Characteristics of water conditions in the inner part of Ariake Bay with hypoxic water and red tide and causes of decline of the ecosystem on the tidal flats faced to the bay.

从2005年4月至2007年12月，在有明湾内部的9至12个采样站每月或每两周监测一次水质状况。其中四个采样站位于海湾最里面的区域，在相同的采样时间对底栖生物群落进行了定量评估。该湾每年雨季结束后的7月底至8月，最深处20 m以下的水域出现缺氧水。2006年8月5日，这些地区出现了最严重的DO下降。中层水体形成缺氧水体，底层水体溶解氧也降至1 mg/L以下。在这段时间里，地表水温度超过30℃，浮游植物，主要是在雨季开花的硅藻，由于水温极高而死亡。浮游植物的尸体变成了大量悬浮在水中的死亡有机颗粒，并被分解、消耗、分解和分解。 ...更多信息 水里的ng。这一现象表明，缺氧的水已经发生了从海底溶解氧消耗的增加与有机富集的他沉积物，而且由于最近的全球变暖的水温上升正在成为另一个因素，增加水中的耗氧量，并导致缺氧或缺氧的海湾的进展。由于缺氧或缺氧水体的出现，湾内底栖动物群落呈逐年下降趋势。它们的密度和生物量呈周期性波动，夏季迅速减少，秋季到冬季恢复。然而，底栖生物群落并没有完全恢复在寒冷的季节。底栖动物群落由小型的多毛类和小型的双壳类等限制性成员组成，对环境波动具有较强的适应性。因此，春季底栖动物群落的总生物量很低（低于10 g/m^2），但在春季底栖动物群落的总生物量往往达到高峰。如果夏季大规模赤潮发生导致的有机物排放量增加和缺氧水体的发展，海湾内部的底栖生态系统将在不久的将来受到严重破坏。少

The water conditions were monitored monthly or biweekly at 9 to 12 sampling stations in the inner part of Ariake Bay from April 2005 to December 2007. At four of these sampling stations, which are located in the innermost areas of the bay, the benthic communities were assessed quantitatively at the same sampling occasions. In this bay, hypoxic water occurred between the end of July after the rainy season and August in the innermost areas of less than 20 m in depth every year. On August 5, 2006, the most severe decrease of DO occurred in these areas. In the middle layer of the water, anoxic water was formed, and DO of the bottom water also fall to the levels of less than 1 mg/L. In this time, the surface water stood over 30℃, and the phytoplankton, mainly diatoms that bloomed during the rainy season, died due to the extremely high water temperature. The dead body of the phytoplankton became large amounts of dead organic particles suspended in the water, and was being decomposed, consumi … More ng DO in the water. This phenomenon indicate that the hypoxic water has occurred by the increase of DO consumption from the sea floor with organic enrichment of he sediment, but also the increase of water temperature due to the recent global warming is becoming another factor that increase oxygen consumption in the water and results in the progress of hypoxia or anoxic in the bay. The benthic communities in the innermost areas of the bay were declining markedly year to year due to the occurrence of the severer hypoxic or anoxic water. They repeated a cyclic fluctuation in density and biomass, that they decreased rapidly in summer, and recovered from autumn to winter. However, the benthic communities did not recover fully in the cold seasons. The benthic communities consisted of restricted members including small spionid polychaetes and small bivalves that had high adaptability against the environmental fluctuations. Therefore, the total biomass of the benthic communities were very poor (less than 10g /m^2) in spring, when they tended to reach a peak. If the present benthic conditions with increasing organic discharge from the occurrence of large scales of red tide and developing hypoxic water in levels and areas continued in summer, the benthic ecosystem in the inner parts of the bay would be seriously destroyed in near future. Less