Crustaceans from the Mediterranean Sea: Possible Sentinel Species for Metal Pollution in Aquatic Environments

Introduction: The marine environment is an ecosystem where toxic metals can accumulate, affecting the health of aquatic organisms. Filtrating species, such as crustaceans, can be considered sentinels of marine environmental pollution. The aim of this study was to evaluate the presence of toxic metals in crustaceans, crabs, and shrimps from the Mediterranean Sea.

Methods: The study was carried out on the carapace and pulp of various crabs, including warty crab (Eriphia verrucosa), brown crab (Cancer pagurus), and marbled crab (Pachygrapsus marmoratus), and on carapace and abdomen of pink shrimp (Parapenaeus longirostris), collected along the Sicilian coastlines. All samples were digested with HNO₃ and H₂O₂ and analyzed in ICP-MS for the determination of Hg, Cd, Pb, and As. Data were considered significant at p < 0.05 and p < 0.01.

Results: The results confirmed the presence of toxic metals in all crustacean samples, with the highest concentration of Hg and Pb, an intermediate concentration of As, and the lowest of Cd. The metal content was higher in the carapace than in the pulp of crabs and in the abdomen of shrimps. In particular, in the carapace pulp of E. verrucosa, Hg (0.543 ± 0062 mg/Kg) and Pb (0.554 ± 0.016 mg/Kg) were higher than MRL of 0.50 mg/kg, while in C. pagurus, only the Pb levels were higher (0.671 ± 0.062 mg/Kg) [1]; in both crabs and shrimps, As was higher than the MRL of 0.10 mg/kg [2]. However, the Metal Pollution Index (MPI), which calculates the metal accumulation in each organ and tissue, was < 1 (the safety level) in crabs and shrimps.

Conclusions: The results obtained confirmed that crabs and shrimps can be valid sentinel species of the Mediterranean Sea. Metal pollution is correlated to its exposure in the aquatic environment and the residual levels of Hg, Pb, and As, higher than the MRLs, also represent a potential toxicological risk for consumers.

REFERENCES: [1] EU Regulation 2023/915; [2] Commission Regulation (EU) 2025/1891.