These micro-organisms survive in water, can photosynthesize, and produce neurotoxins that poison terrestrial and marine fauna.
"Our latest tests have detected cyanobacterial neurotoxins to be the cause of deaths… We still have many questions to answer, including why only elephants were affected, why it happened in the area involved, and what might trigger the changes we have seen in the zone," the DWNP Principal veterinary officer Mmadi Reuben said.
This expert also mentioned that it has been proven that the deaths ended when the pools of water around the Seronga town dried up.
"From now on we are going to monitor the situation and devise procedures to avoid more deaths in the next season," he added.
The alarms about the death of the Botswana elephants went off in early May when the carcasses of several animals were located in the surrounding area of the Okavango Delta. At that time, however, wildlife experts could not find a cause of death.
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Subsequent scans led to the discovery of around 300 dead pachyderms with signs of sudden neurological damage. No other species were affected, not even animals such as hyenas or vultures that could have fed on the carcasses of elephants.
Because of mobility restrictions related to the COVID-19 pandemic, field investigations into the death of elephants were complicated and scientific samples had to be sent to laboratories in other countries.
Botswana has the world's largest elephant population, which is estimated at over 125,000 individuals in the wild. About 10 percent of them live in the area affected by this bacterial outbreak, the Okavango Delta, which is well known internationally for its luxury safari tourism.