Effects of a Rapid Invasion of Pacific Lionfish, Pterois Volitans, On Reef Fish Communities At Artificial Reefs in the Northern Gulf of Mexico

Pacific lionfish, Pterois volitans/miles complex, were introduced to waters off southeastern Florida in the early 1990s. They became established in the south Atlantic Bight in the 1990s and across the Caribbean Sea in the 2000s, but were not reported in the Gulf of Mexico (Gulf) until 2009. Lionfish have spread rapidly in the Gulf and they have quickly become established residents on both artificial and natural reefs. Unfortunately, throughout the range of the lionfish invasion in the western Atlantic there are few datasets to document their effect on native reef fish communities. A series of 18 artificial reefs sites off Pensacola, FL that have been studied since 2004 provide one such dataset. Mean lionfish density on these reefs has tripled in the past year and a half and current densities (~10 fish 100 m^-2) are among the highest reported in the western Atlantic. Significant changes in reef fish community structure have occurred as lionfish density has increased (PERMANOVA, p<0.001). Trophic shifts also are apparent as small pelagic planktivores, such as scads, herrings, and sardines, have increased approximately 3-fold in response to declines in piscivore and invertivore/piscivore abundance of as much as 60%. Small (<100 mm) demersal planktivores that are likely prey for piscivorous lionfish have shown the most dramatic declines, with their abundances dropping by over 80%. The focus of ongoing research is determining lionfish diet and bioenergetics in the northern Gulf, as well as testing whether declines in various reef fish taxa may be due to predation by lionfish, competition with lionfish for prey resources, or avoidance of reefs with high lionfish density.