Nanoplastic exposure inhibits growth, photosynthetic pigment synthesis and oxidative enzymes in microalgae: A new threat to primary producers in aquatic environment

Abstract

The acute toxicity of graded concentrations of polysterene nanoplastic (PS NPs) spheres (Size 0.1 µm) was evaluated to ascertain the effects of NPs on growth, vital photosynthetic pigments, protein and oxidative stress enzymes. The findings show that PS NPs inhibited the growth of microalgae (Chlorella vulgaris and Spirulina (Arthrospira) platensis) in a dose-dependent manner. The growth inhibition percentage reached 40.12 % for C. vulgaris and 42.57 % for S. platensis, compared to the control. Additionally, pigment content decreased by 31.62 % to 35.06 %, while protein content dropped by 37.27 % to 48.48 % of both the tested microalgae as the concentration of PS NPs in the medium increased. The oxidative stress created by PS NPs was evident from an increase in catalase and peroxidase activity. The findings conclusively endorse that NPs pollution in the aquatic environment will disrupt the functioning of ecosystems through its detrimental effects on microalgae forming the base of the food chain and supporting the successive trophic levels in the aquatic environment. This research will give a deeper insight into the ecotoxicological impacts of NPs in aquatic environments and the baseline information will be helpful in developing an effective strategy for mitigation of plastic pollution with a greater emphasis on nanoplastics.