Invasive lionfish dispersal between shallow- and deep-water habitats within coastal Floridian waters

Abstract

Invasive lionfish threaten native fishes and ecosystem health of the Atlantic, Gulf of Mexico, and Caribbean communities. Controlling their spread and population growth can be difficult given their early maturity, high fecundity, a long larval dispersal period, and preference for structure. Mitigation efforts are further complicated by the existence of large and numerous, deep water refugia. Despite the potential importance of these refugia, their connection with shallow water populations and their role in recruiting pelagic larvae is poorly understood. We examined the post-settlement dispersal patterns of invasive lionfish using δ13C and δ18O stable isotope analysis on otoliths and Bayesian stock mixture analysis. We find that there is settlement within both deep- and shallow- water habitats. It is estimated that 34.5% of the shallow-water population is composed of individuals that settled in deep-water habitat and dispersed into these shallow regions post-settlement. Only 4.1% of the deep-water population is composed of individuals that settled in shallow-water habitat before dispersing. These results demonstrate a link between deep and shallow habitats within the coastal waters of Florida, with the flow of individuals from deep to shallow water being the predominate dispersal direction of post-settlement individuals. We suggest that post-settlement dispersal can contribute to the invasion of new habitat and potentially hinder shallow-water removal efforts in currently colonized areas.