The effects of habitat fragmentation on diversity and ecosystem functioning have received much recent attention given the increasing rate of anthropogenic habitat destruction. However, ecologists still have to elucidate the complex feedbacks operating among processes of fragmentation, ecosystem function, and community. In this study, we use intertidal mussel aggregations (Mytilus spp.) and their associated organisms within a metaecosystem approach in order to elucidate the potential feedbacks linking habitat connectivity, species diversity and ecosystem processes in a spatially subdivided habitat. Specifically, we conducted a field experiment to mimic natural sub-artic mussel beds (Mont-Joli, Quebec, Canada) and partition the effects of their constituents on ecosystem properties (i.e. productivity, nutrient flow and oxygen load) and individual mussel growth. After allowing two months for colonization, mussel beds and their associated communities were separately examined using incubation chambers to evaluate their response to two levels of habitat (i.e. experimental mussel bed) connectivity. In addition, mimic mussel transplants incorporated measurement of individual mussel growth in order to assess feedbacks between mussel aggregations and mussel productivity.

Results/Conclusions

Results show that variation in associated community metabolism and nutrients fluxes are modulated by habitat connectivity. In addition, individual mussel growth is directly and negatively affected by their ecosystem engineering. This individual-ecosystem feedback is also modulated by habitat (i.e. mussel bed) connectivity. Our study reveals the potential for feedback interactions among habitat, community and ecosystem level dynamics in marine systems. The demonstrated strong but complex effect of connectivity on all levels of organization (from individual to ecosystem level properties) means that conservation efforts attempting to maintain connectivity among subdivided habitats should consider biological processes occurring at different organizational scales in order preserve natural metacommunities.