The role of sound and sociability in the success of invasive lionfish (Pterois spp.)

Abstract

Animals use sensory information to guide a range of behaviours such as foraging, navigating, avoiding predators, and interacting with conspecifics. When invasive species are introduced into novel environments, however, they may face “information landscapes” different to those experienced in their native ranges. In these cases, if and how invasive species use different forms of information to inform their decision-making in invaded regions is likely to influence their invasive success. For marine invaders, sound is likely to be a particularly important cue since the characteristics of ambient soundscapes can correlate with biodiversity and habitat health, potentially providing information about suitable habitats. Moreover, the tendency of animals to locate and join conspecifics in invaded regions may further affect their ability to invade. This thesis investigated the distribution, sonic anatomy, and behaviour of two species of closely related lionfishes (Pterois volitans and P. miles, hereafter referred to as “lionfish”) in relation to sound as well as sociability. These two species are widely invasive in the Western Atlantic Ocean and Caribbean Sea, and the Mediterranean Sea, where they pose a threat to native fauna through predation. In Chapter 2, I first used a citizen science approach to map the distribution and behaviour of lionfish in their invaded range of the Western Atlantic and Caribbean Sea. While lionfish abundance was not correlated with the local pressure or frequency of human hunters, lionfish were more likely to be encountered deeper and in larger maximum group sizes in areas with more hunting pressure. This suggests that lionfish may be adapting their behaviour to reduce their mortality risk in areas with increased human hunting. In Chapter 3, I found that lionfish displayed a preference to share a shelter with a conspecific, rather occupy a shelter than alone, potentially due to the foraging or anti-predator benefits afforded by group formation. In Chapter 4, I found that in P. volitans, there was no evidence of ontogenetic or sexual differences in vocal muscle investment, suggesting that the primary function of vocalisation in lionfish may be agonistic in nature. In Chapters 5 and 6, while I found no evidence for directional orientation in response to in-situ playbacks of different habitat types during daylight hours, lionfish altered their activity in response to the acoustic content of healthy and degraded coral reef soundscapes played back in the laboratory at night, but not in the day. Overall, my thesis explores the sensory and social behaviour of lionfish with a focus on sound. An understanding of the social and acoustic preferences of lionfish could aid in designing unmanned lionfish traps to improve their attractiveness and efficacy in targeted removals.