Accumulation of Microplastics by the Siberian Wood Frog Rana amurensis (Anura, Amphibia) in the Western Baikal Region

The results of a quantitative assessment of the content of microplastics (MPs) in Siberian wood frog (Rana amurensis) larvae and the gastrointestinal tract (GIT) of adults from the floodplain of the Goloustnaya River flowing into Baikal Lake are presented. MP particles are 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 are 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 is 3.5 ± 3.6 per individual, with a spread from 0 to 11.6 particles. No significant correlations are found between the level of MP accumulation and the age of individuals of different sexes. No MPs are 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, and hay harvesting). The detection of MPs in the GITs of adult Siberian wood frogs indirectly indicates the contamination of the valley and the mouth of the Goloustnaya River, including the coast of Lake Baikal. The data obtained in this study are the first evidence of the presence of MPs in amphibians in the Russian Federation.