Anthropogenic impacts on seagrass habitat connectivity: a model to explore potential links between human activity and marine invertebrate metapopulation persistence

Coastal ecosystems face numerous stressors from anthropogenic activities. Furthermore, local stressors that directly impact ecological processes in one location can scale up to have indirect regional consequences. In the case of dispersing marine invertebrates, human activity may impact dispersal and survival rates, which can then alter connectivity patterns and metapopulation dynamics across the seascape. Here, we developed a framework to model metapopulation persistence of seagrass-associated invertebrates in the Salish Sea, focusing primarily on British Columbia, Canada. We combined a biophysical model of dispersal with metrics of habitat naturalness to model how local human activities that may impact dispersal can alter habitat connectivity patterns and potentially impact regional metapopulation persistence. We found that human activities that potentially impact dispersal can reduce population persistence across a region, although the effect varied based on location, population dynamics, and severity of the impacts modeled. The majority of populations, however, remained persistent, suggesting that there are robust and redundant pathways of dispersal that can maintain population connectivity in the face of local disturbances. This study highlights the importance of understanding human impacts and connectivity together in a regional context which could have implications for future marine spatial planning and the effective management of biodiversity.