Pulicat Lake is the second-largest brackish-water lagoon in India (after Chilika Lake), measuring . A major part of the lagoon lies in the Tirupati district of Andhra Pradesh and rest with Thiruvallur district of Tamil Nadu. The lagoon is one of three important wetlands that attracts northeast monsoon rainclouds during the October-to-December season. The lagoon comprises the following regions: Pulicat Lake (Andhra Pradesh and Tamil Nadu), Marshy/Wetland Land Region (AP), Venadu Reserve Forest (AP), and Pernadu Reserve Forest (AP). The lagoon was cut across in the middle by the Sriharikota Link Road, which divided the water body into lagoon and marshy land. The lagoon encompasses the Pulicat Lake Bird Sanctuary. The barrier island of Sriharikota separates the lagoon from the Bay of Bengal and is home to the Indian Space Research Organisation's Satish Dhawan Space Centre.]] 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, Ptolemy's list of ports on this coast included Podouke Emporion.
In the 13th century, Arabs migrated to the shores of the lagoon after they were banished from Mecca for refusing to pay tributes to a new caliph. Streets with dilapidated masonry houses once occupied by these Arab Muslims are still found in the area and resident families claim records in Arabic testifying the migration.
The Portuguese colonized the lagoon 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 lagoon. 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 a.m.s.l. and (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 ± 110 years BP in Sullurpeta, west from the present shoreline. The radiocarbon dates of peat bed at Kasdreddinilem reveal an age of 4608 ± 122 years BP, indicating the shift in mangrove line eastwards during the regressive phase. 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.
Hydrology
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 an outflow channel of about width at its southern end, both of which carry flows only during the rainy season. Recently, the lagoon likely experienced up to 40% desalination due to the impact of freshwater floods from the 2015 South India floods.
Flora and fauna
The lagoon has rich flora and fauna diversity, which supports active commercial fisheries and a large and varied bird population.
Limnology
Fishing is the major occupation in the many villages located around the lagoon periphery and on the islands.
An average 1,200 tonnes of fish and crustaceans are harvested annually, of which prawns constitute 60%, followed by mullets. The Andhra Pradesh portion of Pulicat Lake Bird Sanctuary, established in September 1976, has an area of 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. 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, Indian spot-billed 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
There are 59 species of aquatic vegetation, eight of Cyanophyceae, seven Chlorophyceae, 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. However, a beneficial effect of the tsunami was the widening of the opening to the lagoon.
Restoration and social activities
Various groups and non-governmental organizations are active in the area. The AARDE Foundation maintains the Pulicat Museum at Pazhaverkadu to create awareness among inhabitants and city dwellers. The AARDE Foundation represented Pulicat at the United Nation's World Urban Forum and Habitat III as an associate-partner. Pulicat Day, 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 lagoon Sanctuary" has envisaged setting up a hydrobiological research station and visitor center, providing shallow-bottomed boats to enable sanctuary staff to patrol the lagoon, and preparing a management plan and conservation strategy for the entire area. COPDANET is striving to implement a traditional "Paadu system" and regular desilting to ensure adequate salt and fresh water mix in the lagoon, which could enhance fish resources. A research study by Loyola College, Chennai reported in 2007 that the lagoon has made an ecological turnaround, recording toxicity levels well within permissible limits.
The southern part of the lagoon in Tamil Nadu from the estuary is rich in fishes, and the fishing is controlled by a traditional Paadu system. Sullurpeta station is from Sriharikota. The Buckingham Canal on the western side of the lagoon is the navigation route through the lagoon used by cargo and passenger vessels.