Abstract
We investigated uptake of dissolved organic carbon (DOC) by Daphnia pulex by exposing individuals to radiolabeled DOC. Daphnids exposed to DO14C were more radioactive than either control (anesthetized) or unexposed daphnids (P=0.0001), indicating direct uptake of DOC. Waste product radioacitvity was greater than that of exposed daphnids, suggesting that assimilation of DOC is probably low.