Linking fishes to multiple metrics of coral reef structural complexity using three-dimensional technology

M González-Rivero,A Ganase,Y.-M Bozec,A Rogers,O Hoegh-Guldberg,A R Harborne,A Herrera-Reveles,A Friedman

doi:10.1038/s41598-017-14272-5

Abstract

Structural complexity strongly influences biodiversity and ecosystem productivity. On coral reefs, structural complexity is typically measured using a single and small-scale metric (‘rugosity’) that represents multiple spatial attributes differentially exploited by species, thus limiting a complete understanding of how fish associate with reef structure. We used a novel approach to compare relationships between fishes and previously unavailable components of reef complexity, and contrasted the results against the traditional rugosity index. This study focused on damselfish to explore relationships between fishes and reef structure. Three territorial species, with contrasting trophic habits and expected use of the reef structure, were examined to infer the potential species-specific mechanisms associated with how complexity influences habitat selection. Three-dimensional reef reconstructions from photogrammetry quantified the following metrics of habitat quality: 1) visual exposure to predators and competitors, 2) density of predation refuges and 3) substrate-related food availability. These metrics explained the species distribution better than the traditional measure of rugosity, and each species responded to different complexity components. Given that a critical effect of reef degradation is loss of structure, adopting three-dimensional technologies potentially offers a new tool to both understand species-habitat association and help forecast how fishes will be affected by the flattening of reefs.

Highlights

Complex habitats provide shelter, food and other resources to a larger number of species when compared with less structurally complex habitats[1]
For the models using partitioned structural complexity as explanatory variables, the relative contribution of each variable to the R2m has been segregated by calculating the relative variable importance (VIMP) and represented by different shades of red
Using novel technologies for measuring the three-dimensional complexity of reef structures on the Mesoamerican Barrier Reef, this study explored the relationship between substrate structure and the within-reef distribution of three damselfish species

Summary

Introduction

Complex habitats provide shelter, food and other resources to a larger number of species when compared with less structurally complex habitats[1] This relationship occurs because the three-dimensional (3D) complexity of a habitat increases the availability of refuges and barriers that fragment the living space, resulting in more heterogeneous assemblages of associated reef organisms[2]. Both geological features and the underlying carbonate matrix, which is formed by organisms and modified over time, contribute to the structural complexity of reef habitats along with foundation species of coral[6] These multiple scales of structure lead to more complex coral reefs hosting a greater diversity, abundance and biomass of species[4], including fish[7]. Potentially useful metrics, such as the field of view available to a fish in different microhabitats, are very difficult to measure in situ[35,36]

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Conclusion