Africa’s most feared snake has found a new role as an environmental guardian, with researchers having discovered that black mambas can serve as detectors of air pollution.
A new study shows the snakes – which are Africa’s most venomous – absorb heavy metals such as lead, arsenic, cadmium and mercury into their bodies.
By clipping small fragments of scales from live animals – a process which does not harm them – scientists can measure pollution levels across different landscapes. Tissue samples from snakes killed in accidents or human conflict were also analysed.
The research, by the University of the Witwatersrand in Johannesburg, was the first of its kind on an African snake species.
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The study focused on black mambas collected in Durban, in South Africa’s KwaZulu-Natal province.
Snakes from industrial and commercial areas carried far higher concentrations of heavy metals than those found in reserves or green spaces.
“Snakes constitute a very good indicator of pollution patterns, because they are excellent predators, at the top of the food chain,” Graham Alexander, professor of herpetology and co-author of the study, told RFI.
“They do not move around a lot. And they also have a long lifespan, about 30 or 40 years, which allows them to accumulate good indicators of pollution over time in different areas,” he said.
Mirror effect
Black mambas absorb heavy metals when they feed on contaminated birds and rodents. That makes them a mirror of the risks also faced by people.
“Humans who live in these industrial areas may not be as exposed to heavy metals, because they don’t eat rats,” Alexander said with a laugh. “But they are still exposed. This therefore provides important information for human wellbeing as well as for the environment and other natural species present.”
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“We found a clear association between land use and exposure to heavy metals. What is exciting is that these data can be obtained without danger to the snakes,” Marc Humphries, an environmental chemist and director of the study, told RFI.
The study, published last month in the journal Environmental Pollution, offers a model that could be applied across the African continent. Researchers say the method could help cities build detailed maps of pollution and identify the worst-affected areas.
“In the future, this technique will become more generalised and will become an even more efficient and precise measuring instrument,” Alexander said.
This story was partially adapted from the original version in French
