Lionfish invasion in nearshore waters of the Bahamas : an examination of the effects of artificial structures and invader versus native species colonization rates

• Main Author: Smith, Nicola Simone
• Language: English
• Published: University of British Columbia 2010
• Online Access: http://hdl.handle.net/2429/27242

Artificial structures can facilitate invasion of non-native marine epibiota by providing unoccupied habitat for colonization. Few studies have examined whether similar effects occur in mobile taxa like reef fishes, despite the widespread occurrence of anthropogenic structure in the world’s coastlines and the critical importance of structured habitat to many fishes. I assessed the distribution and colonization of invasive Indo-Pacific lionfish Pterois volitans/miles in nearshore waters of the Bahamas where artificial structures are prevalent in human-modified seascapes. I hypothesized that artificial structures may promote lionfish range expansion by providing sites for colonization, particularly if lionfish are superior colonizers relative to Atlantic taxa. Using an observational survey, I examined how the type of human modification and habitat may influence invader abundance. I also used a manipulative experiment to determine: (1) if lionfish were faster colonizers than native species, and (2) if local patterns of colonization were consistent at a regional (island-wide) scale. I found that lionfish were evenly distributed between habitats dominated by sand and seagrass meadows, hard bottoms and coral patch reefs. However, nearly 100% of lionfish were associated with artificial structures in sand-seagrass habitat, 25% in hard bottoms, and zero in patch reefs. Lionfish were poor colonizers of experimental reefs relative to Atlantic taxa, although their colonization rate was not different from the most ecologically similar native species in my study (the small-bodied grouper, Epinephelus guttatus). Families, but not species, that were good colonizers at one site tended to arrive quickly at other sites as well, implying some predictability in colonization rate among fish families at an island-wide scale. Artificial structures are a consequence of human coastal development and illegal dumping, but are also often added intentionally to create reef fish habitat. My results suggest that lionfish are capable of invading natural patch reefs in the absence of such structures, but that their presence facilitates colonization of marginal habitats like sand-seagrass and to a lesser extent, hard bottoms. Removing or preventing the dumping of debris may therefore slow the spread of lionfish, but is unlikely to prevent their expansion.