Preliminary investigation on the changes in trophic structure and energy flow in the Yangtze estuary and adjacent coastal ecosystem due to the Three Gorges Reservoir

Abstract Water projects in the Yangtze River basin, especially the Three Gorges Reservoir (TGR), have strongly affected the biological and ecological integrity of the Yangtze estuary and adjacent coastal ecosystems. The Ecopath with Ecosim model was applied to study trophic structure and energy flow after the impoundment of TGR based on field surveys in 2006. The model results showed that the trophic levels ranged from 1.000 to 4.058; and 44% of the energy flows originated from the detritus food chain, while 56% originated from the grazing food chain in the trophic transfer process; the transfer efficiency of the ecosystem was 10.0%, and TPP/TR (Total Primary Production/Total Respiration) was 1.899. Compared with model results in 2000 (before impoundment of TGR), the trophic structure of the ecosystem did not exhibit substantial changes; however, the mean trophic level and catch amount decreased remarkably after impoundment. The estuary and adjacent coastal ecosystems were found to be more sensitive to external perturbations after impoundment.

[1]  Marta Coll,et al.  Novel index for quantification of ecosystem effects of fishing as removal of secondary production , 2008 .

[2]  Xihua Cao,et al.  Nutrient characteristics in the Yangtze River Estuary and the adjacent East China Sea before and after impoundment of the Three Gorges Dam. , 2009, The Science of the total environment.

[3]  S. Opitz,et al.  Trophic network model of a shallow water area in the northern part of the Lagoon of Venice , 1999 .

[4]  E. Odum.  Fundamentals of ecology , 1972 .

[5]  Y. Lü,et al.  Three Gorges Project: Efforts and challenges for the environment , 2010 .

[6]  B. Zhang,et al.  Trophic interactions, ecosystem structure and function in the southern Yellow Sea , 2013, Chinese Journal of Oceanology and Limnology.

[7]  D. Pauly.  Fish population dynamics in tropical waters: A manual for use with programmable calculators , 1984 .

[8]  Villy Christensen,et al.  ECOPATH II − a software for balancing steady-state ecosystem models and calculating network characteristics , 1992 .

[9]  J. Castilla,et al.  Challenges in the Quest for Keystones , 1996 .

[10]  A. W. Morris,et al.  Seasonal variability of salinity, temperature, turbidity and suspended chlorophyll in the Tweed Estuary. , 2000, The Science of the total environment.

[11]  M. Jiang,et al.  Annual variability of ichthyoplankton in the Yangtze River estuary of China from August 2002 to 2009 , 2013 .

[12]  L. H. Sipaúba-Tavares,et al.  Study on feeding habits of Piaractus mesopotamicus (Pacu) larvae in fish ponds , 1999 .

[13]  Kerim Aydin,et al.  Ecopath with Ecosim as a model-building toolbox: Source code capabilities, extensions, and variations , 2016 .

[14]  D. Pauly,et al.  A multiple regression model for prediction the food consumption of Marine Fish populations , 1989 .

[15]  G. Winberg,et al.  Rate of Metabolism and Food Requirements of Fishes , 1962 .

[16]  K. Radway Allen,et al.  Relation Between Production and Biomass , 1971 .

[17]  Yujun Yi,et al.  Ecological risk assessment of heavy metals in sediment and human health risk assessment of heavy metals in fishes in the middle and lower reaches of the Yangtze River basin. , 2011, Environmental pollution.

[18]  Marta Coll,et al.  An ecological model of the Northern and Central Adriatic Sea: Analysis of ecosystem structure and fishing impacts , 2007 .

[19]  Zhenyao Shen,et al.  Spatial and temporal variations in nitrogen and phosphorous nutrients in the Yangtze River Estuary. , 2012, Marine pollution bulletin.

[20]  K. Bjorndal,et al.  Historical Overfishing and the Recent Collapse of Coastal Ecosystems , 2001, Science.

[21]  Zhang Bo.  Study on the Structure and Energy Flow of the Yangtze River Estuary and Adjacent Waters Ecosystem Based on Ecopath Model , 2009 .

[22]  E. Odum.  The strategy of ecosystem development. , 1969, Science.

[23]  K. Kadokami,et al.  Occurrence and aquatic ecological risk assessment of typical organic pollutants in water of Yangtze River estuary , 2013 .

[24]  S. Monismith,et al.  Isohaline Position as a Habitat Indicator for Estuarine Populations , 1995 .

[25]  Minghui Zheng,et al.  Distribution of polycyclic aromatic hydrocarbons in sediments from Yellow River Estuary and Yangtze River Estuary, China. , 2009, Journal of environmental sciences.

[26]  Alfred Wüest,et al.  Disrupting biogeochemical cycles - Consequences of damming , 2002, Aquatic Sciences.

[27]  D. Pauly,et al.  A method for identifying keystone species in food web models , 2006 .

[28]  Z. Shi.  Behaviour of fine suspended sediment at the North passage of the Changjiang Estuary, China , 2004 .

[29]  M. Coll,et al.  Trophic flows, ecosystem structure and fishing impacts in the South Catalan Sea, Northwestern Mediterranean , 2006 .

[30]  Baodong Wang,et al.  Annual cycle of hypoxia off the Changjiang (Yangtze River) Estuary. , 2012, Marine environmental research.

[31]  V. Christensen.  Ecosystem maturity - towards quantification , 1995 .

[32]  V. Christensen,et al.  Modeling changes in the coastal ecosystem of the Pearl River Estuary from 1981 to 1998 , 2009 .

[33]  W. L. Quesne,et al.  Trophic controls of jellyfish blooms and links with fisheries in the East China Sea , 2008 .

[34]  Carl J. Walters,et al.  Ecopath with Ecosim: methods, capabilities and limitations , 2004 .

[35]  H. Savenije,et al.  Water abstraction along the lower Yangtze River, China, and its impact on water discharge into the estuary , 2012 .

[36]  S. Lluch-Cota,et al.  Ecosystem trophic structure and energy flux in the Northern Gulf of California, México , 2004 .

[37]  Richard Stone,et al.  Three Gorges Dam: Into the Unknown , 2008, Science.

[38]  J. Diamond,et al.  China's environment in a globalizing world , 2005, Nature.

[39]  P. Failler,et al.  A trophic model of the Pearl River Delta coastal ecosystem , 2009 .

[40]  Raymond L. Lindeman.  The trophic-dynamic aspect of ecology , 1942 .

[41]  J. Polovina.  An overview of the ecopath model , 1984 .

[42]  Yonghong Wu,et al.  Dynamics of arsenic in salt marsh sediments from Dongtan wetland of the Yangtze River Estuary, China. , 2012, Journal of environmental sciences.

[43]  Carl J. Walters,et al.  Ecopath, Ecosim, and Ecospace as tools for evaluating ecosystem impact of fisheries , 2000 .

[44]  Thomas Brey,et al.  A collection of empirical relations for use in ecological modelling , 1999 .

[45]  Zhenyao Shen,et al.  Role of living environments in the accumulation characteristics of heavy metals in fishes and crabs in the Yangtze River Estuary, China. , 2012, Marine pollution bulletin.