Osmoregulatory responses to cadmium in reference and historically metal contaminated Gammarus fossarum (Crustacea, Amphipoda) populations. (August 2017) - Dayras, Paul
Abstract: In order to better understand the variable sensitivities of crustaceans to metals, we investigated the impact of cadmium exposure in 3 populations of Gammarus fossarum from different rivers of France. The first population lives in a Cd-contaminated river from a geochemical background, while the others inhabit Cd-free sites. Osmoregulation, a relevant biomarker to evaluate crustacean health following metal contamination, was used as a proxy to evaluate the intra- and inter-populationnal sensitivities to Cd. Specimens from each population were experimentally exposed to 9 μg Cd 2+ /L Cd for 7 days and hemolymph osmolality (HO) was then individually measured. In exposed populations, high inter-individual variations in HO values were noted, resulting in their separation into non-impacted and slightly or highly Cd-impacted (with lower HO) animals. In gills of impacted organisms, deep histopathological alterations and protein overexpression of Na + /K + -ATPase and V-H + -ATPase were observed through histology and immunolocalization, while non-impacted animals showed profiles comparable to controls. Moreover, the osmoregulatory processes in the population living in the Cd-contaminated site were impacted by acute Cd exposure in the laboratory as much as for one of the two populations originating from Cd-free sites. The observed changes did not reveal any obvious adaptive osmoregulatory phenomena at the population scale, but they may be due to differences in fitness between individuals and between populations in relation to the features of their respective environments, unrelated with the presence of the metal. Highlights: Osmoregulatory responses to Cd were studied in 3 Gammarus populations. One population lives in a Cd-contaminated river, the others inhabit Cd-free sites. High inter-individual variations in osmoregulation were noted in 2 populations. Gills of Cd-impacted animals showed histopathology, ion transporters overexpression. No obvious correlation was found between osmoregulatory responses and sampling sites.