Algae blooms caused 350 elephants to die in Botswana

More than 350 mysterious dead elephants may have drank poisoned water, according to new research published in the journal Science of the Total Environment. The incident warns of worrying trends in poisoning caused by climate change. The deaths of elephants in Botswana’s Okavango Delta have been described by scientists as a “conservation disaster”. In 2020, hundreds of elephants of all ages walked in circles before collapsing and slowly dying. Their carcasses were first discovered in northeastern Botswana in May and June 2020, with many theories surrounding the cause of the elephants’ deaths, including cyanide poisoning or an unknown disease, according to Guardian.

The above incident is the largest mass elephant death ever recorded with an unknown cause, according to research team leader Davide Lomeo, a doctoral student at King’s College, London. Research results show that elephants are poisoned by water containing blue-green algae blooms. The climate crisis is increasing the frequency and severity of toxic algal blooms.

Researchers used satellite data to analyze the distribution of elephant carcasses relative to puddles. They were unable to directly test the sample due to its unavailability. The team believes that the elephants traveled more than 100 km from the water puddle and died within 88 hours of drinking the water. In total, they tested 3,000 puddles and found that puddles with an increased number of algal blooms in 2020 had high concentrations of elephant carcasses. According to Lomeo, the elephants had no choice but to drink water there. It is possible that many other animals died from drinking water in the pool, but their carcasses could not be detected from aerial surveys, and small carcasses could have been carried away by predators.

In the same year, 35 elephants died in neighboring Zimbabwe due to a bacteria that entered the bloodstream, linked to prolonged drought conditions. In 2015, 200,000 saiga antelopes died due to an outbreak of a blood infection called pasteurellosis in Kazakhstan. Mass die-off events are becoming increasingly common in a warming world, potentially pushing species toward extinction.

In southern Africa, 2019 was the driest year in decades, followed by an extremely wet 2020. These conditions lead to more sediment and nutrients suspended in the water, causing unprecedented algae growth. Under climate change, much of the world will become hotter and drier with intermittent heavy rain. Experts concluded the study highlighted the need to monitor water quality for timely treatment if possible.