Phytoplankton habitats and size distribution during a neap-spring transition in the highly turbid macrotidal Chikugo River estuary
Phytoplankton habitats and size distribution during a neap-spring transition in the highly turbid macrotidal Chikugo River estuary
复制标题
高浑浊大潮汐筑后河口小春过渡期间浮游植物栖息地和大小分布
DOI：
10.1016/j.scitotenv.2022.157810
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发表时间：
2022
影响因子：
9.8
通讯作者：
Azhikodan Gubash
中科院分区：
文献类型：
--
作者：
Nwe Lett Wai;Yokoyama Katsuhide;Azhikodan Gubash
2021年，在日本高浑浊的大潮汐筑后河口，研究了小潮-春季转变对不同浮游植物物种细胞尺寸分布的时空变化及其基于尺寸的生境分布的影响。在小潮到大潮的转变过程中，河口混合从分层变为充分混合，咸水（1-5）侵入直到17公里，河流排放的影响可以忽略不计。小潮期间悬浮泥沙浓度（SSC）较低（<40 mg L−1），而大潮期间悬浮泥沙浓度（SSC）最高（1000 mg L−1），且混合强烈，导致在8至12 km之间形成河口最大浊度（ETM）区。河口共鉴定出浮游植物159种，分为七类。硅藻（淡水和海洋栖息地）被发现是重要的群体（79-86%）。主成分分析（PCA）结果表明，盐度（p < 0.05）和混合度（p < 0.05）是浮游植物栖息地分布的主要控制因素。硅藻丰度从小潮开始增加，小潮后两天达到最大丰度（174.714 个细胞/mL），然后向大潮减少（69.257 个细胞/mL）。此外，优势硅藻物种（中肋骨条藻和针状菱形藻）的细胞大小从小潮到中潮增大，并持续增大直至大潮。在空间上，由于ETM的形成，河口中部的硅藻丰度（67-86细胞/mL）低于其他地区，尽管存在较大的尺寸分布。本研究得出的结论是，浮游植物的丰度和大小分布受到河口混合的影响，在潮汐主导的河口，小潮-春季过渡阶段对于浮游植物的生长比单个小潮和大潮更为重要。此外，除了盐水入侵和ETM之外，尺寸增加模式对于维持其在强湍流条件下的生存策略也发挥着重要作用。
The effect of neap-spring transition on the spatial and temporal changes in the cell size distribution of different phytoplankton species and their size-based habitats distribution were investigated in the highly turbid macrotidal Chikugo River estuary, Japan in 2021. The estuarine mixing changed from stratified to well-mixed over the transition from neap to spring tides and saltwater (1–5) intruded until 17 km with negligible effect from river discharge. The suspended sediment concentration (SSC) was low (<40 mg L−1) during neap tide and highest (1000 mg L−1) during spring tide associated with strong mixing, which led to the formation of an estuarine turbidity maximum (ETM) zone between 8 and 12 km. A total of 159 phytoplankton species were identified in the estuary and are classified into seven groups. The diatoms (freshwater and marine habitats) were found as significant groups (79–86 %). Principal component analysis (PCA) results showed that salinity (p< 0.05) and mixing (p< 0.05) were the major controlling factors in the phytoplankton habitats distribution. The diatoms abundance started to increase from neap tide and reached the maximum abundance (174.714 cells/mL) two days after neap tide, then decreased towards spring tide (69.257 cells/mL). Additionally, the cell sizes of dominant diatoms species (Skeletonema costatumandNitzschia acicularis) increased from neap to intermediate tides and continued increasing until the spring tide. Spatially, the abundance of diatoms was lower in the middle estuary (67–86 cells/mL) than in other parts because of ETM formation, although larger size distribution occurred. This study concludes that the abundance and size distribution of phytoplankton are influenced by estuarine mixing, and the neap-spring transition phase is more essential for phytoplankton growth than individual neap and spring tides in tide-dominated estuaries. Furthermore, size-increasing patterns play an important role in sustaining their survival strategy under the strong turbulent conditions in addition to saltwater intrusion and ETM.