In search of an underground species that indicates water quality

In southwest France, researchers are surveying rivers and caves to record new species of micro-crustaceans, some of which are unknown to science, in the hope of using them as a thermometer of groundwater quality.

This micro-predator comes from the little-known fauna of deep waters, populated by crustaceans, molluscs and miniature worms, which live in the interstices of the sediments forming a vast layer between the surface and the water tables underground.