Physical Environment

The Gulf of Mannar is endowed with three distinct Marine ecosystems namely Coral ecosystems, Sea grass ecosystem and Mangrove ecosystem. Most of the islands have luxuriant growth of mangroves on their shorelines and swampy regions. The sea bottoms of the inshore area around the islands are carpeted with sea grass beds, which serve as ideal feeding ground for Dugong. Highly productive fringing and patch coral reefs surround the islands and are often referred to as underwater tropical rainforest and treasure house for marine ornamental fishes. Occurrence of these specialized ecosystems makes Gulf of Mannar as a unique large marine ecosystem in the Indian subcontinent. The islands located in the GOM, for practical purposes are classified in to three categories as mentioned above.

The Gulf of Mannar region falls within the rain-shadow region of south west India caused by the large island of Sri Lanka to the east. The narrow range of the Western Ghats effectively blocks the moisture and rain of the south west monsoon in June and July. Therefore, the area has direct rain only from the north east monsoon in October and November. Most of the bio geography of the region reflects aridity, and the largely red sandy and lateritic soils are not the most fertile soils for agriculture. The predominant plant of the area is the Palmyrah palm, which provides wood, leaves and nectar which is tapped to make palm molasses or jaggery. Good arable land along the Gulf is sparse, and where available, is constantly under threat from saline ingress. The poor maintenance of the natural river systems of the area and the large underground fresh water aquifer extending about 35 km on the coast, has reduced the availability of fresh water for irrigation and drinking.