Differential effects of microplastic exposure on anuran tadpoles: A still underrated threat to amphibian conservation?

Abstract

Microplastics (MPs) have been reported to threaten a wide variety of terrestrial, marine, and freshwater organisms. However, knowledge about the effects of MPs on anuran amphibians, one of the most threatened taxa worldwide, is still limited. To assess the effects of MPs on the growth and survival of the Italian agile frog (Rana latastei) and green toad (Bufotes balearicus), we exposed tadpoles to three different concentrations (1, 7, and 50 mg L^-1) of an environmental relevant mixture of microplastics (HPDE, PVC, PS and PES), recording data on their activity level, weight and mortality rates. While the effects of MPs on green toad tadpoles were negligible, Italian agile frog tadpoles were severely affected both in terms of growth and activity level, with high mortality rates even at the lowest MP density (1 mg L^-1). Our results suggest that MP contamination of freshwater habitats may contribute to the ongoing decline of anuran amphibians.

Keywords: Activity level; Bufotes balearicus; Larval growth; Plastic polymers; Rana latastei.