5202 
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Figure 1. Sampling stations during RV Meteor cruise M156 including zoom-in into the eddy (a), temperature at 5 m depth (b), salinity at 5m 
depth (c), and chlorophyll a at 5m depth (d). The background in (a) shows the variations in absolute dynamic topography (ADT) obtained 
from https://www.aviso.altimetry.fr, last access: 4 December 2021. The direction and speed of surface water geostrophic currents are shown 
as arrows. The solid circle in (a)-(d) indicates the core of the eddy, and the dashed circle outlines the periphery. 
Bacteria were quantified using a flow cytometer (FAC- 
SCalibur, Becton Dickinson, Oxford, UK). Seawater sam- 
ples (1.7 mL) were fixed with 85 uL glutaraldehyde (1 % fi- 
nal concentration) and stored at —80 °C until analysis. Sam- 
ples were stained with SYBR Green I (molecular probes), 
enumerated with a laser emitting at 488 nm, and detected 
by their signature in a plot of side scatter (SSC) versus 
green fluorescence (FL1). Heterotrophic bacteria were dis- 
änguished from photosynthetic bacteria (Prochlorococcus 
and Synechococcus) by their signature in a plot of red flu- 
orescence (FL2) versus green fluorescence (FL1). Yellow- 
Biogeosciences, 19. 51995219. 202; 
green latex beads (1 um, Polysciences) were used as an in- 
ternal standard (Gasol and del Giorgio, 2000). Cell counts 
were determined with the CellQuest software (Becton Dick- 
inson). For autotrophic pico and nanoplankton <20um, 
2mL samples were fixed with formaldehyde (1 % final con- 
centration) and stored frozen (—-80°C) until analysis. Red 
and orange autofluorescence was used to identify Chl a 
and phycoerythrin cells. Cell counts were determined with 
CellQuest software (Becton Dickinson); picoplankton and 
nanoplankton populations containing Chl a and/or phyco- 
erythrin (Le. Synechococcus) were identified and enumer- 
https://doi.org/10.5194/bg-19-5199-2022