Abstract
We measured the influence of two food-related variables, prey type and ingestion rate, on Cd uptake by larvae of the aquatic insect Chaoborus punctipennis. Larvae collected from a low-Cd lake (0.1 nM total dissolved Cd) were held in the laboratory where they were exposed to water and to various quantities of either copepods (Diaptomus minutus) or cladocerans (Diaphanosoma birgei) from a high-Cd lake (1 nM total dissolved Cd). The Cd content of larvae exposed to the metal in water only did not increase, confirming the results of previous experiments in which food was demonstrated to be the major Cd source for C. punctipennis larvae. Prey type did not influence predator Cd content, likely because Cd concentrations in the two prey types were approximately the same (~10 µg Cd·g-1) and because Cd was assimilated with the same efficiency by the predator from the two prey types. Cadmium assimilation efficiencies were greater at low prey ingestion rates (nearly 100%) than at high prey ingestion rates (~30%), which is likely explained by a shorter residence time of food in the gut at high prey consumption rates.
Published Version
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