Low susceptibility of invasive Indo-Pacific lionfish Pterois volitans to ectoparasitic Neobenedenia in the eastern Caribbean

Since its introduction to the tropical western Atlantic in the 1980s, the Indo-Pacific lionfish, Pterois volitans, has become one of the most devastating species invasions in the marine environment. It remains unclear whether release from parasitism has played a role in its success. The capsalid monogenean Neobenedenia pargueraensis is a common Caribbean ectoparasite with a broad host range that, in high numbers, can kill hosts. However, previous research found that lionfish collected from the Bahamas, Puerto Rico and the US Virgin Islands were not parasitized by N. pargueraensis. Possible explanations for this are that 1) lionfish do not occupy habitat where infective stages are present; and 2) lionfish are not susceptible to this parasite. The goal of this project was to determine the susceptibility of lionfish to N. pargueraensis. Experiments were conducted in spring and summer of 2012 and 2013 on St. Thomas, US Virgin Islands. Lionfish (n = 24) and control blue tang, Acanthurus coeruleus (n = 19) were caught from nearby shallow reefs, treated to remove pre-existing ectoparasites, and exposed to high concentrations of N. pargueraensis for 14 days. Despite exposure to high concentrations of parasites, only one of 24 lionfish was parasitized, and only one individual parasite was found on the infected fish. In contrast, all blue tang were infected with an average of ten parasites per fish. These results suggest that invasive lionfish are not highly susceptible to N. pargueraensis, which may contribute to their successful invasion of the Caribbean.