Title: REVISITING DEPTH-DIVERSITY GRADIENTS IN REEF-BUILDING CORALS

Abstract: Species are not distributed evenly across geographical space, and understanding the mechanisms generating species' distributions is a fundamental goal of ecology. Among the most prominent of these patterns are changes in species richness over gradients (e.g. latitude, altitude, or depth). Depth is a strong environmental gradient on coral reefs, with depth zonation recognized as a ubiquitous feature of coral ecosystems. However, depth ranges of reef-building corals at any particular site are influenced by a combination of factors (e.g. turbidity, latitude). Species richness is considered to either decline with depth, or peak at intermediate depths (15-35 m), mirroring altitudinal richness gradients in terrestrial ecosystems. Understanding depth-diversity patterns is a crucial component of revealing how species occupy ecological and geographical space. However, robust analyses of depth-diversity relationships have been compromised by a chronic under-sampling of deeper habitats (> 20 m), and considerable changes in coral nomenclature in recent decades. As such, the generality of this pattern is questionable. Here, we use modern statistical techniques and a novel comprehensive, species-level data set conducted over a large depth gradient (0-45 m) to revisit fundamental questions about depth-diversity relationships in reef-building corals. We show how species richness changes over depth, and identify ecological traits associated with coral depth ranges. Our results provide new insights into ecological factors influencing depth ranges and depth-diversity relationships in corals.

Authors: Roberts TE, Bridge TC, Caley MJ, Baird AH

Presentation: Oral

Session: 7

Date: 06/22/16

Time: 15:00

Location: 311

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