Biodiversity

What does mean by biodiversity?

Meaning: the diversity (number and variety of species) of plants and animals life within a region.

Diversity of living creatures forms a support system which has been used by each civilization for its growth and development. Biodiversity is part of nature which includes the differences in genes among the individuals, the variety and richness of all the plant and animal species at different scales, locality, region, country and world. We can also include various types of ecosystems; both terrestrial and aquatic, within a defined area because they have also their particular habitat for survive.

The number and variety of plants, animals and other organisms that exist is known as biodiversity. It is an essential components of nature which provides food, fuel, shelter, medicines and other resources  to mankind for their survivals. The richness of biodiversity depends on the climatic conditions and area of the region. Biodiversity is important in human managed as well as natural ecosystem.

Importance of biodiversity:          

1) Ecological stability – each species of biodiversity performs a particular function within an ecosystem.

Ecosystem provide support of production and services without which human could not survive. These include soil fertility, decomposition of wastes, purification of the air and water, stabilization and moderation of the climate, decrease of flooding, drought and other environmental disasters.

2) Economic benefits to humans - some of the important economic commodities that biodiversity supplies to humankind are:

Food: crops, forestry and fish

Medication: quinine (used to treat malaria) comes from the Amazonian tree Cinchona tree, digitalis from the Foxglove plant (used for chronic heart trouble), and morphine from the poppy plant (used for pain relief)

Industry: fiber for clothing, wood for shelter and warmth. Other industrial products are oils, rubber, perfumes, fragrances, paper, poisons and so on which we got from the plant species. Animals are also gives us wool, silk, leather, lubricants and also used some times as mode of transportation.

Tourism: biodiversity is a source of economical wealth for many areas, such as many parks and forests, where wild nature and animals are a source of beauty and joy for many people.              

• Maintenance of soil quality 
• Climate stabilization                
• Provision of food security
• Maintenance of air quality                           
• Crop production                            
• Decomposition of wastes
• Maintenance of water quality                   

Biological diversity deals with the degree of nature’s variety in the biosphere. This variety can be observed at three levels; the genetic variability within a species, the variety of species within a community, and the organization of species in an area into distinctive plant and animal communities.

1. Genetic diversity:  (for example, the difference between your genes and those of your friends) each member of any animal or plant species differs widely from other individuals in its genetic because of the genes.
2. Species diversity: (the difference between two species, such as a monarch butterfly and a goldenrod plant) the number of species of plants and animals that are present in a region constitutes its species diversity. This diversity is seen both in natural ecosystems and in agricultural ecosystems. Some areas are more rich in species than others. Natural undisturbed tropical forests have much greater species richness than plantations developed by the Forest Department for timber production.
3. Ecosystem diversity: (the range of different habitats and ecosystems, such as farmlands and forest) There are a large variety of different ecosystems on earth, which have their own complement of distinctive inter linked species based on the differences in the habitat. Ecosystem diversity can be described for a specific geographical region, or a political entity such as a country, a State or a Taluka.  

Value of Biodiversity

Biodiversity is most precious gift of nature with that humankind is blessed. The role of biodiversity in providing ecosystem service is two way: Firstly, biodiversity is directly used as a source for food, fiber, fuel and other resource. Secondly, biodiversity plays an important role in ecosystem providing the regulating, cultural and supporting services. Ex, vegetation protects the soil erosion by binding soil particles and minimizing the effects of water runoff. Biodiversity has fundamental value to humans because we are dependent on it for our cultural, economic and environmental well-being.

Environmental services from species and ecosystems are essential at global, regional and local levels. Like production of oxygen, reducing carbon dioxide, maintaining the water cycle, protecting soil is important services. Global warming is melting ice caps, resulting in a rise in the sea level which will submerge the low lying areas in the world. It is causing major atmospheric changes, leading to increased temperatures, serious droughts in some areas and unexpected floods in other areas. Biological diversity is also essential for preserving ecological processes, such as fixing and recycling of nutrients, soil formation, circulation and cleansing of air and water, maintaining stream and river flows throughout the year, erosion control and local flood reduction.                

Food, clothing, housing, energy, medicines, are all resources that are directly or indirectly linked to the biological variety present in the biosphere. Preservation of biological resources is essential for the long-term survival of mankind. This diversity of living organisms which is present in the wilderness, as well as in our crops and livestock, plays a major role in human ‘development’. The preservation of ‘biodiversity’ is therefore integral to any strategy that aims at improving the quality of human life.

Consumptive use value                                                                          

Consumptive use value means the direct utilization of timber, food, fuel wood, and fodder by local communities. So, goods that are consumed locally that are neither bought nor sold and therefore do not contribute to the economy of a country. This consumptive use value can also be seen in the use of fuel wood for heating and cooking. It is estimated that about 2.4 billion people use of fuelwood and other forms of biomass for cooking and heating.

 The biodiversity held in the ecosystem provides forest dwellers with all their daily needs, food, building material, fodder, medicines and a variety of other products. They know the qualities and different uses of wood from different species of trees, and collect a large number of local fruits, roots and plant material that they use as food, construction material or medicines. Fisherfolk are highly dependent on fish and know where and how to catch fish and other edible aquatic animals and plants.

             The Biodiversity of an area influences every aspect of the lives of people who inhabit it. Their living space and their livelihoods depend on the type of ecosystem. Even people living in urban areas are dependent on the ecological services provided by the wilderness. It is linked with every service that nature provides us. The quality of water we drink and use, the air we breathe, the soil on which our food grows are all influenced by a wide variety of living organisms both plants and animals and the ecosystem of which each species is linked with in nature.

Productive use value

Productive use value means for marketable goods, product is commercially sold in national and international market. Many industries are dependent upon these values. Ex, textile, leather, silk, paper and pulp industry etc.  

To the pharmacist, biological diversity is the raw material from which new drugs can be identified from plant or animal products. To industrialists, biodiversity is a rich store-house from which to develop new products. For the agricultural scientist the biodiversity in the wild relatives of crop plants is the basis for developing better crops.

Even today, species of plants and animals are being constantly discovered in the wild. Thus these wild species are the building blocks for the betterment of human life and their loss is a great economic loss to mankind. Preservation of biodiversity has now become essential for industrial growth and economic development. A variety of industries such as pharmaceuticals are highly dependent on identifying compounds of great economic value from the wide variety of wild species of plants located in undisturbed natural forests.

Social value

Traditional societies which had a small population and required less resource had preserved their biodiversity as a life supporting resource. Apart from the local use or sale of products of biodiversity there is the social aspect in which more and more resources are used by affluent societies. The biodiversity has to a great extent been preserved by traditional societies that valued it as a resource and appreciated that its depletion would be a great loss to their society. 

Many plants and animals are considered holy and sacred in India and are worshipped like Tulsi, peppal, cow, and snake. In Indian society great cultural value is given to forest and such as tiger, peacock and lotus is named as the national animal, bird and flower respectively.    

The consumptive and productive value of biodiversity is closely linked to social concerns in traditional communities. People value biodiversity as a part of their livelihood as well as through cultural and religious sentiments. A great variety of crops have been cultivated in traditional agricultural systems and this permitted a wide range of product to be grown and marketed throughout the year. In recent years farmers have begun to receive economic incentives to grow cash crops for national or international markets, rather than to supply local needs. This has resulted in local food shortages.

Ethical and moral values

Many traditional societies have played an important role in preserving their biodiversity. They value biodiversity as a part of their livelihood as well as through cultural and religious sentiments. Traditional agricultural societies have been growing a great variety of crops, which act as an insurance against the failure of one crop.

It is based on the ‘live and let other live’. Ethical values related to biodiversity conservation are based on the importance of protecting all forms of life. All forms of life have the right to exist on earth. Man is only a small part of the Earth’s great family of species. Morality and ethics reach us to preserve all forms of life and not to harm any organism unnecessarily. Some people take pleasure in hunting the animals. People also sometimes degrade and pollute the environment by their unethical actions.

 Apart from the economic importance of conserving biodiversity, there are several cultural, moral and ethical values which are associated with the sanctity of all forms of life. This has been an important part of the ancient philosophy of many of our cultures. We have in our country a large number of sacred groves preserved by tribal people in several States. These sacred groves around ancient sacred sites and temples act as gene banks of wild plants.

Aesthetic value

Biodiversity is a beautiful and wonderful aspect of nature. Like, sit in a forest and listen to the birds, watch a spider weave its complex web, observe a fish feeding; these all things are magnificent and fascinating. Quite apart from killing wildlife for food, it is important as a tourist attraction. Symbols from wild species such as the lion of Hinduism, the elephant of Buddhism and deities such as Lord Ganesh, and the vehicles of several deities that are animals, have been venerated for thousands of years. The ‘Tulsi’ has been placed at our doorsteps for centuries.

There is a great aesthetic value which is attached to biodiversity. Natural landscapes at undisturbed places are a delight to watch. People go far off places to enjoy the natural surroundings and wildlife. This type of tourism is referred to as ecotourism, which has now become a major source of income in many countries. In many societies, the diversity of flora and fauna has become a part of the traditions and culture of the region and has added to the aesthetic values of the place.

Option value

Keeping future possibilities open for their use is called option value. To continue to improve cultivars and domestic livestock, we need to return to wild relatives of crop plants and animals. Thus the preservation of biodiversity must also include traditionally used strains already in existence in crops and domestic animals.

These values include the unexplored or unknown potentials of biodiversity.  The most important benefits of biodiversity are maintenance of environment service which includes:

• Carbon dioxide fixation
• Maintaining water cycle and recharging of ground water
• Soil formation and protection from erosion
• Regulating climate by recycling moisture into the atmosphere
• Decomposition of waste

The potential of wild plants as medicinal source is an example of the option value. Many pharmaceuticals companies and government health agencies are intensively trying to discover new medical materials from biodiversity in its natural habitat in order to treat disease such as AIDS and cancer.

India as a mega diversity Nation

India is rich in biodiversity from north to south and from east to west. It has two global terrestrial biodiversity hot spot – the North-eastern States and the Western Ghats.  India is one of the 12 mega-diversity countries in the world. It host about 7% of global flora and 6.5% of fauna.

India’s special geographical position between three distinctive centers of biological evolution and radiation of species is responsible for our rich and varied biodiversity. Among the biologically rich nations, India stands among the top 10 or 15 countries for its great variety of plants and animals, many of which are not found elsewhere. India has 350 different mammals, 1,200 species of birds, 453 species of reptiles and 45,000 plant species. India has 50,000 known species of insects, including 13,000 butterflies and moths.

                It is estimated that 18% of Indian plants are endemic to the country. Apart from the high biodiversity of Indian wild plants and animals there is also a great diversity of cultivated crops and breeds of domestic livestock. This is a result of several thousand years during which civilizations have grown and flourished in the Indian subcontinent. There are too many varieties of vegetables, rice and fruit and so on are found. The highest diversity of cultivars is concentrated in the high rainfall areas of the Western Ghats, Eastern Ghats, Northern Himalayas and the North-Eastern hills.

                India has 27 indigenous breeds of cattle, 40 breeds of sheep, 22 breeds of goats and 8 breeds of buffaloes.

Threat to biodiversity

Threats to biodiversity come from many source, mostly humans as well as some natural ting also.  Historically, human have always taken what they needed from the earth itself and from its plant and animal species. Both plant and animal species are under threat of extinction primarily due to modification, degradation and loss of their habitats, causes by various developmental projects like industries, urban housing complexes, rail, road, and over exploitation, pollution and global warming. So it is now the prime responsibility of all scientists and technocrats to ensure that developmental activity promoted by them cause no loss to biodiversity of an area. 

Man has begun to overuse or misuse most of these natural ecosystems. Due to this ‘unsustainable’ resource use, once productive forests and grasslands have been turned into deserts and wasteland has increased all over the world. The current destruction of the remaining large areas of wilderness habitats, especially in the super diverse tropical forests is the most important threat worldwide to biodiversity.

Climate change – rising oceans temperatures and diminishing sea affects marine biodiversity and can shift vegetation zones, having global implications. The increase in CO2 in the air affects the physiological  functioning of plant, and other life. 

Deforestation and habitat loss – deforestation is direct cause of extinction and loss of biodiversity. An estimated 18 million acres of forest are lost each year, due in part to logging and other human practices, destroying the ecosystems on which many species depend. Habitat loss is one of the biggest threats to biodiversity. Clear cutting  forest to create fields, filling in wetlands to build houses, and creating dams that change river flow are all examples of habitat destruction. There are some basic reason for deforestation & habitat loss:

• agriculture, farming
• harvesting natural resources for personal use
• for industrial and urbanization development

Over exploitation – Over exploitation means harvesting species from the wild at rates faster than natural populations can recover.  Over-hunting, over fishing and over-harvesting contribute greatly to the loss of biodiversity, killing off numerous species over the past several hundred years. Human have to eat, but we have been taking fish for food faster than they can replenish their wild population.

Invasive species – the introduction of non-native species into an ecosystem can threaten endemic wildlife (either as predators or competing for resources), affect human health and upset economies.

Pollution – from the burning of fossil fuels (releasing dangerous chemicals to atmosphere and causes ozone levels) to dumping into the oceans every year, pollution completely disrupts the Earth’s ecosystem. 

Ecosystem

What does mean by ecosystem?

Meaning: the living community of plants and animals in any area together with the non-living components of the environment such as soil, air and water is called ecosystem.

Ecosystems have been formed on land and in the sea by evolution that has created species to live together in a specific region. Thus ecosystems have both non-living and living components that are typical to an area giving its own special characteristic that are easily observed. Natural ecosystem includes forests, grasslands, deserts, and aquatic ecosystem such as ponds, rivers, lakes and the sea. Man modified ecosystem includes agricultural land and urban or industrial land.

Ecosystem and man – every region of our earth has different ecosystem based on its climatic conditions and geographical feature. Ecosystems are divided into terrestrial or land based ecosystems and aquatic ecosystems in water. These form the two major habitat conditions for the Earth’s living organism. All the living organism in an area live in communities of plants and animals. They interact with their non-living environment and with each other at different points in time for a large number of reasons. Life can exist only in small proportion of the earth’s land, water and its atmosphere. Ecosystems are the basis of life itself: the natural ecosystems in the wilderness provide a variety of products without which human civilization would not be able to exist.

Producers, Consumers and Decomposers

Every living organism is in some way dependent on other organism. Plants are food for herbivorous animals that are in turn food for carnivorous animals. Thus there are different trophic levels in the ecosystem. Some organism such as fungi lives only on dead material and inorganic matter.

Plants are the ‘producers’ in the ecosystem as they manufacture their food by using energy from the sun. In the forest, these form communities of plant life.

The herbivorous animals are primary consumer as they live on the producers. In a forest, these are the insects, reptiles, and birds. The herbivorous animals include for example deer and elephants that live on plants life. They gaze on grass of feed on the foliage (trees leaves) from trees. In grass lands, there are herbivorous such as the blackbuck that feed on grass. In the sea, there are small fish that live on algae and other plants.

There are carnivorous animals, or secondary consumers, which live on herbivorous animals. In our forests, the carnivorous animals are tiger, leopards, foxes and small wild cats. In the sea, carnivorous fish live on other fish.

Decomposers are a group of organism consisting of small animals like worms, insects, bacteria and fungi, which break down dead organic material into smaller particles and finally into simpler substances that are used by plants as nutrition. Decomposition thus is a vital function in nature, as without this, all the nutrients would be tied up in dead matter and no new life could be produced.

Every ecosystem has several interrelated mechanisms that affect human life. These are the water cycle, the carbon cycle, the oxygen cycle, the nitrogen cycle and the energy cycle. While every ecosystem is controlled by these cycles, in each ecosystem its abiotic and biotic features are distinct from each other. All the functions of the ecosystem are in some way related to the growth and regeneration of its plant and animals species. These linked processes can be depicted as the various cycles. These processes depend on energy from sunlight. The water cycle depends on the rainfall, which is necessary for plants and animals to live. The energy cycles recycles nutrients into the soil on which plant life grows. Our own lives are closely linked to the proper functioning of these cycles of life. If human activities o on altering them, humanity cannot survive on the earth.

Food chains, Food webs and Ecological pyramids

            The transfer of energy from the source in plants through a series of organism by eating and being eaten constitutes food chains. These food chains are not isolated sequences, but are interconnected with each other. This interlocking pattern is known as the food webs. Each step of the food web is called a trophic level. Green plants occupy the first level, herbivorous the second level, and carnivorous the third level. This trophic level together forms the ecological pyramids.

Food chain: The most obvious aspect of nature is that energy must pass from one living organism to another. When herbivorous animals feed on plants, energy is transferred from plants to animals. In an ecosystem, some of the animals feed on other living organism, while some feed on dead organic matter. So, this is the connection of food. At each linkage in the chain, a major part of the energy from the food is lost for daily activities.

The food web: In an ecosystem there are very large numbers of interlinked chains. This forms food webs. If the linkages in the chains that make up the web of life are disrupted due to human activities that lead to the loss or extinction of species, the web breaks down.

The ecological pyramids: In an ecosystem, green plants-the producers are called ‘first trophic level’ of the food pyramids. The herbivorous animals that eat plants are ‘second trophic level’ and are also called primary consumers. The predators (carnivorous) that feed on them form the ‘third trophic level’ and are known as secondary consumers. This is how energy is used by living creatures and flows through the ecosystem from its base to the top. Much of the energy is used up in activities of each living organism.

Forest ecosystem

Forest is formed by a community of plants that is predominantly structurally defined by its trees, and shrubs. The landscapes that make up various types of forests look very different from each other. Their distinctive appearance is a fascinating aspect of nature. Each forest type forms a habitat for a specific community of animals that are adapted to live in it.

What is forest ecosystem?

As the plant and animals species are closely depend on each other, together they form different types of forest communities. Man is also part of this forest ecosystem and the local people depend directly on the forest for several natural resources that act as their life support systems. People who do not live in the forest buy forest products such as wood and paper, which has been extracted from the forest. Thus, they use forest product indirectly from the market.

The forest ecosystem has two parts:

      1.       The non-living or abiotic aspects of the forest

      2.       The living or the biotic aspects of the forest

Forest utilization: Natural forests provide local people with a variety of products if the forest is used carefully. Natural forest ecosystem plays an important role in controlling local climatic and water regimes, as well as preventing soil erosion.

Forest product:  Forest products that are collected by people include food such as fruit, roots, herbs and medical plants. Wood from different species of trees has special uses. These forest products are of great economic value as they are collected, sold and marketed. Forest dwellers and agricultural people use these goods directly. Other people get them indirectly from the market.

Forest services: Forest services include the control of the flow of water in stream and rivers. Forest also reduces runoff of rainwater and allows ground water to be stored. It also prevents erosion of soil. Once soil is lost by erosion, it can take thousands of years to reform. Forest regulates local temperature.

What are the threats to the forest ecosystem?

There are number of trees or plants which more sensitive species of forest and because of climatic changes it cannot survive. Overutilizing forest resources is an unsustainable way of misusing our limited forest resources. We are now creating more and more goods that are manufactured from raw material from the forest. This leads to forest degradation and finally changes the ecosystem into wasteland.    

The increasing use of wood for timber, wood pulp for paper and the extensive use of fuel wood results in continual forest loss. Forests are also lost by mining and building dams. As the forest resources are exploited beyond what they can produce with this also, the ecosystem is degraded and its wildlife is seriously threatened.

How can forest ecosystems be conserved?

• It can conserve only if its resources will use carefully.
• This can be done by using alternate sources of energy instead of fuelwood.
• There is a need to grow more trees than cut down from forests every year for timber.

Desert ecosystem

Desert and semi arid lands are highly specialized and sensitive ecosystem that is easily destroyed by human activities. The species of these dry areas can live only in this specialized habitat.

What is desert ecosystem?

Desert and semi arid areas are located in Western India. The climate in these vast tracts is extremely dry. The most typical desert landscape that is seen in Rajasthan is in the Thar Desert. This has sand dunes. There are also areas covered with spare grasses and a few shrubs, which grow if it rains.

Desert and semi arid regions have a number of highly specialized insects and reptiles. There are animals include the Indian Wolf, desert Cat, and desert Fox and birds such as the Great Indian Bustard.

The Great and Little Rann of Kutch are highly specialized arid ecosystem. The Great Rann is famous, as it is the only known breeding colony of the Greater and Lesser Flamingos in our country. The Little ran is only home of the wild ass in India.

How are desert and semi-arid ecosystems used?

Areas of scanty vegetation with semi-arid scrubland have been used for camel, cattle, sheep and goat grazing in Rajasthan and Gujarat. Areas that have a little moisture, such as along the watercourses, have been used for growing crops such as jowar, and bajra. The natural grasses and local varieties of crops have adapted to growing at very low moisture levels. These can be used for genetic engineering and developing arid land crops for the future.

What are the threats to desert ecosystem?

                Several types of development strategies as well as human population growth have begun to affect the natural ecosystem of the desert and semi arid land. Conversion of these lands through extensive irrigation systems has changed several of natural characteristics of this region. The region becomes highly unproductive as it becomes saline. Pulling excessive groundwater from tube wells lower the water table creating an even drier environment. Thus human activities destroy the naturalness of this unique ecosystem.

How can desert ecosystem be conserved?

Desert ecosystems are extremely sensitive. Their ecological balance that forms a habitat for their pants and animals is easily disrupted. The Indira Gandhi Canal in Rajasthan is destroying this important natural arid ecosystem, as it will convert the region into intensive agriculture. In Kutch, areas of the Little Rann which is only home of the Wild Ass, will be destroyed by the spread of salt works.

Aquatic ecosystem (Fresh water & Marine ecosystem)

The aquatic ecosystems constitute the marine environment of the seas and the fresh water systems in lakes, rivers and ponds. These ecosystems provide human beings with a wealth of natural resources. They provide goods that people collect for food such as fish and marine salt water. If aquatic ecosystems are misused or over utilized, their ability to provide resources suffers in the long term. Over-fishing leads to a fall in the fish catch. River courses that are changed by dams to provide electricity affect thousands of people who do not get a continuous supply of water downstream for their daily use. Water is an important factor in all our ecosystems. Several ecosystems exist in freshwater and marine salt water. There is very little fresh water on earth, which is a key resource for people all over the world.

What is an aquatic ecosystem?

In aquatic ecosystems, plants and animals live in water. These species are adapted to live in different types of aquatic habitats. Aquatic ecosystems may be classified as being stagnant ecosystems, or running water ecosystems. The special abiotic features are its physical aspects such as the quality of the water, which includes its clarity, salinity, oxygen content and rate of flow. The aquatic ecosystems are also classified into freshwater, brackish and marine ecosystems, which are based on the salinity levels.

The fresh water ecosystems that have running water are streams and rivers. Ponds and lakes are ecosystems where water does not flow. Marine ecosystems are highly saline, while brackish areas have less saline water such as in river deltas. Brackish water ecosystems in river deltas are covered by mangrove forests and are among the world’s most productive ecosystems in terms of biomass production.

Pond & Lake ecosystem: Pond is temporary and has water only in the monsoon but lakes are seen throughout the year. When a pond begins to fill during the rains, its life forms such as the algae and microscopic animals, aquatic insects, snails and worms. After that a large number of food chains are formed. Algae are eaten by eaten by small fish on which larger carnivorous fish depend. These are in turn eaten by birds such as kingfisher, herons. Aquatic insects, worms and snails feed on the waste material by the dead or decaying plant. A lake ecosystem functions like a giant permanent pond. A large amount of its plant material is the algae, which derives energy from the sun. This is transferred to the microscopic animals, which feed on the algae. There are fish that are herbivorous and are dependent on algae and aquatic weeds. The small animals such as snails are used as food by small carnivorous fish, which in turn are eaten by larger carnivorous fish.

Stream and River ecosystems: Streams and rivers are flowing water ecosystems in which all the living forms are specially adapted to different rates of flow. The community of flora and fauna of stream and river depend on the clarity, flow and oxygen content. The stream and river have their different plants and animals. As deforestation occurs in the hills the water in the streams that once flowed throughout the year become seasonal. This leads to flash floods in the rains and a shortage of water once the streams dry up after the monsoon.

Marine ecosystems: In the coastal area the sea is shallow while further away, it is deep. Both these are different ecosystems. There are many different types of coastal ecosystems which are highly dependent on the tide. The marine ecosystem is used by coastal fisherfolk for fishing which forms their livelihood. In the past, fishing was done at a sustainable level. The marine ecosystem continued to maintain its abundant supply of fish over many generations.

Now with intensive fishing by using giant nets and mechanized boats, fish catch in the Indian Ocean has dropped significantly. Several different species of fish are caught by fishermen. In many areas the fish catch has decreased during the last decade.

How are aquatic ecosystem used?

Man uses aquatic ecosystems for the clean freshwater on which his life is completely dependent. We need clean water to drink and for other domestic uses. Water is essential for agriculture. Fisherfolk use the aquatic ecosystems to earn a livelihood. People catch fish and crabs. They also collect edible plants. This is used locally as food or for sale in the market. Over fishing leads to a serious decline in the catch and a long-term loss of income for fisherfolk. Modern man impounds water in dams to be able to store it throughout the year. Agriculture and industry are highly dependent on large quantities of water. Dams are built across rivers to generate electricity. A large proportion of this energy is used by urban people, by agriculturists in irrigated farmlands and in enormous quantities for industry.

What are the threats to aquatic ecosystems?

Water pollution occurs from sewage and poorly managed solid waste in urban areas when it enters the aquatic ecosystem of lakes and rivers, which destroy life in the water. In rural areas the excessive use of fertilizers and pesticides increase nutrients but kills aquatic and pollute water.

How can aquatic ecosystems be conserved?

For sustainable use of an aquatic ecosystem, water pollution must be prevented. Changing the nature of the aquatic ecosystem from a flowing water ecosystem to a static ecosystem destroys its natural biological diversity. Thus dams across rivers decrease the population of species that require running water, while favoring those that need standing water.