Local variations in microhabitat use by Stegastes fuscus (Cuvier, 1830) (Teleostei: Pomacentridae) in a tropical reef of Brazil

Paulo Roberto De Medeiros,Ana Luisa Pires Moreira,Ana Maria Alves De Medeiros

doi:10.21472/bjbs.030613

Abstract

Due to their widespread abundance and territorial habits, damselfishes play central roles in reefs worldwide, but the extent to which they modify the reef's substrate varies both amongst and within species. The present study evaluated microhabitat preferences and the role of the common damselfish Stegastes fuscus (Cuvier, 1830) (Teleostei: Pomacentridae) as a benthic community modifier in a tropical algal-dominated reef. We employed video survey techniques to assess fish density and microhabitat use and, additionally, the biomass of sessile components were compared inside and immediately outside algal farms of S. fuscus. Individuals showed pronounced microhabitat preference, but with prominent local (i.e. small-scale) variations in benthic cover. These local variations are reported for the first time and were due to individuals defending one of two contrasting microhabitats (i.e. turf-dominated or Palythoa caribaeorum-dominated). Further, significant differences in the biomass of sessile organisms were observed within algal farms suggesting that S. fuscus plays a keystone role in the benthic community of the reef. The implications of the prominent local variation in microhabitat use are discussed and strongly illustrate the behavioral plasticity of this damselfish.

Highlights

Territorial pomacentrids such as the damselfishes play central roles as benthic modifiers in reefs worldwide (Hixon, 1996; Ceccarelli, 2007)
The two most common damselfishes in tropical reefs of Brazil (Stegastes fuscus and S. variabilis) show distinct territorial defense patterns, the former being more aggressive towards intruders than the latter (Medeiros et al, 2010a)
Given that the video transects included all microhabitats of the reef, we evaluated the degree of microhabitat fidelity by comparing benthic composition of still frames where one or more S. fuscus individuals appeared in the center frame with 50, randomly chosen frames

Summary

Introduction

Territorial pomacentrids such as the damselfishes play central roles as benthic modifiers in reefs worldwide (Hixon, 1996; Ceccarelli, 2007). These ecologically significant tasks are largely the result of their ability to specific remove undesired and surplus components, maintaining selected species (Ceccarelli et al, 2001; Ceccarelli et al, 2005) and, often, monoculture algal farms (Hata and Kato, 2002; Hata and Kato 2003). Variations may show an intraspecific component, with fish of different size (Foster, 1985) and from different stages (Medeiros et al, 2010a) defending territories with different algal composition

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