Satellite data analysis reveals that harmful algal blooms may be the culprit behind the mass deaths of elephants in 2020.
More than 350 elephants mysteriously died possibly after drinking contaminated water, according to a new study published in the journal Science of the Total Environment. This incident raises alarming concerns about toxicity caused by climate change. The deaths of elephants in the Okavango Delta in Botswana were described by scientists as a “conservation disaster.” In 2020, hundreds of elephants of various ages were seen walking in circles before collapsing and dying. Their bodies were first discovered in northeastern Botswana in May and June 2020, with several hypotheses surrounding the cause of death, including cyanide poisoning or an unknown disease, according to the Guardian.
Mass elephant deaths in Botswana in 2020. (Photo: Guardian).
This incident is the largest recorded case of unexplained elephant deaths, according to lead researcher Davide Lomeo, a PhD student at King’s College London. The study’s findings indicate that the elephants were poisoned by water containing harmful blue-green algae. The climate crisis is increasing the frequency and severity of toxic algal blooms.
Researchers utilized satellite data to analyze the distribution of elephant carcasses relative to waterholes. They were unable to directly examine the samples due to their unavailability. The research team suggested that the elephants traveled over 100 kilometers from the waterholes and died within 88 hours after drinking the water. They examined a total of 3,000 waterholes and found that those with an increased frequency of algal blooms in 2020 had a high density of elephant carcasses. According to Lomeo, the elephants had no choice but to drink from these waterholes. It is possible that other animals also died from drinking the water, but their remains could not be detected from aerial surveys, and smaller animals’ bodies may have been removed by predators.
In the same year, 35 elephants died in neighboring Zimbabwe due to a type of bacteria entering their bloodstream, linked to prolonged drought conditions. In 2015, 200,000 saiga antelopes died from an outbreak of a bacterial infection called pasteurellosis in Kazakhstan. Such mass die-offs are becoming increasingly common in the context of global warming, potentially pushing species towards extinction.
In Southern Africa, 2019 was the driest year in decades, followed by an extremely wet 2020. These conditions led to significant sediment and nutrient runoff into the water, causing unprecedented algal growth. Amid climate change, much of the world is expected to become hotter and drier with irregular heavy rainfall. Experts conclude that the study highlights the need for monitoring water quality to take timely action when necessary.
