Effect of Copper on the Uptake of Carbon from Medium to Daphnia magna

Effect of Cu on the carbon transfer from medium to Daphnia magna has been studied. The concentration of Cu in the medium containing mixed algae was 0.1 ppm, 0.3 ppm and 0.5 ppm. The 13C added in the medium was 20 mg/50mL as NaH13CO3. The temperature in the room used for incubation was controlled at 24°C and the light intensity at the medium (in 50 mL beaker) was about 3000 lux (14 hours: light, 10 hours : dark) . After 24 hour incubation, The Daphnia magna and the phytoplankton were dried and 13C abundance of each sample were measured by a 13CO2 analyzer. The 13C abundance in Daphnia magna were 2.9 atom% excess in control, 1.1 atom% excess in 0.1 ppm, 0.6 atom% excess in 0.3 ppm and 0.6 atom% excess in 0.5 ppm, respectively. And in phytoplankton, they were 6.7 atom% excess in control, 6.5 atom% excess in 0.1 ppm, 6.1 atom% excess in 0.3 ppm and 4.0 atom% excess in 0.5 ppm. The 13C abundance in phytoplankton was not so decreased as in Daphnia magna. The lower 13C abundance observed in Daphnia magna were mainly caused by the less intake of phytoplankton derived by the Cu in the medium.