RETRACTED: Uptake and excretion of cobalt in the crustacean Portunus trituberculatus (Retracted article. See vol. 269, pg. 1168, 2011)

An experimental study of the uptake of trace elements from water was undertaken to develop a technique for setting labelled crab (Portunus trituberculatus) fry free in the sea. Ten elements, Mn, Co, Cs, La, Pr, Sm, Eu, Gd, Dy and Ho, were used for the test. Three concentrations, 0.1, 0.01 and 0.001 ppm, were used for each element, and mixtures of all 10 elements with the same concentration were used. Fry were reared in water containing the 10 added elements for two weeks, living crabs were sampled just after the end of marking, and after one month natural rearing. The intake of elements was then studied by NAA. The intake of elements was successful and no effects on the survival rate and growth were detected. Just after the marking period and sample preparation, the concentrations of elements taken into and adsorbed onto living crabs reflect the concentrations applied, and after one month of natural rearing, there were no significant differences between the treated crabs and the controls. Marking crustacea with elements in this manner has not yet been shown to be unrealistic. It was found that there is a large volatile component of Co compounds that is missed by normal measurement methods in the early stages of neutron activation gamma-ray measurement. The non-volatile Co compound component reflected treated concentrations. The volatile Co compound component is thought to be derived from organic Co chelates (e.g., vitamin B-12) which are essential for living tissue. On the other hand, the non-volatile Co compound component is thought to originate from the inorganic Co compound CoCl2 which was added for the marking experiments.