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Gulf of Mannar Marine National Park

The Gulf of Mannar Marine National Park has the core area of about 560 sq.KM from Rameswaram to Tutucorin lying within the Gulf of Mannar Biosphere Reserve covering an area of 10,500 Sq.KM. on the south-east coast of India. It covers the coast of Rameswaram, Tutucorin, Tirunelveli and Kanyakumari. It is one of the world’s richest regions from marine bio diversity perspective and the first marine Biosphere Reserve in Southeast Asia. The Biosphere Reserve comprises 21 islands with estuaries, mudflats, beaches, forests of the near shore environment, including marine components like algal communities, sea grasses, coral reefs, salt marshes and mangroves.

Pamban Coast
Pamban Coastl
Among the Gulf’s 3600 plant and animal species, there are the globally endangered species Sea Cow (Dugong dugong) and six mangrove species endemic to peninsular India.

The inhabitants are mainly Marakeyars, a local Community principally engaged in fishing. There are about 125 villages along the coastal part of the biosphere reserve which support about 100,000 people .This coupled with dynamite fishing, machanised fishing boats, use of destructive type of fishing nets catching untargetted marine animals and corals and over harvesting of fish makes the efforts of conservation challenging here.

The Gulf of Mannar Marine National Park lies within 08o47’ to 09o15’ N;and 78o12’ to 79o14’ E .

The 21 islands are 1 to 10 KM away from the coast of mainland and their extent vary from 0.25 ha to 130 ha.

Acropora Cytherea
Acropora Formosa
Acropora Valida
Sea Tentacles

Major ecosystem types available are Coral reefs, mudflats, beach, island, shallow water, and mangrove .

Sea grass beds dominated by family like Hydrocharitaceae and Potamogetonaceae and species Halodule uninervis, Cymodocea rotunds, C.Serulata ; Coral reefs; mangroves including Rhizophora muctonata, Avicennia alba, Bruguiera gymnorrhiza, Ceriops tagal, Lumnitzera racemosa are also common in the stretch.
The area has all the mangrove species available in India with Pemphis acidula being endemic and all the 11 sea-grasses of india occur here with Enhalus acoroides being endemic . The area supports 147 species of sea-weeds.

Lion Fish
Coral Reef Algae
Green Sea Turtle
Coral fish – Yellow Butterfly

Abundance of sea-weeds and sea-grasses in grazing ground attract Sea cow (Dugong dugong) – the flagship species of the protected area. Other marine creatures like Dolphins, Sea-horse, Sea-cucumber, Sea-anemone are common here. 137 coral reef species form the basis of the ecosystem where 3600 species of plants and animals are associated.

Peculiar animal like Balanoglosses living –fossil linking invertebrates and vertebrates is endemic here. Sandy shores of islands is feeding ground for five endangered marine turtles – Green turtle, Olive ridley turtle, Hawksbill turtle, Leatherback turtle and Loggerhead turtle and the first two breed here too.

The islands form a good habitat and a stop over between Chilka lake, Point Calimore and Sri lanka for migratary birds. Nearly 180 birds are found here warders and sea-birds being most common. Lesser sand piper, Curlew sandpiper, Little stint are abundent; Rare birds like Red knot, Eastern knot, Crab plovers Bar tailed Godwit, Broad billed Sandpiper, Dunlin, Longtoed stint, Rednecked phalarope are regulars here. Little tern, Kentish plover, Stone plover, Stone curlew, Lesser crested sterna breed here. Thousands of larger flamingos winter here before returning towards Rann of Kuch.

Musal Thivu
Sea Gulls
Pamban Coast
The Algal Flora of the Coral Reefs
The algal species composition on the coral reefs is different from that found in the lagoons. The following species are noticed in the reefs:
Acropora Cytherea
Coral Reef Algae
Ulva recticulata
Halimeda opuntia
Caulerpa racemosa V.Clavifera
Pocockiella sp.
Chnospora implexa

Sargassum sp.
Turbinaria conoides
Gelidiella acerosa
Chondrococcus harnemanni
Coral Reef Algae

Padina was observed on the shores and lagoons. Gracilaria Lichenoides was found more on the shore and lagoon than on reefs. Sargassum and Turbinaria are found on the shoreward part of the reefs.

The predominant species on the coral reefs is Halimeda opuntia. Caulerpa, Sargassum, Amphiroa fragilissima, Gracilaria lichenoides are the other dominant species.

The Seagrass Ecosystem
The Gulf of Mannar is rich in sea grasses. The following species belonging to Hydrocharitaceae and Potamogetonaceae have been recorded. The sea grass beds provide food sources for the sea mammals, particularly Dugong dugong which feeds upon these pastures on the Gulf shoreline and surrounding islands like Krusadai. The Dugongs prefer pastures of Halodule uninervis for food. The species composition of sea grasses is as follows:
Sea Gulls

Enhalus acoraides - with ribbon-shaped blades
Thalassia hemprichii
Holophila ovalis

Cymadocea serrulata
Halodule uninervis
Syringodium isoetifolium
Pamban Coast
It is significant to observe that among marine angiosperms, only Enhalus acoroides shows aerial surface pollination. Most sea grasses are dioecious and cross fertilization is the rule. Not a single marine angiosperm is closely related to terrestrial plants. The marine share, however, in total angiospermic species is negligible. No marine dicot has been recorded so far.

Among the monocotyledons only one order (Halobiae) has produced some marine representatives (belonging to the families Potamogetonaceae and Hydrocharitaceae, as stated earlier). Den Hartog quotes that Syringodium invertifolium was reported from Tuticorin in 1900 by A.E. Thurston as Cymadocea aeguorea. Also this has been recorded on Musal Tivu, Hare island, and on Pamban (with flowers) by F.Boergersen and M.O.P.Iyengar. The latter has made a special mention of the necessity to take up these seagrass studies in view of their fascinating diversity (Iyengar 1927). Recent work also substantiates this view (Lakshmanan and Rajeswari, 1979).
The Mangrove Vegetation
The Gulf of Mannar islands possess unique mangrove vegetation, It is interesting to note that such vegetation consists of species belonging to Rhizophora, Avicennia, Bruguiera, Ceriops, Lumnitzera, etc. Although mangroves are obtained on a good majority of the islands, this vegetation on Manalli is striking for its luxuriance and diversity. They are not very tall trees, perhaps the height is curtailed due to strong winds lashing here perennially and with greater velocity during monsoons, periodicals cyclones, etc. The plants are healthy. The whole island is carpeted as it were with pneumatophores wherever the mangrove forests are formed. The mangrove were seen with flowers on the island during December-January.
Acropora Valida
On Krusadai island, Iyengar (1927) observed a very luxuriant and diversified vegetation which has now passed into legend. He recorded many plants on the northern muddy shore to the west of Porites Bay belonging to mangrove vegetation. The species included many plants of Avicennia officinalis, Excoecaria agallocha Bruguiera caryophyllioides (now known as B.cylindrical) Ceriops candolleana (now known as C.tagal) Lumnitzera racemosa was noticed inside the swampy regions of the island where also avicennia officinales were seen. He recorded also many halophytes Suaeda maritime, S. monoica, Arthocnemum indicum, A.fruticosum var. glaucum, Sesuvium portulacastrum, Atriplex repends, etc. He further records very many algae.
The Coral Reef Formations
In the Gulf of Mannar fringing and patch coral reefs occur. The reef framework is complex. It forms the basis of a very elaborate and functional ecosystem. The coral reefs exert influence on the course of water current. They also provide shelter to a great diversity of algae, sponges, and fishes, just to mention three groups. With the help of calcareous algae in shallow sea, the harmatypic corals build primary reef formation with secondary detrital reefs in deeper water. Apart from the sedimentary and fixed algae, we encounter drifting and imprisoned phytoplankton. Calcification is important for the formation of the coral reefs. There is no relationship between photosynthesis and calcification. Upon coral reefs, phytoplankton and algal populations assume greater significance. The hermatypic coral harbour filamentous algae in their “skeletal framework” as well as symbiotic zooxanthellae in their soft parts. The imprisoned algae release oxygen during photosynthesis, enough to meet the entire respiratory needs of corals and even spares the surplus production of oxygen.
Dhanush Island
Sea Urchin
There are three major reef formations. The Manalli reef is autotrophic, synthesizing an annual organic net production of 2,500 gm c/m2. Apart from algae, the reefs also harbour boring sponges, mollusks, worms, echinoderms, common “shrimps”. Fishes etc. The corals are exploited mostly for limestone, as earlier stated, for use in various industries on the mainland.
Sea Urchin Of the Gulf of Mannar islands, the eastern side of the islands would appear to have a greater expanse of living coral reefs. The human exploitation of the coralline stones is concentrated on the northern and the western sides. Hence the eastern sides remain now relatively free of human influence and interference and so exploitation is less (Isaac Rajendran and Kanagaraj David 1972). Recently, on the initiative of the Tamilnadu Forest Department, the Government of Tamil Nadu have prohibited quarrying of corals after considerable loss of reefs to the point of extinction.
The coral reef flora, as stated earlier, were investigated by early workers. Recently the flora were studied by Umamaheswara Rao (1972) and by the Team Report (1978) - among many others. The pioneering works in this direction were by Iyengar. Thivy Desikachary, Krishnamurthy, Boergesen, among many others.

The boring sponges cause considerable destruction to corals. Thomas (1972) reported occurrence of 20 species of boring sponges in this region. Spirastrella aurivilli he recorded for the first time for the Indian Ocean region here and Aka minuta as new to science. Burton’s (1937) work on Krusadai island Porifera is still a masterpiece on the subject. The coral boring bivalves also cause great damage to corals. Appukuttan (1972) records about 20 such species for the Gulf of Mannar. There are about 120 species of corals in the Gulf of Mannar alone (Gopinadha Pillai, 1971). They belong to 33 genera. Of this 110 species belong to the families Acroporidae, Poritidae and Faviidae. It is said that the corals here are fast deteriorating, particularly due to human interference. There is also a Reef in the Palk Bay at Mandapam. There is a general resemblance as regards the distribution of species of Scleractinia of the corals in the Indo-Pacific Region.

Turbineria Mesenterina
Ariaman Sunrise
The conspicuous species of the corals belong to the family Acroporidae (Acropora, Astreopora and Montipora). Montipora and Acropora, put together, constitute 39% of the total species recorded. Species belonging to Poritidae and Faviidae constitute the dominant reef builders here (Gopinatha Pillai, 1971) At the same time the conspicuous absence of certain very common Indo-Pacific genera either due to inadequate regional sampling or insufficient exploration or real extinction or just absent because of unfavourable conditions is noteworthy. The “absent” genera are Stylophora, Alveopora, Caulastrea, Diploastrea, Labophylla and Euphyllia.

The paucity of speices belonging to Fungidae is significant. The presence of Goniospora nigra is interesting. It shows clear affinity to the fossil member of the genus, a relic of the Tethys Sea. The genera Endopsammia and Polycyathus occur in the gulf exclusively when other areas like Red Sea, Tulear (Madagascar), Maldives, Andamans, Singapore and Cocos-Keeling are compared. The genera Siderastrea and Paracyathus occur here and in Red Sea alone. Malagasay (Madagascar) has 26 genera in common with the Gulf of Mannar.
Some of the factors affecting coral reef growth are regression of coral growth due to silt-laden water with greater load of suspended matter during monsoon flow, wind blown sandy deposition, cyclone, quarrying for limestone, effect of current etc.

A detailed account on the exploitation of corals, using it (in trade of the exploited products) as raw materials in industrial ventures such as cement industries, brick manufacture masonry work, limekilns, etc, is given by Mahadevan and Nagappan Nair (1972). For the industries in the adjoining Tirunelveli District, the exploited materials are ferried from islands north of Nalla Thanni Tivu. Tuticorin fishermen go up to Valai Tivu upto 60 km from Tuticorin, and after quarrying land then at Tuticorin.

Marine Island
Green Sea Turtle
Although legally quarrying of corals from the reef is stopped now, at its peak 250 m3 of reef were removed daily. The species affected most belonged to Porites and the other corals attached with them. The reefs on some islands have been totally exploited beyond recognition. The coral reefs are fast deteriorating due to human interference, greater silt inflow draining from the mainland, etc. The wind force spoils racemose types of corals greater than the encrusting and massive coral types. The coral reefs act as breakers and their removal will alter the current pattern along the coastline. They act as coastguard against powerful tidal waves. Hence caution should be exercised against indiscriminate exploration and extensive siltation due to loss of forest cover on the coastline.
Manadapam is 150 KM from Madurai
Tourist info
All the islands are uninhabited. Antipoaching sheds are operating. Glass bottomed boats available cater to the tourists visiting the area.

The Wildlife Warden
Gulf of Mannar Biosphere Reserve

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