The Oxygen Consumption of Ephemerid Nymphs From Flowing and From Still Waters in Relation to the Concentra-Tion of Oxygen in the Water

ABSTRACT Fox & Simmonds (1933) and Fox et al. (1935) have shown that certain may-fly nymphs, a caddis larva and an isopod from swift streams have a higher oxygen consumption than nearly related forms from still waters or slow-flowing streams. Their results were summarized in Table IV1 of Fox et al. (1935). It has since been shown by Washbourn (1936) that the oxygen consumption of trout fry reared in swiftly flowing water is greater than that of fry reared in slow water. Wolsky & Holmes (1933) found the oxygen consumptions of four individuals of the crayfish Astacus leptodactylus Eschscholtz, from Lake Balaton, to be 90, 103, 104 and 105 mg. of oxygen per kg. of animal per hour at 19–21° C., the animals weighing 16, 22, 36 and 64 g. respectively. The mean of these values for oxygen consumption is 101. Without studying the problem we are now considering, Wolsky (1934) later found that the oxygen consumptions of seven individuals of A. torren-tium (Schrank), living in a swift stream in Hungary, were 160, 188, 157, 157, 170, 102 and 137 mg. oxygen per kg. of animal per hour at 19–21° C., the animals weighing 8, 8, 15, 17, 17, 21 and 32 g. respectively. The mean of these values for oxygen consumption is 153. The oxygen consumption of A. torrentium is thus 50 per cent greater than that of A. leptodactylus, and the relation between oxygen consumption and weight suggests that habitat, not size, was responsible for this difference.