A water-borne bacteria caused the deaths of 330 elephants in Botswana, the government says, after weeks of mystery surrounding what killed the animals.

“Special data analysis taken from among others, carcasses, soil, blood and water from seasonal water pans were taken for laboratory tests leading to cyanobacteria being detected and diagnosed,” said Mamadi Reuben, the principal veterinary officer at the Department of Wildlife and National Parks.

He said cyanobacteria that live in the water in the Okavango Delta can produce deadly toxins, noting the elephants showed signs of nervous system breakdown.

Conservationists first noticed the mass deaths while conducting an aerial survey.

Mr Reuben added that other animals who drank from the same source might not have been similarly affected because the pachyderms “use their trunks to access water below the surface where this bacteria resides.”

“We also discovered that when the pans started to dry up around June this year, the mortality also stopped.

“We know that the rainy season is just around the corner and we are working on some strategies to ensure that we don’t register more deaths of elephants in that area again.”

The first elephant carcass was found on May 11 by researchers in a helicopter who were trying to find out why an elephant with a satellite tracker hadn’t moved for some time.

They found it dead, along with several others, at a water hole.

Botswana is known for its nature and is a popular tourist destination because of its wildlife. It is home to home to almost a third of
Africa’s elephants but the lifting of a ban on hunting them in 2019 caused international outrage.

President Mokgweetsi Masisi said at the time that hunting was necessary to keep the elephant population in check.

While Africa’s overall elephant population is declining due to poaching, numbers in Botswana have grown from 80,000 in the late 1990s to 130,000.

However, elephants are seen as a nuisance by some farmers, whose crops have been destroyed.

-with AAP