Diet and Biology of Deep-reef Lionfish (Pterois volitans) at Curaçao

Abstract

Indo-Pacific Red Lionfish (Pterois volitans) are a well-established invasive species in the western Atlantic Ocean and have been documented at depths of 0-304 m. However, our knowledge of lionfish biology and diet below 40 m is limited due to the constraints of recreational SCUBA diving depth limits. Communities below 40 m are distinct from communities above 40 m, thus it cannot be assumed that lionfish have the same impacts or consume the same species below 40 m. Studies targeting lionfish diet and biology below 40 m are necessary to determine potential impacts on understudied mesophotic communities and consequences for invasion management. Specifically, understanding where on the reef lionfish reach the largest sizes will give insights into what areas of the reef may experience the highest predation pressure. Understanding where lionfish are spawning on the reef may indicate long term effectiveness of removal efforts. The purpose of this study was to describe the diet, size, and reproductive characteristics of lionfish across depth in Curaçao, Southern Caribbean. Using a combination of SCUBA and manned submersible diving, 136 lionfish off the southern coast of Curaçao were collected along the reef slope down to 189 m. Lionfish below 40 m were longer and heavier than lionfish above 40 m but did not have better body condition (Fulton’s condition factor). Significantly more males than females were collected above 40 m. Fertile females were present along the entire depth range, however no actively spawning females, based on gross morphology of gonads, were found below 126 m. Using DNA metabarcoding of the mitochondrial COI gene of gut contents, 598 exact sequence variants from prey species were recovered representing 51 species of fishes from 18 families and an additional 13 families of invertebrates. Across all individuals, the four most commonly occurring teleost families were Pomacentridae, Apogonidae, Gobiidae, and Scorpaenidae. Gobiidae was frequently consumed above and below 40m, while Apogonidae and Serranidae were more frequently consumed below 40m. No dietary trends were detected with increasing lionfish length or mass. Eighteen teleost taxa were recorded for the first time from lionfish guts. Overall, species of fishes identified in lionfish guts closely reflect prey that is available at the depth at which the lionfish were collected, suggesting that lionfish on mesophotic and rariphotic reefs are consuming mesophotic and rariphotic prey. These deep-reef taxa may be especially vulnerable to lionfish predation given their naturally low abundances coupled with the larger sizes and lack of top-down control of lionfish on deep reefs. Given that culling has been successful in controlling local shallow populations, developing an effective means of culling lionfish below 40 m may be critical reducing the impact of lionfish predation on vulnerable deep-reef fishes.