Snakes found in industrial and commercial areas had higher concentrations of metals than those found in nature reserves and other clean environments.
The black mamba (Dendroaspis polylepis), so named for its black mouth rather than the color of its scales, can be used in tracking pollutant and detecting heavy metals such as arsenic, lead, cadmium and mercury, scientists said in a research paper published in Environmental Pollution.
The snake can be an indicator of these pollutants due to the prey items that they eat. The scientists, with the University of the Witwatersrand in Johannesburg, South Africa say that the birds and rodents that the black mamba preys upon transfer the pollutants that have entered their bodies into the black mamba. And these pollutants end up in the scales of the venomous snake, which enables the scientists to examine the heavy metal accumulation in the snakes. The scientists clip the scales of these snakes for examination, which does not harm the snakes in any way.
Black mambas in urban environments had higher concentrations of heavy metals than those found in natural environments. Image via Prof. Marc Humphries, et.al
“Black Mambas are common in the Durban area, and individuals often live in the same refuge for years,” Professor Graham Alexander, a herpetologist at Wits said in a statement released by the university. “If the body tissue of individuals contain high levels of heavy metals, it is a strong sign that the local environment is under threat.”
The scientists took a look at the scale clippings from live snakes that were taken from domestic, commercial and industrial properties. Tissue samples from snakes killed on the road or via human-snake conflict were also analyzed. Their findings determined that the snakes found in industrial and commercial areas had higher concentrations of metals than those found in nature reserves and other clean environments. Durban’s Metropolitan Open Space System (D’MOSS) network is such a clean and open space that the would produce snakes with cleaner properties.
“We found a clear association between land use and heavy metal exposure in black mambas. Snakes living in connected green spaces around the city generally had significantly lower heavy metal concentrations in their scales compared to those in more industrial and commercial areas,” Humphries said. “The exciting thing is that we can get this information from a quick, harmless scale clipping, It’s safe for the snake and could be used in cities across Africa where snakes are already being relocated from homes and businesses.”
The complete paper, “Black mambas (Dendroaspis polylepis) as novel bioindicators of urban heavy metal pollution” can be read on the Environmental Pollution website.
