Abstract: Ecological communities that utilise similar habitats may exhibit functional convergence despite significant geographic and evolutionary separation. On coral reefs, steep gradients in key environmental variables (e.g. light and wave energy) may restrict many species to shallow depths. Here, we show that depth‐generalist reef fishes are correlated with two traits: caudal fin aspect ratio and diet. Fishes with high aspect ratio (lunate) caudal fins produce weak vortices in the water column while swimming, reducing the likelihood of detection and providing an advantage on deeper reefs with lower light irradiance and water motion. Significant differences in depth preference among trophic guilds reflect changes in the availability of different food sources along a depth gradient. The significance of these two traits across geographically and phylogenetically distinct assemblages suggests that deep-water habitats exert a strong environmental filter on coral reef fishes

Bio: Dr Tom Bridge is a marine ecologist interested in how depth gradients structure marine communities. Tom is originally from Sydney and completed a B.Sc (Honours) at the University of Sydney. His honours thesis examined the influence of environmental variation on the distribution of juvenile black marlin off eastern Australia. After spending time travelling and in the diving industry, Tom moved to Townsville in 2007 to begin his PhD in the School of Earth and Environmental Science at JCU, studying mesophotic coral reefs on the GBR. His major field work comprised a 3-week expedition on board the RV Southern Surveyor, which conducted the first detailed study of the biology of the Great Barrier Reef outer-shelf. Completing his PhD in 2011, Tom has continued his research on mesophotic coral reefs at the ARC Centre of Excellence for Coral Reef Studies, JCU. He is currently a joint-postdoc between the ARC Centre of Excellence and the Australian Institute of Marine Science.