This article looks into local discourses of the risks and benefits of opening the water gates of the sea dyke built for the Isahaya Bay land reclamation project in Japan. It introduces the research results with analysis of the interviews with and documents from various stakeholders. The discourses of the benefits of opening the gates included: improvements to the oceanic and agricultural environments, increased tourism in the area, an opportunity to reverse poor decisions made in the past, opportunities to re-learn how to live with nature, and ending conflict among citizens. The discourses of the risks included: the possible loss of lives and possessions through flooding, loss of irrigation for agriculture, salt damage to agricultural land, damage to fisheries, loss of current biodiversity, the introduction of risks through new endeavors which might be futile, wasting tax payers' money, and spending money for the benefit of only a specific group in the community. Whether they are 'for' or 'against' the project, the research identified that each opinion had roots in the following five main discourse areas: ① meaning of restoration action, ② worries and past experience of loss, ③ ensuring 'fairness', ④ views towards future, and ⑤ discourse of compromise to overcome conflicts.

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[in Japanese]

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[in Japanese]

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Effects of migratory waterfowls on nutrient concentration were examined in a hypereutrophic lake, Lake Miyajima-numa, which is a major stopover for greater white-fronted goose (Anser albifrons) in Japan. Hydrological budget and water-borne fluxes of total nitrogen (TN) and total phosphorus (TP) were investigated during its ice-free period (April–November) in 2007–2008. We calculated the residuals in a nutrient budget model. To estimate the nutrient loads from the migratory waterfowls, we compared the residuals between the period when waterfowls had stayed in the lake and the period when waterfowls had flown away. TN and TP loads from migratory waterfowls represented 11–18 kg d-1 and 2.0–3.6 kg d-1, respectively, during the early parts of waterfowls’ staying periods. The loads from migratory waterfowls represented 1–3 times (TN) and 4–30 times (TP) higher than those of water-borne nutrient loads during the same period, corresponding to non-irrigation period. This suggested the significant contribution of migratory waterfowls as an allochthonous TP source in lake water. Reducing not only water-borne but also bird-borne nutrient loads appeared to be important for inhibiting eutrophication in Lake Miyajima-numa.

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