Fig. 4. The frequency of breathing pauses (A,C) and the proportion of total
breathing occupied by apnea (B,D) in control (black bars, N=7) and
hyperoxia pre-exposed (white bars, N=8) zebrafish Danio
rerio exposed to acute hypoxia (A,B) or acute hypercapnia (C,D).
Statistically significant differences (P<0.05) *within the groups;
between the two groups.