Effects of Nanoplastics, Lithium, and Their Mixtures on Corbicula fluminea: Preliminary Findings Rafaela S. Costa, Patrícia Oliveira, and Lúcia Guilhermino Abstract The effects of polystyrene nanoplastics (NP), lithium (Li), and their mixtures were investigated using the exotic invasive bivalve Corbicula fluminea as test organism for ethical reasons. In a 96 h laboratory bioassay, groups of bivalves were exposed to water (control), 0.8 mg/L NP, 3.2 mg/L NP, 1 mg/L Li, 4 mg/L Li, 0.8 mg/L NP + 1 mg/L Li (Mix1) or 3.2 mg/L NP + 4 mg/L Li (Mix2). Effect criteria were filtration rate (FR), lipid peroxidation levels (LPO), and the activity of the enzymes cholines- terases (ChE), isocitrate dehydrogenase (IDH), octopine dehydrogenase, glutathione S-transferases and glutathione reductase. Bivalves exposed to NP alone or in mixture had IDH activity inhibition (22%), and LPO reduced by 33%. Bivalves exposed to Li alone or in mixture had 22% of ChE inhibition. Bivalves exposed to Mix2 had FR induction (twofold). These results suggest that the NP tested may decrease the cellular energy production by anaerobic pathways despite providing some reduction of lipid oxidative damage that Li has anticholinergic effects, and that NP and Li may cause toxicological interactions in bivalves exposed simultaneously to the two substances. Further studies are needed to understand potential toxi- cological interactions between NP and Li under different abiotic conditions and exposure periods. Keywords Nanoplastics  Lithium  Bivalves  Corbicula fluminea  Biomarkers 1 Introduction Microplastics (MP) are global pollutants of high concern. In the environment, MP are fragmented into smaller particles eventually reaching dimensions in the nanoscale known as nanoplastics (NP). NP used in several applications are also introduced in the environment. NP are considered an emerging environmental threat (Lehner et al. 2019). More knowledge on the effects of NP and their toxicological interactions with common contaminants is needed. Lithium (Li) is a widely used metal (e.g., medicine, several indus- tries, batteries) and a common contaminant that is toxic to aquatic species at ecologically relevant concentrations. Therefore, investigating the toxicological effects of NP, Li, and their mixtures is of interest. Corbicula fluminea is an exotic invasive species in Eur- ope and other regions and is considered an adequate bioindicator (Oliveira et al. 2015a), including in relation to MP pollution (Su et al. 2018), and a good test organism (Oliveira et al. 2015b). Its use in environmental assessments helps to control bioinvasions and avoids the use of native species (Guilhermino et al. 2018). C. fluminea uptakes dif- ferent types of MP (Li et al. 2019) and was used to assess the effects of some MP (Guilhermino et al. 2018; Oliveira et al. 2018) and NP (Rochman et al. 2017). The goal of the present study was to conduct a prelimi- nary assessment of the effects of polystyrene NP, Li, and their mixtures using C. fluminea as test organism to avoid the use of Portuguese native bivalves for ethical reasons. R. S. Costa  P. Oliveira  L. Guilhermino (&) ICBAS—Institute of Biomedical Sciences of Abel Salazar, Department of Populations Studies, Laboratory of Ecotoxicology and Ecology (ECOTOX),, University of Porto, Porto, Portugal e-mail: lguilher@icbas.up.pt R. S. Costa  P. Oliveira  L. Guilhermino CIIMAR—Interdisciplinary Centre of Marine and Environmental Research, Research Team of Ecotoxicology, Stress Ecology and Environmental Health (ECOTOX), University of Porto, Porto, Portugal © Springer Nature Switzerland AG 2021 M. Abrunhosa et al. (eds.), Advances in Geoethics and Groundwater Management: Theory and Practice for a Sustainable Development, Advances in Science, Technology & Innovation, https://doi.org/10.1007/978-3-030-59320-9_57 279