Temporal use of two artificial reef morphologies by coral reef fishes
Coral reefs are important marine ecosystems with high biodiversity that provides food and socioeconomic benefits to people in tropical regions around the world. In the last thirty years coral cover has declined and has been wiped out in some areas. The coral loss affects all benthic organisms and fishes supported by these habitats. Artificial reefs have been used to enhance coral recruitment and to provide a habitat for reef fishes. In Bonaire, Dutch Caribbean, reef fish species richness, diversity, and density were measured at two types of artificial reefs, branching and block-style, at various times of the day. Field observations of reef-fish species richness and density were conducted at midday, dusk, and night. Branching artificial reefs supported higher species richness and diversity. Multiple herbivorous species utilized this habitat for grazing while other species used it for shelter. The block-style reefs supported a higher density (ind m -2 ) of reef fish. Fish density, species richness, and diversity decreased at night at the branching reef. The decrease in fish community complexity could be because the complexity of the block-style reef was not suitable for nighttime sheltering needs. Species richness and diversity also decreased at night at the block-style reefs; but density at night was no different than midday and dusk because the blocks supported a very high number of small individuals during nighttime. Two different artificial reef structures were found to support complex fish assemblages; however the species richness and fish abundance varied between the structures. This suggests that morphology of artificial reefs is a tool that can be utilized to attract specific reef fish communities. During a time of reef degradation and habitat loss, artificial reefs can be used to supply reef fish a habitat to live.