Gold mining in the Amazon does more than scar the landscape. It also wipes out the insects that keep the forest floor clean. A new study from Brazil shows that dung beetle communities collapse in areas where miners have dug for gold.
Beetle numbers drop by more than half near mining sites
Researchers surveyed dung beetles in the Brazilian Amazon near the town of Itaituba, a hub for illegal and small scale gold mining. They set traps in forests that had been mined and in intact forests nearby. The results were stark. In mined areas, the number of individual beetles fell by 55 percent. The number of different species dropped by 27 percent. Some species disappeared entirely.
Why local people should care about dung beetles
Dung beetles do a dirty job that matters. They bury animal waste, which helps recycle nutrients into the soil and spreads seeds. Without them, the forest floor changes. The study found that in mined areas, dung beetles were not just fewer. They were also smaller. Large beetles that bury dung deep underground were replaced by smaller beetles that do less work. That shift can slow down the whole cycle of decomposition and regrowth.
Mercury and mud leave a lasting mark
Gold mining in the Amazon often uses mercury to separate gold from sediment. Miners also clear trees and churn up soil. The study found that mercury contamination in the soil was higher near mining sites. The beetles that remained in those areas had lower body condition. The combination of toxic metals, loss of forest cover, and compacted soil made it hard for the insects to survive. The researchers collected beetles over two years and compared mined plots with control plots. They found that even after mining stopped, the beetle communities did not recover.
The study adds to a growing body of evidence that small scale gold mining causes long term damage to Amazon ecosystems. Dung beetles are not charismatic animals. But their disappearance signals a breakdown in the invisible machinery that keeps the rainforest running.
