This summer, the summer of 2020, scary pictures of hundreds of dead elephants in the Okavango-delta in Botswana could be seen. For a long time, it was a mystery what had caused their death. A disease? Or had someone poisoned them?
Last week, the answer came. The elephants’ drinking water was contaminated with cyanotoxins produced by cyanobacteria (blue-green algae) blooms. The blooms were probably caused by a warmer climate and soil over-fertilization. Elephants drink a lot of water why especially they were the ’victims’ in this case.
Cyanobacteria are unpopular organisms, but in fact they are very important for the Earth, in that they are the greatest contributors to atmospheric oxygen due to their photosynthesis. They are neither really algae or bacteria, but rather something in between. They ‘invented’ photosynthesis, as they were the first organisms to make photosynthesis – 2.4 billion years ago. This led to the “great oxygenation” event, where the content of oxygen in the atmosphere increased dramatically and fundamentally changed the living conditions for all types of life on Earth.
In addition to making photosynthesis, they produce cyanotoxins – as a defense mechanism. Luckily, the population of elephants in the Okavango is large and thus the deaths – so far – do not represent a great catastrophe. And the blooms of cyanobacteria? They stopped by the end of the summer as temperatures dropped.
Watch my animation about it here.