Progression of invasive lionfish in seagrass, mangrove and reef habitats

Abstract

The invasion of the Indo-Pacific lionfish Pterois volitans into the western Atlantic, Caribbean Sea, and Gulf of Mexico is the fastest ever documented for a marine fish. Few studies have addressed the establishment of lionfish populations within a location, and habitats other than reefs have been largely overlooked. The present study reconstructed the invasion around South Caicos, Turks and Caicos Islands (TCI), from multiple sources of data. Densities and size frequencies of lionfish were compared in deep reefs (10 to 30 m) and shallow habitats (seagrass, mangrove, sheltered reef, and exposed reef < 5 m deep) over a 4 yr period (2007 to 2010). By the end of 2010, lionfish had been observed in all 5 habitats. There was a lag of almost 7 mo between the first sightings in shallow habitats (December 2007) and in deep reefs. After 2 to 3 yr, the density of lionfish in deep reefs surpassed those in shallow habitats. In November 2010, mean density was over 10× higher on deep reefs (9.51 lionfish seen observer −1 h −1 ± 5.37 SD) than in seagrass (0.87 ± 0.41; p < 0.05), which was significantly higher than in other shallow habitats (sheltered reef: 0.52 ± 0.47; exposed reef: 0.12 ± 0.13; and mangrove: 0.06 ± 0.10; p < 0.05). Lionfish on deep reefs (TL = 22.7 ± 7.5 cm) had significantly larger total lengths (TL; mean ± SD) than those in seagrass (TL = 15.0 ± 4.3 cm; p < 0.05) or sheltered reefs (TL = 14.6 ± 6.8 cm; p < 0.05). Assuming one population with ontogenetic movement between habitats, density and age estimates suggest that lionfish may have moved to deep reefs from other habitats. The results suggest that lionfish may settle preferentially, but not exclusively, in shallow habitats before moving to deep reefs. Only 2 studies have explicitly compared lionfish between different habitats. Barbour et al. (2010) found that mangroves supported higher densities of smaller-sized individuals than nearby reef areas, which has since been interpreted as displaying the nursery function of mangroves (Barbour et al. 2011). Similarly, Biggs & Olden (2011) reported that lionfish in seagrass were smaller than those found on reefs and suggested that lionfish may use seagrass as nurseries. Although the global concern focuses on lionfish's impact on reefs (Sutherland et al. 2010), evidently the threat also extends to other habitats such as mangroves and seagrass, especially in the context of their nursery function for native species (Nagelkerken 2000, Nagelkerken et al. 2001, Mumby et al. 2004. Therefore, whether ontogenetic changes in habitat use are also displayed by P. volitans warrants further investigation (Barbour et al. 2010).Additionally, whilst the international effort to document the spread of lionfish throughout its invasive range has been considerable (Schofield 2009, 2010, Johnston & Purkis 2011, far less emphasis has been placed on how a population develops within a new location as it becomes colonized. Thus, quantitative assessments of densities and sizes of lionfish across habitats, depths, and time have n...

Coping with the Lionfish Invasion: Can Targeted Removals Yield Beneficial Effects?

“…In the Bahamas, for example, lionfish on experimental patch reefs reduced recruitment of native reef fishes that serve as forage for important fishery species by an average of 79% (Albins and Hixon, 2008), and lionfish reduced the total biomass of 42 prey species by 65% on 9 natural reefs . Further concerns arise from observations that lionfish can occupy and feed in alternative habitats, including mangroves (Barbour et al, 2010;Claydon et al, 2012) and seagrass beds (Chevalier et al, 2008;Biggs and Olden, 2011;Claydon et al, 2012), which serve as important nurseries for juvenile reef fish (Beck et al, 2001). In addition to these direct effects, lionfish predation on parrotfishes, surgeonfishes, and damselfishes reduces grazing on algae, potentially leading to overgrowth of reefs and subsequent loss of corals (Albins and Hixon, 2011).…”

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

“…Our study design did not include surveys of shallower areas, which might explain why we did not observe juveniles. Claydon et al (2012) suggest that lionfish generally prefer to settle in shallow habitats before moving to deeper reefs as they grow. A related factor may be the absence of mangrove and seagrass ecosystems in our study area; in GNP the coast consists of sandy beaches, rocky coastline, and cliffs.…”

Temporal and Spatial Dynamics of the Lionfish Invasion in the Eastern Gulf of Mexico: Perspectives from a Broadscale Trawl Survey

“…In studies from Roatan, Honduras (Biggs and Olden 2011), and the Turks and Caicos islands (Claydon et al 2012), smaller lionfish tended to occupy seagrass habitats, whereas mature individuals were associated with structured reef environments. Consequently, the lionfish abundance and length data collected from low-relief habitats in the eastern Gulf of Mexico may not represent the portion of the population associated with more structured habitats.…”