Microplastic Exposure for Pinnipeds (Pinnipedia): A Rapid Review

The widespread distribution of microplastics (MPs) is causing increasing concern among the scientific community and the public. Marine mammals are considered indicators of the ecological health of marine ecosystems, and many species, suffering from numerous anthropogenic factors, have been granted protected status. Pinnipeds (Pinnipedia) are susceptible to ingestion and bioaccumulation of MPs from their environment, through direct consumption and trophic chain transfer. This literature review describes MP exposure for representatives of the three pinniped families—true seals (Phocidae), eared seals (Otariidae), and walruses (Odobenus)—and is based on 26 studies. Data on MP content was reported in scat in 17 articles, in the gastrointestinal tract (GIT) in 8 articles, and in the blubber in 1 article. Plastic material was detected in 22 studies, with its overall occurrence varying from 0 to 100% of samples. In addition to the quantitative assessment of MP content, one study provides data on the correlation between MP levels in animal organisms and pollution biomarkers such as phthalates and porphyrins. The contemporary experience of studying MP ingestion and MP exposure for pinnipeds (Pinnipedia) is discussed step-by-step, focusing on: (1) collection, (2) extraction, and (3) identification methods. This review provides current and collated information on the methods and results of studies concerning MP exposure for pinnipeds (Pinnipedia), which can serve as a guide for future researchers in this area.