title: Ecological and morphological traits predict depth-generalist fishes on coral reefs.
abstract: Ecological communities that occupy similar habitats may exhibit functional convergence despite significant geographical distances and taxonomic dissimilarity. On coral reefs, steep gradients in key environmental variables (e.g. light and wave energy) restrict some species to shallow depths. We show that depth-generalist reef fishes are correlated with two species-level traits: caudal fin aspect ratio and diet. Fishes with high aspect ratio (lunate) caudal fins produce weaker vortices in the water column while swimming, and we propose that 'silent swimming' reduces the likelihood of detection and provides an advantage on deeper reefs with lower light irradiance and water motion. Significant differences in depth preference among trophic guilds reflect variations in the availability of different food sources along a depth gradient. The significance of these two traits across three geographically and taxonomically distinct assemblages suggests that deep-water habitats exert a strong environmental filter on coral reef-fish assemblages.
authors.affiliation: Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia Australian Institute of Marine Science, Townsville, Queensland 4810, Australia thomas.bridge@jcu.edu.au.
authors.forename: Tom C L
authors.initials: TC
authors.lastname: Bridge
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
authors.forename: Osmar J
authors.initials: OJ
authors.lastname: Luiz
authors.affiliation: Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, HI 96822, USA.
authors.forename: Richard R
authors.initials: RR
authors.lastname: Coleman
authors.affiliation: Washington State University, Pullman, WA 99164, USA.
authors.forename: Corinne N
authors.initials: CN
authors.lastname: Kane
authors.affiliation: Papahānaumokuākea Marine National Monument, Honolulu, HI 96818, USA.
authors.forename: Randall K
authors.initials: RK
authors.lastname: Kosaki
mesh_terms: D000818:Animals; D057894:Coral Reefs; D003710:Demography; D005247:Feeding Behavior; D005399:Fishes / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology*
keywords: aspect ratio; caudal fin; depth range; environmental filtering; mesophotic; trophic guild