abstract
Plastics, particularly microplastics (MPs) and nanoplastics (NPs), have been regarded as pollutants of emerging concern due to their effects on organisms and ecosystems, especially considering marine environments. However, in terms of NPs, there is still a knowledge gap regarding the effects of size and polymer on marine invertebrates, such as benthic organisms. Therefore, this study aimed to understand, regarding behavioural, physiological, and biochemical endpoints (neurotransmission, energy metabolism, antioxidant status, and oxidative damage), the effects of 50 nm waterborne polymethylmethacrylate (PMMA) NPs (0.5 to 500 mu g/L) on the marine benthic polychaete Hediste diversicolor, a key species in estuarine and coastal ecosystems. Results demonstrated that worms exposed to PMMA NPs had a shorter burrowing time than control organisms. Nevertheless, worms exposed to PMMA NPs (0.5 and 500 mu g/L) decreased cholinesterase activity. Energy metabolism was decreased at 50 and 500 mu g/L, and glycogen content decreased at all concentrations of PMMA NPs. Enzymes related to the antioxidant defence system (superoxide dismutase and glutathione peroxidase) displayed increased activities in H. diversicolor specimens exposed to concentrations between 0.5 and 500 mu g/L, which led to no damage at the cell membrane and protein levels. In this study, polychaetes also displayed a lower regenerative capacity when exposed to PMMA NPs. Overall, the data obtained in this study emphasize the potential consequences of PMMA NPs to benthic worms, particularly between 0.5 and 50 mu g/L, with polychaetes exposed to 50 mu g/L being the most impacted by the analysed NPs. However, since sediments are considered to be sinks and sources of plastics, further studies are needed to better understand the impacts of different sizes and polymers on marine organisms, particularly benthic species.
keywords
ELECTRON-TRANSPORT SYSTEM; NEREIS-DIVERSICOLOR; SUBLETHAL PREDATION; MYTILUS-EDULIS; IN-VITRO; MICROPLASTICS; EXPOSURE; ACETYLCHOLINESTERASE; BIOACCUMULATION; INVERTEBRATES
subject category
Marine & Freshwater Biology; Toxicology
authors
Silva, MSS; Pires, A; Vethaak, AD; Martínez-Gómez, C; Almeida, M; Pinto, R; Figueira, E; Oliveira, M
our authors
Ricardo Pinto
Researcheracknowledgements
Thanks are due to Portuguese Fundacao para a Ciencia e a Tecnologia (FCT)/MCTES for the financial support to CESAM (UIDP/50017/2020+UIDB/50017/2020+LA/P/0094/2020) and the project Nano-Planet (DOI: 10.54499/2022.02340.PTDC) through national funds. Marta Silva benefited from PhD grant (2020.06496.BD) , given by the National Funds through FCT. AP was funded by national funds (OE) through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.