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-

在大阪南子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。还进行了室内试验，以检查对空气暴露和低盐度的耐受性。在大阪南子鸟类保护区的北池中有大量的绿藻Ulva pertusa，而南池中有大量的Chaetomorpha sp.。除了两个池塘的小区域外，未观察到紫藻和毛藻的共存。这些现象可以部分解释为两个池塘之间暴露在空气中的时间不同，以及与毛藻相比，紫藻对干燥条件的耐受性更高。在大阪-南子Sakishima运河，春末底水的溶解氧浓度超过了水面。这种现象是由于底部沉积物上的一种绿藻（Chaetomorpha sp.）的积极光合作用造成的。在运河水闸附近3米以下深度处观察到营养物质浓度明显下降。结果表明，降低水渠水位，加深水闸口，加强水交换，对改善水渠水质，抑制水藻繁殖是有效的。潮滩底栖生物的氮收支和直立作物。比较了大阪湾及其附近的盐沼。结果，由于底栖生物在新生的人工潮滩上大量繁殖，氮的净交换在建设后的2 - 3年内显著地从源转变为汇。半自然滩涂孳生大量双壳类动物，其氮收支与人工滩涂相比平衡良好。

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.