A recent wave of media attention is again focusing on the mysterious mass die-off of over 300 elephants in Botswana since March. Now, Botswanan officials have reported that the deaths were caused by a specific kind of bacteria in drinking water, but some are rejecting these claims.
Mmadi Reuben, a veterinary officer of the Department of Wildlife and National Parks, said the deaths were due to poisoning from cyanobacteria that was growing in small pools of stagnant water and that the plateauing of deaths in June was the result of those same pools drying out. However, some fear the explanation, which doesn’t yet carry any concrete evidence, is getting in the way of a thorough criminal investigation into the true cause of the tragedy.
First of all, a quick recap on bacteria. Cyanobacteria is a kind of microscopic algae that collects in soil and water, such as the small pools described by Reuben. 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.
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 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 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 question 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."