Behavioral trade-offs and habitat associations of coraldwelling damselfishes (family Pomacentridae)

Abstract

Many coral reef fishes are intimately associated with branching corals. While these fishes rely on their host corals for shelter, fishes may exhibit behavioral trade-offs linked to spatial and temporal variations in their association with corals. This study quantified variation in coral use by 5 species of damselfishes, assessing key behavioral traits that determine the extent to which damselfishes interact with their host colonies. In situ behavioral observations revealed marked interspecific differences in diurnal and nocturnal behavior among 5 damselfish species. Dascyllus aruanus and D. reticulatus consistently displayed frequent and sustained interactions with and around corals (i.e. frequent colony visits and high aggressiveness towards other fishes) compared to Chromis viridis, Pomacentrus moluccensis, and P. amboinensis that exhibited weaker associa- tions (i.e. few colony visits and low aggression) with host colonies. Coral bleaching impacted modal diurnal swimming positions, thereby altering damselfish−coral interactions under thermal stress. This research demonstrates that coral-associated damselfishes utilize host colonies in very different ways, with complex variations in behavior that extend beyond simple proximity to host coral. Such among-species variation is likely the result of behavioral trade-offs related to coral association. Understanding species-specific foraging and colony-use behavior is important be- cause habitat degradation may undermine habitat associations of coral−damselfish and associated mutualistic services.