Coral is actually a living animal.

has a symbiotic relationship (each gives something to the other and gets something back in return) With ‘zooxanthellae’ microscopic algae which live on coral [i.e. instead of living on the sea  floor, the algae lives up on the coral which is closer to the ocean surface and so that the algae gets lots of light.

The tissues of corals themselves are actually not the beautiful colors of the coral reef, but are instead clear (white). The corals receive their  coloration from the zooxanthellae living within their tissues.

• There are two types of corals: hard corals and soft corals, such as sea fans and gorgonians. Only hard corals build reefs.
• The builders of coral reefs are tiny animals called polyps. As these polyps thrive, grew, then die, they leave their limestone (calcium carbonate) skeletons behind. The limestone is colonized by new polyps.
• found in tropical and sub-tropical water, there are also deep water corals in colder regions
• The United Nations Environment Programme reports that there are more cold water coral reefs worldwide than tropical reefs.
• There are only about 6 different coral species associated in building with these reefs.
• The largest cold-water coral reef is the Rost ‘Reef off Norway occur in shallow tropical areas where the sea water is clean, clear and warm.
• one of the most productive and complex coastal ecosystems with high biological diversity classified depending on their locations into fringing, patch, barrier and atoll.
• The fringing reefs are contiguous with the shore and they are the most common – by occurring reef form, found in Andamans.
• Patch reefs are isolated and discontinuous patches, lying shoreward of offshore reef structures as seen in the Palk bay, Gulf of Mannar and Gulf of Katchchh.
• Barrier reefs are linear offshore reef structures that run parallel to coastlines and arise from submerged shelf platforms. The water body between the reef and the shore is termed as lagoon. Barrier reefs are seen in Nicobar and Lakshadweep.
• Atolls are circular or semi-circular reefs that arise from subsiding sea floor platforms as coral reef building keeps ahead of subsidence. The examples are the atolls of Lakshadweep and Nicobar.
• Among the four major reef areas of India, Andaman and Nicobar Islands are found to be very rich in species diversity followed by the Lakshadweep Islands, the Gulf of Mannar and finally the Gulf of Kachchh.

Coral Bleaching

Bleaching, or the paling of coral colour occurs; when (i) the densities of zooxanthellae decline and (ii) the concentration of photosynthetic pigments within the zooxanthellae fall.

Ecological causes of coral bleaching

• Temperature (Major Cause)
• Sub aerial Exposure-Sudden exposure of reef flat corals to the atmosphere during events such as extreme low tides, ENSO-related sea level drops or tectonic uplift can potentially induce bleaching.
• Sedimentation
• Fresh Water Dilution
• Inorganic Nutrients(e.g. ammonia and nitrate)
• Xenobiotics -Zooxanthellae loss occurs during exposure of coral to elevated concentrations of various chemical contaminants, such as Cu, herbicides and oil.
• Epizootics

Biosphere is a part of the earth where life can exist.

represents a highly integrated and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land) Life in the biosphere is abundant between 200 metres (660 feet) below the surface of the ocean and about 6,000 metres (20,000 feet) above sea level. absent at extremes of the North and South poles. Living organisms are not uniformly distributed  throughout the biosphere

• It is the long term change in the statistical distribution of weather patterns over periods of time
• Though it has been happening naturally for millions of years, in recent years it has accelerated due to anthropogenic causes and has been causing global warming.
• UNFCCC defines climate change as – “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”

BT Brinjal

• In 2006, Maharashtra Hybird Seeds Company submitted biosafety and efficacy data to the GEAC and applied for permission to conduct large-scale trials
• At the same time SC imposed a ban on the on-going field trials
• An expert committee was constituted by GEAC to look into the concerns raised by several civil society actors
• SC later lifted the ban on field trials
• After a series of reviews the environment ministry declared a moratorium on Bt Brinjal in Feb 2010

Risk assessment

• Civil society has demanded that the science of risk assessment be made rigourous, independent and peer-reviewed

Fresh water ecosystems- The salt content of fresh bodies is very low, always less than 5 ppt  (parts per thousand). E.g lakes, ponds, pools, springs, streams, and rivers

Marine ecosystems – the water bodies containing salt concentration equal to or above that of sea water (i.e., 35 ppt or above). E.g shallow seas and open ocean   Brackish water ecosystems- these water bodies have salt content in between 5 to 35 ppt. e.g. estuaries, salt marshes, mangrove swamps and forests.

AQUATIC ORGANISMS

The aquatic organisms are classified on the basis Of their one of occurrence and their ability to cross these zones. can be classified on the basis of their life form or location into five groups

1. Neuston:

These are unattached organisms which live at the air-water interface such as floating plants, etc.

Some organisms spend most of their lives on top of the air-water interface such as water striders, while others spend most of their time just beneath the air-water interface and obtain most of their food within the water.

E.g., beetles and back-swimmers.

2. Periphyton:

These are organisms which remain attached to stems and leaves of rooted plants or substances emerging above the bottom mud such as sessile algae and their associated group of animals.

3. Plankton

This group includes both microscopic plants like algae (phytoplankton) and

animals like crustaceans and protozoans (zooplankton) found in all aquatic

ecosysteins, except certain swift moving waters

The locomotory power of the planktons is limited so that their distribution is

controlled, largely, by currents in the aquatic ecosystems.

4. Nekton:

This group contains animals which are  swimmers.

The nektons are relatively large and powerful as they have to overcome the water currents.

5. Benthos:

The benthic organisms are those found living in the bottom of the water mass.

Practically every aquatic ecosystem contains well developed benthos

Factors Limiting the Productivity of Aquatic Habitats

1. Sunlight :

Sunlight penetration rapidly diminishes as it passes down the column of water.

The depth to which light penetrates a lake determines the extent of plant distribution.

Based on light penetration and plant distribution they are classified as photic and aphotic zones

Photic zone:

It is the upper layer of the aquatic ecosystems, up to which light penetrates and within which photosynthetic activity is confined.

The depth of this zone depends on the transparency of water.

photic (or .”euphotic”) zone is the lighted and usually well-mixed portion that extends from the lake surface down to where the light level is 1% of that at the surface.

Aphotic zone:

The lower layers of the aquatic ecosystems, where light penetration and plant growth are restricted forms the aphotic zone.

Only respiration activity takes place.(photic-both respiration and photosynthesis take place )

Aphotic zone is positioned below the littoral and photic zones to bottom of the lake where light levels are too low for photosynthesis.

This deep, unlit region is also known as the profundal zone.

Dissolved oxygen:

Oxygen enters the aquatic ecosystem through the air water interface and by the photosynthetic. average concentration of dissolved oxygen as 10 parts per million by weight.

Dissolved oxygen escapes the water body through air-water interface and through respiration of organisms (fish, decomposers, zooplanktons, etc )

The amount of dissolved oxygen retained in water is also influenced by temperature.

Other limiting factors which influence on aquatic productivity are

Transparency:

Transparency affects the extent of light penetration.

Suspended particulate matters such as clay, silt, phytoplankton, etc make the water turbidity. Consequently it limits the extent of light penetration and the photosynthetic activity in a significant way.

Temperature:

The water temperature changes less rapidly than the temperature of air because water has a considerably higher specific heat than air.

Since water temperatures are less subject to change, the aquatic organisms have narrow temperature tolerance limit.

The components of the ecosystem is categorised into abiotic of non-living and biotic of living components. Both the components of ecosystem and environment are same.

1. Abiotic Components

the inorganic and non-living parts of the world.  consists of soil, water, air, and light energy etc.  involves a ,large number of chemicals like oxygen, nitrogen-, etc. and physical processes including volcanoes, earthquakes, floods, forest fires, climates, and weather conditions.

Abiotic factors are the most important determinants of where and how well an organism exists in its environment. Although these factors interact with each other, one single factor can-limit the range of an organism.

1. a) Energy

Energy from the sun is essential for maintenance of life. Energy determines the distribution of organisms in  the environment.

1. b) Rainfall
2. c) Temperature :-Temperature is a critical factor of the environment which greatly influences survival of organisms. Organisms can tolerate only a certain range of temperature and humidity.
3. d) Atmosphere :It is made up of 21% oxygen, 78% nitrogen , 0.038% carbon dioxide and other inert gases  (0.93% Argon, Neon etc).
4. e) Substratum :Land is covered by soil and a wide variety of microbes, protozoa, fungi and small animals (invertebrates) thrive in it
5. f) Materials:

(i) Organic compound

Such as proteins, carbohydrates,  lipids,  humic  substances are formed from inorganic compound on decomposition.

(ii) Inorganic compound

Such as carbon,   carbon dioxide, water, sulphur, nitrates, phosphates, and ions of various metals are essential for organisms to survive.

1. g) Latitude and altitude

Latitude has a strong influence on an area’s temperature, resulting in change of climates such as polar, tropical, and temperate. These climates determine different natural biomes. From sea level to highest peaks, wild life is influenced by altitude. As the altitude increases, the air becomes colder and drier, affecting wild life accordingly.( wild life decrease as altitude increase)

2. Biotic Components :Biotic components include living organisms comprising plants, animals and microbes and are classified according to their functional attributes into producers and consumers.

Primary producers – Autotrophs (self-nourishing) Primary producers are basically green plants (and certain bacteria and algae). They synthesise carbohydrate from simple inorganic raw materials like carbon dioxide and water in the presence of sunlight by the process of photosynthesis for themselves, and supply indirectly to other non- producers.

In terrestrial ecosystem, producers are basically herbaceous and woody plants, while in aquatic ecosystem producers are various species of microscopic algae.

1. b) Consumers — Heterotrophs or phagotrophs (other nourishing)

Consumers are incapable of producing their own food (photosynthesis).

They depend on organic food derived from plants, animals or both.

Consumers can be divided into two broad  groups

(i) Macro consumers- They feed on plants or animals or both and are categorised on the basis of their food sources.

Herbivores are primary consumers which feed mainly on plants e.g. cow, rabbit.

Secondary consumers feed on primary consumers e.g. wolves.

Carnivores which feed on secondary consumers are called tertiary consumers e.g. lions which can eat wolves.

Omnivores are organisms which consume both plants and animals e.g. man.

(ii) Micro consumers – Saprotrophs (decomposers or osmotrophs)

They are bacteria and fungi which obtain energy and nutrients by decomposing dead organic substances (detritus) of plant and animal origin.

The products of decomposition such as inorganic nutrients which are released in the ecosystem are reused by producers and thus recycled.

Earthworm and certain soil organisms (such as nematodes, and arthropods) are detritus feeders and help in the decomposition of organic matter and are called detrivores.