Functional responses of predator lionfish (Pterois volitans): how prey densities under different light intensities effects predator-prey interactions

The lionfish invasion over the Western Atlantic and Caribbean continues to expand and there is an increasing demand to understand their behaviour, especially foraging. Their high fecundity, growth rates, and success in varying habitats has allowed them to rapidly spread in extensive geographic and depth ranges, reaching over 300m (Darling et al., 2011). Functional response (FR) methodology is used as a proxy to define impacts on prey populations (Hollings, 1965), where the curves produced show changes in predator-prey relationships, comparing how predator impacts change under different conditions. The purpose of the study was to investigate the FR and behaviour of lionfish (Pterois volitans) under different light treatments that simulate diurnal and nocturnal conditions, including moonlight and darkness. The greatest differences in FR came from the dark nocturnal trials in which the consumption of prey was significantly lower than during day or moonlight light simulations. Similarly, lionfish behaviour changed from actively hunting when there was light (day and moonlight) to a slow-stalking movement in the dark, feeding only over long periods of time. The results show that light levels have significant effects on the FR of P. volitans, suggesting that their impact at depths where no light reaches could be less than in shallow habitats. The increasing rate in which the ocean is warming along with the impacts of climate change could cause bigger problems for lionfish when used in the context of this study where feeding rates will be reduced. Lionfish predation have coincided with the loss of biodiversity directly impacting on tourism and the local economy therefore highlighting the importance of further study.