Fish community structure on coral habitats with contrasting architecture in the Tropical Eastern Pacific

María Del Mar Palacios,Fernando A Zapata

doi:10.15517/rbt.v62i0.16360

María Del Mar Palacios, Fernando A Zapata

Open Access

https://doi.org/10.15517/rbt.v62i0.16360

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Abstract

Reefscape architecture, shaped by dominant coral morphologies, can play a major role in determining the structure and composition of fish assemblages by affecting niche and resource availability and mediating interspecific interactions. To explore the role of dominant coral morphologies on reef fish communities, we carried out a comparative study of the fish community associated with a Massive Coral Community (MCC) and a Branching Coral Community (BCC) at Gorgona Island, Tropical Eastern Pacific (TEP). On each community, the benthic substrate was assessed through the “chain transect method” while the fish assemblage was evaluated through visual surveys on belt transects. We found differences between both fish assemblages in terms of the abundance, diversity (H’), and evenness (J’). The BCC, despite being formed by morphologically complex pocilloporid colonies, had a simple and relatively flat architecture that attracted principally small and territorial fishes. Significant higher abundances of Chromis atrilobata and Thalassoma lucasanum at the BCC boosted the total fish abundance but caused low fish evenness and diversity. Conversely the MCC, composed of massive coral species with considerable sizes and diversity of shapes, held a complex and high-relief reefscape capable of sustaining a more diverse and even fish community, although with the same species richness as the BCC. Fishes with large sizes, roving behavior and piscivore-feeding preferences were especially attracted to the MCC. Although, massive coral species are important in determining a diverse and complex reefscape architecture, both dominant coral morphologies (massive and branching) attract and provide resources to different types of fish according to their size, mobility and trophic group. Our results suggest that a loss of massive coral species and a community shift towards stress-resistant taxa (such as Pocillopora spp.), could alter the structure and function of fish assemblages in the TEP due to the habitat loss for large, mobile and piscivore species. Rev. Biol. Trop. 62 (Suppl. 1): 343-357. Epub 2014 February 01.

Highlights

Pratchett et al, 2008; Messmer et al, 2011)
The SIMPER analysis revealed that 39.3% of the dissimilarity between the two coral assemblages was due to variation in the abundance of the branching corals (P. capitata and P. damicornis) which covered 70% of the benthic cover at the Branching Coral Community (BCC), but represented 3% of the Massive Coral Community (MCC) substrate
By comparing the fish assemblages of two coral communities that differed mainly in their dominant coral morphologies, we examined how coral morphology and the resulting reefscape architecture affects the assemblage structure of conspicuous fish

Summary

Introduction

Pratchett et al, 2008; Messmer et al, 2011) Among these habitat features, architectural complexity (defined here as the structure of the physical environment) usually plays the most important role in shaping the richness, diversity, abundance and biomass of reef fish assemblages (Luckhurst & Luckhurst, 1978; McCormick, 1994; Almany, 2004; Alvarez-Filip et al, 2011a). It is believed that a high structural complexity boosts fish diversity because it reduces interspecific competition by providing a greater spectrum of niches and resources It increases fish survivorship by diminishing prey-predator encounter rates and/or by offering additional prey refuges (Beukers & Jones, 1997; Friedlander & Parrish, 1998; Almany, 2004; Gratwicke & Speight, 2005). Considering a large spatial scale (the gross reefscape morphology) we addressed the following questions: (1) Are there differences in the fish assemblages inhabiting habitats dominated by branching and massive corals?, (2) which reefscape pattern or habitat architecture features the highest fish species richness, diversity, and abundance?, and (3) which types of fish species and trophic groups are most attracted to each of the two coral communities assessed?

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