Multi-specific assessment of microplastic ingestion by Antarctic fish from the Ross Sea (Southern Ocean)

Abstract

Microplastics contaminate all places on Earth, including remote areas such as polar regions. To date, our knowledge on the impact of synthetic materials on the Antarctic ecosystems is still very limited. To the best of our knowledge and considering the number of individuals analyzed, this study provides the largest assessment currently available of microplastic ingestion by Antarctic fish, including the first evidence of microplastics occurrence in Chionodraco hamatus, Pagothenia borchgrevinki, and Trematomus newnesi. The analysis of 145 samples of seven different species from the Ross Sea (Southern Ocean) reveals diffuse contamination in three important locations such as Tethys Bay, Silverfish Bay, and Inexpressible Island. The overall frequency of microplastic ingestion (32.4 % of individuals examined) is similar to the averages estimated for non-polar marine environments on a global scale. In contrast, the average ± se number of microplastics per individual (0.53 ± 0.04) results to be lower. Differences in habitat use and feeding habits appear to underlie the different ingestion rates across species, with cryopelagic planktivores and demersal piscivores being more exposed to microplastics than benthopelagic planktivores and demersal benthivores. Furthermore, the microplastic ingestion rates detected in white-blooded species are higher than those found in red-blooded species. This evidence suggests that the physiology of these organisms may alter the detection of microplastic ingestion events, indicating that the low metabolic rates that characterize species lacking hemoglobin could determine an increase in the retention time of microplastics in internal organs, raising concern for the possible impacts of these contaminants on cold-adapted species.