Ocean Connectivity and Nearshore Marine Species Population Dynamics

Abstract

This dissertation addresses the spatial dynamics of marine species in nearshore environments. These are some of the most productive and diverse regions on earth, providing essential goods and services to a large number of people around the globe. However, they are also under increasing stress from numerous perturbations such as oil spills, over-harvesting, and from changes in our atmospheric and oceanic climates. These disturbances are but a few examples for why it is important that we develop our understanding, and have some predictive capacity for the population dynamics of nearshore marine species. This is no trivial task for nearshore systems are complex, being characterized by interacting physical, ecological and social processes, and it is often difficult to understand why certain species are where, and how they might respond to certain management actions. Nevertheless, this has been the focus on my Ph. D., specifically, I have studied the role that ocean circulation plays in the demography of nearshore marine species. Most nearshore marine species are sedentary as adults, with home ranges ∼ 10 km. It is as newly spawned larvae that they travel greater distances, sometimes traveling hundreds of kilometers. During this stage, dispersal is primarily directed by ocean currents, and as a result, these species exist in a complex system of connected subpopulations. This spatial connectivity is the heart of my dissertation. I have worked on answering four research questions that each have a focus on connectivity: (1) what do patterns of larval connectivity look like in the Southern California Bight? (2) is connectivity important for the robustness of nearshore metapopulations and their management? (3) does connectivity change in time and, if so, what are the demographic consequences? (4) does connectivity in uence the composition of species in nearshore communities?