Zimbabwe’s Department of Wildlife and National Parks blames cyanobacteria for the deaths of over 300 elephants this year.
Cyril Taolo, deputy director of the Department, told a news conference the number of elephant carcasses found since deaths were first reported in early May had risen to 330 from 281 in July.
According to the director, toxins in water produced by cyanobacteria killed the mammals.
Taolo said this when he announced the result of an investigation into the deaths which had baffled and alarmed conservationists.
Cyanobacteria are microscopic organisms common in water and sometimes found in soil. Not all produce toxins but scientists say the toxic ones are occurring more frequently as climate change drives up global temperatures.
“What we just know at this point is that it’s a toxin caused by cyanobacteria,” said Taolo.
He added that the specific type of neurotoxin had yet to be established.
Authorities will monitor the situation during the next rainy season, and Taolo said for now there was no evidence to suggest that Botswana’s wildlife was still under threat as officials were no longer seeing deaths.
The department’s principal veterinary officer Mmadi Reuben told the same news conference that questions remained as to why only elephants had been affected since other animals in the Okavango Panhandle region appeared unharmed.
In neighbouring Zimbabwe, about 25 elephant carcasses were found near the country’s biggest game park and authorities suspect they succumbed to a bacterial infection as well.
The animals were found with tusks intact, ruling out poaching and deliberate poisoning. Parks authorities believe the elephants could have ingested the bacteria while searching for food.
The carcasses were found near water sources.
The possibility of cyanobacteria was considered but the authorities had no evidence to go on,” said Chris Foggin, a veterinarian at the Victoria Falls Wildlife Trust, which tested samples from dead elephants from Zimbabwe and Botswana.
Zimbabwe has sent samples to Britain and is waiting for permits to send samples to two other countries, Foggin said.
Africa’s overall elephant population is declining due to poaching but Botswana, home to almost a third of the continent’s elephants, has seen numbers grow to around 130,000.