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(P299) Metal body burdens versus Ceriodaphnia dubia reproduction.
SOFYAN, AGUS*,1, BIRGE, WESLEY1, SHAW, JOSEPH2, 1 University of Kentucky, Lexington, KY, U.S.A.2 Darmouth College, Darmouth, NH, U.S.A.
ABSTRACT- We investigated the effects of four metals (i.e, cadmium, chromium, copper and silver) on reproduction of Ceriodaphnia dubia using the U.S. EPA three-brood test. Metal body burdens from water column exposure followed similar trends for all four metals used in the experiment where C. dubia body burdens increased dose dependently. Dietary exposure, on the other hand, did not give a specific trend for the four metals used. Dietary cadmium and copper gave a similar trend where body burden in C. dubia increased dose-dependently at lower to medium dietary exposure concentrations ≤0.56 and 74.74 g /g algae (Dry Weight) for cadmium and copper, respectively, but decreased sharply at higher dietary concentrations. However, body burdens in C. dubia from dietary chromium remained elevated at higher dietary concentration, whereas body burdens in C. dubia from dietary silver remained high at the highest dietary exposure used. Metal body burdens from water column exposures correlated well with C. dubia reproduction; on the other hand, metal body burdens from dietary exposures did not correlate well with C. dubia reproduction. These results suggested that dietary metals might have affected the digestive system before building up in the body. It caused the C. dubia to avoid the food. Results from feeding experiment showed that dietary metals exposure decreased animal feeding as much as 87, 60, 68, and 73% for dietary cadmium, chromium, copper and silver, respectively. These could indirectly affect C. dubia reproduction due to the low energy input. Ignoring feeding impairment, critical body burdens that gave significant effects on C. dubia reproduction were 2.08, 4.00, 8.55, and 0.001 g/g DW for cadmium, chromium, copper, and silver respectively. Based on critical body burdens, metal toxicity followed the order: silver >> cadmium > chromium > copper.
Key words: dietary exposure , water column exposure , critical body burdens, C dubia reproduction
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