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Indo-Pacific red lionfish (Pterois volitans) have invaded the western Atlantic, and most recently the northern Gulf of Mexico (nGOM), at a rapid pace. Given their generalist habitat affinities and diet, and strong ecological overlap with members of the commercially valuable snapper-grouper complex, increased density and abundance of lionfish could result in significant competitive interactions with nGOM commercially important species. We experimentally investigated the intensity of behavioral interactions between lionfish and indigenous, abundant and economically important juvenile nGOM red snapper (Lutjanus campechanus), and other increasingly abundant juvenile tropical snapper species (gray snapper—L. griseus and lane snapper—L. synagris) in large outdoor mesocosms to examine snapper vulnerabilities to lionfish competition. When paired with lionfish, red snapper swimming activity (i.e., time swimming and roving around experimental tank or at structure habitat during experiments) was significantly lower than in intraspecific control trials, but gray and lane snapper swimming activities in the presence of lionfish did not significantly differ from their intraspecific controls. Additionally in paired trials, red and lane snapper swimming activities were significantly lower than those of lionfish, while no significant difference in swimming activities was observed between lionfish and gray snapper. We found that red snapper prey consumption rates in the presence of lionfish were significantly lower than in their intraspecific 3-individual control trials, but when paired together no significant differences in prey consumption rates between red snapper and lionfish were observed. When paired with lane or gray snapper, lionfish were observed having comparatively higher prey consumption than snappers, or as observed in lionfish intraspecific 1-individual controls. However, lane and gray snapper consumption rates in the presence of lionfish did not significantly differ from those in intraspecific controls. These findings suggest that competition between juvenile snappers and invasive lionfish may be variable, with lionfish exhibiting differing degrees of competitive dominance and snappers exhibiting partial competitive vulnerability and resistance to lionfish. While the degree of intensity at which these interactions may occur in nGOM reefs may differ from those observed in our findings, this study enables greater understanding of the potential ecological effects of red lionfish on native reef fishes. [ABSTRACT FROM AUTHOR]

Abstract: Understanding how individuals within a population of invasive organisms disperse during various life history stages has obvious implications for long term population dynamics in the invaded range. With the rapid expansion of the invasive Indo-Pacific lionfish (Pterois volitans and Pterois miles) in the western Atlantic and Caribbean, it has become increasingly important to understand how individuals move following initial recruitment, as this may have critical implications for population control and management. We conducted a 10-month mark–recapture study in the lower Loxahatchee River estuary (Florida, USA) to identify movement patterns and site fidelity in juvenile and young adult lionfish. We tagged 55 lionfish, ranging in size from 45 to 185mm standard length (66–256mm total length). Eighty percent of the tagged fish were recaptured at least one time during the course of the study. Lionfish in this system exhibited extremely high site fidelity over extended periods of time and across multiple size classes. Maximum range occupied by individuals along the shoreline of the estuary was small (mean=28m, asymmetrical 95% CI: 10 to 51m), and did not vary with lionfish size. The majority of lionfish recaptures (74%) occurred at or near (0–10m) the previous capture site, even after weeks or months at liberty. In systems where lionfish exhibit extremely high site fidelity and small maximum ranges, localized population control may be feasible, since lionfish removed from a given habitat would be replaced largely through larval recruitment rather than migration of older individuals. However, since lionfish grow extremely rapidly (averaging 0.46mm/day, but reaching as high as 0.78mm/day in one individual), localized control efforts would need to be carried out frequently in order to maintain a younger, smaller population. Localized control may be less effective if lionfish exhibit greater movement and lower site fidelity in other invaded systems. [Copyright &y& Elsevier]