Riccardo Liguori In 2020, Botswana witnessed the mass death of over 350 pachyderms. A new study published in Science of the Total Environment indicates cyanobacterial poisoning as the probable cause, a phenomenon amplified by the climate crisis and destined to repeat itself with increasing frequency
@Canva
In 2020, deep in Botswana, more than 350 elephants were found dead in the Okavango Delta of Africa’s ninth-longest river.
Images of these majestic creatures wandering in circles before collapsing lifeless stirred a wave of speculation as to the cause. Now, a new study published in Science of the Total Environment sheds light into this tragic mystery.
Cyanobacteria: the likely culprit
An international research team has identified cyanobacteria, or microscopic aquatic organisms more commonly known as blue-green algae, as the probable cause of this mass die-off. Under specific conditions, these organisms can produce toxins lethal to both animals and humans.
“This is the largest documented mass death of elephants with an unknown cause,” Davide Lomeo, a researcher and PhD student in geography at King’s College London, told The Guardian in an interview. “That’s why it raised so much concern.”
Satellite data analysis indicated a striking correlation between the distribution of elephant carcasses and waterholes with high concentrations of cyanobacteria. The elephants, compelled to drink from these waterholes during the dry season, most probably died within 88 hours of ingesting the infected water.
Climate crisis behind toxic blooms
What sparked this toxic proliferation of cyanobacteria? Scientists point to the climate crisis. The increase in temperature and the variation of strong droughts with sudden downpours created a setting that is quite favorable for their growth.
“Globally, the event indicates the terrifying development of sudden climate-induced wildlife diseases,” the researchers warn. Not that it was the first. In 2015, for instance, Kazakhstan experienced a death toll of 200,000 saiga antelopes caused by an outbreak of hemorrhagic septicemia linked to climate change. Then there was 2020, in which 35 elephants died from bacterial infections enhanced by drought conditions in Zimbabwe.
“It’s tragic that so many elephants died,” Lomeo said. “But it’s also part of this global trend of climate-induced sudden diseases. there’s compelling evidence that this could happen again to any species“.
A call to action for wildlife conservation
The study, supported by independent experts, raises serious concerns for the future of wildlife. “This research adds to the growing body of evidence that climate change can have a range of lethal effects on wildlife,” said Dr. Niall McCann, director of Conservation at the UK-based charity National Park Rescue.
Scientists emphasize the urgent need for action: increasing water quality monitoring and taking steps to prevent climate change that will further reduce water supplies. Without action, mass die-offs such as Botswana’s may become routine, and a large number of species are likely to go extinct.
Study: a multifactorial analysis
Titled “Probable Cyanobacteria Poisoning as the Cause of Mass Elephant Mortality in Botswana,” this study incorporated a holistic investigation with the use of satellite data.
Researchers mapped the distribution of elephant carcasses and identified waterholes frequented by the animals. They then analyzed these waterholes for factors such as water temperature, nutrient concentration, and cyanobacteria presence.
The results showed a strong correlation between elephant deaths and toxic cyanobacteria in waterholes. In addition, the movement patterns of elephants confirmed that the animals drank from contaminated waterholes shortly before dying.
The study points to the necessity of taking into consideration the role of climate change in promoting cyanobacterial blooms. With rising temperatures and changing rainfall, the chances of toxic outbreaks increase, which poses a serious threat to wildlife.
