Bioaccumulation, organotropism and fate of cadmium in Gammarus fossarum exposed through dietary pathway

Despite a good knowledge of cadmium accumulation in Gammarus fossarum, studies to date have focused on Cd accumulated via the dissolved pathway, leaving aside the trophic pathway. The aim of this study was to assess cadmium organotropism and bioaccumulation processes following a trophic exposure of the species Gammarus fossarum. Adult male gammarids were fed with ¹⁰⁹Cd contaminated alder leaves discs for 6 days and then with clean alder leaves for 12 days. During both phases, some gammarids were collected and dissected, and intestines, hepatopancreas, cephalons, gills and remaining tissues were separated to measure their Cd concentrations. Their relative proportions of Cd and their respective BMFs were estimated. The ingestion rate (IR) measured during the exposure phase was divided by 3 between days 2 and 6, indicating that gammarids reduced their feeding activity and therefore the exposure pressure. A multi-compartments TK model was developed, and an iterative inference process was run to select the most parsimonious model that best fits all organ datasets simultaneously. The results showed that: i) intestine and hepatopancreas bioconcentrate Cd the most; ii) no cadmium was quantified in gills, meaning that they do not appear to play a role in Cd storage or elimination with a trophic exposure; iii) Cd elimination occurs only through the intestine; and iv) the general pattern of Cd fate in gammarids, obtained here after dietary highlights once again the importance of the intestine and hepatopancreas, as for the dissolved pathway.