Editor's choice: Disease dynamics in marine metapopulations: modelling infectious diseases on coral reefs

Coral reefs are experiencing devastating mortality due, in part, to emerging disease. Despite this growing problem, the long-term consequences of infectious disease in marine ecosystems remain poorly understood, and the application of epidemiological models to marine disease systems represents a research priority for managing resources in the world's oceans. Metapopulation models may provide a framework for modelling coral population dynamics at the regional scale, and we use this approach to investigate the effects of infectious disease. The model presented here incorporates a susceptible-infected or 'S-I' disease into a system of patchily distributed, dynamic coral hosts, and highlights some basic differences that set many marine disease systems apart from their terrestrial counterparts. The model predicts several possible long-term outcomes of disease introduction, and suggests that the consequences of disease may vary considerably among different pathogens and regions. Due to the long time-scales for coral dynamics, epizootics are expected to be prolonged with recovery slow at the regional scale. Our model results show how infectious disease can substantially alter host metapopulation dynamics, with some non-linear relationships which are likely to affect the response of these systems to management and environmental change. For example, higher rates of coral colonization can have variable consequences for host population occupancy (i.e. coral cover) when infectious disease is considered, and chronic diseases with long-lived pathogens pose the highest risks for regional coral extinction. Synthesis and applications. We present a tractable epidemiological model within a metapopulation framework and compare the model output with empirical data for a white plague type II (WPII) outbreak among coral of the upper Florida Keys. We conclude that this model fits well with the spatial and temporal patterns of WPII over a decade. Despite terrestrial-marine differences, many patterns derived from our model are consistent with epidemiological principles. Thus, the careful application of these principles within the context of marine management may be a promising research frontier. Although we focus on coral disease, the methods and results may apply to other marine metapopulations.