Estuarine fronts have significant effects on estuarine circulation, water quality, and productivity. However, there are limited studies on the joint ecological effects of sediment and plume fronts caused by tidal mixing and a low-salinity plume in and off the Changjiang River Estuary (CRE). Based on observational data during the summers of 1988–2016, we analyzed the spatial correlations between environmental factors and chlorophyll-a (Chl-a) concentrations along the two frontal boundaries. The water mass that is shoreward of the sediment front was characterized by the highest nutrients and total suspended matter (TSM); extensive light limitation caused by TSM consequently led to the lowest Chl-a. The water mass between the sediment and plume fronts displayed the highest Chl-a, which benefited from increased light availability due to rapid deposition of TSM across the sediment front and higher nutrients contributed by the plume and coastal upwelling. Shelf water mass beyond the plume front showed the lowest TSM and nutrients; the distinct reduction of nutrient supply resulted in a relatively low Chl-a. The spatial pattern of summer phytoplankton biomass tended to be a result of the balance of light and nutrients constructed by the two fronts and coastal upwelling in and off the CRE.

河口前沿对河口循环，水质和生产力有重要影响。然而，关于长江口内外的潮汐混合和低盐度羽流引起的沉积物和羽流锋联合生态效应的研究很少。基于1988-2016年夏季的观测数据，我们分析了环境因子与沿两个前沿边界的叶绿素a（Chl-a）浓度之间的空间相关性。沉积物前沿的水团的特征是养分含量最高和总悬浮物（TSM）最高。因此，由TSM引起的大范围光限制导致最低的Chl-a。沉积物和羽状流锋之间的水团显示出最高的Chl-a，这得益于TSM在沉积物前沿的快速沉积以及羽状流和沿海上升流带来的更高养分，从而增加了光的利用率。羽状前沿以外的陆架水量显示出最低的TSM和养分；营养素供应的明显减少导致相对较低的Chl-a。夏季浮游植物生物量的空间格局往往是由于两个前沿所构成的光和养分平衡以及CRE内外的沿海上升流所致。