Pulicat Lagoon is the second largest brackish water lagoon in India, after Chilika Lake. Pulicat Lagoon is considered to be the second largest brackish water body in India measuring 759* km2. The Lagoon is one of the three important wetlands to attract North-East Monsoon rain clouds during October to December season to Tamil Nadu. The lagoon comprises the following regions, which adds up 759 km2 according to Andhra Pradesh Forest Department*: 1) Pulicat Lake (Tamil Nadu-TN & Andhra Pradesh-AP) 2) Marshy/Wetland Land Region (AP) 3) Venadu Reserve Forest (AP) 4) Pernadu Reserve Forest (AP) The lagoon was cut across in the middle the Sriharikota Link Road, which divided the water body into lake and marshy land. The lake encompasses the Pulicat Lake Bird Sanctuary. The barrier island of Sriharikota separates the lake from the Bay of Bengal and is home to the Satish Dhawan Space Centre. Major part of the lake comes under Nellore district of Andhra pradesh.
Palm trees lining the barrier islands
|Type||brackish to salty|
|Primary inflows||Arani river, Kalangi River and Swarnamukhi River|
|Primary outflows||Bay of Bengal|
|Max. length||60 km (37.3 mi)|
|Max. width||17.5 km (10.9 mi)|
|Surface area||250–450 km2 (97–174 sq mi)|
(from low tide to high tide)
|Average depth||1 m (3.3 ft)|
|Max. depth||10 m (32.8 ft) at the mouth|
|Islands||Irrukam, Venadu and several smaller ones|
In the 1st century, the anonymous mariner who wrote Periplus of the Erythraean Sea listed Podouke (Pulicat) as one of the three ports on the east coast of India. In the 2nd century, Ptolomey's list of ports on this coast included Podouke emporion.
In the 13th century, Arabs migrated to the shores of the lake after they were banished from Mecca for refusing to pay tributes to a new calif. Streets with dilapidated masonry houses once occupied by these Arabian Muslims are still found in the area and resident families claim records in Arabic testifying the migration.
Portuguese colonized the lake in 16th century followed by the Dutch. The Dutch drifted to the lagoon as their ships got stuck on the shores of Karimanal village on the opposite side of the mouth of the lake. During the Dutch occupation, Pulicat was known by the name Pallaicatta. Fort Geldria dating to 1609, a church, a cemetery with tombs and mausoleums constructed by the Dutch are protected by the Archaeological Survey of India (ASI). The Dutch transacted business with the British East India Company and other countries in the region.
A scientific study of the palynological characteristics of the lagoon was conducted by taking sedimentary soil samples from four test pits. It shows that the vegetational reconstruction from peat beds at 4.98 metres (16.3 ft) a.m.s.l. and 1 metre (3.3 ft) (a.m.s.l.) in the west at Sullurpeta and Kasdredinilem, respectively, is indicative of a palaeoshoreline. The sea level reached its maximum around 6650 plus or minus 110 yrs BP in Sullurpeta, 18 kilometres (11 mi) west from the present shoreline. The radiocarbon dates of peat bed at Kasdreddinilem reveals an age of 4608 plus or minus 122 yrs BP, indicating the shift in mangrove line eastwards during the regressive phase.
Geography and topographyEdit
The lagoon’s boundary limits range between 13.33° to 13.66° N and 80.23° to 80.25°E, with a dried part of the lagoon extending up to 14.0°N.; with about 96% of the lagoon in Andhra Pradesh and 3% in Tamil Nadu. The lagoon is aligned parallel to the coast line with its western and eastern parts covered with sand ridges. Area of the lake varies with the tide; 450 square kilometres (170 sq mi) in high tide and 250 square kilometres (97 sq mi) in low tide. Its length is about 60 kilometres (37 mi) with width varying from 0.2 kilometres (0.12 mi) to 17.5 kilometres (10.9 mi). Climate of the lagoon coast line is dominated by Tropical monsoons. Air temperature varies from 15 °C (59 °F) to 45 °C (113 °F). The large spindle-shaped barrier island named Sriharikota separates the lake from the Bay of Bengal. The sandy barrier islands of Irkam and Venad and smaller islands in the north are aligned north–south and divide the lagoon into eastern and western sectors. The morphology of the lagoons is categorized under four types with large areas under mudflats and sandflats. The fishing village of Pulicat is at the south end of the lake. The Satish Dhawan Space Center is located on the north end of the island. Pulicat, Dugarājupatnam and Sullurpeta are villages located on the periphery of the lagoon.
Two rivers which feed the lagoon are the Arani river at the southern tip and the Kalangi River from the northwest, in addition to some smaller streams. The Buckingham Canal, a navigation channel, is part of the lagoon on its western side. The lagoon's water exchange with the Bay of Bengal is through an inlet channel at the north end of Sriharikota and out flow channel of about 200 metres (660 ft) width at its southern end, both of which carry flows only during the rainy season. The lake acts as buffer to retain the accumulated flood water till the flood water is discharged gradually to the sea during the monsoon period and cyclones. The lake and its river basins are located both in Andhra Pradesh and Tamil Nadu states. The lake and its drainage river basins become interstate river basin as per Interstate River Water Disputes Act 1956. Most of the lake area including its water outlet to the sea is located in Andhra Pradesh.
The water quality of the lake varies widely during various seasons – summer, pre–monsoon, monsoon and post–monsoon – as the depth and width of the lake mouth varies causing a dynamic situation of mixing and circulation of waters. The resultant salinity variation and DO (dissolved oxygen) affects the primary production, plankton, biodiversity and fisheries in this lake. Salinity values vary from zero during the monsoon to about 52,000 ppm (hyper saline) during post and pre–monsoon seasons. Adjustment to this wide variation is difficult for sessile and sedentary species in the lake. However, euryhaline species still dwell in the lake. The benthic or the bottom habitat of this lagoon is classified into three zones. The southern zone, the first zone, is dominated by sand with some admixture of mud. The second zone at the northern region is wholly muddy. The third zone with sand and mud in equal parts is overgrown with patches of weeds and is reported to be rich in benthic biodiversity. Toxicity levels of heavy metals such as magnesium, lead, zinc, nickel, cadmium, aluminum and copper and chemicals such as ammonia, sulphate and fluoride in the lake are well within permissible limits. Recently, the lagoon likely experienced upto 40% desalination due to the impact of freshwater floods from the 2015 South India floods
Flora and faunaEdit
The lagoon has rich flora and fauna diversity, which supports active commercial fisheries and a large and varied bird population.
Fishing is the major occupation in the many villages located around the lake periphery and on the islands. The lake has rich fish diversity, mostly marine species, some truly brackish water and a few freshwater species. Mullets and Catfish are the major brackish water fish, which have supported sustenance fishing for the lake fishermen. The lake is a nursery for several species of fish. Two thirds of the settlements in the lake area are in Tamil Nadu and the balance in Andhra Pradesh. 12,370 fishermen live on full-time fishery in the lake (6,000 in Andhra Pradesh and 6,370 in Tamil Nadu).
An average 1200 tonnes of fish and crustaceans are harvested annually, of which prawns constitute 60%, followed by mullets. Seafood exports of white and tiger prawns, jellyfish, finfish and live lagoon green crabs are also economic benefits from the lagoon. 168 total fish species are reported. The frequently found ones are the mullets: M. cunnesius, M. jerdoni, M. dussumieri, M. cephalus, M. bornensis and blowfish T. nigropunctatus, T. leopardus, Barbus dorsalis, catfish Macrones vittatus, sardines, Sardinella fimbriata and milk fish. Finfish, green crabs, clams and prawns are the most commercially exploited fishes of the lagoon. Endangered green sea turtles are found on the beaches of Sriharikota beach. Apart from prawns, salt is also produced from the lagoon.
The shallow lake is known for its diversity of aquatic birds and is an important stopover on migration routes and is reported to be the third most important wetland on the eastern coast of India for migratory shorebirds, particularly during the spring and autumn migration seasons. In view of the rich avifauna of the lagoon, two bird sanctuaries are established in the lagoon, one in each of the two states of Andhra Pradesh and Tamil Nadu. The Andhra Pradesh portion of Pulicat Lake Bird Sanctuary, established in September 1976, has an area of 172 square kilometres (66 sq mi) within the lagoon’s total area in the state in the Tada Taluk of Nellore district. The Wildlife Division of the state has listed 115 species of water and land birds in the sanctuary. Nelapattu Bird Sanctuary is also located nearby in its catchment area. The Tamil Nadu part of the lagoon of 60 square kilometres (23 sq mi) area, extending over the Ponneri and Gummidipundi taluks of Thiruvallur district was declared a Bird Sanctuary in October 1980.
Every year approximately 15,000 greater flamingos are reported to visit the lake along with pelicans, kingfishers, herons, painted storks, spoonbills and ducks. The highest concentrations of flamingo are found in the periphery of the lagoon where the water level is below40 centimetres (16 in). The concentrations of flamingos are also associated with high algal, fish and benthic diversity. Other water birds in the area include spot-billed pelican, seven species of herons and egrets, painted stork, greater flamingos, ducks, 20 species of shorebirds, gulls, terns, little grebe, Indian cormorant, little cormorant, Asian openbill stork, black-headed ibis, Eurasian spoonbill, lesser whistling teal, spotbill duck, great thick-knee and stone curlew. Several species of wintering waterfowl have been noted including bar-headed goose, ruddy shelduck, Eurasian wigeon, common teal, northern pintail, garganey, northern shoveller, common pochard, brown-headed gull, black-headed gull, whiskered tern, gull-billed tern and Caspian tern. Birds of prey which appear in winter are the: white-bellied sea eagle, harriers and peregrine falcons. The largest concentrations of flamingos occur in the Andhra Pradesh part of the sanctuary, around the islands of Vendadu and Irukkam.
Aquatic vegetation reported are 59 species, including eight Cyanophyceae, seven Chlorphyceae and two Rhodophyceae. Patches of residual, dry, evergreen forest and large areas of littoral scrub in woodlands in fishing villages bordering the lagoon are seen. Invasive phytoplankton species of Prosopis juliflora, Spirulina major, Oscillatoria spp., Anabaena spp., Rhizosolenia castracanei, Eucampia cornuta and Climacodium frauenfeldianum in the plains on the periphery of the lake have been recorded.
Threats and issuesEdit
In the Andhra Pradesh part of the lake several threats to the lagoon have been identified. These are: pollution from sewage, pesticides, agricultural chemicals and industrial effluents – from Arani and Kalangi rivers draining into the lake that bring in fertilizers and pesticides with the run off from the agricultural field in to the drainage basin, domestic sewage, effluents and wastes from numerous fish processing units; oil spills from the mechanized boats; release of4,780 hectares (11,800 acres) of the sanctuary for a marine chemicals and salt-manufacturing industry and shrimp farming in more than 1,000 acres (400 ha) on the eastern part of the lagoon have affected the Pulicat Bird Sanctuary; livelihood of 30,000 fishermen and 20,000 agricultural labourers (for whom fishing is an off-season economic activity) have also been disturbed. This activity is also reported to have serious impact on aquaculture development.
Siltation and periodic closure of the bar mouth due to the dynamic process of sediment transport has caused reduction of size and seasonal closure of the mouth of the lake has reduced fresh sea-water exchange and made the lake shallow and turbid. It is reported that average depth of 1.5 metres (4.9 ft) in the early 20th century, has reduced to less than about 1 metre (3.3 ft) now, in the lagoon. This has caused difficulties such as mouth getting silted up and getting closed during the summer season (June–July to Oct–Nov); raise in flood level occurs during the rainy season; the lake acts as a large evaporating basin when the bar is closed resulting in salinity levels remaining low or high subject to the flood discharge into the lake during the north east monsoon; fluctuation of water level in the lake (above or below the sea level) is affecting flora, fauna and fisheries; siltation has caused variation of the lake mouth resulting in reduction of tidal inflows and consequent decline in stocking of commercially important species of prawns and mullets. The flood plains reclamation in Arani river basin for industrial and residential purposes is also increasing lake maximum water level during the floods.
The Arani and Kalangi rivers carrying run off from agricultural fields in the drainage basin cause increase in pollution load from fertilizers and pesticides into the lake; pollution from domestic sewage being released to the lake; Petrochemical complex, power plant and a satellite port on Ennore creek have further aggravated the problem; there is threat of flooding of 14 island – villages of the lake; subsequent to the tsunami in 2004, the number of fishing boats have increased resulting in the `Catch Per Unit Effort' of fish, prawns and crabs declined from 1000 tonnes to about 700 tonnes; and this has increased the social and fishing rights conflicts between marine based fishermen and the lagoon fishermen.
Due to the 2004 Indian Ocean earthquake, lagoon fishery was adversely affected, with many fishing communities losing all means of livelihood until the middle of April 2005, as the loss of lives, homes and boats prevented them from going fishing in the sea and the lake. They subsisted on relief supplies provided by the government and other agencies. Many people in fish related trades were also affected. However, a beneficial effect of the tsunami has been the widening of the opening to the lagoon.
Various groups and non governmental organizations are active in the area. The AARDE Foundation maintains Pulicat-Museum at Pazhaverkadu to create awareness among inhabitants and city dwellers. AARDE Foundation represented Pulicat at United Nation's World Urban Forum and HABITAT-III as an associate-partner. Annual PULICAT-DAY event as part of RAMSAR's World Wetlands Day is celebrated every February by AARDE to bring attention to this fragile environment. An expert plan on "Wildlife Action Plan for Conservation Measures on the Pulicat Lake Sanctuary" has envisaged to set up a hydro biological research station, visitor center, provide shallow-bottomed boats to enable sanctuary staff to patrol the lagoon and to prepare a management plan and conservation strategy for the entire area. COPDANET is striving to implement traditional "Paadu system" and regular desilting to ensure adequate salt and fresh water mix in the lagoon which could enhance fish resources. Centre for Research on New International Economic Order (CReNIEO) has been promoting welfare of fishermen and management of the natural resources of the lake. A research study by Loyola College, Chennai reported in 2007 that the lake that bore the brunt of industrial pollution has made an ecological turnaround, recording toxicity levels well within permissible limits. Under the "Tsunami Emergency Assistance Project" (TEAP), construction of a high level bridge across Pulicat lake along with approach roads on both sides of the lake has been constructed providing a safe escape route for people residing on the islands and also access for emergency response operations.
The southern part of the lagoon in Tamil Nadu 5 kilometres (3.1 mi) from the estuary is rich in fishes and the fishing is controlled by a traditional Paadu system. Paadu is a traditional system of getting entitlements to eligible members of a particular community for undertaking specified fishing activity in certain designated areas. The fishing grounds fall within a radius of5 kilometres (3.1 mi) from the mouth of the lake with a salinity well maintained without much drying even during low tides. However, this traditional practice is based on caste control of the access rights to the high productive areas and is opposed by eastern fishermen and ocean-side villages. As a result, conflicts leading to violence have been reported.
The Tamil Nadu part of the lake is 60 kilometres (37 mi) north of Chennai and the nearest airport and major railway station are in Chennai. The nearest suburban railway station is at Ponneri. To reach Pulicat on the National Highway 5 from Chennai, drive north toward Nellore, after 30 kilometres (19 mi), turn right towards Ponneri village and continue 18 km (11.2 mi) to Pulicat village. Sullurpeta station is 17 kilometres (11 mi) from Sriharikota. The Buckingham Canal on the western side of the lagoon is the navigation route through the lake used by cargo and passenger vessels.
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