The coastal areas of northeastern part of Japan were heavily impacted by the recent earthquake and tsunami on March 11th, 2011. How can ecologists contribute to enhance resilience of coastal ecosystems, and help local human societies to rehabilitate after the disaster? As for natural science, we can quantitatively assess impacts of the catastrophic event by comparing ecological data taken before and after the event. For example, based on the data taken by “Monitoring Site 1000 Coastal Ecosystem Project”, we revealed that the impacts of tsunami varied greatly among different localities, different habitat types, and even among different depths within a single habitat. The obtained knowledge can be used for evaluating which parts of coastal ecosystems are sensitive to catastrophic disturbances like tsunamis, and for estimating their recovery speed. A further challenge to ecologists is to develop a way to effectively utilize our science-based knowledge for decision-making processes of coastal human communities and societies, such as by making rehabilitation plans of coastal biodiversity, and by promoting effective restoration projects of marine resources. Some ongoing attempts include to plan marine protected areas (national parks) to enhance recovery of largely damaged habitats (such as seagrass beds) from remaining local populations, and to establish marine aquaculture systems considering metapopulation structure (larval connectivity) of target populations.