Dense mangroves and their pencil roots in Muthupet Lagoon

Muthupet Lagoon is located at the southern end of the

Cauvery The Kaveri (also known as Cauvery, the anglicized name) is one of the major Indian rivers flowing through the states of Karnataka and Tamil Nadu. The Kaveri river rises at Talakaveri in the Brahmagiri (hill), Karnataka, Brahmagiri range in th ...

river delta on the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line between ...

, covering an area of approximately 6,803.01 ha of which only 4% is occupied by well-grown

mangrove A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...

s. The rivers Paminiyar, Koraiyar, Kilaithankiyar, Marakkakoraiyar and other tributaries of the Cauvery flow through the area and adjacent villages. At the tail end, they form a lagoon before meeting the sea. The northern and western borders of the lagoon are occupied by muddy,

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

y ground, which is devoid of mangroves. The mangroves beyond the lagoon are found intermittently along the shore and extend up to

Point Calimere Kodiakkarai also called Point Calimere or Cape Calimere, is a low headland of the Coromandel Coast, in the Nagapattinam district of the Indian state of Tamil Nadu. The Cape is located about south of Vedaranyam in the delta region of the Cau ...

. The mangrove forest was under the control of

Chatram Department Chamran ( fa, چمران, also Romanized as Chamrān; also known as Chamram, Chamarom, Chamarūm and Chatram) is a village in Aq Kahriz Rural District, Nowbaran District, Saveh County, Markazi Province, Iran Iran, officially the Isl ...

from 1853 to 1912 (Chengappa, 1918). The Government of the Presidency of

Madras Chennai (, ), formerly known as Madras ( the official name until 1996), is the capital city of Tamil Nadu, the southernmost Indian state. The largest city of the state in area and population, Chennai is located on the Coromandel Coast of th ...

Gazette (1937) shows, from 1923 to 1936, half of the revenue obtained from selling mangrove products was paid to the revenue department and the remaining half was spent to maintain the "Chatrams" (Charity homes). The Government declared the Muthupet mangrove forest as a revenue forest in February 1937 and accordingly the mangrove forest was handed over to the forest department of the Madras Presidency. The forest is maintained by the Tamil Nadu Forest Department. The entire mangrove forest is divided into Palanjur reserve forest, Thamarankottai reserve forest, Maravakkadu reserve forest, Vadakadu reserve forest, Thuraikadu reserve forest and Muthupet reserve forest. Fringing_mangroves,_mudflat_and_in_Muthupet_Lagoon

Fringing_mangroves,_mudflat_and_in_Muthupet_Lagoon

The word 'lagoon' refers to the shallow salt or brackish water body that lies close to the sea. Muthupet reserve forest covers the lagoon, river creeks and the mudflats. Muthupet (mullipallam) Lagoon is a spectacular natural creation, which is 8 km from nearby Muthupet town and can be reachable only by boat. The lagoon is shallow with the average of 1m depth. The bottom of the lagoon is formed of silt clay substratum. The tidal fluctuations can be observed well with the exposure of oyster beds and roots during low tide. The tidal fluctuations are playing a major role in dispersing the mangrove seeds. Dense mangroves mostly cover the lagoon shore. The islets are found on western side which are submerged during high tide. The salinity is the major environmental factor, controlling zonation of Muthupet mangrove forest.

Avicennia marina ''Avicennia marina'', commonly known as grey mangrove or white mangrove, is a species of mangrove tree classified in the plant family Acanthaceae (formerly in the Verbenaceae or Avicenniaceae). As with other mangroves, it occurs in the intertid ...

is the conqueror of the forest which is found as a single dominant species. Southern side (mud flat) separates the lagoon from adjacent sea that also leaves a permanent mouth of lagoon with seasonally opened shallow waterways. The width of mudflat is increased from lagoon mouth to the eastern direction. The

mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...

looks like a desert in summer, but the presence of dead gastropods under the surface soil layer and the erosion of soil at the centre of mudflat reveal the submergence of mudflat during flood. There is a difference between the lagoon shore and seashore of the same mudflat, in the aspect of distance of mangroves from fluctuating water level. A traditional canal fisher

The mangroves have grown close to water level in lagoon side but not in seashore. The reason may be the difference in the nature of fine clayey silt deposition that carried by the rivers. The

salt marshes A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated ...

are found as under herb as well as lining the inner side of the forest. In the degraded central part of the mudflat, the soft fine silt is found only around the salt marshes. But, the remaining barren ground is hard (clay) which may due to the erosion of surface silt by wind or floodwater. Thousands of partially decomposed rooted trunks that found on the southeastern side of Muthupet lagoon are indicating the past, indiscriminate exploitation. A bird in Muthupet

(100–150 m in width and 5–6 km in length). The density of mangroves in eastern side of Muthupet lagoon is comparatively lower than other areas. Tamil Nadu forest department has excavated several canals across the mudflat. Each main canal which enhances the water movement between sea and lagoon, has several sub canals on either side with a substantial number of mangrove seedlings. The western side is not straight a protruding land pocket has formed an islet like structure. This part of the lagoon lies near to Koraiyar river mouth with small mangrove patches.

References

* * {{coord, 10.323, 79.521, type:waterbody_region:IN, display=title Lagoons of India Tiruvarur district