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

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.