Ocean acidification does not affect the trophic transfer of Ag, Co, and Zn in the cuttlefish Sepia officinalis

Cephalopods are known to efficiently accumulate metals and may therefore play an important role in the trophic transfer of contaminants within marine food webs. However, the influence of environmental changes such as ocean acidification on trace element assimilation and retention in these organisms remains poorly understood. In the present study, the trophic transfer of three trace elements (Ag, Co, and Zn) was investigated in juvenile cuttlefish Sepia officinalis under two seawater pH conditions representative of present-day (pH 7.92) and near-future ocean acidification scenarios (pH 7.63). Using radiotracer techniques and a pulse-chase feeding experiment with radiolabelled shrimp, we quantified assimilation efficiencies, depuration kinetics, and tissue distribution of these elements following a single contaminated meal. Juvenile cuttlefish showed high assimilation efficiencies for all three trace elements: 94-100% for Ag and Co, and 77-78% for Zn. Depuration kinetics revealed element-specific retention patterns, with biological half-lives of several weeks to months for Ag and Zn, whereas Co was eliminated more rapidly. Tissue distribution showed a strong organotropism towards the digestive gland, which acted as the main storage compartment for Ag and Co, while Zn showed a wider distribution across tissues. No significant differences in assimilation efficiencies, depuration kinetics, or tissue distribution were observed between pH treatments. These results suggest that moderate ocean acidification scenarios projected for the coming century are unlikely to significantly affect trophic transfer and internal handling of trace elements in juvenile cuttlefish.