As old as the hills, cyanobacteria could prove fatal to mankind and the climate.
Botswana’s rangers had never seen anything like it. Last spring, rangers in Botswana’s main nature reserves counted over 300 elephant corpses in the space of a few days. None of the bodies showed any signs of bullet wounds. And the tusks were all intact. For once, the poachers seemed to be off the hook. It took weeks of painstaking research to explain the mystery.
The pachyderms had been poisoned by cyanobacteria.
Dangerous for nerves and liver
All the animals died between March and June, according to Botswana’s Ministry of Wildlife and National Parks. This is precisely the period when many of the savannah’s waterholes dry up. Scientists believe that the lack of water and the heat have created the right conditions for the famous toxic blue bacteria to proliferate in the ponds.
These micro-organisms produce toxins (cyanotoxins) that are devastating to the neurological and hepatic systems, with potentially fatal effects if ingested in large quantities. Elephants have had cruel experience of this.
Threats in calm waters
The phenomenon is not confined to African fauna. In France, the authorities frequently prohibit fishing or swimming in rivers or lakes where blue-green bacteria proliferate.
A proliferation favored by the heat, but also by the nitrate and phosphorus content of the water. According to a recent report by the French Agency for Food, Environmental and Occupational Health Safety (Anses), poison control centers counted around a hundred cases of human poisoning between 2006 and 2018.
Not to mention animal mortality. Every summer, veterinarians report the deaths of dogs that have drunk or played in contaminated water. With global warming, the phenomenon is becoming more widespread every year in Canadian lakes. In Brazil, in 1996, 60 people suffering from kidney failure died following haemodialysis in water contaminated with microcystins, one of the toxins produced by the terrible bacteria.
Powerful greenhouse gas
Harmful to humans and their best friends, cyanobacteria also pose a threat to climate stability. Earlier this year, a team of scientists led by Mina Bizic (Leibniz Institute for Freshwater Ecology and Inland Fisheries) made a worrying discovery. According to these researchers, cyanobacteria can produce methane under all kinds of conditions.
This information is not to be taken lightly. Cyanobacteria are ubiquitous, on land and in calm waters. And methane is a greenhouse gas 28 times more potent than CO2.
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