On June 18, 2020, we reported about the mysterious deaths of 154 elephants in Botswana. At the time, wildlife officials in Botswana said that the cause of the deaths was being investigated. According to a statement released by the Botswana Wildlife Conservation on Monday, it turns out that the elephants were killed by cyanobacteria.

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Cyanobacteria is a type of algae that is found in many warm, calm waters around the world. Some species of this blue-green algae can produce toxins that are harmful to other organisms, including humans. The World Health Organization indicates that people who are exposed to cyanobacterial toxins either by drinking or bathing in infected waters may suffer symptoms including skin irritation, stomach cramps, vomiting and fever. At the same time, animals, birds and fish can be poisoned by the bacteria if it is available at high levels.

Related: Scientists discover algae species that may affect coral reefs

In May and June, concern was raised after several elephants died in Botswana in the Okavango Delta. According to Botswana officials, a total of 330 elephants died in just two months, prompting investigations into the actual causes of death. The findings have now been released after several months of tests in specialist laboratories in South Africa, Zimbabwe, Canada and the U.S.

Although several of the elephants were found near watering holes, wildlife officials did not believe cyanobacteria to be the issue. Blue-green algal blooms mainly appear along the edges of the water, while the elephants typically drink from the center of a watering hole.

Speaking in a press conference, Botswana’s Department of Wildlife and National Parks’ Principal Veterinary Officer Mmadi Reuben confirmed that the deaths had been caused by cyanobacteria. Reuben further noted that the deaths subsided toward the end of June, around the same time that the water pans began drying up. The elephant carcasses had tusks intact, which led officials to rule out poaching as a cause of death.

Meanwhile, in Zimbabwe, 25 more elephants have recently died. Samples have been sent to the U.K. for testing to help determine the cause of these deaths. Scientists and wildlife officials are still looking for possible measures that could be taken to stop such deaths in the future.


Image via Herbert Bieser