THE POSSIBLE TRANSPORT OF TRACE METALS VIA MOULTED COPEPOD EXOSKELETONS1

Abstract

Concentrations of Ca, Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, Sr, and Zn in 10 surface‐zooplankton samples were compared with the values determined for 12 samples collected at 100 or more meters. Average values for Cu, Fe, Mn, Ni, Pb, Sr, and Zn were higher in the deep samples. It was postulated that more of these elements had become adsorbed to copepod exoskeletons at greater depths because food‐dependent moulting rates were lower; thus more time was available for elemental adsorption to take place. If this hypothesis is correct, moulted copepod exoskeletons may be important in biogeochemical cycles. Copepods are the most abundant multicellular animals in the world, and there are 11 cast exoskeletons for every adult; these slow‐sinking exuvia may well be capable of taking up elements by adsorption‐exchange long after leaving the living animals. Thus, a large total surface‐area is provided on which important chemical reactions may take place.