Fig. 3. Temperature dependence of mitochondrial H₂O₂ formation in body wall tissue of Arenicola marina winter (A) and summer (B) animals. Data are means ± S.D. of 5–10 mitochondrial isolations. Black bars, 10°C; hatched bars, 1°C. State 3 values were significantly lower in winter than in summer mitochondria at both temperatures; H₂O₂ formation at 10°C differs significantly from formation at 1°C (P<0.001), except of the 10°C value of the winter animals. State 4 and 4+ values at both temperatures differ significantly from state 3 (P<0.01) and with season (P<0.001), as well as between temperatures (P<0.01). (ANOVA; Newman–Keuls test).