Tribute to P. L. Lutz: respiratory ecophysiology of coral-reef teleosts.

One of the most diverse vertebrate communities is found on tropical coral reefs. Coral-reef fishes are not only remarkable in color and shape, but also in several aspects of physiological performance. Early in life, at the end of the pelagic larval stage, coral-reef fishes are the fastest swimmers of all fishes in relation to body size, and show the highest specific rates of maximum oxygen uptake. Upon settling on the reef, coral-reef fishes have to adopt a demersal lifestyle, which involves coping with a habitat that can become severely hypoxic, and some fishes may even have to rely on air breathing when their coral homes become air exposed. Oxygen availability appears to be a major ambient selection pressure, making respiratory function a key factor for survival on coral reefs. Consequently, hypoxia tolerance is widespread among coral-reef fishes. Hypoxia can even be a factor to gamble with for those fishes that are mouthbrooders, or a factor that the coral inhabitants may actively seek to reduce by sleep-swimming at night. Here, we summarize the present knowledge of the respiratory ecophysiology of coral-reef teleosts. From an ecophysiological perspective, the coral reef is an exciting and largely unexplored system for testing existing hypotheses and making new discoveries.