In 2020, in the heart of Botswan, Over 350 elephants have been found dead in the Okavango Deltathe ninth longest river in Africa.
Images of these giants walking in circles before collapsing lifelessly fueled a wave of theories about possible causes. Today, thanks to a new study published in the journal Science of the Total Environmentthe veil of mystery finally seems to be torn apart.
The research, conducted by an international team of scientists, indicates cyanobacterial poisoning as the probable cause of the mass deathaquatic microorganisms also known as blue-green algae. These organisms, under certain conditions, they can produce toxins that are lethal to animals and humans.
“It’s about the largest documented elephant die-off with unknown cause“, he told the Gaurdian Davide Lomeoresearcher and doctoral student in geography at King’s College London. “That’s why it caused so much concern.”
Analysis of satellite data revealed a significant correlation between the distribution of elephant carcasses and waterholes with high concentrations of cyanobacteria. The elephants, forced to drink in these pools during the dry season, they would have died within 88 hours of ingesting the contaminated water.
But what triggered this proliferation of killer cyanobacteria? The answer, according to scientists, is to be found in the climate crisis. The increase in temperatures and the alternation of periods of extreme drought and torrential rains they create ideal conditions for the flourishing of these toxic microorganisms.
“Globally, this event highlights the worrying trend of sudden climate-induced illnesses,” the researchers warn. And this is not an isolated case. In 2015, 200,000 saiga antelopes died in a climate-related blood poisoning epidemic in Kazakhstan. And also in 2020, 35 elephants died in Zimbabwe due to a bacterium favored by prolonged drought conditions.
“It is very sad that so many elephants have died,” comments Lomeo, “but this is also a sign of this global trend of climate-induced sudden illnesses… there is compelling evidence that this could happen again to any animal“.
The study, also corroborated by independent experts, raises serious concerns for the future of wildlife. “This study adds to the growing body of evidence that climate change may have a range of lethal effects on wildlife,” says Dr. Niall McCanndirector of conservation at the UK charity National Park Rescue.
The need to act is compelling. Scientists ask for one increased surveillance of water quality and the adoption of preventive measures to mitigate the effects of climate change. Otherwise, mass mortality events like the one in Botswana could become increasingly frequent, putting the survival of numerous species at risk.
The study, titled “Probable cyanobacterial poisoning as a cause of mass die-off of African elephants in Botswana,” is based on a multifactorial analysis including satellite data.
The researchers used satellite imagery to map the distribution of elephant carcasses and identify waterholes used by animals. They then analyzed the characteristics of these pools, such as water temperature, nutrient concentration and the presence of cyanobacteria.
The results showed a clear correlation between elephant mortality and the presence of toxic cyanobacteria in waterholes. Furthermore, elephant movement patterns have confirmed that the animals drank from the contaminated pools shortly before dying.
The study also highlights the importance of considering the impact of climate change on the proliferation of cyanobacteria. The increase in temperatures and the alteration of rainfall regimes can favor the growth of these microorganisms, increasing the risk of poisoning to wildlife.
