"Marine invasions: patterns, processes, and impacts"

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With globalisation proceeding apace, species are being introduced to areas out of their native range at an ever increasing rate. Some of these species become invaders which can cause extensive changes to recipient ecosystems and exact a heavy economic toll. In the marine realm, most invaders occupy the lower rungs of the food chain. They can compete with native species but generally do not cause extinctions. The dynamics and impacts of higher-levels marine invaders, such as predators, may be very different but are generally unknown because of the rarity of such invasions. I propose to use the invasion of shallow-water habitats by Indo-Pacific lionfish, which is currently unfolding across the Caribbean region, as a model system to elucidate the patterns, process and impacts of invasive marine predators. I will first compare the patterns of population growth across a number of invaded sites using publically available databases of lionfish sightings, in an effort to predict when lionfish populations are likely to 'explode' at any given location. I will then examine three processes, namely native species diversity, habitat variability and propagule pressure, that are known to influence the likelihood of terrestrial invasions and assess whether these are also important for invasions by marine predators. These studies will include observations of lionfish on natural reefs as well as experimental manipulations of native fish communities on small patch reefs to assess effects on lionfish movement, growth and survival. Finally, I will focus on the impacts of lionfish on native reef fishes, asking whether lionfish predation triggers cascades of indirect effects throughout the lower levels of a coral reef food chain and whether native fish can learn to identify lionfish as a predator. I will also examine whether lionfish removal strategies can be devised to mitigate these impacts. The lionfish invasion offers a unique opportunity to understand the effects of predator introductions in marine ecosystems. The knowledge generated will be applicable not only to human-mediated introductions but also to climate-mediated dispersal of species into new marine habitats, which may generate a suite of novel predator-prey interactions not unlike those involving lionfish in its new range.