Cascading Impacts of Foundation Species Loss on Ecosystem Functioning Within Oregon Rocky Intertidal

Foundation species create shelter, enhance biodiversity, and maintain ecosystem functioning within their environment. Within the rocky intertidal ecosystem, a coastal ecosystem dominated by mussels and surfgrass, foundation species are expected to decrease in abundance with climate change, temperature abnormalities, and increased human impact. However, there is a need to better understand how foundation species loss will affect ecosystem functioning via changes in resource fluxes and community structure. Using tide pools in coastal Oregon as a study system, we tested how the loss of mussels (Mytilus californianus) and surfgrass (Phyllospadix spp.) affect short-term community composition, biogeochemistry, thermal buffering, and ecosystem metabolism (net ecosystem calcification [NEC] and net ecosystem production [NEP]) using a Before-After-Control-Impact (BACI) experimental design. Our results show that foundation species loss altered ecosystem function and was dependent on short-term community composition shifts. This study will anticipate immediate cascading impacts of foundation species loss on ecosystem function to aid in conservation management policies of our intertidal ecosystems.