Zoological Studies

Vol. 54, 2015

Trophic structure of the pelagic food web in the East China Sea

Mei-Ling Bai1,2,*, Fan-Sian Lin1, Yu-Ching Lee1, Gwo-Ching Gong3, and Chih-hao Hsieh1,2,4

1Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan
2Ocean Data Bank, Ministry of Science and Technology, Taipei 10617, Taiwan
3Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 20224, Taiwan
4Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei 10617, Taiwan

Abstract
Background: Trophic structure and trophic transfer efficiency are among the most fundamental characteristics of an ecosystem. They characterize the transfer of nutrient and energy and are crucial in estimating the yield of harvestable biomass. In this study, we investigated the regulation of trophic structure (phytoplankton, zooplankton, and larval fish abundance) and biomass ratio of zooplankton to phytoplankton (as an indicator of transfer efficiency) in the East China Sea, one of the largest marginal seas in the world and an important fishing ground.
Results: The results showed that when sea surface temperature was below 25C, temperature co-acted with resource availability (zooplankton for larval fish and phytoplankton for zooplankton) in determining the trophic structure. When sea surface temperature was above 25C, resource availability dominated the regulation of trophic structure. Biomass ratio of zooplankton to phytoplankton decreased with increasing phosphate concentration.
Conclusions: Our study suggested that the trophic structure of the East China Sea might be controlled by bottom-up processes, and this control is mediated by temperature.

Key words: Bottom-up control; Top-down control; Transfer efficiency; Phytoplankton; Zooplankton; Fish; Temperature;
Nutrient status; East China Sea.

*Correspondence: E-mail: meilingbai@ntu.edu.tw