PARENT SESSION

3D - Exposure and effects of environmental contaminants in marine organisms
Hall 7
8:30 AM - 12:30 PM, Tuesday, 29 April 2003
Chair: Scholz, N.¹, ¹
Co-chair: Karbe, L.², ²

(TU7/8) Uptake of cadmium in Marine Copepods: active uptake vs. diffusive transport.

Hattink, Jasper¹, Granmo, Åke², ¹ University of Antwerp, Antwerpen, Antwerpen, Belgium² Göteborg University, Göteborg, Bohuslän, Sweden

ABSTRACT- The study to the environmental and ecotoxicological behaviour of cadmium is a longstanding one. In the last decade, subject of dispute is the transport mechanism of waterborne cadmium in marine organisms. The present work focuses on the uptake of cadmium from water by pelagic copepods. This route may present an important part of the accumulation of cadmium in these small crustaceans. Copepods were sampled from the field during copepod blooms dominated by Acartia clausi (>90%). In order to reveal the mechanism of Cd uptake, accumulation and sorption onto the exoskeleton were determined at different salinities, cadmium concentration, and temperature. The results indicated that i) the free cadmium ion is the only cadmium form transported over the cell membrane, ii) the uptake mechanism is characterised by a saturable part and a linear part. The saturable part is characterised by a maximum free Cd uptake rate of 0.27 mol/g/h dw and an affinity constant of 0.29 mol/l. The linear part shows an uptake rate constant of 0.09 l/g/h dw. At environmental realistic concentrations, the saturable part is responsible for the uptake of Cd in copepods. The saturable part showed a relation with temperature, characterised by a Q10-factor of 3, indicating biological processes involved. This mechanisms is most likely involved in calcium regulation, but this was not tested in the present study.

Key words: uptake kinetics, cadmium, zooplankton, copepodae