Behavioral changes of a Brazilian endemic damselfish Stegastes rocasensis when guarding egg clutches

This study aimed at comparing the feeding, territorial and agonistic behavior of the Rocas Gregory Stegastes rocasensis when guarding egg clutches. This was accomplished through underwater observations of 80 S. rocasensis individuals observed in four sampling sites in the Fernando de Noronha archipelago (SW Atlantic). Several differences were detected in the behavior of S. rocasensis, such as the reduced size of the territory, the feeding preferences and the aggressiveness towards intruders. Males guarding eggs defended territories twice as small as the ones that did not present egg clutches inside their territories. Additionally, they fed mostly on turf algae, while individuals without eggs in their territories fed mostly on turf and macroalgae. Fish guarding egg clutches elicited agonistic reactions mainly towards planktivores and omnivorous fishes, which could potentially prey on their eggs, while individuals without eggs clutches in their territories elicited agonistic reactions mainly towards herbivorous fishes. The results of the present study reinforces that damselfishes are able to identify the intruder’s identity and elicit agonistic reactions only toward species that may represent a threat to their eggs and/or farmed algae.