to the success of agriculture along large rivers. Sediment is also vital for maintaining aquatic fertility and physical stability of floodplains and deltas.

5. Tampering with wetlands can also damage their ability to deal with various contaminants and nutrients.

Biological, chemical and physical processes in wetlands are often able to immobilize and transform a wide range of environmental contaminants and nutrients, which, in excess, would cause severe eutrophication and pollution. Heavy metals, pesticides and industrial wastes, for instance, can be bound to soil and sediment particles, and there be rendered more or less inert.

6. Wetlands can act as a ‘sink’, preventing nitrate build-up which could lead to eutrophication. It prevents nitrates from reaching freshwater streams and lakes. Nitrate run-off from fertilized agricultural areas can be recycled to harmless nitrogen gas by this mechanism.

7. Wetland flora in particular are able to sink nutrients and contaminants. Nutrients can be decomposed and needed in agriculture thereafter.

A generalized values of wetland is shown in Table 8.3:

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Science Fair Project # 6. Functions of Wetlands:

Wetlands serve a number of functions:

i. Ground Water Recharge:

This is the movement of surface water through wetland soils into the water table or artesian aquifers (water-bearing layers).

ii. Ground Water Discharge:

It is the water movement from the aquifers into surface water resources. It generally occurs during dry seasons.

iii. Flood Storage:

Wetlands have the capacity to store peak flows of surface and groundwater (from storms, snow melting) and thus it delays the downstream flooding.

iv. Shoreline Anchoring and Preven­tion of Erosion:

The fibrous root systems of wetland vegetation has the capacity to anchor shoreline soils and it prevents the washing of shoreline soils downstream by serving as a physical barrier to hydraulic flow.

v. Sediment Trapping:

Wetland vege­tation are able to trap suspended particulate matter within the wetland and thus prevent it from entering groundwater aquifers or downstream surface waters.

vi. Nutrient Retention:

Nutrient reten­tion occurs as a result of trapping of the runoff sediments that contain mineral or organic nutrients. It may also occur due to uptake of dissolved nutrients from runoff water by wetland vegetation.

vii. Nutrient Removal:

If refers to the loss of nitrogenous nutrients to the atmos­phere. This may occur during mineralization of organic matter entrained during runoff into the wetland.

viii. Food Web Support:

Wetlands directly or indirectly provide food (seed, fruit, detritus etc.) for animals and thereby play a significant role in food web support. Euryale ferox (a dry fruit crop) is most extensively grown in wetlands of North Bihar.

(a) Wetland productivity:

Productivity is high in marshes. According to Westlake (1963) the annual NPP for “reed swamp” on fertile sites in temperate climate is 3,800 g/m². Tropical marshes (example: India) are still more productive. Bogs are not very pro­ductive and their production is as low as 50g/m²/yr.

(b) Agricultural use:

Marshes and fens are nutrient rich producing dark rich soils. These wetlands are converted to drier, more agriculturally productive land by draining them. Some wetlands are cultivated in their water-logged state, as paddy fields for rice crops. Peat bogs are, however, not threatened for agriculture.

(c) Higher order consumers:

The bio-mass of primary consumers like fishes serve as a food supply for secondary or higher order consumers such as amphibians, rep­tiles, birds and humans.

ix. Gardening:

Sedge peats of old marshlands are used as a gardening material.

x. Essential Habitat:

Wetlands provide suitable niche for a variety of fishes, birds and other aquatic animals including insects, snails etc. As flood plains and marshes are sometimes not accessible they serve as a secure place for many kinds of wild life.

Wetlands serve as a breeding ground for many aquatic animals. It acts as a breeding, and nursery ground for water fowls, flamingoes and a host of other birds.

xi. Biodiversity:

Wetlands support diversified flora and fauna. Many species of plants are characteristic for a particular type of wetland (Example: Sphagnum for bogs).

xii. Recreational Use:

Wetlands include activities that are essentially water depen­dent such as boating, swimming, fishing etc. Other recreational activities include picnick­ing, aesthetic enjoyment and nature photo­graphy.

xiii. Heritage Value:

Wetlands have some heritage value that refers to their potential importance for the preservation of socially significant features, including archaeological, geological, historical and biological.

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Science Fair Project # 7. Researches on Indian Wetlands:

In India, wetlands are distributed in various regions ranging from the cold arid zone of Ladakh through the wet Imphal in Manipur and the warm and arid zone of Rajasthan-Gujarat to the tropical monsoonal central India and the wet humid zone of the southern Peninsula.

On the basis of survey made in 1990, the Ministry of Environment and Forests made an inventory of wetlands in the country. According to this survey about 4.1 million hectares are covered by wetlands of different categories (Table 8.6).

In addition, mangroves—the coastal wetlands—occupy an area of about 6740 km², about 80% of which is the Andaman and Nicobar Islands. Stretches of mangrove vegetation are also found in coastal Orissa, Andhra Pradesh, Tamil Nadu, Karnataka, Maharashtra, Gujarat and Goa.

Recently National Committee on Wetlands, Mangroves and Coastal Reefs identified twenty four wetlands as major wetlands of national importance (Table 8.7). Among them management action plans for 10 sites has been prepared, based on problems identified so far.

Realising the importance of wetlands, conservation of wetland ecosystem has been taken up since Seventh Plan and a national committee thus formed with a view to make report on management of wetland areas in India. In India, origin of wetlands is diverse.

Kashmir has a wide range of natural lakes at altitudes varying from 1,585 to 1,600 m above sea level. These lakes occur mainly in the flood plain of river Jhelum, and are derived either from ox-bows or abundant flood channel.

The lakes include Dal, Anchal, Mansbal and Wular. Many high altitude wetlands are formed by the glacial action, such as Kumaon lakes in Uttar Pradesh. Small lakes in limestone tracts of Khashi and Jaintia hills of Assam are believed to have been formed by dissolution of underlying rock. Pichola-Fates agar complex of Rajasthan are formed as a result of movement of fine loose clay and sand particles by wind.

Similarly, salt lakes of Sambar (Rajasthan) are depressions created by the shifting dumps, forming swamps. Most wetlands of Bihar and West Bengal are of ox-bow type and are formed as a result of shifting of river courses in the geological part.

India has a vast coastline stretching over 3,600 km with sandy shores mangroves, backwaters, lagoons, mudflats and estuaries. Among the coastal wetland the most important one is that of Chilika (Orissa) is the largest brackish water lake. This is followed by Pulicat in Tamil Nadu and Ashtamudi in Kerala.

Among the man-made wetlands, the best one is the Keoladeo National Park of Bharatpur (Rajasthan) created about 250 years ago, by the then ruler of the State. It is a classic example of man-made conversion of natural rain-fed depression into a permanent waterfowl reserve by containing and regulating water column by means of various canals and sluice gates.

In addition the construction of several multipurpose projects in the states of Punjab, Haryana, Uttar Pradesh, Himachal Pradesh, Madhya Pradesh and other states has resulted in the formation of large reservoirs, creating man-made wetlands.

In general, wetland communities are highly dynamic as they are located at the interface of terrestrial and aquatic ecosystem. The species richness and so also Oxo diversity in such an area is quite high, as it offers a specialised habitat for many macrophytes, planktons, invertebrates and vertebrates.

The richness is mainly attributed to the “spatial heterogeneity, that is, the greater the number of niches, the greater is the opportunity for successful invasion by a species.”

The basic components of a wetland ecosystem are:

The water regime where the physical and chemical characteristic of water determine the nature of the wetland; the hydrological characters and water quality control the composition of the wetland communities; sediment and substrate which influence the ability of the vegetation to establish in such areas, and they serve to maintain a steady flow of nutrients and energy through the system; decomposers which release the nutrients required from the organic matter; and, finally, vegetation which support the major biota.

The species richness in macrophytes vegetation varies, depending on the period of Hooding. Area flooded for long periods have lower species diversity than less frequently flooded areas. In presence of high concentration of salts and sulfides in salt marsh water such as Pulicat lake, the species diversity is low but a definite zonation and distribution of vegetation is noticed.

In contrast, flowing water is considered to act as a stimulus to diversity, probably due to its ability to renew minerals and reduce anaerobic conditions

In the wetlands of Himalayas and Nilgiris, peat bogs are often formed. It has its own characterize flora and fauna. Peat is often characterised by grasses, sedges and mosses. Apart from richness am diversity of flora, the presence of large number of ‘wild’ relatives of cultivated plants for desirable character; make the wetland unique.

The common examples are ‘wild species’ of Oryza, Elettaria. Saccharum, Zinzibei Curcuma, Coffee, Cinnamomum and Dioscorea.

Due to presence of high amount of dissolved oxygen and nutrients, wetlands in general support a large invertebrate fauna, form a feeding ground for fishes and protect them from predators among submerged vegetation.

Wetlands vegetation also harbours several air-breathing snails such as Pila virens, Lymnaea sp., Indoplamorbis sp. and Bellamya sp. Due to the presence of gastropods and fishes the wetland habitat forms an excellent site for visit of both residential and migratory bird population.

Some wetlands of West Bengal, Assam and Bihar in India were surveyed in the past for limnological investigation.

Pathak (1989) made comparative studies of the limnological features of three beels (viz., Dhir beel of Assam, Kulia beel of West Bengal and Muktapur Mann of Bihar), in which he described the hydro chemical features, dynamics of chemical constituents and evaluation of productivity trends, nutrient cycles, organic bottom deposits, detritus energy, energy transformation and flow of energy in beels ecosystem.

He found that the bottom deposits of decaying weeds contribute very rich organic carbon 2.8 – 9.0%, nitrogen (605 – 988 ppm) and phosphorus (40 – 185 ppm) in all the beels studies. This rich nutrient status of the beels shows immense production potential. Vaas (1989) discussed the productivity status, physicochemical and biological factors of beels and their exploitation and productivity in West Bengal.

Babu Lai (1989) also studied the energy flow in Kulia beel ecosystem in West Bengal and found the beel heavily choked with luxuriant growth of the macrophytes (Eichhornia, Hydrilla, Ceratophyllum, Najas, Azolla etc.) and very low fixation of solar energy by the primary producers are found (2500 cal m² day¹) in the first year of the study.

But in the second and third years—after the removal of the macrophytes— energy fixation increased many times (photosynthetic efficiency increased from 0.12% at the beginning to ten-fold immediately after the removal of the macrophytes). This was due to sudden increase in phytoplankton bloom, when the chlorophyll concentration in the beel also increased.

Various types of limnological studies were also conducted in adjoining countries like Bangladesh. These studies include the following aspects:

(a) Limnology, pollution and phytoplankton of ponds, lakes, beels and rivers.

(b) Limnology, growth of benthic flora and fauna; 

(c) Limnology, water quality and primary productivity of a hypertrophic lake; 

(d) Limnology of fish ponds, zooplankton and other animals; 

(e) Limnology, macrophytes and algae of deep water rice-fields of Brahmaputra and Meghna floodplain

(f) Limnology, pollution and domestic, agricultural and industrial pollutants in the river system.

Wetland Loss:

Over the years, wetland loss is a global concern. The rate of wetland loss is mostly not quantified except a few countries, however, the causes of such losses were well-documented (Table 8.4). Over 90 wetlands of various countries were seriously threatened in Asia alone (Table 8.5). Thus there needs detailed conservation strategies for protection of such extinct habitats.

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