Accumulation of microplastics by the Siberian frog Rana amurensis (Anura, Amphibia) in the West Baikal region

The results of the quantitative assessment of the microplastics (MPs) content in the Siberian Wood Frog (Rana amurensis) larvae and gastrointestinal tract (GIT) of adults from the floodplain of the Goloustnaya River flowing into Baikal Lake are presented. MP particles were found in the GITs of 83% (n = 18) of Siberian Wood Frogs aged 1+ to 4+. In the GITs of R. amurensis adults, MP particles were represented by microfibers (84.6%), microspheres (6.2%), microfilms (6.2%), and irregularly shaped fragments (3.0%). The sizes of MPs range from 0.3 to 5 mm. The average number of particles in frog’ GITs was 3.5 ± 3.6 per individual, with a spread from 0 to 11.6 particles. No significant correlations were found between the level of MP accumulation and the age of individuals of different sexes. No MP were found in R. amurensis larvae (n = 120), which is largely due to the low productivity of temporary shallow breeding water bodies in the floodplain of the Goloustnaya River, which are experiencing powerful anthropogenic pressure (transport, grazing, hay harvesting). The detection of MP in the GITs of adult Siberian Wood Frogs indirectly indicates contamination of the valley and the mouth of the Goloustnaya River, including the coast of the Baikal Lake. The data obtained in this study are the first evidence of the presence of MP in amphibians in the Russian Federation.