BIODIVERSITY: Threats and Conservation

 

Introduction

• The term “Biodiversity” is a concise form of “Biological Diversity” and was coined by Walter G. Rosen in 1986.
• The variety and variability of organisms around us, is referred to as “Biodiversity”.
• It is the variability among living organisms from all sources including terrestrial, marine, freshwater, desert ecosystem around the ecological complex of which they are a part. This includes diversity within species, between species and of ecosystem. Thus, biodiversity encompasses the whole range of mammals, birds, amphibians, reptiles, fishes, fishes, insects, worms, protozoans, plants, fungi, algae, micro-organisms (bacteria, viruses). The range and number of there organisms vary in different ecosystem and climatic condition. Rich biodiversity is the indicator of balance ecosystem.
• According to reports of IUCN, 1980, the earth support 13-14 million species of plants and animals of which 1.75 million species have been described which is result of 3 billion years of evolution involving mutation, recombination and natural selection.

Threats of Biodiversity

• Biodiversity is a source of significant, economic aesthetic health and cultural, benefits. It forms the foundation of sustainable development. There is a general scientific consequences that the world is becoming loss. Biologically diverse in terms of genes, species and ecosystem.
• Rapid loss of biodiversity causes a global threat to human well being. The scale of human impact on biological diversity is increasing rapidly the cause of Worldwide patterns of consumption, production and trades.
• Besides, agricultural, industrial settlement, development and population growth adversely effect the biodiversity.
• Land degradation is linked to biodiversity at ecosystem level where it decreases the productivity of the habitat, increase soil erosion and sedimentation of aquatic ecosystem. Such consequences increase the flood and drought and enhances the desertification. It causes the habitat loss leading to species extinction as well as invasion of exotic species that are able to compete better endemic species. 
• Wide spread deforestation reduces local, regional and global species diversity and also causes climatic change and enhances green house effect. There will be species migration to higher latitude and altitude. As a result of warming particularly in mountain.
• Pollution from organic and inorganic wastes can be transported across natural boundaries and effect fisheries as well as other freshwater biodiversity due to biomagnification and bioaccumulation of non-degradable pollutant.
• Large number of species gradually disappear due to catastrophe geological time scale. For example- extinction of dinosaur, cretaceous and tertiary period.
• Habitat loss leads to the fragmentation of continuous stretches of land and consequently fragments the wild life population in habituating them. These small population are increasingly vulnerable to inbreeding depression and extinction, not only that, it also leads to primary food species for wildlife, decline in food species of wildlife.
• Poaching is another threat of extinction of species.
• Over exploitation of natural resources, fishing, catching of animal species are serious threat to biodiversity.
• Disturbance in migratory root of several fishes (Hilsa due to siltation and construction of dam), the migratory fish are unable to reach their spawning grounds and face extinction.
• IUCN has recognized eight red list categories of species like (i) extinct in wild, (ii) critically endangered, (iii) endangered, (iv) vulnerable, (v) lower risk, (vi) data deficient, (vii) not evaluated, extinct.
• IUCN red list is a catalogue of those taxes which are facing the risk of extinction. The uses of red list are as follows-
• To develop awareness about the importance of threatened biological diversity.
• Identification and documentation of endangered species.
• Providing global index of decline of biodiversity.
• Definitely conservation priorities at the local level and guiding conservation action.

Conservation of Biodiversity

• The Ministry of Environment and forests (MoEF) is the main agency in the Government of India for planning, promotion, coordination and overseeing the implementation of the environmental and forestry programs. The mandates of MoEF included survey of flora, fauna, forests and wildlife, conservation of natural resources.
• These are two basic strategies of biodiversity conservation-

1.       In-situ (on site)

2.       Ex-situ (off site)

1. In-situ conservation (within natural habitat)

This includes protection of a group of typical ecosystems through a network of protected areas, i.e., conservation in natural habitat. It includes biosphere reserve, national park and wildlife sanctuaries.

-          Protected areas:-

• The areas of land or sea, specially for protection and maintenance of biodiversity and of natural and associated cultural resources. These areas are managed through legal or effective means.
• World Conservation Monitoring center (WCMC) has recognized 37,000 protected areas around the world.
• In India, approximately 4.7% of the total geographical area of the country has been earmarked for extensive in-situ conservation of habitats and ecosystems. A protected area network of 89 national parks and 492 wildlife sanctuaries has been created (MoEF,2002).  

                               List of some major National Parks of India

S.No.	Name	State	Established	Area (in km2)
1.	Corbett	Uttaranchal	1921	1318.5
2.	Dudhwa	Uttar Pradesh	1977	490.29
3.	Gir	Gujrat	1965	258.71
4.	Kanha	Madhya Pradesh	1955	940
5.	Kaziranga	Assam	1974	471.71

 

* Jim Corbett National Park, Nainital, Uttaranchal is the first National park in India.

- Biosphere Reserve program:-

• Biosphere reserves are a special category of protected areas of land or coastal environments, wherein people are an integral component of the system.
• A terrestrial biosphere reserve consists of core, buffer and transition zones.
• The natural or core zone comprises an undisturbed and legally protected ecosystem.
• The buffer zone surrounds the core area, and is managed to accommodate a grater variety of resources use strategies and research and educational activities.
• The transition zone, the outermost part of the biosphere reserve. This is an area of active cooperation between reserve management and the local people, wherein activities like settlements, cropping, forestry, recreation and other economic uses continue in harmony with people and conservation goals. 
  

                                         List of some major Biosphere Reserves of India

S.No	Name	State	Established	Area (in km2)
1.	Nanda Devi	Uttaranchal	1982	5,860.69
2.	Manas	Assam	1990	2837
3.	Gulf of mannar	Tamil Nadu	1980	10,500
4.	Great nicobar	Andaman & Nicobar Islands	1989	885
5.	Panchmarhi	Madhya Pradesh	1999	4,926.28

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        Sacred forests or groves and sacred lakes:-

• Sacred grooves is another aspect of biodiversity protection controlled by local habitats.
• In India and other Asian countries, a traditional strategy for the protection of biodiversity has been in practice in the form of sacred groves. These forest patches of varying dimensions are protected by local people due to their religious sanctity.

 2. Ex- situ conservation (outside natural habitats)

This includes protection of plants, animals in outside their natural habitat for medicinal or other purposes, i.e., it includes seed bank, botanical gardens, zoological gardens, aquarium etc.

-          Seed-gene banks

It make the easiest way to store germplasm of wild and cultivated plants at low temperature.

-          Cryopreservation  

This type of in-vitro conservation is done in liquid nitrogen at a temperature of -196°C. This is particularly useful for conserving vegetative propagated crops, e.g., potato.

-          Botanical gardens

An scheme entitled “Assistance to Botanic Gardens” provides one-time assistance to botanic gardens to strengthen and institute measure for ex-situ conservation of threatened and endangered plant species in their respective regions.

-          Zoological parks

In India, there are 275 Zoos, deer parks, safari parks, aquaria, etc. A central ‘Zoo Authority’ was set up to secure better management of Zoos.     

 

 

  

  

Origin of Lake and Thermal Stratification of Lake

Introduction

Lakes

·         Lakes are naturally formed large, deep inland standing water on the surface of the earth. They may range in depth and size.

·         ‘Ford’ define lakes as a body of standing water occupying a distinct basin and lacking continuity with sea.

·         Muttouskii (1918) refers to lake as a standing water body of large expends and deep enough to stratify thermally.

·         Belch (1952), regards all large bodies of standing water as lakes.

  Thermal Stratification

·         Differences in temperature of at different depths in deep lakes are called thermal stratification.

 

Origin of Lakes

Lakes arises in many ways. Naturally lakes are of diverse lake origin. The chief mode of lake formation as follows:

1.       Glacial action-

Glaciers form basin of lakes by substrate excavation and appropriate basin will form. Example- Lakes of Pongong Valley in Kashmir.

North America lakes will form by glacial erosion and deposition. Glacier aberration of slopes in high mountain valley form the basin of lake which later on filled with rain water and melting snow to produce a mountain lake. Besides valley, glaciers left behind a crested shaped ridges of rock debris which form a barrier of water behind them. Lakes are also formed by the deposition of morans and debris. So, as to form a closed basin. Example- Wular lake, Dul lake and Anchor lake of Kashmir and Kumao hills.

 

2.        Land slide-

It also creates lake. Land slide generally obstruct valley and forming natural dams and thereby creates lake basin. Most of the Kumao lakes are created due to land slides.

 

3.       Volcanic action-

Craters of extinct volcanoes filled with water and land slide that block the streams and valleys to form a lake known as crater lakes.

 

4.       Dissolution of substratum rocks-

Dissolution of underlying rocks with subsequent sinking creates a basin which, when filled with water are called dissolution lakes. The Nainital lake which has its outlet over solid limestone may have been produced by the collapse of the surface caused by the removal of lime stone due to solvent action of underground water. Many small lakes in the limestone tracks of the Khasi and Jaintia hills of Assam are believed to be dissolution lakes.

 

5.       Crustal movement of earth-

Movement of the earth crust such as up wrapping form dam or down wrapping form basin. Lakes having such basin are called tectonic lakes.

 

6.       Wind action-

In arid zone, the movement of sand particles and fine loose material may form a lake basin. The removal of soil and sand form an area that may leave behind a depression which form a lake basin. The salt lake of Rajasthan known as Shambhar lake, form due to wind action. The source of water in these lands due to inland drainage.

 

7.       River meanderings-

Various activities of river such as channel producing Oxbow lake, obstruction at mouth of tributaries forming lakes in lower ridges of Ganga and the Brahmaputra are certain common lakes. Further man- made lakes are formed by the construction of urban dam across the river and stream exclusively for irrigation and water storage for fisheries purpose. Naturally formed lakes constitute a great potential of fishing resource in India. Natural lakes are estimated to have about 2.92 million hectare in the country. 

  

  

Thermal stratification of lake

• Lake stratification is separation of lakes into three layers:

-          Epilimnion: the top of the lake

-          Metalimnion: the middle layer, which may change depth throughout the day

-          Hypolimnion: the bottom layer

• The thermal stratification of lakes refers to a change in the water temperature at different depths in the lake, and is due to change in water’s density with temperature.
• Cold water is denser than warm water and the epilimnion generally consists of water that is not as dense as the water in the hypolimnion. However, the temperature of maximum density for freshwater is 4°C.
• In temperate regions where lake water warms up and cools through the seasons, a cyclical pattern of overturn occurs that is repeated from year to year as the cold dense water at the top of the lake sinks. For example, in dimictic lakes, the lake water turns over during the spring and the fall. This process occurs more slowly in deeper water and as a result, a thermal bar may form. If stratification of water lasts for extended periods, the lake is meromictic.
• Photosynthetic biological activity tends to deplete the epilimnion of nutrients; while breakdown of detritus in the hypolimnion depletes it of oxygen.
• On cooling in the autumn, the temperature of the epilimnion falls to that of the hypolimnion. At this point, the water is the same density throughout and wind-induced vertical mixing is possible, a process is called turnover. This facilitates the oxygenation of the deeper parts of the lake, while bringing nutrients to the upper waters.
• In the winter, stratification may also occur with water at less that 4°C floating on water at 4°C in the depths.
• If the water freezes, the lower density of ice ensures that it does so from the top down. The insulting properties of the ice layer retard cooling so inhibiting the complete solidification of the lake.
• In the spring, the upper layers warm until the waters of the lake are all at the same temperature and density, therefore turnover can once again occur. Continued warming of the upper layers leads to the reintroduction of the summer stratification.
• In contrast, lakes in the polar and subpolar regions that are frozen for most of the year do not show stratification in the summer, but exhibit turnover for the duration of this season.
• Stratification occurs in tropical and subtropical lakes, in comparison with temperate lakes, the temperature of the waters of the epilimnion and hypolimnion is higher, while the temperature difference between these strata is less marked. Turnover on cooling is relatively easily induced in these warm water lakes.
• As a result, those in subtropical zones tend to have a winter circulation period, while those n tropical climates with little seasonality may either turnover frequently or have rare or irregular periods of turnover.
• Thermal stratification in lake influence the vertical profile of other physico-chemical parameter like DO₂  ( Clinograde condition), free CO₂, pH, bicarbonate and nutrients.

Typical thermal stratification of a lake into three strata