Department of Environment, Climate Change and Forest - Tamil Nadu State Wetland Authority
Tamil Nadu Wetlands Mission


Gulf of Mannar Biosphere Reserve (GoMBR), extends between Toothukudi and Ramanathapuram districts. It is located in the southeastern coastline of India, and is a unique marine environment rich in biodiversity. The GoMBR came into existence on 18th February 1989, by a joint declaration of the Government of India and the Government of Tamil Nadu. The same has been recognized by the Man and Biosphere (MAB) Programme of UNESCO.

GoMBR is one of the most biologically diverse regions in India, comprising 117 species of corals, 450 species of fishes, 4 species of sea turtles, 38 species of crabs, 2 species of lobsters, 12 species of sea grasses, 147 species of marine algae, 160 species of birds, 641 species of crustaceans, 108 species of sponges, 731 species of molluscs, 99 species of echinoderms, 4 species of sea horses, 12 species of sea snakes, besides 11 species of mangroves. The Reserve is also home to several globally important and highly threatened species like the Dugong, whale shark, sea horses, Balanoglossus, green sea turtle, Hawksbill turtle, dolphins, sacred chanks etc. The region has a recorded history of over 2000 years of settled agriculture, well established human-made tanks and supportive water bodies.
Seagrasses provide immense indirect ecosystem services to commercially important fishes and macroinvertebrates by acting as nesting and nursery grounds. Abundance of fish larvae in the seagrass bed, reported at 198 individuals/100 m2, was higher than the open sandy areas, with 112 individuals/100m2 in GoMNP in 2008. The region has a high potential for eco-tourism, as the MNP is situated between Rameswaram and Tuticorin, with rich coral reefs and seagrass. It also acts as an educational site, where researchers, bird watchers have studied the area for years.
The soil is typical coastal sand, strewn with shingles, and there are swamps in areas of Van Island, Kasuwari Island, Poomarichan Island, Pullivasal Island, Krusadai and Shingle islands. Quick sand is seen in parts of Mulli and Krusadai Island. Mangrove soils are slightly acidic. Anaerobic condition in the soils helps sulphate-reducing bacteria to produce hydrogen sulphide. The characteristic black or grey colour of the soil is due to reduction of ferric compounds to ferrous sulphides. Landscape composed of beaches, algal beds, minor deltas, backwater areas, creeks, mudflats, sea grass beds, coral reef, salt marshes& mangroves. Beaches-extensively spread along GoM coast. It is gently sloping marked with altered crusts& troughs formed by wave action; coastal areas between Mandapam &E of Vaippar River-covered by 12 beach ridges; sand spits are in the S. side of Tuticorin& SW Rameswaram shore. Swales& backwater zones are between coastal plains of Mandapam& Kottakkarai River. Mudflats are near Vaippar River mouth, around Valinokkam backwater lagoon, Kallar River mouth& Gundar River mouth; 21 offshore islands-made up of calcareous dead reef &sand. Coral reefs extend from S of Rameswaram-Tuticorin, believed to be once covered with dense mangrove forests.
Salinity values of GoM range between 31.7 to 35.2 ppt (part per thousand). Peak salinity values coincide with peak temperatures in the Gulf. Coastal areas-the rate of evaporation exceeds rate of freshwater input, hence salinity has been reported to exceed 40 ppt. Salinity of mangroves fluctuates considerably ranging from 3 to 33 ppt. Dissolved Oxygen (DO) in the waters GoM is dependent on temperature, salinity, oxygen solubility, consumption and production. Sandy Beaches contributes sand, minerals and better catchment area. Coral reefs are tapped for building material, live trade and as source material for medicine. The site is noteworthy as it is located in one of the major bird migratory routes, called “Flyways”. It lies in CAF (Central Asian Flyway), of the international flyway zones Coral mining or dredging, anchoring of boats, Coral Bleaching, Predator-Crown of Thorn starfish Siliceous Sponges-fragment the corals, Over exploitation-especially-Holothurians+Ornamental fishes.

Salient Features


Criterion 1: unique marine environment consists of coral reefs, sea grass meadows, mangroves, islands, sand dunes and beaches, mud flats etc
Criterion 2: supports endangered and threatened species like dugong (vu), whale shark (en), olive ridley turtle (vu), green sea turtle (en), hawksbill turtle (cr), indo-pacific humpback dolphin (vu) and several water bird species
Criterion 3: supports diverse bio-diversity i.e., birds (160) mammals (10) corals (117) fishes (450) sea turtles (5) sea grasses (12) crustaceans (641) sponges (108) mangroves (11) for maintaining the biological diversity of the bio geographical region.
Criterion 4: breeding ground for several species of mammals, turtles, fishes and fauna thus supporting during critical stages of their life cycles
Criterion 5: supports 20,000 or more water birds including both resident and migratory birds i.e., terns, gulls, ibises, egrets, herons, storks, pelican, ducks, cormorants, small waders.
Criterion 6: regularly supports 1% population of black headed ibis (nt) and spot-billed pelican (nt).
Criterion 7: supports more than 450 species of indigenous fishes which uses the site during critical stages of their life cycle.
Criterion 8: the coral islands form a network of spawning ground, nursery and/or migration path both resident and migratory fishes.
Criterion 9: regularly supports 1% population of non-avian animals like dugong (vu), olive ridley turtle (vu) and green sea turtle (en) Iucn status – critically endangered (cr), endangered (en), vulnerable (vu), near threatened (nt), least concerned (lc)



Site NameGulf of Mannar Biosphere Reserve
Site No2472
Declaration Date08.04.2022
Designated Date 08.04.2022
Co-Ordinates9°9'12.38" N - 78°46'44.05" E
Area Exrent ( Hectare) 52671.88
District Thoothukudi & Ramanathapuram
Elevation ( meters) 1
Depth (m)5.8
Rainfall (mm)817 ( Ramanathapuram) 646 ( Thoothukudi)
Salinity (ppt) 31.7 to 35.2
Wetland TypePermanent Shallow Marine Waters ( Mannar Valaiguda)
Soil Typical Coastal Sand
Water pH6.89 to 7.21

RAMSAR Certificate