Accumulation of Cd-109 by second-generation chironominae propagated from wild populations sampled from low-, mid-, and high-saline environments

Our objective was to determine if second-generation (F2) chironomids propag ated from adults of larvae sampled from low-, mid-, and high-saline environ ments differed in their ability to accumulate cadmium from their environmen t. Second-generation chironomids cultured from wild populations were expose d to Cd-109 at 0, 0.7, and 4.3 ppt salinity for 10 days, at which time surv ival and amounts of Cd-109 accumulated were determined. Cultures included t wo of Chironomus tentans from a freshwater lake (lake 78; 0 ppt), and the e uryhaline C. athalassicus from a mid- (lake 71; 0.7 ppt) and high (lake 56; 4.3 ppt)-saline environment. A laboratory-reared culture of C. tentans was included as a positive control. Species-dependent accumulation of Cd-109 o ccurred; second-generation C. athalassicus cultured from the high-salinity lake survived in the three salinities and accumulated significantly greater amounts of the radiotracer at 0 and 0.7 ppt compared to the second-generat ion freshwater species, C. tentans. Second-generation C. athalassicus cultu red from lake 71 also survived all salinities with Cd-109 accumulation tend ing to be greater than the freshwater species at the mid-salinity range. In contrast, the freshwater species cultured from lake 78 as well as the labo ratory-reared culture did not survive the highest salinity of 4.3 ppt and a ccumulated less Cd-109 compared to the species from the high-saline environ ments. Species-dependent differences in metal accumulation need to be consi dered in studies that assess metal concentrations in aquatic organisms acro ss an environmental gradient, such as salinity.