Ecology and evolution of the lionfish invasion of Caribbean coral reefs: Resistance, adaptation and impacts

The lionfish (Pterois volitans) invasion of the Caribbean is a notable example of the successful establishment of a predatory marine fish outside of its native range. In 20 years lionfish have spread over most of Caribbean and the western Atlantic. Lionfish densities in their new range can be up to fifteen times higher than in their native range. On reefs in the Caribbean, lionfish reduce fish populations to the point that this invasive species is considered one of the top ten most serious emerging environmental issues in the world. Native prey can be vulnerable to consumption by exotic predators with which they lack an evolutionary history. Such prey naiveté has been assumed to be a major cause of extinction for endemic species. Yet prey naiveté has been tested rigorously in few cases and never in the marine environment. In Chapter 1 and 3 of my dissertation I used metrics of predator avoidance by small, native Caribbean and Pacific fishes to quantify their responses to lionfish. Field experiments and observations revealed that Caribbean native prey do not recognize of lionfish as a predator, indicating prey naiveté towards this exotic threat. In Chapter 2 and 4, I tested biotic and environmental resistance to the early success of the lionfish invasion in two Bahamian islands and the Belizean Mesoamerican Barrier Reef. Lionfish abundance was negatively related to large grouper biomass in Belize but not in the Bahamas. Wave exposure and marine protection from reef fishing were also negatively related to lionfish abundance and field observations suggested that high-energy of exposed environments might be the dominant determinant of the lionfish density pattern. The direct and indirect effects of lionfish on marine ecosystems in the Caribbean are of great concern for conservation. In Chapter 4 I assessed lionfish impacts on abundance and community structure of reef-fish at large spatial scales. Surveys at 15 sites located along the Belizean Mesoamerican Barrier Reef were performed before and after the lionfish invasion. A negative effect of lionfish abundance on the reef-fish abundance and community composition was detected only 2 years after first lionfish detection on Belizean coral reefs.