Interacting impacts of damming and metal pollution on the Pyrenean Brook Newt, Calotriton asper (Dugès, 1852)

Abstract

The Pyrenean Brook Newt, Calotriton asper, is a key component of the ecosystem in Pyrenean headwater streams. We here describe the effects of metal pollution and damming on a newly discovered population of C. asper by assessing differences in population density and body size of subpopulations above and below the dam, using available environmental data to discern their causes. We found a decrease in population density and body size in the upstream subpopulation due to metal pollution. Water diversion by the dam reduced the metal pollution impact downstream. Water flow reduction and warming due to damming are threats to this C. asper population, and the issue is particularly pressing in the Pyrenees due to the expected reduced water availability caused by climate change. We also tested for chytridiomycosis in this population but did not find any infected individuals despite their proximity to an infected population