Heavy metal pollution may have contributed to some of largest extinction events

A 415-million-year-old malformed fossil plankton has revealed that heavy metal pollution might have contributed to some of the world's largest extinction events.

Thijs Vandenbroucke of the French CNRS presented evidence that malformed fossil remains of marine plankton from the late Silurian contained highly elevated concentrations of heavy metals such as iron, lead and arsenic.

These are well-known toxins which cause morphologic abnormalities in modern aquatic organisms.

These findings led the authors to conclude that metal poisoning caused the malformation observed in these ancient organisms and might have contributed to their extinction.

Documented chemical behavior of these metals strongly suggests that these metal increases resulted from reductions of ocean oxygenation.

Therefore, metal toxicity and its expressions in fossilised malformations could provide the 'missing link' that relates organism extinctions to widespread ocean anoxia.

The study is published in the Journal Nature Communications.