Plasticity in Three-Dimensional Geometry of Branching Corals Along a Cross-Shelf Gradient

Neil Doszpot,Michael Mcwilliam,Will Figueira,Andrew Hoey,Morgan Pratchett

doi:10.3390/d11030044

Abstract

Scleractinian corals often exhibit high levels of morphological plasticity, which is potentially important in enabling individual species to occupy benthic spaces across a wide range of environmental gradients. This study tested for differences in the three-dimensional (3D) geometry of three branching corals, Acropora nasuta, Pocillopora spp. and Stylophora pistillata among inner-, mid- and outer-shelf reefs in the central Great Barrier Reef, Australia. Important attributes of coral morphology (e.g., surface area to volume ratio) were expected to vary linearly across the shelf in accordance with marked gradients in environmental conditions, but instead, we detected non-linear trends in the colony structure of A. nasuta and Pocillopora spp. The surface area to volume ratio of both A. nasuta and Pocillopora spp. was highest at mid-shelf locations, (reflecting higher colony complexity) and was significantly lower at both inner-shelf and outer-shelf reefs. The branching structure of these corals was also far more tightly packed at inner-shelf and outer-shelf reefs, compared to mid-shelf reefs. Apparent declines in complexity and inter-branch spacing at inner and outer-shelf reefs (compared to conspecifics from mid-shelf reefs) may reflect changes driven by gradients of sedimentation and hydrodynamics. The generality and explanations of observed patterns warrant further investigation, which is very feasible using the 3D-photogrammetry techniques used in this study.

Highlights

Variability in traits is known to influence species’ functional importance in ecosystems [1].Trait plasticity among individuals of the same species constitutes a major component of this variation [2], intraspecific variability is often ignored due to difficulties in measuring the traits of individuals at large scales and with readily quantifiable metrics
Coral morphology is associated with critical attributes including growth [3], photosynthesis [4], fecundity [5], susceptibility to disturbance [6] and life history [7]
That previous measures of trait diversity in corals are heavily focused on among-species differences in morphology [10,11]

Summary

Introduction

Variability in traits is known to influence species’ functional importance in ecosystems [1].Trait plasticity among individuals of the same species constitutes a major component of this variation [2], intraspecific variability is often ignored due to difficulties in measuring the traits of individuals at large scales and with readily quantifiable metrics. Variability in traits is known to influence species’ functional importance in ecosystems [1]. Morphological variation among reef-building corals is a conspicuous and functionally important source of trait variation. The structural complexity, surface area and hole size of corals can influence the diversity and abundance of associated reef fish species [8,9]. It is not surprising, that previous measures of trait diversity in corals are heavily focused on among-species differences in morphology [10,11]. Our understanding of morphological plasticity within species is still emerging, putting into question

Methods

Results

Conclusion