Advection by ocean currents modifies phytoplankton size structure

Advection by ocean currents modifies phytoplankton size structure at small scales (1–10 cm) by aggregating cells in different regions of the flow depending on their size. This effect is caused by the inertia of the cells relative to the displaced fluid. It is considered that, at larger scales (greater than or equal to 1 km), biological processes regulate the heterogeneity in size structure. Here, we provide observational evidence of heterogeneity in phytoplankton size structure driven by ocean currents at relatively large scales (1–10 km). Our results reveal changes in the phytoplankton size distribution associated with the coastal circulation patterns. A numerical model that incorporates the inertial properties of phytoplankton confirms the role of advection on the distribution of phytoplankton according to their size except in areas with enhanced nutrient inputs where phytoplankton dynamics is ruled by other processes. The observed preferential concentration mechanism has important ec...

洋流平流作用会依据浮游植物(phytoplankton)细胞的尺寸，将其汇聚至流场的不同区域，进而在小尺度（1至10厘米）范围内改变浮游植物的尺寸结构。该效应源于浮游植物细胞相对于置换流体的惯性特性。学界普遍认为，在大于等于1千米的大尺度下，生物过程会调控尺寸结构的异质性。本研究提供了观测证据，证明在1至10千米的相对大尺度下，洋流驱动了浮游植物尺寸结构的异质性。研究结果显示，浮游植物的尺寸分布变化与沿岸环流模式存在关联。构建纳入浮游植物惯性特性的数值模型后，证实了平流作用对浮游植物按尺寸分布的调控作用，但在营养盐输入增强的区域除外——这类区域的浮游植物动力学由其他过程主导。本次观测到的优先汇聚机制具有重要的生态学