Toward Realizing the Sustainable use of and Healthy Marine Environments in an Open-Type Enclosed Bay

Abstract Coastal waters forming an ecotoone between land and the sea include important habitats that provide many ecosystem services for human beings. Pressure brought by human activities has accumulated, however, and is beyond the capacity of coastal waters, as noted by the concept of the planetary boundary. No studies have been done about the impact of the open ocean and land-based loads from rivers and aquacultures on the environmental conditions in an open-type enclosed bay. These characteristics are different from those of a typical enclosed bay, which is influenced mainly by human activities. Few studies have been about the management methods of coastal waters, realizing that human beings can live connected with nature. Yanagi defined Satoumi as coastal waters whose productivity and biodiversity are increased by human interventions that generate fat, long, and smooth material flows. According to Yanagi, material flows can be accomplished through management of the environments in the watersheds from the mountains to the sea and the management of marine bioresources, including human consumers, who are top predators in a marine food chain. Matsuda noted that sound coastal fisheries are indispensable for maintaining healthy material flows and a sound marine environment. These two objectives form Satoumi activities, but no studies can present how to accomplish these objectives in an open-type enclosed bay. When we obtain an answer, we will be able to put them into practice for realizing a sound, prosperous, and sustainable open-type enclosed bay.