The Lion's Share: Assessing the Risk of Invasive Pterois volitans to Coral-Reef Community Structure through Direct and Indirect Predation

Abstract

The deleterious effects of invasive species on native populations have been well documented. After introduction to a non-native environment, invasive species tend to multiply rapidly in population density via logistic expansion. Thus, complete eradication of invasive species through conservation efforts is often unsuccessful. To reach an estimate for a sustainable invasive population, conservationists would benefit from a comprehensive understanding of the direct and indirect impacts an invasive species may have on the native community it invades. We apply this framework to managing the invasive predator Pterois volitans, whose spread through the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea works as a representative case study for other invasive species. Pterois volitans predate a range of species, including herbivorous grazing reef fish, whose declining populations may contribute to a reef phase-shift. Pterois volitans may also indirectly impact herbivorous grazing habits by invoking a predator-prey fear response in these grazers. The direct consumptive impacts of Pterois volitans have been well documented, but the potential indirect non-consumptive impacts have been less documented. This study assesses direct lionfish predation through stomach content analysis. This study also utilizes camera trap techniques to quantify the non-consumptive impacts of Pterois volitans on herbivorous fish grazing behavior. The results show that lionfish diet consists significantly of native grazers, and that grazing behavior of native herbivores on the Banco Capiro reef is negatively correlated with lionfish presence. The supplementation of this novel non-consumptive data with the consumptive data provides insights into the scope of Pterois volitans’s impact on the native coral-reef community it invades, allowing for a better understanding of a sustainable Pterois volitans population for mitigation and control.