Native Predators Do Not Influence Invasion Success of Pacific Lionfish on Caribbean Reefs

Abstract

Biotic resistance, the process by which new colonists are excluded from a community by predation from and/or competition with resident species, can prevent or limit species invasions. We examined whether biotic resistance by native predators on Caribbean coral reefs has influenced the invasion success of red lionfishes (Pterois volitans and Pterois miles), piscivores from the Indo-Pacific. Specifically, we surveyed the abundance (density and biomass) of lionfish and native predatory fishes that could interact with lionfish (either through predation or competition) on 71 reefs in three biogeographic regions of the Caribbean. We recorded protection status of the reefs, and abiotic variables including depth, habitat type, and wind/wave exposure at each site. We found no relationship between the density or biomass of lionfish and that of native predators. However, lionfish densities were significantly lower on windward sites, potentially because of habitat preferences, and in marine protected areas, most likely because of ongoing removal efforts by reserve managers. Our results suggest that interactions with native predators do not influence the colonization or post-establishment population density of invasive lionfish on Caribbean reefs.

On the relationship between native grouper and invasive lionfish in the Caribbean

“…The authors of this paper made a number of assertions of confounding effects in the previous study (Mumby et al 2011) but as we show here, these assertions were factually incorrect and belied an inattentive reading of our paper. Here, we discuss some of the assertions made by Hackerott et al (2013) and consider whether their results really provide evidence that grouper and lionfish abundances are unrelated. In so doing, we hope to clarify the level of evidence on this question and discuss putative mechanisms.…”

“…Recently, a second paper was published on this topic (Hackerott et al 2013) which purported to find no effect of grouper on lionfish abundance in the Caribbean. The authors of this paper made a number of assertions of confounding effects in the previous study (Mumby et al 2011) but as we show here, these assertions were factually incorrect and belied an inattentive reading of our paper.…”

Density, size, biomass, and diet of lionfish in Guanahacabibes National Park, western Cuba

“…According to Hackerott et al (2013), the presence of predators does not appear to be a limiting factor for lionfish populations in the Caribbean. Hackerott et al (2013) found high densities of lionfish on reefs that also supported large populations of potential predators, such as in the Jardines de la Reina National Park in Cuba, which has the highest biomass of fishes in the Caribbean but also high densities of lionfish, similar to those found in the Mesoamerican reef where predators are less common.…”

Assessing the Effects of Marine Protected Areas on Biological Invasions: A Global Review

“…For example, both studies conducted to assess the performance of the invasive lionfishes (Pterois volitans, P. miles) in the Caribbean Sea found that the species presented lower density and biomass in the MPAs than unprotected sites (Mumby et al, 2011;Hackerott et al, 2013). However, one study attributed the lower values within the MPAs to the restoration of predatory relationships (more and larger top predatorsgroupers-controlled the densities of lionfishes within the MPA; Mumby et al, 2011), whereas the other study attributed the lower densities to targeted removal (by spearfishing) within MPAs (Hackerott et al, 2013). Another study examining the effects of MPAs on alien fishes in the Mediterranean Sea, found that the density of alien species did not show any response to protection (Guidetti et al, 2014).…”

“…Secondly, based on the "biotic resistance hypothesis" (i.e., ecosystems with high species richness are more resistant to invaders than those with low biodiversity; Levine and D'Antonio, 1999), the high native species richness within MPAs could prevent the penetration and settlement of alien species. Thirdly, the restoration of top-down regulation processes (e.g., restoration of top predators' populations) in MPAs could help control the population of some alien species inside MPAs (e.g., Mumby et al, 2011 but see also Hackerott et al, 2013). On the other hand, several mechanisms could support the opposite argument, that MPAs favor the spreading of alien species.…”