Fish Assemblage Structure in the Northwestern Hawaiian Islands Is Associated with the Architectural Complexity of Coral-Reef Habitats

Atsuko Fukunaga,Kailey H Pascoe,John H R Burns,Randall K Kosaki

doi:10.3390/d12110430

Abstract

The architectural complexity of coral-reef habitat plays an important role in determining the assemblage structure of reef fish. We investigated associations between the reef habitats and fish assemblages in the Northwestern Hawaiian Islands (NWHI) using in situ fish counts and data on habitat metrics and benthic community composition that were obtained from three-dimensional (3D) photogrammetric reconstructions of the surveyed sites. The structure of fish assemblage as a whole on the basis of Bray–Curtis dissimilarity, species richness and the abundances of herbivores and piscivores were associated with habitat metrics, with higher levels of architectural complexity generally supporting greater numbers of fish species and individuals. Benthic cover did not explain additional variation in these variables after the effects of habitat metrics were taken into account. Corallivorous fish was the only group that showed positive associations with both habitat metrics and benthic cover (Acropora and Pocillopora corals). The total fish abundance and the abundances of planktivores and invertivores did not show associations with either habitat metrics or benthic cover. This study suggests that an appropriate combination of habitat metrics can be used to account sufficiently for the effects of habitat architecture on fish assemblages in reef monitoring efforts in the NWHI.

Highlights

The architectural complexity of coral-reef habitat, which is primarily driven by the abundance of hermatypic corals, plays an important role in determining the community structure of reef-associated organisms [1]
There were 23,842 individuals of reef fish from 148 taxa identified at these sites, with 141 taxa being identified to species, three taxa to genus, three taxa to family and one taxon that could not be identified by the surveyors
The associations between fish assemblages and habitat metrics found in the present study were mostly positive, supporting previous findings that increases in the architectural complexity of habitats were linked to higher levels of fish abundance and diversity [1,2,3]

Summary

Introduction

The architectural complexity of coral-reef habitat, which is primarily driven by the abundance of hermatypic corals, plays an important role in determining the community structure of reef-associated organisms [1]. High levels of coral cover and species richness support high levels of fish abundance and species richness [2]. Coral growth forms are associated with fish abundance and species richness, likely due to the increased availability of microhabitat [3]. Complex morphologies such as branching forms generally support higher numbers of fish individuals and species than architecturally less complex ones such as mounding forms [3]. The effects of reef architecture and benthic composition need to be considered when assessing the status and structure of fish assemblages on coral reefs

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