Over the years, 'Maduganga of Balapitiya' identified as an estuary by environmentalists has become a sought after tourist attraction located on the south coast of Sri Lanka.
Both local and foreign environmentalists explore Maduganga for its richness in biodiversity of fauna and flora.
Nature lovers who frequent Maduganga right throughout the year both local and foreign irrespective of whatever clime they may arrive whisper 'paradise could not be so far from here' when enchanted by its natural beauty at first sight.
Even the Sri Lankans get this feeling due to its unique natural beauty enhanced by the innumerable islets fringed by profusely grown mangroves and other mangrove related species of foliage.
Out of the total area of 915 hectares of the estuary, nearly 770 hectares identified as water while the land mass of the existing islets in only 144.7 hectares. Maduganga meanders through islets surrounded by 53 hectares of different species of mangroves.
'Lumnitzera racemosa' (Berliya", 'Lumnitzera littorea' (Rathmilla), 'Excoecaaria agallocha' (Thelakiriya), 'Acrosticum aurem' (Karan koku), 'Bruguiera gymnorhiza' (Mal kadol), 'Rhizophora apiculata' (Ela Kadol) and 'Sooneratia caseolaris' (Kirala) have been identified as the important mangroves found on the banks of Maduganga and on the islets.
In addition to these mangroves several species of endemic plants are also found profusely grown among the mangroves.
As usual due to human action several species of animals are no longer found in this wetland. Sixty species of birds and twenty eight species of fish, different species of prawns are also found according to scientific surveys carried out both by the Central Environmental Authority (CEA) and the IUCN - World Conservation Union.Throughout the country, in almost all the wetlands, illicit makeshift distilleries of 'Kasippu' are found and Maduganga estuary and its islets are no exception. Inside the thickly grown mangrove swamps, large areas could be seen cleared for this purpose.
Removing Mangroves to put to illicit Kasippu distilleries and speedy motor boats were considered the major human activities which exerted great impact on the biodiversity of sensitive Maduganga ecosystem. The emergence of alien invasive aquatic plant species known as 'Najas marina' (Katu penda) according to environmentalists is worst in comparison to other environmental constraints. While numerous environmentalists conservation organisations had launched numerous conservation programmes unfortunately certain mushroom organisations merely on pecuniary interests on the pretext of promoting ecotourism are engaged in compiling 'project reports' to gain funds from public sector environmental institutions and foreign donors. These organisations had done nothing to improve the living conditions of the islanders nor to protect the environment of Maduganga estuary.
Amidst planning and research and compiling project reports, invasive 'Najas marina' is fast spreading on the upper reaches of Maduganga like a thick green carpet. The islanders of Maduganga estuary are of the opinion the so called friends of Maduganga are really its enemies.
Addressing a media briefing on Wetlands, held in Sri Lanka Country Office of IUCN - The World Conservation Union, the Head of the Biodiversity Section, Dr. Channa Bambaradeniya revealed the gravity of the damage caused by this alien invasive aquatic plant species to the biodiversity of the wetlands in the country.
According to Dr. Bambaradeniya, 'Najas marina' had already invaded even the important lagoons of Ramsar Wetland of Bundala.
In addition to coastal lagoons, marshes, estuaries and irrigation canals even the tanks have been invaded by this plant.
So far no remedial action has been taken against the spread of this plant species. Recently a team of environmentalists and trainees of Environmental Journalism made a field study tour to Maduganga sponsored by Sri Lanka Environmental Journalist Forum headed by its Chairman, Dr. Dharman Wickremaratne. All of these Trainee Environmental Journalists could observe the impact of this invasive plant species on the biodiversity of Maduganga estuary.
According to the book on 'World Weeds, Natural History and Distribution, 'Najas marina' has become an invasive aquatic plant in many of the continents including Asia, Africa, Australia and Europe.
Now just after a few months since its emergence, the upper reaches of the banks of Maduganga are inaccessible due to thickly grown 'Najas marina'.
All the stakeholders living on the resources of Maduganga estuary have been affected by this invasive aquatic plant. Motor boat operators of Maduganga take extreme care to avoid areas covered by this invasive plant as the blades of the propellers of motor boats could be damaged and if entangled they said it was extremely difficult to extricate the net like plant.In addition, the traditional fishermen engaged in sustainable methods of fishing in the lagoon, using 'hook and the line' said that their only livelihood was gravely affected both by the speedy motor boats carrying the sightseers and the 'invasive plant species' found in the shallow areas of the Maduganga.
Earlier these anglers fished in close proximity to banks of the river avoiding massive ripples caused by the speedy motor boats but now as this invasive plant is thickly grown by the bank, small time fishermen of Maduganga have found it extremely difficult to survive.
Dr. Bambaradeniya said that there were millions of minute seeds in the pods of the plant and any attempt to remove the plant would only facilitate to spread the seeds. It was revealed that both the ornamental plant and fish importers who had also imported this invasive plant. Some researchers claimed that the migratory birds from other climes could also be instrumental on the dispersal of the seeds of 'Najas marina' to the wetlands of Sri Lanka.
Higher levels of nutrients such as phosphorus and nitrogen commonly associated with agricultural runoffs used to promote a condition called 'eutrophication.'Eutrophication is a biological process leading to rapid growth of invasive species of plants such as 'Najas marina'.
The speedy growth of 'Najas marina' in Maduganga is also attributed to the run offs of chemical fertilizers used in the bordering cinnamon cultivations of Maduganga.
If no immediate action is taken to control the spread of this invasive plant, the wetland ecosystem would soon transform into a terrestrial ecosystem, said Dr. Bambaradeniya.
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