After months of concern and speculation, the Botswana government on Monday said that thein northwestern Botswana earlier this summer may have occurred because they drank water contaminated by a toxic blue-green algae.
The elephants in the Seronga area in Southern Africathat appears to have been caused by drinking water tainted by "a toxic bloom of cyanobacterium in seasonal pans (water sources) in the region," according to Cyril Taolo, the acting Director of Wildlife and National Parks.
Unusually no other wildlife species were affected by the toxic water in the Seronga area, close to Botswana's famed Okavango Delta, said Taolo. Even scavengers — like hyenas and vultures — observed feeding on the elephant carcasses showed no signs of illness.
With an estimated 130,000 elephants, Botswana has the, which attracts international tourists.
Most of the surviving elephants fled the area after the deaths, which occurred mainly near seasonal water areas and did not spread beyond that region.
Samples from the elephants carcasses were sent to laboratories for testing in Southern Africa, and now experts are saying the most likely cause is a cyanobacteria that lives in the water and could have caused paralysis and death mainly related to respiratory failure.
However, Taolo could not explain why these toxins did not affect any other animals drinking the affected water. Meanwhile, the Botswana government has also ruled out human causes like anthrax poisoning, poaching and sabotage.
Dr. Niall McCann, director of the National Park Rescue's Conservation, told CBS News that many unanswered questions remain. He explained that the Botswana government has not said where the toxins were found. If they found it in water samples, he said, that would make their conclusions "highly suggestive but not conclusive."
The climate "threat amplifier"
McCann also said there are different types of cyanobacteria and it's crucial to pinpoint exactly which one it is to mitigate against any future harm to the elephants.
He told CBS News that this period, the start of summer in the southern hemisphere, always brings blooms of toxic algae, and deaths from anthrax and other naturally occurring poisons are typical. But, he said the large number of deaths this year serves as another example of how the world is interlinked.
Natural die-offs "will be exacerbated by climate change," he said, with the hotter summer temperatures seen across Africa acting as a "threat amplifier" to the elephant herds and other wildlife.
Botswana's government said it would implement "a monitoring plan of seasonal water-pans," to track any future occurrences.