Effects of differences in hole size of artificial reef units on coral reef fish abundance and species richness
The biodiversity of coral reefs will decline as the global degradation of reefs continues, pushing the science of restoration techniques such as the utilization of artificial reefs, to the forefront of coral reef ecology. Artificial reefs provide shelter and habitat through design features such as topographic complexity, substrate diversity, refuge hole size, vertical relief, and percentage live coral cover. These elements have been manipulated to study the relationship between design and fish community response. This study examines the relationship between hole size in artificial reef units (ARUs) and species richness and abundance of coral reef fish at a study site on Bonaire, Dutch Caribbean. Four types of ARUs were constructed including units with no holes, small holes, large holes and a combination of small and large holes. Various fish and invertebrate species utilized ARUs for grazing, benthic egg laying, protection and hunting. There was no difference in fish density or species richness among the four ARU types. However, differences in species composition among the four ARU types were found. The smaller, benthic fish were more prevalent at the small hole ARU, while the larger, territorial fish were found utilizing the large hole and no hole ARUs more often. Mixed hole ARUs exhibited a compilation of both small and large fish. Since there are differences in community composition, specialized artificial reef designs could possibly be used to enhance particular species that are important to maintain community structure of degraded reefs.