Frogs exposed to road salt appear to benefit then suffer

Of course, this is relevant to humans, too.

http://ekaweb01.eurekalert.org/pub_releases/2015-08/cwru-fet081715.php

Public Release: 17-Aug-2015
Frogs exposed to road salt appear to benefit then suffer
Tadpole size increases but juvenile survival drops
Case Western Reserve University

Millions of tons of road salt are applied to streets and highways across the United States each winter to melt ice and snow and make travel safer, but the effects of salt on wildlife are poorly understood.

A new study by biologists from Case Western Reserve University suggests exposure to road salt, as it runs off into ponds and wetlands where it can concentrate--especially during March and early April, when frogs are breeding--may increase the size of wood frogs, but also shorten their lives.

Wood frog tadpoles exposed to road salt grew larger and turned into larger frogs at metamorphosis than those raised without being subjected to the contaminant, researchers found.

But, contrary to expectations that larger body mass is associated with greater survival, frogs exposed to salt as tadpoles had a higher mortality rate as juveniles.

"This study really shows that you need to look across multiple life stages to get a good look at what environmental pollutants are doing," said Kacey Dananay, a Case Western Reserve PhD student who led two experiments in the study.

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