A volcanic rift lake is struggling to survive a collapse of its keystone species

Countries & Cities · Published 29 September 2026 Swipe more like this →

In short: Straddling the border of Uganda and the Democratic Republic of the Congo, Lake Edward is a vital ecological and economic lifeline. Yet, a dramatic decline in its hippopotamus population—once numbering 29,000—has triggered a cascading failure, starving the lake of nutrients and devastating the local fishing industry that relies on tilapia.

Lake Edward sits within the Albertine Rift, a geologically volatile region shaped by intense volcanic activity over the last 5,000 years. Once part of a larger body of water shared with Lake George, the two were separated by lava flows that created the Kazinga Channel. The surrounding landscape remains defined by craters and cones, including the nearby Lake Katwe, which serves as a primary salt source for Uganda. Despite its natural beauty, the lake is a site of persistent tension, caught between the protected status of Virunga and Queen Elizabeth National Parks and the competing interests of regional governments and illegal resource extraction.

The lake’s health is intrinsically linked to its hippopotamus population, which acts as a keystone species. Hippos deposit roughly 25 kilograms of dung into the water daily, providing essential nutrients that support thousands of tilapia. Following a 95% population collapse due to poaching—dropping from 29,000 in the 1970s to a few hundred by 2006—the nutrient cycle stalled. This collapse has decimated the tilapia population, which previously supported an annual harvest of 15,000 to 20,000 metric tons. With the fish stocks depleted, local communities that once supplied the eastern DRC now struggle to sustain their own markets.

Human conflict further complicates the lake's recovery. In 2014, oil prospecting attempts within the park boundaries sparked violent clashes, while ongoing geopolitical friction has led to naval skirmishes between Uganda and the DRC. As illegal fishing and poaching persist, the ecosystem remains fragile. Although a 2019 census recorded a modest recovery to 1,500 hippos, the lake remains a precarious environment where the survival of both wildlife and the human populations dependent on its waters hangs in the balance.

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