Trace metal concentrations in post-hatching cuttlefish Sepia officinalis and consequences of dissolved zinc exposure

International audienceIn this study, we investigated the changes of 13 trace metal and metalloid concentrations (i.e. Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, V, Zn) and their subcellular fractionation in juvenile cuttlefish Sepia officinalis reared in controlled conditions between hatching and 2-months post-hatching. In parallel, metallothionein concentrations were determined. Our results highlighted contrasting changes of studied metals. Indeed, As and Fe concentrations measured in hatchlings suggested a maternal transfer of these elements in cuttlefish. The non-essential elements Ag and Cd presented the highest accumulation during our study, correlated with the digestive gland maturation. During the 6 first weeks of study, soluble fractions of most of essential trace metals (i.e. Co, Cr, Cu, Fe, Se, Zn) slowly increased consistently with the progressive needs of cuttlefish metabolism during this period.In order to determine for the first time in a cephalopod how metal concentrations and their subcellular distributions are impacted when trace metal exposed, we studied previously described parameters in juveniles exposed to dissolved Zn at environmental (i.e. 50 µg l-1) and sublethal (i.e. 200 µg l-1) levels. Moreover, oxidative stress (i.e. glutathione S-transferases (GST), superoxide dismutase (SOD), catalase, lipid peroxidation (LPO)) was assessed in digestive gland and gills after 1 and 2 months exposures. Our results highlighted no or low ability of this stage of life to regulate dissolved Zn accumulation during all studied period, consistently with high sensitivity of this organism. Notably, Zn exposures caused a dose-dependent Mn depletion in juvenile cuttlefish, and an increase of soluble fraction of Ag, Cd, Cu without accumulation modifications, suggesting substitution of these elements (i.e. Mn, Ag, Cd, Cu) by Zn. In parallel, metallothionein concentrations decreased in individuals the most exposed to Zn. Finally, no perturbations in oxidative stress management were detected in gills, whereas level modifications of GST, SOD and catalase activities were recorded in digestive gland, resulting in LPO content increase after 6-week exposure at low Zn concentration. Altogether, these perturbations are consistent with previously described high sensitivity of juvenile cuttlefish towards Zn. Our results underlined the need to study deeply contamination impact on this animal at this stage of life