Over 300 elephant deaths in Botswana since March, the circumstances around the deaths were mysterious. The elephants were found with their tusks still intact, ruling out the possibility that ivory poachers could be to blame, and some of the animals were seen by local witnesses walking around in circles, while the carcasses of others show that they fell suddenly onto their faces just before they perished.
Now, Botswana officials have reported that the deaths were caused by a specific kind of bacteria in drinking water.
Botswana’s mysterious elephant deaths reason
Mmadi Reuben, a veterinary officer of the Department of Wildlife and National Parks, concluded that the elephants died from toxins produced by cyanobacteria which were growing in small pools of stagnant water, and the plateauing of deaths in June was the result of those same pools drying out.
“However we have many questions still to be answered such as why the elephants only and why that area only. We have a number of hypotheses we are investigating.”, he said.
A quick recap on bacteria, Cyanobacteria are a group of photosynthetic bacteria, which can be found in almost every terrestrial and aquatic habitat – oceans, fresh water, damp soil, temporarily moistened rocks in deserts, bare rock, soil, and even Antarctic rocks.
Blooms of cyanobacteria can produce harmful toxins and represent a major ecological and human health problem worldwide. Wildlife authorities have reported that blood samples taken from the animals that died were consistent with the finding that the ingestion of neurotoxins produced by cyanobacteria was the cause.
Scientists believe that elephants may be at increased risk as a result of the amount of time the pachyderms spend bathing and drinking large quantities of water.
While some conservationists accepted the explanation, others did not consider the mystery solved. The government didn’t disclose which labs processed the samples, where the samples were taken, nor which tests were performed. Furthermore, at the time of writing, the specific variety of neurotoxin was not disclosed.
“The matter is by no means closed, despite international media claims to the contrary,” said conservationist Mark Hiley, Operation Director of National Park Rescue (NPR), in an email to IFLScience.
“The algal blooms theory is popular with the scientific community but we have yet to see any verifiable evidence to support it. The theory usefully overcomes any criticisms of failed law enforcement and it’s easy to see why the government might be propagating it, but it remains one hypothesis of many…
Sadly, the propagation of one theory is rapidly replacing the need for a thorough criminal investigation.”
This skepticism over the cyanobacteria theory was further confounded by the lack of collateral death in the area as only elephants seemed to be affected by the algal blooms.
Cattle share the same area of land along with other smaller species, though their escape from symptoms could be the result of consuming less water than the enormously thirsty elephants or that they are naturally more resilient to the variety of cyanobacteria involved.
However, NPR questioned why watering holes across the region that are influenced by identical weather systems were not identically affected.
“There is absolutely no precedent for algal blooms to cause the death of, what is now believed to be, up to 700 elephants in one event,” Hiley wrote.
“Poisonings remain a strong candidate, one for which there is a clear precedent, and a coinciding breakdown in wildlife law enforcement in the country, already responsible for the deaths of over 50 critically-endangered rhino.
“The Botswana government’s sudden refusal to accept assistance from the most experienced and qualified conservation organizations has shaken the conservation world, triggered international criticism, and caused what must constitute one of the most convoluted, shadowy investigations in conservation history.
We all really hope this experience will lead to the restoration of the government’s former culture of openness and cooperation with the conservation world, which helped build Botswana’s reputation as Africa’s top wildlife destination.”