Salting roads causes frogs to change sex

The practice could be affecting frog populations

Salting roads and pavements during winter damages frog populations by turning would-be females into males, a major new study warns.

Naturally-occurring chemicals in de-icing substances find their way into ponds, and change the sex of young frogs in early development stages

Experts at Yale University found that gritting can reduce the number of female frogs by 10% in a given area, as well as harming the quality of their eggs and size of their offspring. 

The new research, published in the Canadian Journal of Fisheries and Aquatic Sciences, concluded that salt had a “masculinising” effect that triggered a “sex reversal” mechanism during the early life of the frog.

“There is a very small testosterone-like effect with one salt molecule,” said Max Lambert, who led the study. “But if you’re dumping lots and lots of salt on the roads every winter that washes into these ponds, it can have a large effect."

Jim Wilson of Irish Widlife told Newstalk the affect gritting has goes beyond frogs.

"What this study shows is that everything we do can have a knock-on effect", he said. "It's not just frogs. Nobody thinks about what happens to the salt after it's laid down.

"The salt changes freshwater habitats to brackish habitats, and the species living in the water are not geared up for that. Something as innocuous as gritting can cause such a huge environmental change."

The National Biodiversity Centre (NBDC) holds 5096 records of frogs in Ireland.