Title

Physiological responses of juvenile rainbow trout to chronic low level exposure of waterborne silver

Document Type

Article

Publication Date

2-1-1998

Abstract

The physiological effects of chronic exposure to AgNO3 in moderately hard freshwater were investigated in juvenile rainbow trout (Oncorrhynchus mykiss Walbaum). Two separate 28 day exposures were performed at silver concentrations of 0.5 and 2.0 μg/L in flowing Hamilton dechlorinated tap water. Exposure to 0.5 μg/L Ag resulted in a slight increase (~14.9%) in food consumption, whereas growth rates remained unaltered. Both plasma Na+ and Cl- levels were significantly decreased by 11.8% and 9.3%, respectively at day 16 of the exposure. Hepatic Ag concentrations were elevated approximately 4-fold in 0.5 μg/L Ag-exposed fish. However, no significant increases in liver metallothionein (MT) concentrations were noted. No mortalities were observed during this 28-day exposure. In comparison, chronic exposure to 2.0 μg/L Ag resulted in a 28.8% decrease in food consumption and a 43.0% reduction in growth rate. Plasma [Na+] was decreased by 18.3%, whereas plasma [Cl-] was reduced by 12.2% at day 7. At both concentrations of silver, plasma ion concentrations appeared to recover thereafter. Silver accumulated steadily in the liver up until day 15 when concentrations were 39.7 μg/g wet weight (285-fold increase) above control levels. In addition, MT levels were increased by 81.2% at day 7. Silver exposure at 2.0 μg/L resulted in approximately 15.0% mortality over the 28-day period.

Publication Source (Journal or Book title)

Comparative Biochemistry and Physiology - C Pharmacology Toxicology and Endocrinology

First Page

131

Last Page

137

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