Elephant Deaths in Botswana: Mystery Solved

In recent months, 330 dead animals were found in the Okavango Delta.

Authorities have now identified the likely cause of death in the elephant die-off from blood samples taken from deceased wildlife.

Authorities in Botswana have identified cyanobacteria as the probable cause of the mass death of elephants in the country. Laboratory tests on blood samples from deceased animals, as well as soil and water samples, indicated that these toxin-producing microorganisms killed the animals in the Okavango Delta in the northwest of the country, said Mamadi Reuben, the chief veterinary officer of the wildlife authority.

Certain species of cyanobacteria, also known as blue-green algae, produce potentially lethal toxins. This can have consequences for animals drinking from bodies of water, for example, when the microbes multiply en masse during algal blooms.

««Elephants are the only animals that drink below the water's surface and suck up the mud in which these toxins are found», explained Reuben.

A total of 330 dead elephants had been found in the Okavango Delta over recent months, said Cyril Taolo of the wildlife authority. Poaching was ruled out early as a cause of death, as the carcasses were found with their tusks intact. It remains unclear why apparently no other species appears to have been affected, said Reuben.

The Okavango Delta is world-renowned for its spectacular landscapes and rich wildlife. Botswana in southern Africa has until now enjoyed a good reputation on the continent in terms of nature and animal protection, but caused outrage last year by lifting the ban on elephant hunting. In the neighboring country of Zimbabwe, at least 22 elephants were recently found dead. There, the cause of death has not yet been determined.

Beaches and lakes repeatedly closed

Strictly speaking, blue-green algae are bacteria capable of photosynthesis, known as cyanobacteria. When they multiply explosively, toxic substances can accumulate in the water.

For example, the liver toxin microcystin — when ingested over a prolonged period — can damage human genetic material and lead to tumors.

Due to a toxic algal bloom, Polish health authorities temporarily closed several beaches on the Baltic Sea at the end of July. Swimming was banned at eight bathing spots due to dangerous cyanobacteria — better known as blue-green algae.

In Switzerland, six dogs died after swimming in Lake Neuchâtel, which was contaminated with a high concentration of cyanobacteria.