Pulicat Lake faces ecological crisis

Nellore: Pulicat Lake, the second largest lagoon in India having rich natural resources, has been facing ecological crisis due to lake-mouth closure issues, siltation, shrinkage of the lake, pollution, over fishing, degradation and destruction of natural habitats.

In fact, coastal zones across the globe are currently experiencing intense and sustained environmental pressures from a range of driving forces that effects its ecology and the Pulicat Lake is not an exclusion.

The 18,440-hectare wide Pulicat lagoon, which runs parallel to the Bay of Bengal across the Tamil Nadu-Andhra Pradesh border, is the second largest brackish water lagoon in the country. At the southern end, it opens into the Bay of Bengal.

Normally, a lagoon has freshwater streams flowing into it from the hinterland on one side; and on the other side, the lagoon opens into the sea through a narrow mouth. Ecologists say that the Pulicat Lake is one of the good productive ecosystems in India and the lake-mouth is a major responsible factor for the hydrology, biodiversity and fisheries in this lake.

Accretion of sand is resulting in the formation of a sand-bar across the lake-mouth and as a result the impact of the low and high tides in the lake tends to be feeble where sea water into the lake is less, and hence the depth of the water in the lake tends to decline.

This has major impact on the biodiversity and fisheries in the lake. Another important ecological crisis is the rapid rate of siltation of the lake. During the northeast monsoon between October and December, floodwater from all catchment
areas around the lake flows inside, erodes top-soil and brings silt into the lake. The rivulets and the Buckingham Canal also bring in heavy loads.

Its average depth was about 3.8 metres, prior to the 17th century when Pulicat Lake served as a natural harbour for the Dutch. Now, it has been reduced to less than a metre as it buries all benthic habitats, flora and sessile fauna resulting in a large-scale disappearance of biodiversity in the lake during every monsoon.

The lake has been shrinking not only in its area of water spread, but also in its depth and hence fishes that prefer deeper waters are rapidly dwindling in the lake.

More than 15 species of fish and one or two species of shrimp have either vanished from the lake completely or fast declining in population for the last 20 years.

Depletion of the lake is the result of massive urbanisation of the region. As the lake is one of the tourist destinations, visitors throng the area and pollute it throwing away the waste near the shore areas which causes death to fishes and other organisms. The Arani and Kalangi rivers carry runoff such as fertilisers and pesticides from agricultural lands through drainage system into the lake.

Shrimp and crab culture ponds located along the shore of the lake also pollute the water body with discharge of untreated effluents. The North Chennai Thermal Power Station (NCTPS) is another major source of pollution as it carries slurry containing toxic fly ash.

The International Union for Conservation of Nature (IUCN) declared the Pulicat lagoon system as a Ramsar site of international importance and the World Wide Fund for Nature declared it as a protected area. But no adequate measures were taken to protect its rich ecosystem.

A port functioned here from early 3rd century BC to 19th century and the revenues were then controlled by Tamil, Telugu and Muslim rulers.

With the British developing a major port in Chennai as the largest port in the east coast, Pulicat port was completely neglected,” said Prof R J Rao, who conducted study on mouths of various rivers that connect to the lagoon system.

By:PV Prasad