Ecological Drivers of Invasive Lionfish (Pterois volitans and Pterois miles) Distribution Across Mesophotic Reefs in Bermuda

Abstract

Invasive lionfish (Pterois volitans and P. miles) are now ubiquitous throughout the Caribbean and Western Atlantic on shallow and deep reefs. Recent surveys in Bermuda have revealed dense aggregations of lionfish on mesophotic reefs (60 m depth), yet these densities are not pervasive across reefs at this depth. Using diver-led visual surveys of mesophotic reef sites, this study examines how variations in potential ecological drivers may affect lionfish distribution. Significant correlations of lionfish densities were found with prey fish density and prey fish biomass, where sites with higher abundances of prey fishes have greater densities of lionfish. Furthermore, higher densities of lionfish also correlated significantly with higher juvenile Paranthias furcifer biomass, a preferred prey type for lionfish. Prey fish diversity, on the other hand, was not related to lionfish density, nor did prey fish community composition differ in a way that reflected lionfish distributions. The influence of seawater temperature was found to have the strongest effect on lionfish distribution, where higher lionfish densities were found at sites with lower bottom temperature. However, temperature co-varied with prey fish density, prey fish biomass, and P. furcifer biomass, implying that physical parameters of the environment (i.e., temperature) likely influence ecological parameters (i.e., prey fish abundance), contributing to the structuring of lionfish distributions. We suggest, therefore, that cold-water upwelling currents may be fueling the food chain in certain locations, resulting in high abundances of prey fishes and thus lionfish. Understanding the factors that influence lionfish distributions will ultimately increase the efficacy of management strategies, which, as the data presented here suggest, must incorporate mesophotic lionfish populations.

Depth-Dependent Structuring of Reef Fish Assemblages From the Shallows to the Rariphotic Zone

“…Lionfish have been widely reported from MCEs in the western Atlantic, including Bermuda (Andradi-Brown et al, 2017b). Although shallow reef culling has been shown to structure lionfish populations across depth (Andradi-Brown et al, 2017a), it seems that, for our study area at least, water temperature might have been a more important driver (Goodbody-Gringley et al, 2019). In Bermuda, shallow inshore reefs experience lower winter temperatures (14-15 • C) compared to the deeper offshore reefs (Coates et al, 2013), and crucially, these lower inshore winter temperatures fall below the thermal threshold (16.1 • C) under which lionfish have been experimentally shown to cease feeding (Kimball et al, 2004).…”

Testing the efficacy of lionfish traps in the northern Gulf of Mexico

“…Invasive Indo-Pacific lionfish (Pterois volitans/miles complex, hereafter "lionfish") are now well established in the western Atlantic, including the Caribbean Sea and Gulf of Mexico [1], and have recently invaded the Mediterranean Sea [2]. Lionfish occupy a wide diversity of invaded marine habitats, including coral reefs, subtropical artificial and natural reefs [3], seagrass beds [4], mangroves [5], estuaries [6], mesophotic reefs [7][8][9], and upper continental slope reefs [10]. High population densities of lionfish [3,11] have caused reductions in native reef fish abundances [12,13], altered marine communities [14,15], and likely exacerbate current stressors on marine systems [16,17].…”

“…Lionfish are primarily removed by spearfishing on SCUBA [21,26]; however, invasive lionfish have been observed at depths >300 m [10] and diver removals are generally limited to depths <40 m. Over 557,000 km 2 of benthic habitat in the western Atlantic invaded range of lionfish lies within mesophotic and upper-bathyal depths of 40-300 m [27,28]. Although survey capacity for deepwater reefs is relatively limited [28], lionfish density has been documented to be higher on mesophotic reefs than on corresponding shallower reefs [9,[29][30][31]. Deepwater lionfish populations likely disrupt food webs on mesophotic reefs [7] and provide refuge for larger and more fecund individuals [32].…”

Testing the efficacy of lionfish traps in the northern Gulf of Mexico

“…Invasive Indo-Pacific lionfish ( Pterois volitans/miles complex, hereafter “lionfish”) are now well established in the western Atlantic, including the Caribbean Sea and Gulf of Mexico [1] and have recently invaded the Mediterranean Sea [2]. Lionfish occupy a wide diversity of invaded marine habitats, including coral reefs, subtropical artificial and natural reefs [3], seagrass beds [4], mangroves [5], estuaries [6], mesophotic reefs [7–9], and upper continental slope reefs [10]. High population densities of lionfish [3,11] have caused reductions in native reef fish abundances [12,13], altered marine communities [14,15], and likely exacerbate current stressors on marine systems [16,17].…”

“…However, lionfish have been observed at depths >300 m [10] and spearfishing removals for lionfish are limited to SCUBA accessible depths (<40 m). Over 557,000 km 2 of benthic habitat in western Atlantic invaded range of lionfish lies within mesophotic depths of 40–300 m [24] where lionfish populations densities are often higher than shallower depths [9,25–27]. Deepwater lionfish populations likely disrupt food webs on mesophotic reefs [7] and provide refuge for larger and more fecund individuals [28].…”