Fig. 2. Coral colonies can be severely hypoxic habitats at night. The graphs show the oxygen levels (A) outside and (B) between branches of Acropora nasuta colonies from dusk to dawn. Values are means ± s.e.m. from six measurements on three corals in an outdoor tank at Lizard Island Research Station. Sunset and sunrise are indicated by broken lines. From Nilsson et al. (Nilsson et al., 2004).