On the prediction of acid precipitation events and their effects on fishes |
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| Authors: | Harold H Harvey Douglas M Whelpdale |
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| Institution: | 1. Department of Zoology, University of Toronto Toronto, M5S 1A1, Ontario, Canada
2. Atmospheric Environment Service Environment Canada, M3H 5T4, Downsview, Ontario, Canada
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| Abstract: | It is possible to predict acid rain events and melts of acid snow some 12 to 24 hr in advance, including estimation of the magnitude and duration of such events. This is sufficient notice to permit monitoring of stream chemistry and fish plasma and muscle ions before acid stress, and to continue this monitoring throughout and after specific events. Such a program has been in place for 2 yr in waters tributary to the Milford Bay Trout Hatchery, Ontario. During one snow melt in February 1984 surface waters showed a decline to pH 4 and associated negative ANC. Rainbow trout held in such water lost plasma Na and Cl rapidly and died within 28 hr. The hatchery water supply, consisting of a mixture of spring and surface water, showed a decline in alkalinity from 300 to 30 μeq.L?1, and a pH change from 6.6 to 5.4, during snow melt. Total A1 concentration increased from 42 to 222 μg.L?1 during snow melt with the “reactive” component increasing from 17 to 112 μg.L?1. Rainbow trout held in this water did not show physiological stress. More rapid run-off of melt water could be expected to exhaust all of the alkalinity in the hatchery water supply permitting the pH to decline and A1 concentration to rise to levels lethal to the hatchery stock of rainbow trout. |
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