PM02 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Monday, 10 November 2003
(PM031) Toxicity of Silver to Rainbow Trout during Early-Life-Stage Studies.
Dethloff, G1, Naddy, R1, Stern, G1, Wood, C2, Kramer, J2, Bell, R2, Gorsuch, J3, 1 ENSR International, Fort Collins, CO, USA2 McMaster University, Hamilton, Ontario, Canada3 Eastman Kodak Company, Rochester, NY, USA
ABSTRACT- Rainbow trout were exposed to silver (as AgNO3) in two early-life-stage studies. In the first study, using source water, a notable increase in egg mortality occurred before thinning, but was not significant in the highest treatment (nominal = 2.0 
g/L). No silver treatments were significantly different from the control for egg mortality after thinning, successful hatch, mean day to hatch, mean day to swimup, and post-hatch and overall survival. Mean values for all weight parameters were decreased in the 2.0 g/L treatment although differences were not significant. In the second study, 30 mg Cl/L (as NaCl) was added to source water. Mean day to hatch, egg mortality, and hatching success were not significantly different among treatments although there was a notable increase in egg mortality and decrease in successful hatch in the highest treatment (nominal = 4.0 g/L). However, post-hatch and overall survival were significantly decreased in the 4.0 g/L treatmnet. Only 10% of alevins in the 4.0 g/L treatment reached swimup; other treatments did not differ significantly for mean day to swimup. Dry weights were significantly decreased in the 1.0 and 2.0 g/L treatments, but not at 0.5 g/L. For unmodified source water, the NOEC for survival and sublethal endpoints was 2.0 g/L but trends in the data suggest a LOEC not much greater than 2.0 g/L. The addition of chloride did not appear to ameliorate toxicity in chronic exposures. Survival was affected at 4.0 g/L and sublethal endpoints were affected at 1.0 g/L. Water chemistry (including silver speciation) and the use of different rainbow trout strains in the two studies may have contributed to differences in sensitivity.
Key words: early-life-stage study, silver, chloride, rainbow trout