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Abstract
Habitat plays a critical role in community dynamics, yet is usually considered a static, rather than dynamic component of a system. Habitat dynamics (including interactions with habitat occupants) are especially relevant when the habitat is living and exhibits variation on a similar time scale as its occupants. Corals and their symbionts are one system where habitat dynamics are relevant. Symbiont settlement processes, movement, and interactions with coral all influence the development of coral colonies and the spatial patterns of colonies in the landscape. These patterns then feed back to affect the dynamics of the symbionts. This dissertation addresses the relationship between corals and their symbionts at both an individual and population level to determine unknown effects of symbionts upon host corals and explore long-term dynamics of the coral and symbiont due to feedbacks within the system through a combination of laboratory, field, and modeling studies. I first explored the spatial distributions of two corallivorous snails, documenting aggregations at multiple spatial scales. Additionally, I explored the role of chemical cues in creating aggregations, and the effect of the aggregations on coral growth. I also tested the effects of the spatial distribution of damage on the response of the coral, demonstrating that the distance between coral lesions affects healing rate, linear extension of the coral, and coral morphology. At a larger spatial scale, I explored how landscape configuration generates long-lasting heterogeneity in the density of symbionts across a landscape. The amount of heterogeneity depends on landscape configuration, and the persistence of this heterogeneity through time depends on factors such as post-settlement density-dependent mortality of the occupant. Finally, I examined feedbacks between occupants and corals with models that included interactions between corals and occupants as well as coral dynamics. Collectively these studies demonstrate how interactions between habitat and occupants can play an important role in the spatial distribution of corals and occupants, which can affect not only the morphology of the coral, but also the distribution of corals and occupants across the landscape.