HEAVY-METALS IN THE SEA-SKATER HALOBATES-ROBUSTUS FROM THE GALAPAGOS-ISLANDS - CONCENTRATIONS IN NATURE AND UPTAKE EXPERIMENTS, WITH SPECIAL REFERENCE TO CADMIUM

Samples of Halobates robustus Barber (Heteroptera: Gerridae) from the Galápagos Islands were analysed by optical emission spectrometry. The levels (in μg g-1 dry weight) of Zn (134), Cu (155), Pb (< 1), Cd (7), and Cr (3) were not significantly different among insects of different sexes or developmental stages. The low natural levels of Cd in H. robustus from the relatively unpolluted environment of the Galápagos Islands are compared to the high concentrations of Cd in Halobates spp. from relatively polluted regions. Since the measured levels of Cd in their natural zooplankton food rarely exceed 10 μg g-1, and very little of the Cd is found in the soft tissues, the high Cd concentrations (100 to 200 μg g-1) in some seaskater species have evidently been derived by drinking from the surface microlayer of the seawater. © 1979 Springer-Verlag.