By Rowenna Hoskin | Science Editor
As reported by Gair Rhydd in June, staggering numbers of Botswana elephants have died in the last year under mysterious circumstances; between May and June, 350 elephants died in the Okavango delta which baffled conservationists.
Recently government officials have said that these elephant deaths were caused from ingesting toxins produced by Cyanobacteria. Mmadi Reuben, the Principal Veterinary Officer at Botswana Development of Wildlife and National Parks, says:
“Our latest tests have detected Cyanobacterial neurotoxins to be the cause of deaths. These bacteria were found in water … However we have many questions still to be answered such as why the elephants and why that area only. We have a number of hypotheses we are investigating.”
Local sources have said that around 70% of these elephant deaths occurred near waterholes containing algal blooms. These can produce a toxic microscopic organism called Cyanobacteria.
Originally this cause of death was ruled out as no other species died – except one horse. They also believed that since elephants drank from the middle of watering holes, the stagnant edges would not have affected them. Now, however, scientists think that elephants were particularly susceptible because they spend so much time bathing and drinking water – they drink up to 50 gallons of water a day and bathe simultaneously. Often going to the watering holes both in the morning and the evening, elephants spend a large amount of time in the water.
Reuben says that the investigation looked at how the mortality affected the elephant population, the injuries to the carcasses, as well as testing water samples at laboratories in Botswana, South Africa and the US.
The investigation results showed that the cause was a “combination of neurotoxins” according to Reuben, but declined to say at which institutions these tests had been carried out.
Dr Niall McCann, the Director of Conservation at the UK-based charity National Park Rescue added:
“I hope what the government has said is true because it rules out some of the more sinister things,”
He originally theorised that the deaths may have been caused by poisoning or from an unknown pathogen.
To properly test tissue samples, they need to be kept in specific conditions and quickly transported to specialised labs. This was not done in Botswana, fuelling speculation and suspicion.
“Just because Cyanobacteria were found in the water that does not prove that the elephants died from exposure to those toxins. Without good samples from the dead elephants, all hypotheses are just that: hypotheses,” says McCann.
Reuben says that he will be monitoring the watering holes for algal blooms next rainy season in order to avoid another mass die-off.
“It is important to monitor now to effectively detect the growth of these algal blooms in the water,” he said.
With climate change increasing more every year, one thing is certain: the intensity and severity of algal blooms are only going to get worse.
McCann has confirmed that he is working with officials to set up a regional early warning system.
Unfortunately, it is not just the Botswanan elephants at risk. Across the border in Zimbabwe more than 20 elephants have been found dead between Hwanger national park and Victoria falls in August. There are concerns that these deaths are linked with the Botswanan deaths.
Authorities currently believe that the deaths in Zimbabwe are caused by a bacterial infection; the leading theory is that it is Pasteurella. This killed 200,000 Saiga antelope in Kazakhstan in 2015, as McCann explained:
“There are various options. Thankfully the UK government have collaborated with the government of Zimbabwe to export these samples and now they’re going to be tested in the UK … New emerging infectious diseases are happening all the time and the more we look into epidemiology the more we discover we don’t know. So, it could be a complete mystery again,”
Whether the two die-offs are linked or not, the responses from the two countries are very different. Where Botswana refused help from other countries and private organisations, ending up contaminating their test samples, Zimbabwe is willing to accept help and get to the bottom of the mysterious source.
While government officials say that they have solved the deaths of the 330 elephants in Botswana, scientists remain unconvinced as there is little scientific evidence.
Science and Technology Rowenna Hoskin