WA3 Metals and Bioaccumulation
254 Portland Ballroom
8:00 AM - 12:00 PM, Wednesday
() Copper homeostasis and sodium turnover in three freshwater fish exposed to waterborne copper.
De Boeck, G1, Hattinck, J1, Blust, R1, 1 University of Antwerp, Antwerp, Belgium
ABSTRACT- We examined effects of sublethal waterborne copper exposure on three freshwater fish: rainbow trout, Oncorhynchus mykiss, common carp, Cyprinus carpio, and gibel carp, Carassius auratus gibelio. The aim of this study was threefold. First, clarify earlier observed differences in uptake, accumulation and excretion of copper between the three species. Using Cu-67, we assessed uptake, internal distribution and excretion of the newly accumulated copper over a three week period. Adding a short-term experiment with Cu-64 isotopes at regular time intervals, allowed taking into account possible effects of acclimation on copper uptake rates. Secondly, Na-22 uptake was tracked in these short-term experiments in order to take a closer look at the disturbance and possible acclimation of ion regulation and to test the hypothesis that sodium turnover rates determine sensitivity to acute copper exposure in freshwater animals. Although earlier experiments showed similar disturbance of absolute plasma sodium concentrations in all species, sodium turnover rates might differ. Possibly the difference in sodium turnover explains the difference in copper sensitivity of our fish. Besides Na-22 uptake, the activity of the most important ion-transporting enzyme, namely Na/K ATPase activity was measured. Copper is known to block the activity of this enzyme, and differences in this event again could help explain differences in sensitivity. Finally, plasma and muscle ammonia and ammonia excretion rates were assessed since increased ammonia production, in combination with impaired ammonia excretion, is thought to be the cause of the reduced swimming capacity under copper exposure.
Key words: accumulation, copper, Na/K ATPase, fish