• located where river meets the sea.
  • the most productive water bodies in the world
  • The complete salinity range from 0-35 ppt is seen from the head (river end) to the mouth (sea end) of an estuary
  • Coastal lakes which have their connection with the sea through small openings are better known as lagoons or backwaters acting as a natural water filter


Estuary Formation:

grouped into four geomorphic categories based on the physical processes responsible for their formation:

1) rising sea level; (2) movement of sand and sandbars; (3) glacial processes; and (4) tectonic processes.

India Estuarine Ecosystem

The Country has 14 major, 44 medium and 162 minor rivers drains into the sea through various estuaries.

Major estuaries occur in the Bay of Bengal.

Most of the India’s major estuaries occur on the east coast. In contrast, the estuaries on the west coast are smaller.



are the characteristic littoral plant formation of tropical and subtropical sheltered coastlines.

are trees and bushes growing below the high water level of spring tides which exhibits remarkable capacity for salt water tolerance.

basically evergreen land plants growing on sheltered shores, typically on tidal flats, deltas, estuaries, bays, creeks and the barrier islands. require high solar radiation and have the ability to absorb fresh water from saline/ brackish water. produces pneumatophores (blind roots) to overcome respiration problem in the anaerobic soil conditions

  • Leaves are thick and contain salt secreting glands.
  • exhibit viviparity mode of reproduction. i.e. SeedS germinate in the tree itself (before falling to the ground). This is an adaptative medianiSintoovercome the problem of germination in Saline water.
  • crystals of salt on the back of the leaves; others block absorption of salt at their roots

The mangroves of Sundarbans are the largest single block of tidal holophytic mangroves of the world. famous for the Royal Bengal Tiger and crocodiles.

The mangroves of Bhitarkanika (Orissa), which is the second largest in the Indian sub continent, harbour high concentration of typical mangrove species and high genetic diversity have (additional) special roots such as prop roots, pneumatophores  which help to impede water flow and thereby enhance the deposition of sediment in areas (where it is already occurring), stabilize the coastal shores, provide breeding ground for fishes. protects coastal lands from tsunami, hurricanes:and floods release oxygen back to the atmosphere, along with a little methane gas



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




  1. Coastal Ocean Monitoring and Prediction System (COMAPS)
  • Being implemented from 1991. Assesses the health of coastal waters and facilitates management of pollution-related issues
  • Programme was restructured and modified in 2000 2001 to include pollution monitoring; liaison, regulation and legislation; and consultancy services.

2.Land Ocean Interactions in the Coastal Zone (LOICZ)


  • Launched in 1995. Investigates the effects of global change on the coastal zone
  • Aims to develop, on a scientific basis, the integrated management of coastal environments
  1. Integrated Coastal and Marine Area Management (ICMAM)
  • Launched in 1998
  • Aims at integrated management of coastal and marine areas.
  • Model plans for Chennai, Goa and Gulf of Kutch being prepared
  1. Society of  Integrated Coastal Management (SICOM)
  • Launched in 2010
  • Major national initiative to protect coastal ecosystems
  • A professional body with experts in various aspects of coastal science and management
  1. Institutions for Coastal Management
  • The Notification on Coastal Regulation Zone (CRZ), 1991 (as amended from time to time) aims at protecting coastal stretches in India.
  • India has created institutional mechanisms such as National Coastal Zone Management
  • Authority (NCZMA) and State Coastal Zone Management Authority (SCZMA) for enforcement and monitoring of the CRZ Notification.
  • These authorities have been delegated powers under Section 5 of the Environmental (Protection) Act, 1986 to take various measures for protecting and improving the quality-of the coastal environment and preventing, abating  and controlling environmental pollution in coastal areas.


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