摘要
Monthly field surveys conducted from April to November 2009 in a tidal front in the Seto Inland Sea, Japan provided a spatial and temporal dataset for investigating seasonal variations in nutrient supply and the formation of a chlorophyll a (Chl-a) maximum. The upward diffusive flux of nutrients is estimated from observational data but it accounted for less than 5% of the nutrients needed to support the primary production of phytoplankton in the front area of the stratification region when the density difference between the surface layer and bottom layer is greater than 0.5 kg m−3. Instead of vertical diffusion, the lateral intrusion of water with high nutrient concentration from the mixed area represented the major nutrient supply in the front area. The depth of the lateral intrusion changed with the month: the surface layer in July became the middle layer in August. According to the calculation of numerical model, an anti-clockwise circulation is intensified by removing river runoff (i.e., low precipitation) in this study area, and the change of lateral intrusion is likely caused by the change of anti-clockwise circulation along with the temporal variation in river runoff. Consequently, the Chl-a peak appeared in the vicinity of the surface front (up to 3 μg L−1) in July, but was in the subsurface (up to 9 μg L−1) in August. Diatom species were a relatively minor taxa of the phytoplankton community up to July, although a relatively high Si(OH)4-Si concentration (up to 20 μmol L−1) was confirmed. In contrast, the subsurface Chl-a maximum (SCM) in August was mainly comprised of diatoms as evidenced by the reduction of both Si(OH)4-Si and Si/N from the surface to subsurface layer (0–20 m depth). Therefore, the supply of both nutrients and the seed population necessary for the formation of the SCM results from the tidal frontal system and phytoplankton assemblages within the tidal front system should be varied on a monthly basis.
摘要译文
从四月潮汐锋在濑户内海进行，以2009年11月每月实地调查，日本调查营养供应季节变化和叶绿素a的形成提供了一个空间和时间的数据集（叶绿素a）最大rients需要支持初级生产浮游植物在分层区域的前部区域，当在表面层和底层之间的密度差大于05公斤米SUP鈭SUP相反垂直扩散的，与从混合区域高养分浓度水的横向侵入表示在前方区域中的主要营养供给横向侵入的深度与月份改变：在七月表面层成为中间层中AugustAccording到数值模型的计算，一个逆时针环流，通过去除河川径流加剧（我竐低沉淀）在本研究领域，和横向侵入的变化可能是由逆时针循环与河流的时间变化沿变化引起runoffConsequently，在表面前方的附近的叶绿素a峰出现（最多3渭克L- SUP鈭SUP）在7月，但是在地下（最多9渭克L- SUP鈭SUP ）八月硅藻是浮游植物群落的一个相对较小的类群截至7月，虽然相对高Si（OH）4 -Si浓度（最多20渭摩尔→SUP鈭SUP）是confirmedIn相比之下，地下叶绿素a在八月最大（SCM），主要是由硅藻如由两个硅（OH）4 -Si和Si / N的从表面减少到次表层（0鈥米深度）因此证明，NTS和必要从潮汐前面系统内的潮汐额叶系统和浮游植物组合单片机结果形成的种子群体应当按月改变
Tomohiro Komorita; Xinyu Guo; Naoki Yoshie; Naoki Fujii[1]; Hidetaka Takeoka. Temporal variation in water intrusion of a tidal frontal system and distribution of chlorophyll in the Seto Inland Sea, Japan[J]. Continental Shelf Research, 2016,112: 68–77