Sri Lanka’s Freshwater Biodiversity Hotspot Faces Mounting Threats

In the rain-washed village of Boralugoda, Sri Lanka, a decades-long effort to protect one of the island’s richest freshwater ecosystems is underway. Research Scientist and artist Shantha Jayaweera has dedicated nearly 40 years to studying, documenting, and defending this fragile environment, which is increasingly under threat.

A Global Biodiversity Hotspot

“Sri Lanka holds a very special place in global freshwater biodiversity,” says Jayaweera, reflecting on his extensive fieldwork. The island nation is part of the Oriental region, recognized as one of the most biologically diverse freshwater zones globally. Within Sri Lanka, the lowland wet zone is particularly species-rich, benefiting from year-round rainfall and dense vegetation.

Boralugoda: An Exceptional Ecosystem

Boralugoda stands out even within the wet zone. “Out of about 94 true freshwater fish species recorded in the country, around 84 are found in the lowland wet zone,” Jayaweera explains. Remarkably, Boralugoda alone supports 53 species – the highest number recorded in any inland location in Sri Lanka. Of these, 26 are endemic, and 23 are currently threatened, ranging from vulnerable to critically endangered.

The Maguru River: A Vital Artery

Flowing through this biodiversity hotspot is the Maguru River, a relatively little river with a significant ecological role. Originating in the rainforest-covered Morapitiya area, the river maintains its clarity due to limited sediment flow, allowing sunlight to penetrate and sustain aquatic life. The river’s varied structure, transitioning from fast-flowing rocky sections to slow-moving sandy areas, supports a diverse range of specialized species.

Threats to the Ecosystem

Sand Mining

Large-scale sand mining, particularly since the early 2000s, has significantly altered the Maguru Riverbed. This has led to the loss of aquatic plants, native riverbank trees, and critical habitats. The endangered Red Neck Goby has become locally extinct, and the Ocellated Pipefish has not been recorded in years, largely due to habitat loss. Sand mining has as well caused bank erosion and long-term instability.

Agricultural Expansion

The expansion of lowland tea cultivation since the 1990s poses another major threat. Conversion of home gardens and forest patches into tea plantations reduces biodiversity and impacts water systems. Riverbank vegetation, crucial for bank stabilization and water filtration, is often cleared for cultivation, despite existing environmental regulations.

Conservation Efforts and the Role of OARM

Shantha Jayaweera, through the Organisation for Aquatic Resources Management (OARM), has led conservation and restoration efforts, including rainforest species replanting, stream bank restoration, and community awareness programs. He emphasizes the importance of community involvement in conservation. Jayaweera also uses his artistic talents to raise awareness, creating illustrations and visual storytelling to connect people emotionally to the ecosystem.

A Call for Action

Despite ongoing efforts, challenges remain, including waste disposal issues. Jayaweera stresses the require for stronger enforcement of environmental laws, increased awareness, and a genuine commitment to conservation to prevent irreversible damage to this unique and irreplaceable ecosystem.