Assistant Professor University of South Florida Tampa, FL, United States
Abstract: Lionfish (Pterois volitans and P. miles) and regal demoiselle (Neopomacentrus cyanomos) are both Indo-Pacific reef fishes that have invaded the Gulf of Mexico and the Greater Caribbean. Lionfish are already known to reduce native species abundance, biomass, and diversity. However, the ecological risk of regal demoiselle is unclear. Given that lionfish consume regal demoiselle, these species may also interact in their shared range. The objective of this study is to gauge the potential for interaction among invasive regal demoiselle and lionfish in the invaded range by identifying areas where invasive regal demoiselle are likely to spread and co-occur with lionfish. We hypothesize that these species prefer habitat with similar environmental characteristics and that their invaded ranges will substantially overlap. To estimate the habitat suitability and habitat overlap of these species, we constructed species distribution models (SDMs) using occurrence records, randomly sampled background points, and a set of environmental predictors (e.g., bathymetry, distance from coral reefs) from Bio-ORACLE and other sources. We considered models for each invasive taxa (lionfish and regal demoiselle) combined with differents SDM algorithms (boosted regression, maximum entropy, and range bagging), background sampling techniques (1000 km buffer or no buffer/convex hull), and spatial extents of the input data (global range, invasive range, and native range), resulting in 36 SDMs along with 12 ensemble models averaging the models using different algorithms. While SDMs for both taxa performed well, with high rates of true positives to false positives (AUCs > 0.97), only models using native and invaded occurrences together captured the current global range of each species. The global models also indicate more potential for future range expansion, although the Mediterranean Sea appears much more suitable for lionfish than regal demoiselle. Bathymetry (depth in meters) and distance from coral reefs (in meters) were consistently among the top five most important predictors for all MaxEnt models, with minimum depth ranking either first or second for each model. Regal demoiselle habitat may not be as widespread as that of lionfish in the Gulf of Mexico, but these species are expected to greatly overlap. As expected, these models support that these species have similar habitat preferences (i.e., depth preferences and coral reef habitat) and highlight the importance of considering interactions among these species in their invaded range.
