Microplastics in intertidal water of South Australia and the mussel Mytilus spp.; the contrasting effect of population on concentration

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

“…Microplastic abundance in the water at Black Point (0.50 microplastics L −1 ) was lower than contamination found in intertidal water across other coastal regions of South Australia, and which ranged from 2.9 to 16.3 microplastics L −1 (Klein et al 2022). However, levels of microplastic in sediment (average 0.36 microplastics g −1 DW) were higher than in coastal areas on the eastern coast of Australia, where microplastics ranged from 0.08 to 0.35 microplastics g −1 DW (Jahan et al 2019).…”

“…Estimates of effluent loads from treated wastewater in Australia can reach up to 133 million microplastics (>25 μm in size) per day (Ziajahromi et al 2021). Despite the low values of microplastic found in this study, communities such as Black Point have seasonal increases in human population over the summer months, and it is worth investigating whether these fluctuations in population density are reflected in the local environment (Klein et al 2022), together with a potential increase in recreational fishing, considering fishing gear may also be a source of microplastic fibres such as polyethylene (Andrady 2011;Silva-Cavalcanti et al 2017).…”

“…Likewise, these trends match global microplastic contamination, where frequency of occurrence and plastic load is generally higher in more populated and urban regions than in isolated areas (Jang et al 2014;Gola et al 2021). In addition to human activity, other factors such as currents, winds and hydrodynamics will also contribute to the spatial variations across regional areas in South Australia (Reisser et al 2013;Klein et al 2022;Ogunola et al 2022;Leterme et al 2023). Nonetheless, accurate comparison of microplastic loads across studies is still difficult because of a wide variety of sampling, laboratory, and quality-control methods (Provencher et al 2020a;Wootton et al 2021b).…”

“…When comparing the contamination of biota from Black Point to other regions, the frequency of occurrence was expectedly low and matched values observed both in Australia and worldwide, namely in regions with lower human presence. For example, 35.5% of fish (Wootton et al 2021a) and 48% of crustaceans (Ogunola et al 2022) across Australian marine waters had microplastic present; however, up to 92% of mussels (Klein et al 2022) and 100% of oysters (Jahan et al 2019) sampled from coastal urban areas contained microplastic. Likewise, these trends match global microplastic contamination, where frequency of occurrence and plastic load is generally higher in more populated and urban regions than in isolated areas (Jang et al 2014;Gola et al 2021).…”

“…Microplastic ingestion has been reported globally, including in wild bivalve molluscs collected along South Australia's coastline (Klein et al 2022), and in South Australian seafood species sold for human consumption (Wootton et al 2021a;Ogunola et al 2022). However, there is still limited research worldwide characterising multiple marine matrices (e.g.…”