Marine Pollution Bulletin 178 (2022) 113607 0025-326X/© 2022 Published by Elsevier Ltd. Baseline The wedge clam Donax trunculus L., 1758 as a bioindicator of microplastic pollution Mohamed Ben-Haddad a , Mohamed Rida Abelouah a , Sara Hajji a , Gabriel E. De-la-Torre b , Hicham Abou Oualid c , Nelson Rangel-Buitrago d, e , Aicha Ait Alla a, * a Laboratory of Aquatic Systems: Marine and Continental Environments, Faculty of Sciences, Ibn Zohr University, Agadir, Morocco b Universidad San Ignacio de Loyola, Av. La Fontana 501, Lima 12, Lima, Peru c Green Energy Park, IRESEN-UM6P, Benguerir, Morocco d Programa de Física, Facultad de Ciencias B´ asicas, Universidad del Atl´ antico, Barranquilla, Atl´ antico, Colombia e Programa de Biologia, Facultad de Ciencias B´ asicas, Universidad del Atl´ antico, Barranquilla, Atl´ antico, Colombia A R T I C L E INFO Keywords: Bivalve Bioindicator Sentinel species Donax trunculus Beach urbanization Coast Morocco ABSTRACT This study describes the use of D. trunculus as a bioindicator of microplastic (MPs) pollution due to beach ur- banization related to the development of the Taghazout Bay tourist resort in Morocco. In six sites located on the coast, MPs densities ranged from 1.75 to 5.93 items per gram of D. trunculus wet weight. MPs contamination was signifcantly infuenced spatiotemporally by the urbanization degree in the area. The shapes found were fbers (90.5%) and fragments (9.5%). The Fourier Transform Infrared Spectroscopy (FTIR) analysis reported two polymers: polyethylene (65%) and polypropylene (35%). MPs colors were dark and light, with a predominance of light blue (23.8%). The species ingested different sizes of MPs, mainly the 0.1 and 0.5 mm fractions. Scanning Electron Microscope coupled with an energy dispersive X-ray analyzer (SEM/EDX) revealed weathered MPs with chemical elements adhered to their surface (Cu, Fe, Mg, S, Cl, etc.). The results of this study recommend the use of D. trunculus as a new bioindicator of MPs pollution following an urban change in the coastal scenery. Also, a sustainable coastal management must be implemented in the study area. The frst known synthetic plastic was invented in 1907: Bakelite. Two years later, the word “plastic” was introduced in the literature to describe all products created from macromolecules (including, among others, resins, elastomers, and artifcial fbers) (Williams and Rangel- Buitrago, 2019). The exponential increase in the production and use of synthetic plastics dates back to the 1950s (Thompson et al., 2009; Geyer et al., 2017). Since then, plastics have become a fundamental and widespread element due to their diverse applications in daily human life. Once plastic materials are discarded and arrive in the environment, they may remain there for hundreds or thousands of years (Geyer et al., 2017). During this time plastics undergo mechanical, chemical and biological degradation, leading to their breakdown into smaller pieces called microplastics - MPs (if size <5 mm) or nanoparticles - NPs (if size <1 μm, Andrady, 2011; Auta et al., 2017). Microplastics are a signifcant threat to all ecosystems (Gracia et al., 2018; Harris, 2020). Their presence entails signifcant pressures on in- dividuals, populations and communities in all trophic levels (Li et al., 2016; Costa et al., 2019; Feng et al., 2020; Matrose et al., 2021; Malakar et al., 2021; Aytan et al., 2022). Because of their small dimensions, MPs become available for inges- tion by many marine organisms such as mollusks (Van Cauwenberghe and Janssen, 2014). Mollusks are rich in nutrition, have high economic value and are easy to breed. They are highly regarded aquaculture resource species, especially bivalves; typical flter feeders constantly fltering out microbes and organic matter from the surrounding water (Xu et al., 2020). Bivalves appear as appropriate integrative sentinel species in several studies (Banaoui et al., 2004; Elazzaoui et al., 2019; Chahouri et al., 2022). They have many advantages justifying their use in eco- toxicological studies because as flter-feeder organisms, they trap accumulating pollutants thanks to their low excretion rates (Jara-Marini et al., 2013; Li et al., 2016). Donax trunculus, a warm-water temperate species, is distributed throughout the Mediterranean and the Atlantic from France to Senegal (Bayed and Guillou, 1985). D. trunculus is common along the central * Corresponding author. E-mail addresses: mohamed.ben-haddad@edu.uiz.ac.ma (M. Ben-Haddad), a.aitalla@uiz.ac.ma (A. Ait Alla). Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul https://doi.org/10.1016/j.marpolbul.2022.113607 Received 6 February 2022; Received in revised form 20 March 2022; Accepted 22 March 2022