Cadmium toxicokinetics and bioaccumulation in turtles: trophic exposure of Trachemys scripta elegans

Ecotoxicological data in reptiles are mainly represented by field studies reporting tissues burden of wild-captured individuals but much less is known on processes of uptake, depuration, accumulation and effects of inorganic contaminants in these species. In this study, females’ Trachemys scripta elegans were exposed to cadmium (Cd) through a CdCl2 supplemented-diet with increased environmental relevant concentrations during 13 weeks and then went through a decontamination phase during 3 weeks being fed uncontaminated food. Blood and feces were collected during the three phases of the experiment and the turtles were sacrificed at the end of the experiment and organs samples collected. The Cd concentrations in blood remained stable over the course of the experiment while Cd concentrations in feces increased with time and with amount of Cd ingested. Assimilation efficiency in liver and kidney together was low (0.7 – 6.1 %) but did occur and Cd accumulated in a dose-dependent manner in organs in the following order of concentrations: kidney>liver>pancreas>muscle. In terms of organs burden, Cd-burden was the highest in liver followed by kidney and pancreas. The assimilation efficiency decreased as Cd ingested increased suggesting that at higher dose of Cd absorption decreased and/or depuration increased. Mineral content of the liver was modified according to Cd level with increased concentrations of zinc and iron with increasing Cd levels. Accumulation of Cd had no effects on survival, food consumption, growth or weight and length suggesting no effect of treatment on females’ body conditions.