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2076585 
Journal Article 
Impact of mild experimental acidification on short term invertebrate drift in a sensitive British Columbia (Canada) stream 
Bernard, DP; Neill, WE; Rowe, L 
1990 
Yes 
Hydrobiologia
ISSN: 0018-8158
EISSN: 1573-5117 
BIOSIS/91/00090 
203 
1-2 
1-2 
eng 
BIOSIS COPYRIGHT: BIOL ABS. We report daytime drift behavior of lotic macroinvertebrates following short term (12 h) additions of HCl or HCl plus AlCl3 to a circumneutral softwater (alkalinity ca. 100 mueq l-1) mountain stream in British Columbia, Canada. Addition of HCl (pH reduced from 7.0 to 5.9) resulted in an overall tripling of invertebrate drift density with rapid (1h) increases in chironomid Diptera and Trichoptera. Small Ephemeroptera also entered the the drift at high densities, but were delayed about 6 h. Addition of AlCl3 (0.71 to 0.95 mg l-1 total Al3+) in HCl (stream pH reduced to 5.9) resulted in an overall 6-fold increase in invertebrate drift, with rapid increases by Ephemeroptera and delayed responses by chironomids and Trichoptera. These results suggest that the behavior of several macroinvertebrates from low alkalinity, unacidified streams can be altered by simulations of short-term, mild acidic deposition events. Further, the magnitude and time of entry into the drift vari