A Coastal wetland of Natural origin located in the Semi-arid Zone of the Western province. Negombo estuary is a very productive shallow coastal body of water, receiving fresh water from the Attanagalu Oya drainage basin via Dandugam Oya and Ja-Ela and connected with the sea by a single narrow opening. There are 13 islands within the inter-tidal channel segments of which four are inhabited. It is interconnected with the Muthurajawela marsh. The estuary is approximately 12.5km in length and 0.6 to 3.6 km wide. Apart from phytoplankton, the estuarine vegetation can be divided into fringing (mangroves and reeds) and submerged (sea grasses and filamentous green algae). Low tidal variations have confined the mangroves to a narrow band of about 10m. Excessive reed beds mainly consisting of Phragmites karka exist along the southern border of the estuary, where the salinity is low and the mangrove vegetation has depleted. The submerged sea grasses constitute critical nursery habitat for the fish and crustaceans. Four penaeid shrimp species (Penaeus indicus, P. monodon, P. semisculcatus and Metapenaeus dobsoni), and two crab species (Scylla serrata and Portunus pelagiucs) are of high economic value. The filamentous green algae Chaetomorpha spp indicates high levels of nutrients in the estuary. Mangrove species observed on the islands include Ceriops tagal (most dominant species), Avicennia marina, Luminitzera racemosa, Bruguiera gymnorhiza, Rhizophora mucronata and Rhizophora apiculata. The dynamicity of the ecosystem is controlled by the tides and river flow. The relatively stable period in this wetland coincides with the winter migration of birds, and as a result the ecosystem serves as an important habitat for migratory birds within the wet zone of Sri Lanka.

Negombo Estuary Related references