New research has confirmed the theory that toxic algal blooms in the water led to the deaths of more than 350 elephants in Botswana.
In May 2020, a mysterious tragedy occurred in Botswana when more than 350 elephants were found dead near the Okavango Delta in July. Initial investigations ruled out common causes such as poaching, starvation, infections and anthrax, leaving toxic cyanobacteria as the prime suspect.
Four years later, a new one led by King’s College London published in Science of The Total Environment confirms this theory about one of the largest mass deaths of any large mammal in recent history.
Using satellite data, geographer Davide Lomeo and his team analyzed water holes near the elephant carcasses. They found that 20 ponds recorded a increased proliferation of toxic algae in 2020, compared to the previous three years. These blooms, found in stagnant, rain-fed ponds, are highly toxic and likely poisoned the elephants, who succumbed 88 hours after exposure.
“Our findings highlight the devastating impact of climate-induced environmental changes in endangered species,” said Lomeo. “Seasonal ponds, not permanent bodies of water, were the likely source of cyanotoxin exposure.”
Botswana, where more than 130,000 elephants live, is home to largest elephant population in the world. The deaths attracted worldwide attention, but this is not an isolated incident. In recent years, mass mortality events have affected several species around the world, from California birds that succumbed to botulism to Australian bats that starved to death.
The study highlights how climate change worsens these phenomena. To the warmer, nutrient-rich waters favor harmful algal blooms, while extreme weather conditions affect wildlife, making them vulnerable to disease, says the .
“This event reflects a broader trend of climate-induced impacts on biodiversity and ecosystem health,” the researchers wrote. Southern Africa is expected to become hotter and drier, facing increased risks to water quality and availability, with dire consequences for wildlife.
