Responses to Crude Oil Contamination by Cricotopus (Cricotopus) bicinctus and C. (C.) mackenziensis (Diptera: Chironomidae) in the Fort Simpson Area, Northwest Territories

Abstract
C. (C.) bicinctus (Meigen) and C. (C.) mackenziensis Oliver, 2 common species of Chironomidae in the Fort Simpson area [Canada], were examined for changes resulting from experimental field exposure to Norman Wells crude oil. Larvae of both species were always present in higher numbers on oiled than unoiled artificial substrates, but numbers of C. bicinctus increased more quickly than C. mackenziensis in response to the oil. C. mackenziensis larvae occurred in higher numbers than C. bicinctus larvae on unoiled artificial substrates. C. bicinctus tended to dominate C. mackenziensis on oiled artificial substrates. Size of larvae, as measured by head capsule width, was unaffected by increased food supply during periods of maximum algal biomass on oiled artificial substrates. Larvae on oiled artificial substrates apparently produced part of another generation when compared to larvae on unoiled artificial substrates.