The effects of a warm-core eddy on chlorophyll a distribution and phytoplankton community structure in the northern South China Sea in spring 2017

Due to the unique physical processes of mesoscale eddies, the chemical properties and biological composition within an eddy and in the surrounding water are distinct. At present, the physical-biological coupling process in warm-core eddies remains unclear. In March 2017, a warm-core eddy formed due to the Kuroshio intrusion into the northern South China Sea (nSCS). The phytoplankton community structure within and surrounding the eddy was measured and determined using HPLC-CHEMTAX analytical techniques. The averaged water column-integrated concentration of total-chlorophyll a (total-Chl a) inside was similar to that outside the eddy, and an enhancement of phytoplankton biomass and a thickening deep Chl a maximum (DCM) layer were detected within the eddy. There were significant differences (one-way analysis of similarity, R = 0.308, P