ECOLOGICAL HERITAGE SITES OF CHENNAI – PART I

Ecological Heritage Sites (EHS) are areas of remnant indigenous vegetation representing a different range of landform, soil, plant associations, habitat or ecosystem that occur in a  particular region. They are the remnants of unique vegetation types that exist in such regions and have high ecological value (Sanjeeva Raj, 2002). There are hundreds of EHS in India:  Sundarbans, Chilka Lake and Pulicat Lake are but a few worth mention. In Chennai alone over 20 sites are identified as EHS and have been assessed and evaluated on various criteria such as the number of native species, degree of disturbance and the area covered by the site.

Classification of EHS in Chennai

According to their vegetation and natural resources, the EHS in Chennai are classified into five broad categories. They are:

Estuaries          –       Adyar, Cooum

Scrub-jungle    –       IIT campus, MCC campus, Guindy Park, Theosophical Society campus and Kattupalli Island

Water bodies    –      Temple tanks, Adambakkam Lake, Mohapper Lake, Red hills, Madhavaram Lake, Korattur Lake, Ambattur Lake and Pulicat Lake

Wetlands          –       Pallikaranai, Velachery and Chembarambakkam

Parks               –         Natesan Park, Nageshvara Rao Park, Panagal Park, etc.,

The EHS are noted for their richness of biological diversity but sadly a number of threats are associated with them.

Adyar Estuary

Chennai is one of the few cities having an estuarine ecosystem. The Adyar creek is of a tidal type and a part of the natural estuarine ecosystem located right in the heart of the city. The original creek area is about 100 acres. Of this, roughly about half the extent remains as a creek, where the tidal effect is felt twice a day.

The Adyar River originates at Chembarambakkam tank in Tiruvallur district. It flows a distance of about 40 kms to join the Bay of Bengal in the southern part of Chennai. At its mouth (the estuary), it takes a bend forming the creek. The estuary extends from the sandbar at the edge of the sea to the Adyar Bridge, with small islands in between. The creek begins near the Chettinad Palace.

The picture of an ecosystem would be incomplete without a description of its flora and fauna. The Adyar creek, inspite of the absence of mangroves, which is an essential part of an estuarine ecosystem, still exhibits a wide range of biodiversity. The flora found in the Adyar creek are Prosopis juliflora (Velikathan) along with Crotons sparciflorous and Ipomea biloba, Thespesia populnea, Cassia occidentalis, Cephalandra coccinia and Pongamia glabra, Abrus precatorius, Lantana camera, Zizyphus jujuba, Azadirachta indica, Morinda species, Antigonon species, Hyptis species and Acacia species. The fauna found here are gastropods and springtails, polychaetes, crabs, hermit crabs and oligochaetes.

Many species of fish earlier found in abundance are no longer seen. Originally there were about 170 species of birds at the estuary now dominated by the omnipresent crows (Exnora Naturalists’ Club, 1997). The Adyar estuary is a textbook case of a fragile natural heritage losing out to frantic urbanization (Theodore Baskaran, 2003).

Fig 1

Threats

The Adyar Creek has several threats such as heavy accumulation of silt over a period of time. Slums have encroached upon more than half the footbridge. The remaining portion and its debris impede the flow of water. It is used as a garbage dump now. A number of cattle sheds, which are set up along the creek, not only reduce the width of the creek but also pollute it. The other sources of pollution are the raw sewage let in at various points from the encroachments, storm water drains and other upstream sources such as industries, hospitals and sewage pumping stations.

Heavy encroachment along the creek has also resulted in gross pollution of the wetland, turning it into a health hazard (Exnora Naturalists’ Club, 1997).

The creek bed is heavily silted and the water is forced to take a meandering course.  Both the banks of the creek are devoid of any native vegetation.  The creek, once a paradise, has now been practically ruined.

To be continued…

Dr. M. Amirthalingam
CPREEC

Source: Eco News, Vol.9, No.1 (April – June), 2003.

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