Invertebrate responses to microplastic ingestion: Reviewing the role of the antioxidant system

Microplastics, microfibres and nanoplastics cause variable sub-lethal responses in mussels (Mytilus spp.)

“…In assessing the response of the copepod Paracyclopina nana to 0.05 and 0.5 µm PS-MP, Jeong et al (2017) drew similar conclusions, hypothesising prolonged cellular exposure to microplastics elevated intracellular ROS levels, triggering the activation of antioxidant genes. In this study, the increase in SOD activity after 24 h would indicate micro-and nanoplastics triggered an oxidative challenge; but given SOD activity was normal after 7days exposure, we can infer this oxidative challenge was short-lived and would therefore not have been energetically taxing (Trestrail et al, 2020).…”

“…Superoxide dismutase (SOD) is an antioxidant enzyme that protects cells from toxic reactions with reactive oxygen species (ROS) and free radicals (e.g. O2 -, OH*, HO2*); prolonged increases in antioxidant activity can require energy that takes away from growth and reproduction (Trestrail et al, 2020). Here, SOD activity was significantly influenced by treatment in the gills (two-way ANOVA, treatment: P<0.05; Figure 3A) being significantly increased in response to PS-NP in the 24 h exposure (Tukey, P<0.05).…”

“…We posit that higher plastic concentrations may be sufficient to cause attrition within the gastro-intestinal tract resulting in the abrasion of tissues, leading to cellular damage and lipid peroxidation. It is recognised that oxidative stress responses can be variable, differing with genotype, age, reproductive status, feeding and temperature, and that a broader suite of biomarkers and wider literature should be considered in inferring biological pathways (Magara et al, 2018;Trestrail et al, 2020). Histological studies have shown that microplastics can permeate into the epithelial cells of the digestive gland resulting in epithelial thickening, the formation of granulocytomas and reduced epithelial cilia densities (Bråte et al, 2018;Paul-Pont et al, 2016;von Moos et al, 2012).…”

“…Mussels are omnivorous suspension feeders with proven capacity for consuming microplastics (Ward et al, 2019a). Numerous field-studies have demonstrated that mussels can readily consume microplastic debris under environmental conditions (De Witte et al, 2014;Li et al, 2018;Li et al, 2015;Rochman et al, 2015;Santana et al, 2016;Van Cauwenberghe and Janssen, 2014;Zhao et al, 2018). In mussels, waterborne particles are captured via the gills, with capture efficiency and ingestion dependent upon particle size, shape, hydrophobicity, and aggregation within biogenic matrices (e.g.…”

“…This study sets-out to better understand the risks plastic particulates, varying in shape and size, pose to marine mussels, and highlight differences in the mechanisms of toxic action, caused by microplastics, microfibres and nanoplastics. Microfibres are among the most commonly observed forms of plastic debris in marine samples (Lindeque et al, 2020;Mishra et al, 2019), but are largely underrepresented in ecotoxicological studies on microplastics (Trestrail et al, 2020), and there are relatively few in vivo studies with nanoplastics. Here, acute (24 h and 7-day) exposure studies using the model organism M. edulis were undertaken to compare the effects polystyrene microplastics (spherical beads), polyamide microfibers and polystyrene nanoplastics (spherical beads) can have on mussel health.…”