Satellite data analysis reveals that algal blooms may have been the culprit behind the mass deaths of elephants in 2020.
Over 350 elephants died mysteriously after potentially drinking contaminated water, according to a new study published in the journal Science of the Total Environment. This incident raises alarming concerns regarding climate change-induced toxicity. The deaths of elephants in the Okavango Delta of Botswana have been described by scientists as a “conservation disaster.” In 2020, hundreds of elephants of various ages were observed moving in circles before collapsing and dying. Their carcasses were first discovered in northeastern Botswana in May and June 2020, with numerous 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 represents the largest recorded case of unexplained mass elephant deaths, according to lead researcher Davide Lomeo, a PhD student at King’s College London. The research findings indicate that the elephants were poisoned by water containing harmful cyanobacterial blooms. The climate crisis is increasing both the frequency and severity of toxic algal blooms.
Researchers utilized satellite data to analyze the distribution of elephant carcasses in relation to waterholes. They were unable to directly examine the specimens due to unavailability. The research team theorized that elephants traveled more than 100 km from the waterholes and died within 88 hours after drinking the water. In total, they examined 3,000 waterholes and found that those with increased occurrences of algal blooms in 2020 had a higher density of elephant carcasses. According to Lomeo, the elephants had no choice but to drink from those water sources. It is possible that many other animals also died from drinking from the waterholes, but their carcasses could not be detected from aerial surveys, and smaller animal remains might have been scavenged by predators.
In the same year, 35 elephants died in neighboring Zimbabwe due to a bacterial infection entering their bloodstream, which was linked to prolonged drought conditions. In 2015, 200,000 saiga antelopes died due to an outbreak of the blood infection known as pasteurellosis in Kazakhstan. Such mass mortality events 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. Under climate change scenarios, much of the world will experience hotter and drier conditions with intermittent heavy rainfall. Experts conclude that the study highlights the need for monitoring water quality to address issues in a timely manner.
