First evidence of microplastics in the Marine Protected Area Namuncurá at Burdwood Bank, Argentina: a study on Henricia obesa and Odontaster penicillatus (Echinodermata: Asteroidea)

Abstract

Large quantities of microplastics end up in the marine environment, constituting a potential threat for many organisms even in remote protected areas where the extent of this type of pollution is still unknown. This study evaluated for the first time the occurrence of microplastics in benthic organisms from the Marine Protected Area Namuncurá at Burdwood Bank, Southwest Atlantic Ocean. Microplastics were isolated from the soft tissue of the sea stars Henricia obesa and Odontaster penicillatus using an oxidative treatment with hydrogen peroxide. The chemical composition of the particles was identified with Raman spectroscopy. Fibers and fragments were found in similar proportions in both species. Fibers were identified as semi-synthetic cellulose, while the polymeric composition of fragments was masked by the synthetic pigment Phthalo blue. Over half of the sea stars contained microplastics (61%). In H. obesa, the mean abundance was 1.00 ± 1.03 particles per individual and 3.34 ± 4.13 particles per gram, and in O. penicillatus, the mean abundance was 2.70 ± 2.91 particles per individual and 1.94 ± 2.09 particles per gram. Fibers were predominantly blue, and all fragments were bluish/turquoise. Microplastic sizes ranged from 24 to 1340 µm, and most particles (approximately 90%) were less than 1 mm. These results provide a baseline assessment of the abundance and type of microplastics in benthic organisms from this sub-Antarctic protected area and contribute to the scant data on microplastic pollution in the South Atlantic Ocean.