Aerial views of elephants found dead in Botswana (National Park Rescue)
  • Toxins created by algae is to blame for the deaths of hundreds of elephants, the government of Botswana now says.
  • The official count of dead elephants is 330, plus one horse.
  • The cyanobacteria believed responsible is common in South African dams.
  • Climate change may make the problem worse, for both Botswana and South Africa.
  • For more stories go to www.BusinessInsider.co.za.


A mass die-off among elephants in Botswana – now 330, according to the official count – was due to toxins created by algae in watering holes, the government of that country now says.

"Mortality event characteristics and the field, clinical, postmortem, histopathological, and laboratory findings suggest the elephants died from neurotoxic cyanobacterium (blue-green alga) toxicosis associated with a toxic bloom of cyanobacterium in seasonal pans in the region,” said the acting director of Botswana's department of wildlife and national parks, Cyril Taolo, reported The Tshwana Times.

Many questions remain, including why only elephants were affected. But with evidence that fits the neurological symptoms observed, of apparently confused elephants staggering about before dying, and cyanobacteria explains why the deaths stopped when seasonal drinking holes dried up.

That leaves Botswana intent on testing watering holes for cyanobacteria to prevent a repeat event in future. Managing the danger has proven tricky though – in South Africa.

Some 50% of South Africa's dams host the same blue-green algae that creates toxins, which can affect humans. That cyanobacteria loves nutrient-rich water, fed by sewage or fertiliser run-off. Once established, it is very hard to get rid of, and even treating the water to make it potable becomes difficult.

The toxin-creating algae is also partial to warmer water, and climate change is expected to encourage its spread and bloom in southern Africa.

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