title: A nose-to-nose comparison of the physiological effects of exposure to ionic silver versus silver chloride in the European eel (Anguilla anguilla) and the rainbow trout (Oncorhynchus mykiss).
abstract: Physiological mechanisms of silver toxicity (as silver nitrate) to the sensitive rainbow trout (Oncorhynchus mykiss) (96 h LC50: 10.2 µg silver l(-1), in soft, low chloride water) and the more tolerant European eel (Anguilla anguilla)(96 h LC50: 34.4 µg silver l(-1), in the same water) were investigated during acute exposure to silver, using concentrations varying from 3 to 22 µg silver l(-1). Silver was present either predominantly in the form of ionic silver, or in the form of silver chloride complexes (AgCl(aq)). Inhibition of the branchial Na(+),K(+)-ATPase enzyme activity and the active influx of Na(+) leading to net Na(+) loss were the key toxic effect in both species. In the rainbow trout, but not in the European eel, Cl(-) influx was also impaired during silver exposure. However, even under control conditions, Cl(-) influx was negligible in the eel. Water Cl(-) clearly protected against the silver-induced physiological disturbance in rainbow trout, presumably by changing the speciation of silver from ionic silver to AgCl complexes. However, such a protective effect was not observed in the European eel. Differences in whole body Na(+) turnover rates between the two species (1.1% per day in the European eel versus 19% per day in the rainbow trout) together with the lack of effect of silver exposure on Cl(-) homeostasis in the European eel are hypothesized to be the main reasons for the different silver tolerance observed in the two species.
authors.affiliation: McMaster University, Department of Biology, 1280 Main Street West, Hamilton, Canada
authors.initials: M
authors.lastname: Grosell
authors.initials: C
authors.lastname: Hogstrand
authors.initials: CM
authors.lastname: Wood
authors.initials: HJ
authors.lastname: Hansen