Swimming speeds of larval coral reef fishes: impacts on self-recruitment and dispersal

The dispersal of larvae during their time in the pelagic environment is critically important to our understanding of marine populations. Recent publications have highlighted the potential importance of larval behaviour in influencing dispersal patterns of larval reef fishes. However, it has not been clearly established if their abilities are of a magnitude comparable to the potential effects of oceanic processes and whether larval behaviour is sufficient to facilitate self-recruitment. This study presents new data on the swimming speed of late-stage larvae to determine how they can swim relative to oceanic currents. The families examined comprised the Acanthuridae, Siganidae, Lutjanidae, Lethrinidae, Pomacentridae, Chaetodontidae, Nemipteridae, Monacanthidae, Psuedochromidae, Pomacanthidae and Apogonidae. The late-stage larvae of all reef fish families examined were able to swim at speeds greater than the mean transport speeds reported around reefs in most locations. However, even the best-swimming reef fish families could not swim faster than the maximum current speeds reported. Based on new and previously published data it appears that the development of swimming ability can be described adequately (80% of variation explained) as a linear increase from zero at hatching to a species-specific maximum at settlement. Calculations based on this developmental pattern suggest that most reef fish families could substantially influence their dispersal patterns relative to ocean currents for over 50% of their larval phase. For all families examined, swimming behaviour could potentially affect dispersal patterns on a magnitude similar to the dispersing effect of oceanic currents. In addition, the swimming capabilities of several reef fish families have the potential to facilitate active self-recruitment in a range of reef systems.