Single and combined effects of phenanthrene and polystyrene microplastics on oxidative stress of the clam (Mactra veneriformis)

Toxicity of single organic pollutants or microplastics on organisms have been reported widely, however, their combined toxicity on bivalves was rarely investigated. In this paper, single and combined effects of phenanthrene (Phe, 20 mu g.L-1 and 50 mu g.L-1) and polystyrene (PS, 17 mu m and 150 mu m with 1 mg.L-1) microplastics on oxidative stress of the clam Mactra veneriformis were assayed under laboratory conditions with biomarkers including superoxide dismutase (SOD), glutathione-S-transferase (GST) and malondialdehyde (MDA). We found that Phe or PS single stress source could induce oxidative stress to clams. Besides, exposed to Phe 50 mu g.L-1 or PS 150 mu m caused the reduced expression of SOD and GST activities, leading to potential oxidative injury in clams. At each Pheconcentration level, the order of single and combined toxicity on clams was Phe+PS150 mu m> Phe approximate to Phe+PS 17 mu m. Phe exhibited a stronger toxic effect on clams than PS. Under joint exposure stress, the toxicity influence of Phe is still dominant. Furthermore, MDA and GST could be considered the most sensitive oxidative stress biomarkers in clams under Phe or PS single and combined exposures, respectively. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The research found that Phe or PS single stress sources can induce oxidative stress in clams. Exposure to Phe 50 μg/L or PS 150 μm caused reduced expression of SOD and GST activities, potentially leading to oxidative injury in clams. Under joint exposure stress, the toxic effect of Phe is still dominant, with MDA and GST identified as the most sensitive oxidative stress biomarkers in clams under single and combined exposures of Phe or PS.