Changes in the trophic interactions and the community structure of Lake Taihu (China) ecosystem from the 1960s to 1990s |
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Authors: | Yunkai Li Bing Song Yong Chen Liqiao Chen Na Yu Derek Olson |
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Institution: | (1) College of Life Science, East China Normal University, Shanghai, 200062, People’s Republic of China;(2) The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, People’s Republic of China;(3) School of Marine Sciences, University of Maine, Orono, ME 04469, USA;(4) Zhejiang Maritime Safety Administration of People’s Republic of China, Hangzhou, 310005, People’s Republic of China; |
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Abstract: | As the third largest freshwater lake in China, Lake Taihu has suffered from overfishing, eutrophication, and physical disturbance
over the last several decades. Evaluating and quantifying changes in the ecosystem can help us better understand and develop
hypotheses to explain the dynamics of the ecosystem. In this study, trophic interactions and community structure of commercial
fisheries species of Lake Taihu ecosystem were analyzed and compared for three time periods (1961–1965, 1981–1987, and 1991–1995)
using the Ecopath with Ecosim model with the aim of evaluating the changes in the population dynamics and ecosystem development
mechanism spanning the period from the 1960s to 1990s. The results show that the biomass of large predators decreased over
the three decades, while the biomass of small species increased. Increases in the P/B ratios and fishing mortality levels
observed for species groups reveal rapidly intensifying fishery stress over the three decades. The fisheries operated at the
highest trophic level during the 1980s, and there are some indications of “fishing down the food web” in this ecosystem between
the 1980s and the 1990s. Drawing upon Odum’s theory of ecosystem maturity, the structured, web-like ecosystem of the 1960s
developed into a highly mature system during the 1980s; yet, in the 1990s, this structure became less complex and the system’s
maturity fell to its lowest observed level. During this period, the successional development of the system occurred in reverse. |
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