Mapping the movement of marine fishes: methods, mechanisms, and implications for invasion management

Movement represents a key ecological trait of individuals that has important implications for the spatial structuring of population, community, and ecosystem processes. However, the spatial ecology of terrestrial organisms is much better understood than that of their comparatively understudied aquatic counterparts. My thesis focuses on the methods and mechanisms underpinning the study of movement ecology in fishes, with special attention on the movement of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) on Caribbean coral reefs and its implications for invasion management. I begin by comparing broad-scale patterns of space use across all vertebrates, including fishes, to draw general conclusions about the factors driving their space requirements. My models reveal that body mass, locomotion strategy, foraging dimension, and trophic level predict ~80% of the variation in vertebrate home range size. I then describe a versatile method for GPS-based underwater mapping that will enable more routine collection of a wide variety of spatial data, including movement patterns, habitat characteristics, and bathymetry. This method is ideal for studies operating on smaller scales and budgets and will help advance the study of spatial ecology in aquatic environments. Next, I apply this mapping method to characterize the movements of tagged lionfish on Bahamian coral reefs, and find that lionfish movement is density dependent, declines at larger body sizes, and varies with seascape structure. Using these movement data, I model the metapopulation dynamics of lionfish in a patch reef network to show how removing lionfish from single patches influences metapopulation dynamics at the network scale, and show how landscape features that facilitate recolonization of cleared patches can negatively influence management outcomes. My thesis helps to fill critical gaps in our understanding of movement and space use of animals in general, and of marine fishes in particular. This work also demonstrates how a better understanding of movement ecology can help to optimize the distribution of limited resources for the management of marine invasive species, which represent a significant and growing threat to marine ecosystem biodiversity and function.