Assessment of metal contamination and shell mineralogy in the snail Bulla ampulla from Great Bitter Lake, Egypt

• Water pollution was monitored in Great Bitter Lake by snails. • Chemical analysis of shell and soft tissue was used for heavy metals evaluation. • Metals accumulations were higher in soft tissue than in shell of snails. • The heavy metals bioaccumulation is high in early ages snails. • The mineral composition of the shell is aragonite at all stages. The present study assesses the ecological role of the snail Bulla ampulla at different ages via shell mineralogy progress and Fe, Al, Pb, Cd metals bioaccumulation in their soft tissues and shells. Inductive coupled plasma (ICP-OES) was employed to analyze metal bioaccumulations in the soft tissue and shell of size-classified snails, while shell minerology was determined using XRD and FTIR. Results demonstrated that metal bioaccumulation was highly tissue- and size-dependent. Soft tissues accumulated significantly higher concentrations of Fe, Al, and Pb than shells (P < 0.01), with the highest mean concentration found in small individuals (Fe: 152.8 ± 1.4 μg/g; Al: 81.3 ± 0.9 μg/g). In contrast, Cd accumulated at low concentrations across all snails’ soft tissue and shells (<0.25 μg/g), indicating the low quality of this species as a bioindicator for Cd in their ambient environment. Mineralogical analysis confirmed that the shell structure was pure aragonite with traces of chitin across all snail sizes, indicating structural conservation despite metals accumulation. We conclude that Bulla ampulla , particularly small-sized individuals, is a robust local bioindicator for Fe, Al, and Pb pollution at Great Bitter Lake, and we recommend size-standardization as a critical protocol for future biomonitoring studies in the region.