The response of phytoplankton community to the co-existing events of coastal upwelling and mud banks in the nearshore waters of Alappuzha (15 m depth), located in the southwest coast of India from April to November 2016, is described based on size-fractionated phytoplankton biomass (chlorophyll a), primary production and community composition. The study region exhibited well-distinct spatio-temporal hydrological changes because of the influence of wind-driven coastal upwelling, prevalent during the southwest monsoon (SWM) period. However, the formation of mud banks, in addition to coastal upwelling, was observed at station M2, which facilitated the substantial increase of water column turbidity and inorganic nutrients (ammonium, phosphate, and silicate) during and after the peak SWM period compared to the non-mud bank reference stations (M1 and M3). The prevailing hydrological changes were complemented the corresponding phytoplankton productivity patterns, in which profound domination of nanophytoplankton (2–20 µm) chlorophyll a and primary production was observed throughout the study region, irrespective of seasons. The SIMPER analysis, based on phytoplankton (mostly >20 µm) species composition data (microscopy), revealed the formation of certain characterizing species, mainly comprised of diatoms and dinoflagellates. The consistent predominance of the nanophytoplankton, established under variable hydrological scenarios, showed that the inorganic nutrient (specifically ammonium) availability was instrumental in defining the widespread growth of nanophytoplankton community compared to the prevailing light levels. The present study thus revealed that even the small-sized phytoplankton community could survive in the nutrient-enriched coastal waters, characterised by the co-existing upwelling and mud banks.

基于尺寸划分的浮游植物，描述了浮游植物群落对2016年4月至11月位于印度西南海岸的Alappuzha（深15 m）近岸水域沿海上升流和泥滩并存事件的响应生物量（叶绿素a），初级生产和社区组成。由于西南季风（SWM）时期盛行的风力驱动的海岸上升流的影响，该研究区域表现出明显不同的时空水文变化。但是，在M2站观察到除了海岸上升流以外，还形成了泥滩，这与SWM高峰期期间和之后相比，促进了水柱浊度和无机养分（铵，磷酸盐和硅酸盐）的显着增加。非泥滩参考站（M1和M3）。普遍的水文变化补充了相应的浮游植物生产力模式，其中纳米浮游植物（2–20 µm）的叶绿素a占主导地位。并且在整个研究区域中观察到初级生产，而与季节无关。SIMPER分析基于浮游植物（大多数> 20 µm）物种组成数据（显微镜），揭示了某些特征物种的形成，主要由硅藻和鞭毛藻组成。在可变的水文情况下建立的纳米浮游植物的一致优势表明，与当前的光照水平相比，无机养分（特别是铵）的可用性有助于确定纳米浮游生物群落的广泛增长。因此，本研究表明，即使是小型浮游植物群落也可以在营养丰富的沿海水域中生存，其特征是同时存在上升流和淤泥。