EFFECT OF AN EXPERIMENTAL INJECTION OF METHOXYCHLOR ON AQUATIC INVERTEBRATES - ACCUMULATION, STANDING CROP, AND DRIFT

A single 0,3 ppm injection of methoxychlor into the Athabasca River, Alberta on 4 June 1974 for 15 min caused catastrophic drift for a distance of over 400 km, and a subsequent large decrease in the drifting population. This decrease, when expressed as a percentage reduction from pretreatment drift, is in close agreement with percentage reduction of standing crop recorded by other sampling methods. The time required for the pesticide to affect different species varied considerably but was not related to the mode of feeding. Methoxychlor residues above ambient levels in water were recorded in all the invertebrate populations sampled. Caged animals had significantly different residues than the natural populations. The use of caged animals as indicators of environmental damage is therefore questioned. © 1979, Entomological Society of Canada. All rights reserved.