Acute exposure of cadmium on Donax trunculus Linnaeus, 1758 (Mollusca Bivalvia) during the vitellogenesis process: histological and biochemical aspects Nawel Kheroufi, Amel Hamdani * & Noureddine Soltani Laboratory of Applied Animal Biology, University Badji Mokhtar of Annaba, 23000 Annaba, Algeria * Corresponding author: a_hamdaniamel@yahoo.fr Biodiversity Journal, 2021, 12 (4): 865–873 https://doi.org/10.31396/Biodiv.Jour.2021.12.4.865.873 Cadmium; oocyte; vitellin; vitellogenin; vitellogenesis. Received 08.09.2021; accepted 20.10.2021; published online 22.11.2021 KEY WORDS ABSTRACT INTRODUCTION Heavy Metals, as elements, are not biodegrad- able; although their chemical state may be altered and form compounds of varying toxicity to aquatic organisms, their toxicity varies according to envi- ronmental conditions (George et al., 2013). Over the last decades, contamination by metallic com- pounds has become a subject of concern world- wide; indeed, marine pollution related to heavy metals raises many concerns for aquatic pop- ulations and humans (Singh et al., 2021; Yap et al., 2021). The Algerian coastline, which extends for more than 1200 km, is considered a coastal ecosystem of great ecological importance. They are home to various animal and plant species. Pollution of these coastal areas by various chemical substances can have serious consequences on the ecological bal- ance (Houma et al., 2011). Previous works have shown that the gulf of Annaba is affected by var- ious heavy metals (Abdennour et al., 2000; Rabei et al., 2018 ; Amira et al., 2018). Indeed, cadmium was particularly detected in sediments and tissues of an abundant edible species Donax trunculus Linnaeus, 1758 (Mollusca Bivalvia Donacidae), in the bay of Annaba (Beldi et al., 2006; Drif et al., 2010; Amira et al., 2018). This species has been used as a bioindicator of marine coastal waters’ quality due to their sedentary and sessile lifestyles. As filter feeders, their tissues tend to bio-accumulate many contaminants at higher levels (Hamdani et al., 2020; Boukari et al., 2021). For many years, cadmium (Cd) has been con- sidered one of the most dangerous toxic heavy metals (Järup, 2003; Xie et al., 2014) because of its intrinsic ionic similarity to calcium. Indeed, marine bivalves can accidentally take up cadmium and pass it into their cells through calcium channels (Vercauteren & Blust, 1999; Shi et al., 2018). It can cause a series of biochemical and physiological dysfunctions both in humans and laboratory ani- This work aims to evaluate the impact of cadmium on the vitellogenesis of Donax trunculus Linnaeus, 1758 an edible Mollusk species, by carrying out a histological study in which the morphometric parameters of the oocytes were measured, and by using vitellogenin (Vtg) and vitellin (Vn) as biomarkers of reprotoxicity. Clams were collected from a clean site (El-Battah) during the period of morphological maturity and reared under laboratory conditions. Cadmium chloride was added to the rearing water at two sublethal concentrations (LC10 and LC25-96h) previously determined. Two-way ANOVA revealed significant effects of Cd concentrations and exposure time on all studied parameters. The data obtained suggest that this metal can act as endocrine-disrupting chemicals in Donax trunculus.