Effects of copper on branchial ionoregulation in the rainbow trout,Salmo gairdneri Richardson |
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Authors: | Darrel Jon Laurén D G McDonald |
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Institution: | (1) Department of Biology, McMaster University, L8S 4K1 Hamilton, Ontario, Canada |
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Abstract: | Summary Hard- and softwater acclimated adult rainbow trout were statically exposed to copper (12.5, 25, 50, 100, and 200 ppb) for
two, 12 h periods at neutral and pH 5.0. Unidirectional Na+, and Cl−, and net Na+, Cl−, K+, and ammonia fluxes were monitored as a measure of branchial ionoregulatory disturbance. Copper concentrations as low as
12.5 ppb led to measurable ion losses. Net Na+, Cl−, and K+ losses were concentration dependent and unaffected by prior acclimation to either hard- or softwater at both neutral pH and
pH 5. From 12.5 to 50 ppb net NaCl losses arose primarily as a result of the inhibition ofJ
in, and at higher concentrations,J
out was also stimulated. In softwater,J
in was more resistant to inhibition than in hardwater. However, in hardwater,J
out recovered to normal levels during the second 12 h period, but no such recovery was found in softwater. Plasma NaCl was inversely
correlated with copper], while plasma glucose and ammonia increased with copper]. At pH 5.0 and copper] from 12.5 to 50
ppb, H+ contributed significantly to the total ion loss, while at 100 and 200 ppb, ion losses were no greater at pH 5.0 than at neutral
pH. In no case were the effects of copper and H+ strictly additive. |
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Keywords: | |
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