Enhancement of recruitment to coral reefs using light-attractors

Methods that enhance larval settlement are required to examine the importan ce of recruitment in the dynamics of coral reef fish populations. Although it is known that larval reef fishes are attracted to light, here we show fo r the first time that a light-attraction device positioned above patch reef s at Lizard Island (Great Barrier Reef) significantly increased the number of fish settling on the reefs below. The device was a modified light trap w ith a tube allowing the vertical movement of larvae from the trap to the re ef. The number of species of settling fishes, and the abundance and diversi ty of immigrant fishes were also greater on the light-enhanced reefs. By co mparison, the alternative technique of enhancing recruitment using surface buoys moored to reefs was unsuccessful. Further studies are now required to determine whether enhanced recruitment using light-attractors leads to a l onger-term increase in population size, as opposed to temporarily concentra ting juveniles on the reef.