Investigating microplastic contamination and biomagnification in a remote area of South Australia

Abstract

Context: Microplastics are widespread in aquatic ecosystems and are commonly recorded in water, sediment and a broad spectrum of marine biota. Yet, the extent to which organisms ingest microplastics directly or indirectly by trophic transfer is largely unknown. Aims: This study characterises microplastic abundance across intertidal water, sediment, and marine biota species of different trophic levels, and investigates whether biomagnification occurs. Methods: Water, sediment, molluscs, crustaceans and fish were sampled from a single area in southern Australia. Key results: Microplastics were recorded in 35% of water, 45% of sediment and 39% of biota samples. Plastic load was 0.36 ± 0.08 microplastics g-1 DW for sediment, 0.50 ± 0.17 microplastics L-1 for water, and 0.70 ± 0.25 microplastics individual-1 for biota. Biomagnification was not found, although similarities in plastic characteristics across biota may imply trophic transfer. Most of the microplastics were fibres (97.5%) of blue, black and transparent colour. Spectral analysis (μ-FTIR) indicated that polyester (50%) and polyethylene (42.3%) dominated the polymer compositions. Conclusions: There were no significant differences in microplastic contamination among biota species, with no biomagnification identified. Implications: We provide information on biomagnification of microplastics alongside a still uncommon characterisation of contamination in water, sediment and biota.