Beyond the reef: The widespread use of non-reef habitats by coral reef fishes

Marine ecology seeks to understand the factors that shape biological communities. Progress towards this goal has been hampered by habitat-centric approaches that ignore the influence of the wider seascape. Coral reef fishes may use non-reef habitats (e.g. mangrove and seagrass) extensively, yet most studies have focused on within-reef attributes or connectivity between reefs to explain trends in their distribution and abundance. We systematically review the evidence for multihabitat use by coral reef fishes across life stages, feeding guilds and conservation status. At least 670 species of "coral reef fish" have been observed in non-reef habitats, with almost half (293 species) being recorded in two or more non-reef habitats. Of the 170 fish species for which both adult and juvenile data were available, almost 76% were recorded in non-reef habitats in both life stages. Importantly, over half of the coral reef fish species recorded in non-reef habitats (397 spp.) were potential fisheries targets. The use of non-reef habitats by "coral reef" fishes appears to be widespread, suggesting in turn that attempts to manage anthropogenic impacts on fisheries and coral reefs may need to consider broader scales and different forms of connectivity than traditional approaches recommend. Faced with the deteriorating condition of many coastal habitats, there is a pressing need to better understand how the wider seascape can influence reef fish populations, community dynamics, food-webs and other key ecological processes on reefs.