Effects of Oxygen in Relation to Temperature on the Development of Embryos of Brook Trout and Rainbow Trout

Abstract

Embryos of the brook trout (Salvelinus fontinalis Mitchill) were incubated in reduced levels of dissolved oxygen of approximately 2.5 ppm, 3.5 ppm, 4.5 ppm, and a control level near air-saturation (10 ppm) at each four temperatures, 2.5, 5.0, 7.5, and 10.0 C, from fertilization to a late stage of development. Embryos of the rainbow trout (Salmo gairdneri Richardson) were incubated in a similar experiment at levels of oxygen approximating 2.5 and 3.5 ppm and a level near air-saturation at each of the four temperatures, to a similar, late stage of development. A third small experiment was conducted in which embryos of rainbow trout were incubated at 12.5, 15.0, and 17.5 C, at a level of dissolved oxygen near air-saturation. In all instances for both species the velocity of embryonic development, measured by the times required to attain a series of selected embryonic stages, was accelerated by increasing temperature. The velocity of development was increasingly retarded by progressively lower levels of dissolved oxygen. The times required to affect hatching and the lengths of the periods of hatching were similarly influenced by temperature and by the level of dissolved oxygen. These findings are discussed in the light of pertinent literature.