Size-based analysis of a zooplankton community under the influence of the Pearl River plume and coastal upwelling in the northeastern South China Sea

Abstract

To examine zooplankton responses to the Pearl River plume (PRP) and coastal upwelling on the northern shelf of the South China Sea (SCS), zooplankton (>160 µm) were investigated in the northeastern SCS during 30 June to 11 July 2008. Zooplankton biomass size spectra (BSS) were constructed to describe zooplankton communities. The BSS parameters such as intercept and slope values were 8.659 ± 0.727 and −0.816 ± 0.074, respectively. On the basis of the BSS parameters, the sampling sites were classified into two main groups, which corresponded to the plume- and upwelling-affected areas, respectively. In addition, a positive correlation between zooplankton and phytoplankton abundance (P < 0.05) was observed in the study waters. These results indicate that (1) zooplankton BSS could be used as an indicator for distinguishing the physical processes, and (2) the PRP and coastal upwelling could regulate zooplankton communities differently through altering nutrient supply for the phytoplankton. The BSS slopes were flatter than expected for a steady-state community and the dominance of jellyfish in the larger size fractions indicated that an energy accumulation in gelatinous organisms occurred in the study waters. Since gelatinous organisms are not food for fish, this energy accumulation may be detrimental to the fishery production in the study area.

Key words:

• Biomass
• river plume
• size spectrum
• South China Sea
• upwelling
• zooplankton

Acknowledgements

The authors thank Professor Dongxiao Wang for providing salinity and temperature data, Professor QingChao Chen for taxonomic identification and Professor Jianqiang Yin for zooplankton sampling. We further acknowledge the captain and crew of RV Shiyan 3 for their assistance.

Funding

This work is supported by the National Natural Science Foundation of China [Grant nos. 41130855; 41276162; 41276159] and the Strategic Priority Research Programme of the Chinese Academy of Sciences [Grant nos. XDA05030403; XDA11020203].

Editorial responsibility: Torkel Gissel Nielsen

Additional information

Funding

Funding: This work is supported by the National Natural Science Foundation of China [Grant nos. 41130855; 41276162; 41276159] and the Strategic Priority Research Programme of the Chinese Academy of Sciences [Grant nos. XDA05030403; XDA11020203].