Microplastic ingestion in commercial and shark species in the western Mediterranean Sea

Abstract

Samples of Mullus surmuletus and Galeus melastomus were obtained with commercial bottom trawling vessels in two areas of the Balearic Islands (western Mediterranean). Both species were seen to ingest microplastics, mainly blue filaments. However, analyses under the stereomicroscope and FTIR analyses revealed film type microplastics in gastrointestinal guts of G. melastomus and not in M. surmuletus. Microplastic ingestion ranged from 0.04 ± 0.04 to 0.92 ± 0.29 MPs/fish. According to M. surmuletus, highest percentage of affected individuals were given in the southwest area while for G. melastomus, percentage of affectation was highest in the northwest area. Variability of the results remark the need of sampling at multiple geographical scales and integrate different species in order to improve the approach to study micro-plastics in marine biota. In addition, chemical biomarkers were analysed for M. surmuletus, providing preliminary data on the response of antioxidant enzymes – catalase and superoxide dismutase, detoxification enzyme glutathione s-transferase (GST) and malondialdehyde (MDA) levels to microplastic ingestion