Wetlands, tidal flats, seaweed beds, and coral reefs are valuable not only as habitats for many species, but also as places where people interact with the sea. Unfortunately, these areas have declined in recent years, so environmental improvement projects to conserve and restore them are being carried out across the world. In this study, we propose a method for quantifying ecosystem services, that is, useful for the proper maintenance and management of artificial tidal flats, a type of environmental improvement project. With this method, a conceptual model of the relationship between each service and related environmental factors in natural and social systems was created, and the relationships between services and environmental factors were clarified. The state of the environmental factors affecting each service was quantified, and the state of those factors was reflected in the evaluation value of the service. As a result, the method can identify which environmental factors need to be improved and if the goal is to increase the value of the targeted tidal flat. The method demonstrates an effective approach in environmental conservation for the restoration and preservation of coastal areas.

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山田 佳裕 1) ，井桁 明丈 2) ，中島 沙知 3) ，三戸 勇吾 3) ，小笠原貴子 4) ， 和田 彩香 4) ，大野 智彦 5) ，上田 篤史 2)，8) ，兵藤不二夫 2) ，今田 美穂 2) ， 谷内 茂雄 2) ，陀安 一郎 6) ，福原 昭一 7) ，田中 拓弥 2) ，和田英太郎 2)，9)The runoff of suspended substances，nitrogen，and phosphorus by enforced draining during the ploughing season Experiments in paddy fieldsThe runoff of suspended substances (SS)，nitrogen，and phosphorus by enforced draining during the ploughing season was calculated from experiments in two paddy fields．The area of a paddy field was 3000m 2 ．The total fluxes were 33 kg (SS)， 85 g (total-N)， and 46 g (total-P) in Field A， with a small decrease in water levels (8mm)， 110kg (SS)，589 g (total-N)，and146 g (total-P) in Field B with a major decrease in water levels (72mm)． Furthermore， the nitrogen/phosphorus ratios (mol ratios) of the waste water by the enforced draining were 4.1 (Field A) and 8.8 (Field B)．In comparison with N/P of the phytoplankton (16)，it was found that the phosphorus flowed out efficiently with the enforced draining．Increasing the supply of the phosphorus to Lake Biwa is not desirable in view of the current problems of eutrophication．The careless water management of paddy fields was a crucial factor in any plan to improve the water quality of Lake Biwa．

Green port structures (i.e. green infrastructure in ports and harbors) featuring habitats for marine organisms have been promoted in Japan as part of a comprehensive policy to reduce the environmental impact of ports and carry out habitat conservation, restoration, and creation. In this study, we evaluated the ecosystem services provided by green port structures in two highly urbanized bays (Tokyo Bay and Osaka Bay) in Japan. Our results show that the provision of some ecosystem services can be limited by circumstances particular to ports and other areas with restricted access. In the case of green port structures that have strong usage restrictions, for example, cultural services can only be provided if relevant authorities are prepared to conduct public events while ensuring participant safety. On the other hand, green port structures with weak usage restrictions are often equipped with incidental facilities such as parking lots and restrooms; these facilities can enhance the provision of cultural services (e.g. recreation and environmental education). Green port structures in highly urbanized bays often have usage restrictions, but their proximity to large populations means that they can potentially provide numerous ecosystem services. However, our study shows that appropriate management goals, such as protecting species and ensuring healthy habitats, are needed to maintain the value of these services in highly urbanized and eutrophic bays.

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