Habitat use, feeding and territorial behavior of a Brazilian endemic damselfish Stegastes rocasensis (Actinopterygii: Pomacentridae)

Abstract

This paper presents the results of the first field study of the Brazilian endemic damselfish Stegastes rocasensis. Underwater data were collected at the Fernando de Noronha Archipelago (NE Brazil), where four sites were visually assayed for local territorial and feeding behaviors, as well as habitat use. S. rocasensis preferentially fed on turf and macroalgae, and during the afternoon period. Its territory size ranged from 0.26 to 13.86 m2 (1.61 ± 0.23 m2). Our findings suggest that adults preferably inhabit shallow, turf-rich areas, while sub-adults and juveniles occupy deeper areas with higher percent cover of invertebrates and hard corals, respectively. With regards to agonistic behaviors, pursuit of intruders was the most frequent reaction recorded (p < 0.001); the highest level of aggression was elicited by territorial herbivores (p < 0.001). Nevertheless, analysis of attacks elicited by different fish species within S. rocasensis’ territory showed that more attacks were launched on conspecifics than on other fish species.