components as oxygen consumed (mm Hg) over time (min) for two individuals. While
aerial consumption of oxygen fit a linear function, aquatic oxygen consumption fit an
exponential function (Figs. 2-4 A,B). To examine if the degree of curvilinearity within
the water phase varied with body size, we fit an exponential function (y=boebl*t) to
individual curves and compared the exponents (bi) among individuals as a function of
body mass. A comparison of the exponents indicated the degree to which the relationship
was curved or departed from a linear relationship. The degree of curvilinearity was
positively correlated with body mass (r = 0.598, p = 0.031, Fig. 2-5). The smallest
individual (2 g) was excluded from this analysis.
Lungfish reduced aquatic respiration to less than 1% of total oxygen consumed at
low aquatic P02 represented by the plateau point where aquatic respiration was nearly
Table 2-1. Respiratory allocation of Protopterus aethiopicus from the Lwamunda
Swamp, Uganda, between water and air at high (130 mm Hg 104 mm Hg)
levels of DO2 and measured at an average temperature of 23' C.
Measurements were made within 3 wks of capture at the Makerere University
Biological Field Station, Uganda.
Mass (g) Percent 02 from Water Percent 02 from Air
17 96 4
21 97 3
27 94 6
55 68 32
77 67 33
83 19 81
89 65 35
107 61 39
108 19 81
111 46 54
120 25 75
123 31 69
149 16 84
160 14 86
169 20 80
180 16 84