Trophic discrimination factors for invasive lionfish ( Pterois volitans and P. miles ) in Bermuda

Invasive lionfishes have spread throughout the west central Atlantic Ocean, Gulf of Mexico and Caribbean Sea, with the potential to impact prey species populations as well as marine ecosystem structure and function. Lionfishes are known to be opportunistic predators with a broad, generalist diet, yet there has been little exploration of their trophic position, or of how this might vary between locations across the invaded range. Stable isotope analysis provides a means of comparing trophic position across locations with different suites of available prey species, but requires the calculation of species-specific trophic discrimination factors (TDFs) for proper interpretation. This study experimentally derived the TDFs for lionfish in Bermuda, where Δ 15 N = 2.7‰ and Δ 13 C = 2.4‰, providing an opportunity to calculate the trophic position of this invasive population. It also furthers our ability to compare lionfish trophic position across the many locations in the invaded range to help gauge their potential impacts as both predators and competitors.