Behavioral response of native Atlantic territorial three spot damselfish (Stegastes planifrons) toward invasive Pacific red lionfish (Pterois volitans)

The Pacific red lionfish (Pterois volitans) has been recognized as a top conservation issue in the world due to its ability as an invasive predator to greatly reduce recruitment of native reef fishes, and with potential long-term ecosystem-level effects. This study tested for territorial aggression of native three spot damselfish (Stegastes planifrons) toward invasive lionfish as a possible source of biotic resistance that may provide prey refugia for coral-reef fish recruits. Throughout July and August 2011, I conducted a field experiment in the Bahamas and the Cayman Islands using a model-bottle design specifically developed for examining three spot damselfish behavior. I compared the behavioral response of 40 damselfish to the presence of invasive lionfish and three native fishes presented individually in clear bottles, as well as to an empty bottle control. Despite lionfish having invaded these islands in different years, damselfish response did not differ between the Bahamas and the Cayman Islands. Overall, damselfish response toward invasive lionfish was not significantly different from the minimal response toward the empty bottle control. In contrast, damselfish actively responded to all native fishes, with species-specific behaviors and levels of aggression that depended on the ecological relationships between damselfish and intruding fishes. Differences in the seafloor rugosity of damselfish territories among study sites also appeared to influence damselfish response. The lack of damselfish response towards lionfish demonstrates that territories are unlikely to serve as native prey refugia, and may indicate lack of recognition of this invasive predator compared to native predators.