Variability across scales in coastal ecosystems

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Strong fluctuations in the total and relative abundance of species remain an unresolved problem in population and community theories. In marine systems, these fluctuations have mostly been studied assuming equilibrium dynamics driven by habitat properties. However, recent work shows how ecological and non-linear feedback processes involved in species interactions could trigger the existence of multiple equilibriums. The goal of my research program is to understand how these ecological processes, and more specifically those associated with spatial aggregation and with the development of ecological structures, operate in synergy to explain strong fluctuations and responses to the environment, from the scale of individuals to that of entire coastal regions. For example, can the development of individual mussels and of mussel beds interact with their spatial connectivity to generate strong feedbacks in their ability to preempt and their susceptibility to loose space? Can these feedbacks in turn drive strong fluctuations of densities across whole landscapes? Finally, can spatial structure at larger scales such as larval dispersal and/or regional habitat heterogeneity maintain fluctuations at the regional level? Toward that goal, I will adopt a multidisciplinary approach integrating (1) reciprocal transplant experiments, (2) non-equilibrium theories of space and ontogeny, and (3) cross-scale monitoring. The research proposed here will first lead to a theory of spatially structured ecosystems with ecological development (i.e. individual to ecosystem level developmental changes) and associated cross-scale fluctuations in heterogeneous landscapes (Project 1.a). Both local feedback processes and predicted fluctuations will be tested in a sub-arctic intertidal community. Landscape level phenomena will then be integrated within a non-equilibrium theory of heterogeneous coastal systems coupled through larval dispersal that will be validated using large-scale data. Finally, I will apply theories to the persistence of seagrass ecosystems. Our effort is meant to lead to major paradigm shifts in large-scale marine ecology, and to reveal novel regional properties that foster predictability and management of complex systems with strong environmental heterogeneity.