Bingzhang Chen, L. Zheng, B. Huang, S. Song,

H. Liu.Biogeosciencesce, 2013. 10, 2775–2785.

We conducted a comprehensive investigation

onthe microzooplankton herbivory effect on phytoplankton inthe northern South

China Sea (SCS) using the seawater dilutiontechnique at surface and deep

chlorophyll maximum(DCM) layers on two cruises (July–August of 2009 and

Januaryof 2010).We compared vertical (surface vs. DCM), spatial(onshore vs.

offshore), and seasonal (summer vs. winter)differences of phytoplankton growth

(μ0) and microzooplanktongrazing rates (m). During summer, both μ0 andm were

significantly higher at the surface than at the DCMlayer, which was below the

mixed layer. During winter, surfaceμ0 was significantly higher than at the DCM,

while mwas not significantly different between the two layers, bothof which

were within the mixed layer. Surface μ0 was, onaverage, significantly higher in

summer than in winter, whileaverage surface m was not different between the two

seasons.There were no cross-shelf gradients of μ0 in summer or wintersurface

waters. In surface waters, μ0 was not correlatedwith ambient nitrate

concentrations, and the effect of nutrient

enrichment on phytoplankton growth was not

pronounced.There was a decreasing trend of m from shelf to basin surfacewaters

in summer, but not in winter. Microzooplanktongrazing effect on phytoplankton

(m/μ0) was relativelysmall in the summer basin waters, indicating a decoupling

ofmicrozooplankton grazing and phytoplankton growth at thistime.On average,

microzooplankton grazed 73% and 65%of the daily primary production in summer

and winter, respectively.

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