Food Chain Length Associated with Environmental Factors Affected by Large Dam along the Yangtze River

Food chain length (FCL) is a critical measure of food web complexity that influences the community structure and ecosystem function. The FCL of large subtropical rivers affected by dams and the decisive factors are far beyond clear. In this study, we used stable isotope technology to estimate the FCL of fish in different reaches of the main stream in the Yangtze River and explored the key factors that determined the FCL. The results showed that FCL varied widely among the studied areas with a mean of 4.09 (ranging from 3.69 to 4.31). The variation of FCL among river sections in the upstream of the dam was greater than that in the downstream. Regression analysis and model selection results revealed that the FCL had a significant positive correlation with ecosystem size as well as resource availability, and FCL variation was largely explained by ecosystem size, which represented 72% of the model weight. In summary, our results suggested that ecosystem size plays a key role in determining the FCL in large subtropical rivers and large ecosystems tend to have a longer food chain. Additionally, the construction of the Three Gorges Dam has been speculated to increase the FCL in the impoundment river sections.

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Food Web Structure and Trophic Interactions Revealed by Stable Isotope Analysis in the Midstream of the Chishui River, a Tributary of the Yangtze River, China

Water ◽

10.3390/w13020195 ◽

2021 ◽

Vol 13 (2) ◽

pp. 195

Author(s):

Qiang Qin ◽

Fubin Zhang ◽

Fei Liu ◽

Chunling Wang ◽

Huanzhang Liu

Keyword(s):

Stable Isotope ◽

Carbon Source ◽

Food Web ◽

Food Chain ◽

Yangtze River ◽

Trophic Niche ◽

The Yangtze River ◽

Food Chain Length ◽

Trophic Pathways ◽

Chishui River

Understanding energy flow and nutrient pathways is crucial to reveal the dynamics and functions of riverine ecosystems and develop appropriate conservation strategies. In this study, we utilized stable isotopes of δ13C and δ15N to examine the fundamental characteristics of trophic position, trophic niche, and carbon source for the food web in the midstream of the Chishui River, a tributary to the Yangtze River. Our results showed that stable isotope signatures among different sorts of basal resources and consumers were significantly distinguishable and that the food chain consisted of four trophic levels, indicating the multiple trophic pathways and long food chain length here. The trophic guilds of fish were classified into four categories, in which herbivorous and carnivorous fish showed greater trophic diversity and omnivorous fish had higher trophic redundancy, which meant that there was a stable trophic niche structure in the study area. Phytoplankton and periphyton presented the largest contributions to consumers, indicating that autochthonous productivity was the dominant carbon source in the midstream of the Chishui River. Since the Chishui River is still in a natural condition without any dam constructions, the autochthonous productivity, stable trophic niche structure, multiple trophic pathways and long food chain length found here demonstrate its high conservation value. Therefore, the strategy to refrain from damming on this river should persist into the future.

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Productivity, Disturbance and Ecosystem Size Have No Influence on Food Chain Length in Seasonally Connected Rivers

PLoS ONE ◽

10.1371/journal.pone.0066240 ◽

2013 ◽

Vol 8 (6) ◽

pp. e66240 ◽

Cited By ~ 29

Author(s):

Danielle M. Warfe ◽

Timothy D. Jardine ◽

Neil E. Pettit ◽

Stephen K. Hamilton ◽

Bradley J. Pusey ◽

...

Keyword(s):

Chain Length ◽

Food Chain ◽

Ecosystem Size ◽

Food Chain Length

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Spatial disturbance synchrony alters the association of food chain length and ecosystem size

Ecological Research ◽

10.1111/1440-1703.12056 ◽

2019 ◽

Vol 34 (6) ◽

pp. 864-871

Author(s):

Akira Terui ◽

Shota Nishijima

Keyword(s):

Chain Length ◽

Food Chain ◽

Ecosystem Size ◽

Food Chain Length

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Food chain length in a large floodplain river: planktonic or benthic reliance as a limiting factor

Marine and Freshwater Research ◽

10.1071/mf16269 ◽

2017 ◽

Vol 68 (7) ◽

pp. 1336 ◽

Cited By ~ 1

Author(s):

M. Saigo ◽

L. Ruffener ◽

P Scarabotti ◽

M. Marchese

Keyword(s):

Chain Length ◽

Food Chain ◽

Trophic Position ◽

Paraná River ◽

The Body ◽

Parana River ◽

Ecosystem Size ◽

Food Chain Length ◽

Top Predators ◽

Middle Paraná

Food chain length (FCL) is a key integrative variable describing ecosystem functioning. The aim of the present study was to test the hypothesis that the relative importance of planktonic and benthic energy pathways is a major factor affecting FCL in the Middle Paraná River. Samples were obtained from in eight waterbodies, measuring chlorophyll-a concentrations and the abundance of benthic invertebrates and the trophic position of top predators by stable isotope analysis. There was no evidence that resource availability, disturbances or ecosystem size limited FCL. Similarly, the body size and trophic position of predators were not correlated. However, the relative abundance of planktonic and benthic resources was correlated with FCL. In addition, stable isotopes analysis showed that the benthic reliance of top predators is correlated with their trophic position. The results of the present study indicate that because the major benthic primary consumer is a large fish (Prochilodus lineatus), the size structure of individual food chains is an important factor determining FCL. Whereas in floodplain rivers large detritivorous fishes are targets of commercial fishing, overfishing in the Middle Paraná River could be expected to increase FCL, the opposite effect to that seen in marine environments.

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