Low salinity negatively affects metabolic rate, food consumption, digestion and growth in invasive lionfish Pterois spp.

Abstract

The establishment of the piscivorous lionfishPteroisspp. in the Western Atlantic and wider Caribbean is a well-documented example of a successful marine invasion. Recently, lionfish have been shown to colonise a wide range of ecosystems and tolerate a wider range of salinities than previously thought. In the present study, lionfish were maintained in aquaria under differing salinity treatments (10, 20 and 37 psu) similar to those they might experience in an estuarine ecosystem. The effects of long-term hyposaline exposure on growth, metabolic rate, maximum food consumption and digestion were examined. Consistent with previous studies, lionfish were able to survive in hyposaline conditions for extended periods of time. However, lionfish in the most hyposaline treatment (10 psu) exhibited reduced growth under low food conditions, lower maximum metabolic rate, lower aerobic scope, lower maximum food consumption, took longer to digest a standardized meal size and occupied a greater percentage of their aerobic scope during digestion. Results suggest that (1) given the ability of lionfish to tolerate low salinity, updated range expansion models should incorporate salinity data to improve accuracy of predicted range expansion and (2) the invasion of lionfish into low salinity ecosystems, although a serious concern, will not likely lead to the same level of population increase observed for coral reef habitats due to the physiological costs associated with living in low salinities.