Rehabilitation of coral reef-fish communities: The importance of artificial-reef relief to recruitment rates

The present study demonstrates that, when considering artificial reefs as potential tools to assist restoration of degraded coral reefs, the construction of complex vertical structures is preferable over low-relief ones to achieve rapid recruitment of coral reef fish. Previous studies have demonstrated that the coral reef fish assemblage on unplanned vertical artificial structures in Eilat, Red Sea, have higher abundance and species richness than nearby natural reefs. In the present study, we tested the hypothesis that high relief artificial reefs had higher recruitment of coral reef fishes, mainly planktivores, than near-bottom low-relief artificial reefs. Indeed, recruitment was about two orders of magnitude higher to the experimental vertical installations than to the near-bottom ones. Most of the initial recruitment occurred at the upper sections of the vertical installations, which may indicate near surface movement of fish larvae as they approach the shore. Alternatively, it may result from preference by planktivorous species for areas with high water/ plankton flux. These results demonstrate that even small, simply-structured, installations with an appropriate orientation and shelter can attract a great number of coral reef fish recruits.