Comparative assessment of nutritional quality and ecotoxicological biomarkers in Paphia textile clams from the coastal areas in Egypt

Abstract

Paphia textile, a commercially vital clam species in Egyptian coastal waters, serves as both a nutritional resource and bioindicator of marine pollution. This study evaluates the spatial variability of proximate composition, fatty acid profiles, elemental and heavy metal concentrations (Cu, Zn, Pb, Cd, Hg), oxidative stress biomarkers (SOD, CAT, GPx, MDA, MT), and genotoxicity (comet assay) in P. textile from Ismailia and Alexandria. Clams from Ismailia exhibited superior nutritional value, with higher protein (0.49 ± 0.06 g/g; p < 0.01) and carbohydrate (0.32 ± 0.04 g/g; p < 0.01) content, alongside significant (p < 0.01) elevated antioxidant enzyme activity (SOD: 3.81 ± 0.43 U/mg; CAT: 2.85 ± 0.68 U/mg; GPx: 59.71 ± 5.09 U/mg), reflecting lower environmental stress. In contrast, Alexandria samples showed heightened oxidative damage (p < 0.05), marked by elevated MDA (41.02 ± 2.91 nmol/mg protein), MT (208.42 ± 9.45 µg/g), and significant DNA damage (tail DNA%: 7.8 %; tail moment: 4.8 units). Although health risk indices were below the threshold limit (THQ < 1; TCR < 1 ×10⁻⁶), heavy metal concentrations, particularly Pb (0.13 ± 0.07 µg/g) and Hg (0.065 ± 0.025 µg/g), were higher in Alexandria highlighting greater dietary hazards despite containing beneficial fatty acids like DHA. Overall, clams from Ismailia demonstrated superior nutritional value and lower health risk, while Alexandria samples reflected greater environmental contamination. These findings highlight the need for continuous environmental monitoring and reinforce Paphia textile as an effective bioindicator for coastal pollution and food safety assessment.