Adaptive preservation of artificial waterside along the mast of urban area-changes of the ecosystem of salt marshes in accompanied with the construction of sluice pipes-

在大坂南光鸟类保护区的南北池塘进行了实地研究，以澄清绿藻的分布和过渡。还进行了室内实验，以检查暴露于空气和低盐度的耐受性。在大坂南光鸟类保护区的北池中，有大量的绿色的孔石莼，而南池中则有大量的硬毛藻。孔石莼和硬毛藻的共存，除了两个池塘的小面积观察。这些现象可以部分解释的差异，暴露时间的两个池塘之间的空气中，沿着具有较高的耐受性，干燥条件下孔石莼相比，毛藻。在大坂，南港崎岛运河，底部沃茨超过表面的溶解氧浓度在晚春。这种现象是由于底质上的一种绿色植物--硬毛藻的光合作用活跃所致。营养盐浓度的显着下降，观察到低于3 m的深度附近的水闸的运河。结果表明，降低运河水位，加深闸口，加强水交换，对改善运河水质和抑制藻华是有效的。本文比较了大坂湾及其附近潮滩和盐沼底栖生物的氮收支和现存量。结果表明，在人工潮滩建成后的2 ~ 3年内，由于底栖生物的大量繁殖，氮的净交换发生了明显的由源向汇的变化。与人工潮滩相比，半自然潮滩产出了大量的双壳类，其氮收支平衡良好。

Field studies were carried out at the north and south ponds of Osaka Nanko Bird Sanctuary to clarify the distribution and transition of Chlorophycean seaweeds. Indoor experiments were also conducted to examine the tolerance to exposure to the air and low salinity. A green alga Ulva pertusa was abundant at the north pond, while Chaetomorpha sp. was densely populated at the south pond of Osaka Nanko Bird Sanctuary. Coexistences of Ulva pertusa and Chaetomorpha sp. were not observed except for small areas of the two ponds. These phenomena could partly be explained by the difference of exposure time to the air between the two ponds, along with a high tolerance to dry conditions in Ulva pertusa compared to Chaetomorpha sp.At Osaka-Nanko Sakishima Canal, bottom waters exceeded surface ones in the concentration of dissolved oxygen in late spring. This phenomenon results from the active photosynthesis of a green alga, Chaetomorpha sp. on the bottom sediment. A marked decline in nutrient concentration was observed below 3m in depth near a sluice gate of the canal. The facts obtained here suggest that decreased water level of the canal, deepened mouth of the sluice gate, together with enhancement of water exchange are effective for the improvement of water quality and depression of algal blooms at the canal.Nitrogen budgets and standing crops of the benthic organism at tidal flats and .salt marshes in and near Osaka Bay were compared. As the result, the net exchange of nitrogen markedly changed from a source to a sink within 2 or 3 years of construction due to the massive reproduction of benthic organisms at the young artificial tidal flat. The semi-natural tidal flat yielded a large quantity of bivalves and its nitrogen budget was well balanced compared to the artificial ones.