In vivo effect of metals in clams Ruditapes decussatus: A multi-marker approach

This study aimed to evaluate the differential biochemical responses of the clam Ruditapes decussatus exposed to cadmium (Cd) and copper (Cu), testing the hypothesis that these contaminants induce tissue-specific alterations in oxidative stress and energy metabolism.

Materials and methods: Specimens of Ruditapes decussatus were collected from the Hnaya region (western Annaba, Algeria), acclimated for 48 h, and then exposed for seven days in triplicate experimental conditions (three aquaria, six individuals per aquarium) to 200 µg/L Cd and 30 µg/L Cu. These concentrations were selected based on published data, representing polluted coastal environments, and are commonly used in laboratory ecotoxicological studies to induce measurable biochemical responses under short-term exposure. Experimental conditions were maintained constant (16 ± 2 °C; salinity: 37 psu; photoperiod: 12 h light/12 h dark), with regular renewal of seawater and metal solutions. Gills and digestive glands were analysed for reduced glutathione (GSH), lipid peroxidation (MDA), total lipids, and proteins. Data were analysed using two-way ANOVA followed by appropriate post hoc tests (p < 0.05).

Results and discussion: Cadmium exposure induced a significant increase in MDA associated with a decrease in GSH, indicating marked oxidative stress, particularly in the digestive gland. This suggests enhanced utilisation of GSH in detoxification processes. Copper exposure induced tissue-dependent responses, including an increase in GSH in some cases, suggesting the activation of antioxidant defence mechanisms potentially related to oxidative stress. Variations in lipid and protein contents indicate disturbances in energy metabolism under metal exposure. The digestive gland appeared more sensitive than gills, consistent with its role in detoxification and storage functions.

Conclusion: Overall, these results highlight the involvement of multiple antioxidant defence pathways and underline the complexity of the relationship between oxidative stress and energy metabolism in Ruditapes decussatus exposed to trace metals. The multi-biomarker approach provides valuable insights for ecotoxicological assessment of contaminated coastal environments.