Coral Reefs in Andaman and Nicobar

Andaman and Nicobar Islands lie in the azure waters of Bay of Bengal. These twin islands offer you natural and immaculate beauty that was shrouded from the nature lovers for a long time. Here, special mention should be made to the unique coral reefs of these islands. Coral reefs in Andaman and Nicobar are of the fringing sort. They are often many hundred meters broad and alienated from the shore by a lagoon of analogous breadth. A barrier reef to the west has been reported as well but its accurate coordinates are still unknown. The coral diversity until a few years back was one of the highest in Indian reefs. Freshly, a great number of documented and illustrated new records have also been made; increasing the entire coral species numbers. The account below throws more light on coral reefs in Andaman and Nicobar Islands.

Coral Reef Zonation in Andaman and Nicobar

Fringing reefs have distinctive zones. They are reef crest, reef flat and reef slope. The reef flat stretches out towards the sea and has a gentle slope so that it materializes nearly level. At the seaward boundary, it suddenly drops down to structure reef slope. The narrow area just between the Profile of a Fringing Reef to reef flat and the reef slope is known as reef crest or reef edge. The reef flat habitually gets uncovered during low tide but reef slope is always underwater. Corals found on reef crests and reef flats are mostly boulder-shaped whereas those on reef slopes exhibit a multiplicity of growth forms.

Coral Diversity in Andaman and Nicobar

Andaman and Nicobar are the richest in coral diversity of the Indian region. They have 179 species belonging to 61 genera. The widespread genera contributing to the reef formation are Montipora, Acropora, Pocillopora, Goniopora, Porites, Heliopora, Favia, Fungia, Millcpora etc.

• A distinguished trait of these islands is the plenty of non- Soft coral (Sarcophyton sp.) soft (scleractinian) corals at definite localities. Some vital soft coral species are Lobophytum sp., Sarcophyton sp. and Sinularia sp.
• Table Coral is Aeropora sp. It forms flat steps and tables.
• Boulder shaped Corals are ordinary corals seen on reef flats. Some significant boulder corals are-
  1. Pore Coral (Porites sp.) has extremely little polyps and can develop into big colonies on upper slope and reef edge.
  2. Larger star coral (Favites abdita) looks just like an asymmetrical shaped colony having adjoining huge polyps sharing common walls.
  3. Lesser star coral (Goniastrea retiformis) has tiny polygonal polyps.
  4. Knob Coral (Favia speciosa) has separate rounded polyps having its own distinctive low walls.
  5. Valley coral (Platygyra sp.) holds individual polyps assimilating to allocate common wavy stretched out walls with the mouth located in a solitary row within the valleys.

Extensive and unrestrained deforestation in the hills, leading to huge siltation of the coastal waters is a severe constraint to the continued existence of corals. Two sections of the Andaman reefs have been declared as Marine National Parks (Mahatma Gandhi National Marine Park and Rani Jhansi National Marine Park) and benefit from protection. The Great Nicobar Island has been stated as a Biosphere Reserve. Several islands here are enveloped by reef fringes, habitually numerous hundred meters broad and separated from the shore by a lagoon of smooth breadth. Precipitously sloping reef- walls and coral knolls and pinnacles are also found.