abstract
Polymethylmethacrylate (PMMA) production has increased almost 20% over the last years. With its release into the aquatic environment, its breakdown or degradation to nano dimensions (nanoplastics-NPLs) due to biological and physical/mechanical action is, theoretically, anticipated. The occurrence of PMMA-NPLs in aquatic ecosystems may thus cause adverse effects particularly to early life stages of amphibians, which may be in contact with PMMA-NPLs suspended in the water column or deposited in upper layers of the sediments. Accordingly, this work aimed at assessing the effects of PMMA-NPLs to aquatic early life stages of the model anuran species Xenopus laevis. To attain this objective, two types of toxicity assays were carried out by exposing embryos [Nieuwkoop and Faber (NF) stage 8-11] or tadpoles (NF 45) to three concentrations of PMMA-NPLs (1, 100 and 1000 pg/L): i) 96-h embryo teratogenicity assay, where survival, malformation, and total body length (BL) of embryos were assessed; and ii) 48-h feeding rate assay, where survival, feeding (FR), malformations and growth rates (body weight-BW and BL) of tadpoles were evaluated. PMMA-NPLs exposure had no significant effects on mortality, malformations of X. laevis embryos but BL was lower at 1000 pg PMMA-NPLs/L. In tadpoles, no effects on survival or FR were observed after exposure to PMMA-NPLs, but significant changes occured in BW and BL. Moreover, anatomical changes in the abdominal region (externalization of the gut) were observed in 62.5% of the tadpoles exposed to 1000 pg PMMA-NPLs/L. Despite the lack of knowledge regarding the environmental levels of NPLs, it is expected that sediments constitute a sink for these contaminants, where they can become available for organisms that, like tadpoles, feed on the organic matter at the surface of sediments. Considering the continuous release and subsequent accumulation of PMMA, the malformations obtained in the feeding assays suggest that, in the future, these nano-polymers may constitute a risk for aquatic life stages of amphibians. (c) 2021 Elsevier B.V. All rights reserved.
keywords
POLYSTYRENE NANOPARTICLES; JELLY COAT; EMBRYOS; QUANTIFICATION; POLYMERIZATION; MICROPLASTICS; ACCUMULATION; PARTICLES; RADIATION; TOXICITY
subject category
Environmental Sciences & Ecology
authors
Venancio, C; Melnic, I; Tamayo-Belda, M; Oliveira, M; Martins, MA; Lopes, I
our authors
Manuel António Martins da Silva
Researcheracknowledgements
Thanks are due to CFE (UIDB/04004/2020) and CESAM (UIDB/50017/2020 + UIDP/50017/2020) , FCT/MEC through national funds, and co-funding by the FEDER (POCI-01-0145-FEDER-00763) , within the PT2020 Partnership Agreement and Compete 2020. This study was also supported by the project GOGOFROG (POCI-01-0145-FEDER-030718) and the COST Action PERIAMAR (CA18221) . C. Venancio is a contracted researcher (REF: IT057-18-7484) . M. Oliveira has financial support of the program Investigator FCT, co-funded by the Human Potential Operational Programme and European Social Fund (IF/00335/2015) .