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Population connectivity is inherently bio-physical: it is determined by physical transport and dispersion, as well as biological processes such as timing of spawning, larval behavior, and mortality. Knowledge of connectivity is essential for understanding ecosystem responses to changing environmental conditions. It establishes the spatial scales over which a population is connected, and in turn the primary spatial scale of population interactions and ecosystem dynamics. Concepts in population connectivity were initially developed in terrestrial ecology, where dispersal may occur at different life stages. In the simplest form, a one-dimensional dispersal curve describes the distribution of settlers away from a source region as a function of distance. As this spatial distribution varies in time, the “dispersal kernel” defines a spatial probability density function of settlers aggregated over time (see, e.g., Okubo and Levin, 2002). This dispersal kernel may be three dimensional, but is often reduced to two dimensions (e.g., animals on a plain) or one dimension (e.g., animals living along the land-water interface).