Abstract
The ocean contamination caused by micro- and nano-sized plastics is a matter of increasing concern regarding their potential effects on marine organisms. This study compared the effects of a 21-day exposure to 1.5, 15, and 150 ng/L of polystyrene microplastics (PS-MP, 3-µm) and nanoplastics (PS-NP, 50-nm) on a suite of biomarkers measured in the Mediterranean mussel Mytilus galloprovincialis. Endpoints encompassed immunological/lysosomal responses, oxidative stress/detoxification parameters, and neurotoxicological markers. Compared to PS-MP, PS-NP induced higher effects on lysosomal parameters of general stress. Exposures to both particle sizes increased lipid peroxidation and catalase activity in gills; PS-NP elicited greater effects on the phase-II metabolism enzyme glutathione S-transferase and on lysozyme activity, while only PS-MP inhibited the hemocyte phagocytosis, suggesting a major role of PS particle size in modulating immunological/detoxification pathways. A decreased acetylcholinesterase activity was induced by PS-NP, indicating their potential to impair neurological functions in mussels. Biomarker data integration in the Mussel Expert System identified an overall greater health status alteration in mussels exposed to PS-NP compared to PS-MP. This study shows that increasing concentrations of nanoplastics may induce higher effects than microplastics on the mussel’s lysosomal, metabolic, and neurological functions, eventually resulting in a greater impact on their overall fitness.
Highlights
IntroductionPlastic is the most prevalently used material in modern society; it supports most socio-economic activities, including household, health, and food sectors, and its production has exponentially soared in the past 70 years, reaching 368 million tons in 2019 [1]
A wide set of biological endpoints were measured in mussels exposed for 21 days to 1.5, 15, and 150 ng/L of polystyrene MP (PS-MP) and polystyrene nanoplastics (PS-NP), including lysosomal biomarker of general stress (LMS, neutral lipids (NL), and lysosome to cytoplasm volume ratio (LYS/CYT)), lipid peroxidation parameters (LF and MDA), antioxidant/detoxification enzymes (GST and CAT activities), neurological (AChE activity) and immunological parameters
This study demonstrated that the 21-day exposure to PS-MP and PS-NP can affect the fitness of the Mediterranean mussel M. galloprovincialis by selectively modulating biochemical, cellular, and physiological processes
Summary
Plastic is the most prevalently used material in modern society; it supports most socio-economic activities, including household, health, and food sectors, and its production has exponentially soared in the past 70 years, reaching 368 million tons in 2019 [1]. The management of plastic waste has emerged as a major environmental issue in the latest decades [2]. According to Pinto da Costa et al [3], 79% of plastics sent to landfills find their way to oceans, for an estimated annual amount of 4.8–12.7 million tons. Plastic polymers do not tend to degrade in marine systems; rather, they experience a swift additive loss with consequent fragmentation into smaller pieces from the effect of weathering forces [2,4,5]. 94% of plastics currently present in oceans are represented by
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