Category: Biology

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Biomagnification Definition and its Effects

Food chains are components of all ecosystems. Producers and consumers form trophic levels in a chain through which energy flow is carried out by the process of eating and being eaten. Usage, storage and transformation of food and biomolecules by metabolism are a normal process. Degradation or breakdown is an essential part of any food chain and hence all naturally occurring substances are degradable.

Biomagnifiation of DDT

When non-degradable substances enter the food chain, they do not get metabolized or broken down or expelled and instead get transferred up the tropic levels of the food chain. During this process, they show an increase in concentration which is referred to as biomagnification.

This results in increased toxicity and may even be lethal. This phenomenon is well established for mercury and DDT. Fig 12.4 schematically shows biomagnifiation of DDT in an aquatic food chain where the concentration of DDT is enhanced at successive trophic levels.

Biomagnification is the method of accruing toxic elements by different organisms within a food chain. A prominent example of it is the presence of mercury within predatory fish. This level is so high that consuming these can cause cancer.

What are the substances responsible for biomagnification. Biomagnification refers to the accumulation of toxic substances in the food chain. The pesticides and chemicals such as DDT, and mercury released into the lakes and rivers are ingested by the aquatic organisms.

Bioaccumulation refers to the accumulation of a toxic chemical in the tissue of a particular organism. Biomagnification refers to the increased concentration of a toxic chemical the higher an animal is on the food chain.

Biomagnification is the accumulation of a chemical by an organism from water and food exposure that results in a concentration that is greater than would have resulted from water exposure only and thus greater than expected from equilibrium.

Biomagnification is the increase of harmful substances or chemicals in the normal food chain process. It is bad because many living things die due increase in harmful chemicals.

Biomagnification can occur in both terrestrial and aquatic environments, but it is generally used in relation to aquatic situations. Most often, biomagnification occurs in the higher trophic levels of the food chain/web , where exposure to chemicals takes place mostly through food consumption rather than water uptake.

Bioaccumulation is when a harmful substance (pesticides or organic chemicals) gets absorbed by an organism at a higher rate than it can be excreted. Even if the environment doesn’t have a high amount of toxin in it, accumulation through the food chain can be devastating for organisms.

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An Overview of Agrochemicals

Chemicals which are used in agriculture for growth of plants and pest control are called agrochemicals or agrichemicals. Overuse of agrochemicals have been observed to generate residues that cause nutrient imbalance. In addition,

1. May kill beneficial bacteria and soil organisms.
2. Can cause eutrophication in water bodies.
3. Affect aquatic animals and their productivity.
4. Pesticide containing water, even in trace quantities is unfi for human consumption.
5. Particles (aerosols) and residues of these chemicals cause air pollution.
6. Inhalation of contaminated air can cause respiratory problems.
7. Consumption can lead to poisoning, side effects and after effects.
8. Chemicals can cause skin rashes and irritation of eyes.
9. Many of these chemicals are reported to be carcinogenic.
10. They can trigger hormonal disorders and neurotoxicity.
11. Beneficial insects and animals can be affected.

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Noise Pollution | Definition, Examples, Effects and its Causes

Sound that is unwanted and undesirable or can disrupts one’s quality of life is called as Noise. When there is lot of ‘noise’ in the environment, it is termed as Noise Pollution. The intensity of noise is meaured in decibels (dB).

Sources of Noise Pollution

Vehicle engines, air horns, audio video systems, trains, low flying aircrafts, factory machines, sirens, motors, drillers and crushers, compressor machines, crackers, explosives, modern supersonic transports are the common sources of noise pollution.

The threshold of pain is about 120 db. World Health Organization has proposed that noise must be recognized as a major threat to human well-being. This is applicable for all living organisms.

Effect of Noise Pollution

• According to the USEPA (United States Environmental Protection Agency) there are direct links between noise and health.
• Heart disease, high blood pressure, stress related illness, sleep disruption, hearing loss (deafness), and productivity loss are the problems related to noise pollution.
• Increased stress and tension, nervousness, irritability, anxiety, depression and panic attacks.
• Peptic ulcer, severe head ache, memory loss.
• Marine animals are affected by noise pollution from offshore activities and port activities.
• Fire crackers frighten animals. Birds are often affected by increased air traffic.

Control

• Planting trees in and around noise sources is an effective solution for noise pollution as plants are known to absorb noise and bring down sound levels.
• Regular servicing and tuning of automobile engines can effectively reduce noise pollution by vehicles and machinery.
• Workers should be provided with ear plugs and earmuffs at work sites that generate high noise levels.
• Lubrication of machinery and regular servicing minimizes noise levels.
• Regulations should be imposed to restrict the usage of loudspeakers in crowded areas and public places.

Legal Protection

Article 48-A and Article 51-A of the Constitution of India, Noise Pollution (Regulation and Control) Rules 2000, and Tamil Nadu State Environment Policy 2017 are some of the legal relief from noise pollution.

According to Noise Pollution (Regulation and Control) Rules, 2000, the permissible limit of noise in areas categorized as commercial is 65 decibels (dB) during day and 55 dB during night.

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Water Pollution | Definition, Causes, Effects and Solutions

Quality of Water

Water is essential for life and for the health of the environment. As a valuable natural resource, it comprises marine, estuarine, freshwater (river and lakes) and groundwater environments that stretch across coastal and inland areas.

Water has two dimensions that are closely linked: quantity and quality. Water quality is commonly defined by its physical, chemical, biological and aesthetic (appearance and smell) characteristics. A healthy environment is one in which the water quality supports a rich and varied community of organisms and protects public health.

Water Pollution

Water pollution occurs when there is a change in the chemical, physical or biological quality of water that has harmful effect(s) on living organisms that consume it or live in it. Water pollution adversely affects water bodies due to the large amounts of natural or man-made materials let into it. When it becomes unfit for its intended use, water is considered polluted.

Sources of Water Pollution

Even though water bodies or sources can be polluted by natural causes, water pollution is usually caused by human activities. There are three main types of sources: point sources, non-point sources, leaks and spills.

Point sources:

Discharge of pollutants at specific locations through pipelines or sewers into the water body. Factory effluents, sewage, underground mines, oil wells, oil tankers and agriculture are common point sources (Fig. 12.2 a).

Non-point sources:

Sources that cannot be traced to a single site of discharge like acid rain, dumping of the plastics in water bodies, agriculture chemical run off are common examples (Fig. 12.2 b).

Leaks and Spills:

This occurs mostly due to ship collision, off shore oil rigs, oil leakages and discharges into sea (Fig. 12.2 c).

Sources of water pollution can also be classified in three ways. They are municipal wastes, industrial wastes, and agricultural wastes.

1. Municipal waste water is from homes and commercial establishments.

2. Industrial discharge (effluents) may contain varieties of compounds such as heavy metals (cadmium, chromium, lead), and organic / inorganic chemicals containing waste water, sometimes in toxic concentrations. These discharges can affect temperatures of the water bodies as well as dissolved oxygen level.

3. Agricultural wastes include fertiliser and pesticide runof from agricultural fields, food processing waste, tree and saw dust from logging operations and bacteria from sewage or livestock operations. Water pollutants reach water bodies like rivers, streams and the marine system by precipitation, run-of and the groundwater by seepage or percolation.

Effect of Water pollution on Ecosystems

1. Destruction of ecosystems:

Ecosystems, especially aquatic systems, can be severely affected or destroyed by water pollution. Water pollutants affect existing niches and habitats and the survival of organisms. Soil fertility is affected and the system becomes uninhabitable.

2. Disruption of food-chains:

Water pollution disrupts the natural food chains as well as food webs. Pollutants such as lead and cadmium are taken up by primary consumers where they can be lethal or get stored. Later, when these animals are consumed by secondary consumers, the food chain can get disrupted at any trophic level or result in enhanced concentration of these pollutants (biomagnifiation). Hot water from industries when released into the water bodies affects aquatic density and diversity.

Effect of Water pollution on Organisms

1. Water pollution can be lethal to aquatic organisms and others that depend on these water bodies.

Accidental oil spills from tanker ships can cause substantial environmental damage. Oil spreads on the water surface, prevents the entry of light and oxygen into the water. This increases BOD and COD, resulting in mass death of organisms and degradation of water quality. It also clogs fish gills and the feathers of aquatic birds.

2. Humans and other organisms can get affected by diseases such as hepatitis and typhoid by consuming contaminated water and food. Excess of fluoride in drinking water causes fluorosis. In many poor nations, outbreak of water borne diseases and epidemics are a result of contaminated water and poor or absence of water treatment processes.

3. Water pollution can cause eutrophication due to nutrient enrichment. This causes algal blooms which affect the quality of water bodies (Fig. 12.3). Red tides, if occur, can be lethal to aquatic organisms.

Control Measures

1. Right to clean water is a fundamental right under the Indian Constitution (Article 21).

2. Water (Prevention and Control of Pollution) Act, 1974, sections 17 to 40 prohibit the pollution of a stream or well by disposal of polluting matter.

3. The Central/State Pollution Control Boards have the power to advise the central/state government on various matters concerned with the prevention and control of pollution of water.

4. The Ministry of Environment, Forest and Climate Change (MoEFCC) is the nodal agency of the Central Government for the planning, promotion, co-ordination and for overseeing the implementation of India’s environmental and forestry policies and programmes.

5. National river conservation plan (NRCP) was enacted in 1995 to improve the water quality of the rivers, which are the major fresh water resources in our country. This important assignment taken up under the NRCP includes, To capture the raw sewage flowing into the river through open drains and divert them for treatment.

Setting up sewage treatment plants for treating the diverted sewage. Construction of low cost sanitation toilets to prevent open defecation on river banks.

Prevention

• Regulate or control of pollutant(s) discharge at the point of generation.
• Wastewater can be pretreated by scientific methods before discharge to municipal treatment sources.
• Setting up of Sewage Treatment Plants (STP) and Effluent Treatment Plants (ETP).
• Regulate or restrict the use of synthetic fertilisers and pesticides.
• Public awareness and peoples’ involvement is essential.

Case study

Namami Gange (National Mission for Clean Ganga) Programme is an Integrated Conservation Mission approved as the ‘Flagship Programme’ of the Union Government in June 2014 with a budget outlay of 20,000 crores to accomplish the twin objectives of effective abatement of pollution, conservation and rejuvenation of River Ganga.

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Environmental Pollution Overview and its Defnition

Pollution is any undesirable change in the physical, chemical and biological characteristics of the environment due to natural causes and human activities. The agents which cause pollution are called pollutants. Pollution is classified according to the types of environment that is affected. They are mainly air, water and soil pollution.

Classification of Pollutants

In terms of eco-system, pollutants can be classified into two basic groups – Nondegradable and degradable. Based on the time taken to breakdown into their ingredients, degradable pollutants are classified as rapidly degradable (non-persistent) and slowly degradable (persistent).

(a) Rapidly degradable or non-persistent pollutants:

These can be broken down by natural processes. Domestic sewage and vegetable waste are examples of such pollutants.

(b) Slowly degradable or persistent pollutants:

These are pollutants that remain in the environment for many years in an unchanged condition and take decades or longer to degrade, as in the case of DDT.

(c) Non-degradable pollutants:

These cannot be degraded by natural processes. Once they are released into the environment, they are difficult to be eliminated and continue to accumulate (biomagnifiation). Toxic elements like lead, mercury, cadmium, chromium and nickel are such common pollutants.

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Biodiversity And Its Conservation

The natural resources of the Earth, including air, water, land, flora and fauna of natural ecosystems must be safeguarded for the benefit of the present and future generations through careful planning and management, as appropriate – Principle of the Stockholm Declaration, 1972. The large-scale loss of biodiversity and its global impact makes conservation the need of the hour.

Conservation of biodiversity is protection and scientific management of biodiversity so as to maintain it at its optimum level and derive sustainable benefits for the present as well as future generations. It aims to protect species from extinction and their habitats and ecosystems from degradation.

General strategies in conservation

• Identify and protect all threatened species
• Identify and conserve in protected areas the wild relatives of all the economically important organisms.
• Identify and protect critical habitats for feeding, breeding, nursing, resting of each species
• Resting, feeding and breeding places of the organisms should be identified and protected
• Air, water and soil should be conserved on priority basis
• Wildlife Protection Act should be implemented

There are two aspects of conservation strategies (Table 11.4).

1. In-situ conservation
2. Ex-situ conservation

In-situ Conservation (Conservation in the natural habitat)

This is the conservation of genetic resources through their protection within a natural or manmade ecosystem in which they occur. It is conservation and protection of the whole ecosystem and its biodiversity at all levels in order to protect the threatened species.

Maximum protection of biodiversity hotspots regions with very high levels of species richness. Although all the biodiversity hotspots together cover less than 2 percent of the earth land area, the number of species they harbour is extremely high and protection of these hotspots could reduce the ongoing mass.

Protected Areas

These are biogeographical areas where biological diversity along with natural and cultural resources is protected, maintained and managed through legal measures. protected areas include national parks, wild life sanctuaries, community reserves and biosphere reserves.

World Conservation monitoring centre has recognized 37,000 protected areas world-wide. India has about 771 protected areas covering 162099 km² comprising of National Parks (104), Wild Life Sanctuaries (544), biosphere reserves (18) and several sacred groves.

National Parks (NP)

It is a natural habitat that is notified by the state government to be constituted as a National Park due to its ecological, faunal, floral, geomorphological, or zoological association of importance. No human activity is permitted inside the national park except the activities permitted by the Chief Wildlife Warden of the state under the conditions given in CHAPTER IV, of the Wildlife Protection Act (WPA) 1972 (Table 11.2).

National Parks in Tamil Nadu

There are 104 existing national parks in India covering an area of 40, 501 km², which is 1.23% of the geographical area of the country (National Wildlife Database, Aug. 2018). National Park is an area which is strictly reserved for the betterment of wildlife and biodiversity and where activities like development, forestry, poaching, hunting, grazing and cultivation are not permitted.

They are large areas of scenic and national beauty maintained for scientific educational and recreational use. They are not used for commercial extraction of resources. Kaziranga National park is a protected area for the one Horned Rhinoceros in Assam.

Wild Life Sanctuaries (WLS)

Any area other than the area comprised with any reserve forest or the territorial waters can be notified by the State Government to constitute as a sanctuary if such area is of adequate ecological, faunal, floral, geomorphological, natural or zoological signifiance. This is for the purpose of protecting, endangered factual species. Some restricted human activities are allowed inside the Sanctuary area details of which are given in CHAPTER IV, of the Wildlife Protection Act (WPA) 1972. Ecoturism is permitted, as long as animal life is undistrubed.

There are 544 existing wildlife sanctuaries in India covering an area of 118,918 km², which is 3.62 % of the geographical area of the country (National Wildlife Database, 2017).

Sanctuaries are tracts of land where wild animals and fauna can take refuge without being hunted or poached. Other activities like collection of forest products, regulated harvesting of timber, private ownership of land are permitted. Periyar wild life sanctuary in Kerala is famous for the Indian Tiger and Asiatic Elephant (Table 11.3).

Wild life sanctuaries in Tamil Nadu

Biosphere Reserve (BR):

Biosphere Reserve (BR) is an international designation by UNESCO for representative parts of natural and cultural landscapes extending over large area of terrestrial or coastal / marine ecosystems or a combination thereof BRs are designated to deal with the conservation of biodiversity, economic and social development and maintenance of associated cultural values.

Biosphere Reserves are thus special environments for both people and nature and are living examples of how human beings and nature can co-exist while respecting each other’s needs. The Biosphere Reserve Programme is guided by UNESCO’s Man and Biosphere (MAB) programme, as India is a signatory to the landscape approach supported by MAB programme.

The scheme called Biosphere Reserve was implemented by the Government of India in 1986. There are 18 Biosphere Reserves in the country Agasthyamalai (Karnataka – Tamil Nadu Kerala), Nilgiri (Tamil Nadu – Kerala), Gulf of Mannar (Tamil Nadu) are the BRs notified in Tamil Nadu.

Sacred Groves

A sacred grove or sacred woods are any grove of trees that are of special religious importance to a particular culture. Sacred groves feature in various cultures throughout the world.

Ex-Situ Conservation

It is conservation of selected rare plants / animals in places outside their natural homes. It includes offite collections and gene banks.

Offsite Collections

They are live collections of wild and domesticated species in Botanical gardens, Zoological parks, Wildlife safari parks, Arborata (gardens with trees and shrubs). The organisms are well maintained for captive breeding programmes.

As a result, many animals which have become extinct in the world continue to be maintained in Zoological Parks. As the number increases in captive breeding, the individuals are selectively released in the wild. In this way the Indian crocodile and gangetic dolphin have been saved from extinction.

Gene Banks

Gene banks are a type of biorepository which preserve genetic materials. Seeds of different genetic strains of commercially important plants can be stored in long periods in seed banks, gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques.

However, it is not economically feasible to conserve all biological wealth and all the ecosystems. The number of species required to be saved from extinction far exceeds the conservation efforts.

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IUCN Definition | Red Data Book

The International Union for Conservation of Nature (IUCN) is an organization working in the field of nature conservation and sustainable use of natural resources. It was established in 1948 and located at Gland VD, Switzerland. It is involved in data gathering and analysis research, field projects and education on conservation, sustainable development and biodiversity.

IUCN’s mission is to influence, encourage and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable. It influences governments and industries through partnerships by providing information and advice. The organization collects, compiles and publishes the IUCN red list of threatened species and their conservation status in the world. It plays a vital role in the implementation of several international conventions on nature conservation and biodiversity.

Red Data Book

Red Data book or Red list is a catalogue of taxa facing risk of extinction. IUCN – International Union of Conservation of Nature and Natural Resources, which is renamed as WCU – World Conservation Union (Morges Switzerland) maintains the Red Data book. The concept of Red list was mooted in 1963. The purpose of preparation of Red List are:

• To create awareness on the degree of threat to biodiversity
• Identification and documentation of species at high risk of extinction
• Provide global index on declining biodiversity
• Preparing conservation priorities and help in conservation of action
• Information on international agreements on conservation of biological diversity

Red list has eight categories of species

• Extinct
• Extinct in wild
• Critically Endangered
• Endangered
• Vulnerable
• Lower risk
• Data deficiency
• Not evaluated.

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Causes of Biodiversity Loss

The major causes for biodiversity decline are:

• Habitat loss, fragmentation and destruction (affects about 73% of all species)
• Pollution and pollutants (smog, pesticides, herbicides, oil slicks, GHGs)
• Climate change
• Introduction of alien/exotic species
• Over exploitation of resources (poaching, indiscriminate cutting of trees, over fishing, hunting, mining)
• Intensive agriculture and aquacultural practices
• Hybridization between native and nonnative species and loss of native species
• Natural disasters (Tsunami, forest fire, earth quake, volcanoes)
• Industrialization, Urbanization, infrastructure development, Transport – Road and Shipping activity, communication towers, dam construction, unregulated tourism and monoculture are common area of specific threats.
• Co-extinction

Habitat Loss

Development of human society is inevitable. Natural habitats are destroyed for the purpose of settlement, agriculture, mining, industries and construction of highways. As a result species are forced to adapt to the changes in the environment or move to other places. If not, they become victim to predation, starvation, disease and eventually die or results in human animal conflict.

Over population, urbanization, industrialization and agricultural advancements require additional land, water and raw materials every year. This is made possible only through fragmentation or destruction of natural habitats by filling wetlands, ploughing grasslands, cutting down trees, forest, desilting rivers, constructing transport ways, caving mountains, extracting, ores, changing the course of rivers and filling
of seashore.

The most dramatic example of habitat loss comes from the tropical rainforests 14% of the earth’s land surface once covered by these tropical forests, is not more than 6% now. The Amazon rainforest, a vast area, harbouring millions of species, also called “Lungs of the planet” is destroyed and being replaced for agriculture and human settlements.

90% of New Zealand’s wetlands have been destroyed and cleared for cultivating soya beans and raising grass for beef cattle. Kodaikanal and Nilgiri hills of Tamil Nadu have been destroyed rapidly for human occupancy. Loss of habitat results in annihilation of plants, microorganisms and forcing out animals from their habitats.

Habitat fragmentation

Habitat fragmentation is the process where a large, continuous area of habitat is both, reduced in area and divided into two or more fragments. Fragmentation of habitats like forest land into crop lands, orchard lands, plantations, urban areas, industrial estates, transport and transit systems has resulted in the destruction of complex interactions amongst species, (food chain and webs) destruction of species in the cleared regions, annihilation of species restricted to these habitats (endemic) and decreased biodiversity in the habitat fragments.

Animals requiring large territories such as mammals and birds are severely affected. The elephant corridors and migratory routes are highly vulnerable. The dwindling of many well-known birds (sparrows) and animals can be attributed to this.

Over exploitation:

We depend on nature for our basic needs such as food and shelter. However, when the need becomes greed, it leads to over exploitation of natural resources. Excessive exploitation of a species, reduces the size of its population to such a level that it becomes vulnerable to extinction. Dodo, passenger pigeon and Steller’s sea cow have become extinct in the last 200-300 years due to over exploitation by humans. Overfishing due to population pressure leads to many marine fish (populations) declining around the world.

Exotic species invasion:

Exotic species (non-native; alien) are organisms oftn introduced unintentionally or deliberately for commercial purpose, as biological control agents and other uses. They often become invasive and drive away the local species and is considered as the second major cause for extinction of species. Exotic species have proved harmful to both aquatic and terrestrial ecosystems.

Tilapia fish (Jilabi kendai) (Oreochromis mosambicus) introduced from east coast of South Africa in 1952 for its high productivity into Kerala’s inland waters, became invasive, due to which the native species such as Puntius dubius and Labeo kontius face local extinction.

The introduction of the Nile Perch, a predatory fish into Lake Victoria in East Africa led to the extinction of an ecologically unique assemblage of more than 200 nature species of cichlid fish in the lake.

Papaya Mealy Bug (Paracoccus marginatus) is native of Mexico and Central America, is believed to have destroyed huge crops of papaya in Assam, West Bengal and TamilNadu.

Global Climate changes

Industrialization is a major contributor to climate change and a major threat to biodiversity. Energy drives our industries, which is provided by burning of fossil fuels.

This increases the emission of CO₂, a GHG, leading to climate change. Due to large scale deforestation, the emitted CO₂ cannot be absorbed fully, and its concentration in the air increases. Climate change increases land and ocean temperature, changes precipitation patterns and raises the sea level.

This inturn results in melting of glaciers, water inundation, less predictability of weather patterns, extreme weather conditions, outbreak of squalor diseases, migration of animals and loss of trees in forest. Thus, climate change is an imminent danger to the existing biodiversity (Fig. 11.4).

Shiftng or Jhum cultivation (Slash-and-burn agriculture)

In shifting cultivation, plots of natural tree vegetation are burnt away and the cleared patches are farmed for 2-3 seasons, after which their fertility reduces to a point where crop production is no longer profitable. The farmer then abandons this patch and cuts down a new patch of forest trees elsewhere for crop production.

This system is practiced in north-eastern regions of India. When vast areas are cleared and burnt, it results in loss of forest cover, pollution and discharge of CO₂ which in turn attributes to loss of habitat and climate change which has an impact on the faunal diversity of that regions.

Coextinctions

Coextinction of a species is the loss of a species as a consequence of the extinction of another. (Eg., orchid bees and forest trees by cross pollination). Extinction of one will automatically cause extinction of the other. Another example for co-extinction is the connection between Calvaria tree and the extinct bird of Mauritius Island, the Dodo. The Calvaria tree is dependent on the Dodo bird for completion of its life cycle.

The mutualistic association is that the tough horny endocarp of the seeds of Calvaria tree are made permeable by the actions of the large stones in bird’s gizzard and digestive juices thereby facilitating easier germination. The extinction of the Dodo bird led to the imminent danger of the Calvaria tree coextinction.

Intensive agriculture

Spread of agriculture is sometimes at the cost of wetlands, grasslands and forests. Intensive agriculture is based on a few high yielding varieties. As a result, there is reduction in the genetic diversity. It also increases vulnerability of the crop plants to sudden attack by pathogens and pests. There are only few varieties of traditional paddy strains today due to use to hybrid varieties in Tamil Nadu.

Loss of biodiversity

Species have been evolving and dying out (extinction) ever since the origin of life. However, species are now becoming extinct at a faster rate. This is destabilizing the ecological stability and the distribution of biological diversity on earth. Human activities greatly contribute to the loss of biodiversity. Natural resources such as land, water and organisms are indiscriminately exploited by human beings.

According to the Convention of Biological Diversity, direct and indirect human activities have a detrimental effect on biodiversity. Direct human activities like change in local land use, species introduction or removal, harvesting, pollution and climate change contribute a greater pressure on loss of biodiversity. Indirect human drivers include demographic, economic, technological, cultural and religious factors.

Even though new species are being discovered, there is little hope for adding new species through speciation into the biodiversity treasure. Monsoon failure, global warming, depletion in ozone layer, landslides in hilly states, pollution are a few indirect effects of human activities which results in the loss biodiversity. IUCN Red List (2004) documents the extinction of 784 species in the 500 years.

It is estimated that the current rate of biodiversity loss is 100 to 1000 times higher than the naturally occurring extinction rate and is still expected to grow in the future. This loss of biodiversity has a immense impact on plant animal and human life. The negative effects include dramatic influence on the food web.

Even reduction in one species can adversely affect the entire food chain which further leads to an overall reduction in biodiversity. Reduced biodiversity leads to immediate danger for food security by reducing ecosystem services.

Hotspots

Hotspots are areas characterized with high concentration of endemic species experiencing unusual rapid rate of habitat modification loss. Norman Myers defied hot spots as “regions that harbour a great diversity of endemic species and at the same time, have been significantly impacted and altered by human activities.”

A hotspot is a region that supports at least 1500 endemic vascular plant species (0.5% of the global total) has lost more than 70% of its original vegetation. There are 35 biodiversity hotspots in the world. India is home to four biodiversity hotspots (as per ENVIS). They are

• Himalaya (the entire Indian Himalayan region)
• Western Ghats
• Indo-Burma: includes entire North-eastern India, except Assam and Andaman group of Islands (and Myanmar, Thiland, Vietnam, Laos, Cambodia and Southern China)
• Sundalands: includes Nicobar group of Islands (and Indonesia, Malaysia, Singapore, Brunei, Philippines)

Endangered organisms

A species that has been categorized as very likely to become extinct is an Endangered species. Endangered (EN), as categorized by the International Union for Conservation of Nature (IUCN) Red List, is the second most severe conservation status for wild populations in the IUCN’s scheme aftr Critically Endangered (CR).

In 1998 there were1102 animal and 1197 plant species in the IUCN Red List. In 2012, the list features 3079 animal and 2655 plant species as endangered (EN) worldwide.

Extinction

Species is considered extinct when none of its members are alive anywhere in the world. If individuals of a species remain alive only in captivity or other human controlled conditions, the species is said to be extinct in the wild. In both of these situations, the species would be considered globally extinct. A species in considered to be locally extinct when it is no longer found in an area it once inhabited but is still found elsewhere in the wild.

In the 450 million years of life on Earth, there had been 5 mass extinctions, which had eliminated at least 50% of the species of flora and fauna on the globe. The extinction of species is mainly due to drastic environmental changes and population characteristics.

There are three types of Extinctions

(i) Natural extinction:

Is a slow process of replacement of existing species with better adapted species due to changes in environmental conditions, evolutionary changes, predators and diseases. A small population can get extinct sooner than the large population due to inbreeding depression (less adaptivity and variation).

(ii) Mass extinction:

The earth has experienced quite a few mass extinctions due to environmental catastrophes. A mass extinction occurred about 225 million years ago during the Permian, where 90% of shallow water marine invertebrates disappeared.

(iii) Anthropogenic extinctions:

These are abetted by human activities like hunting, habitat destruction, over exploitation, urbanization and industrialization. Some examples of extinctions are Dodo of Mauritius and Steller’s sea cow of Russia.

Amphibians seem to be at higher risk of extinction because of habitat destruction. The most serious aspect of the loss of biodiversity is the extinction of species. The unique information contained in its genetic material (DNA) and the niche it possesses are lost forever.

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Threats To Biodiversity

Even though India is one of the 17 identified mega diverse countries of the world, it faces lots of threats to its biodiversity. Apart from natural causes, human activities, both directly and indirectly are today’s main reason for habitat loss and biodiversity loss.

Fragmentation and degradation due to agricultural practices, extraction (mining, fishing, logging, harvesting) and development (settlements, industrial and associated infrastructures) leads to habitat loss and fragmentation leads to formation of isolated, small and scattered populations and as endangered species.

Some of the other threats include specialised diet, specialized habitat requirement, large size, small population size, limited geographic distribution and high economic or commercial value. Large mammals by virtue of their size require larger areas to obtain the necessities of life – food, cover, mates than do smaller mammals. Individual home range of Lion can be about 100 square Km.

Mammals have specialized dietary needs such as carnivores, frugivores and the need to forage over much larger areas than general dietary herbivores and omnivores. Mammals also have low reproductive output other than small rodents.

Five main threats to biodiversity are commonly recognized in the programmes of work of the Convention: invasive alien species, climate change, nutrient loading and pollution, habitat change, and overexploitation.

The core threats to biodiversity are human population growth and unsustainable resource use. To date, the most significant causes of extinctions are habitat loss, introduction of exotic species, and overharvesting.
Climate change is predicted to be a significant cause of extinctions in the coming century.

Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play. A larger number of plant species means a greater variety of crops. Greater species diversity ensures natural sustainability for all life forms.

Climate change, deforestation and loss of habitat and pollution are one of the factors affecting biological diversity. The greatest factor would be climate change wherein animals and other species fail to adapt in changing climate thus resulting to their death.

Biodiversity is an abbreviation for biological diversity. It generally means the ‘diversity of flora and fauna (plants and animals)’ (IB definition). It has three factors, ecosystem, species and genetics.

Biodiversity loss is caused by five primary drivers: habitat loss, invasive species, overexploitation (extreme hunting and fishing pressure), pollution, climate change associated with global warming.

The main threats facing biodiversity globally are: destruction, degradation and fragmentation of habitats reduction of individual survival and reproductive rates through exploitation, pollution and introduction of alien species.

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Biogeographical Regions of India

As per the international ‘biome’ type of classification based upon climate, fauna and flora and the soil conditions, India can be divided into ten different biogeographic zones, (Fig. 11.3 and table 11.1) namely:

Biogeographic classification of India is the division of India according to biogeographic characteristics. Biogeography is the study of the distribution of species (biology), organisms, and ecosystems in geographic space and through geological time. There are ten biogeographic zones in India.

Biogeographic regions are geographical areas that are defined based on the species found in them, which provides invaluable information to ecologists and natural resources managers for understanding large scale processes that affect species and ecosystems.

India is known for its rich heritage of biological diversity, having already documented more than 91,000 species of animals and 45,500 species of plants in its 10 biogeographical regions. Almost 6,500 native plants are still widely used in indigenous health care systems.

The country’s diverse physical features and climatic conditions have resulted in a variety of ecosystems such as forests, wetlands, grasslands, desert, coastal and marine ecosystems which harbour and sustain high biodiversity and contribute to human well-being.

India is one of the eight Vavilov’s centers of origin of cultivated plants in the world and has twenty distinct agro-ecosystems, characterized by variations in edaphic, climatic and geographic features, and consequently a diverse cropping pattern.