DNA of rare mussels found in Seine raises hopes Paris clean-up is working

Scientists taking samples from city's river did not expect to find presence of under-threat molluscs

Traces of rare mussels sensitive to pollution and thought to be on the point of extinction in France have been discovered in the Seine in Paris, raising hopes that efforts to clean up the river that bisects the French capital might be succeeding.

The findings were made after Olympic swimming events were held in the Seine last year - the first time swimming in the river has been deemed safe in a century.