Pelagic energy flow supports the food web of a shallow lake following a dramatic regime shift driven by water level changes

Across the globe, lake ecosystems are exposed to a variety of human disturbances. A notable example is shallow lakes where human-induced eutrophication or water level fluctuation may result in a switch from a clear-water, macrophyte-dominated state to a turbid, phytoplankton-dominated state. Yet, fe...

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Bibliographic Details
Published in:The Science of the total environment Vol. 756; p. 143642
Main Authors: Mao, Zhigang, Gu, Xiaohong, Cao, Yong, Luo, Juhua, Zeng, Qingfei, Chen, Huihui, Jeppesen, Erik
Format: Journal Article
Language:English
Published: Netherlands Elsevier B.V 20.02.2021
Subjects:
Alternative states
Animals
Benthic invertebrates
benthic zone
carbon
Ecosystem
ecosystems
Energy channels
energy flow
environment
epiphytes
eutrophication
fish
Food Chain
food webs
Humans
Invertebrates
Lakes
Macrophyte-dominated
macrophytes
nitrogen
phytoplankton
Stable isotopes
Water
Alternative states
Energy channels
Macrophyte-dominated
Benthic invertebrates
Stable isotopes
ISSN:0048-9697, 1879-1026, 1879-1026
Online Access:Get full text
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Summary:Across the globe, lake ecosystems are exposed to a variety of human disturbances. A notable example is shallow lakes where human-induced eutrophication or water level fluctuation may result in a switch from a clear-water, macrophyte-dominated state to a turbid, phytoplankton-dominated state. Yet, few investigations have described synchronous changes in biotic assemblage composition and food web framework under such a shift between alternative states. We used stable carbon and nitrogen isotopes to test the extent to which switching from macrophyte to phytoplankton dominance in Lake Gucheng, triggered by a water level increase, would alter ecosystem structure and change the basal resources supporting the food web. We found that invertebrates and fish compensated for a reduction of macrophyte and epiphyte resources by deriving more energy from the alternative pelagic energy channel, where benthic invertebrates act as crucial links between primary producers and higher consumers by transporting δ13C-depleted pelagic algae to the benthic zone. Although consumers can respond to large shifts in energy allocation and stabilize food web dynamics through their ability to feed across multiple energy pathways, our study suggest that energy subsidies may promote trophic cascades and enhance the stability of the turbid regime. [Display omitted] •Few studies investigated synchronous changes in biotic assemblage and food web.•Catastrophic shift was not caused by eutrophication but by water level fluctuation.•Consumers derived more energy from pelagic energy channel following a regime shift.•Benthic invertebrates played crucial roles in dominance of pelagic energy subsidies.•Invertebrate and fish respond to changes by feeding across multiple energy pathways.
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ISSN:0048-9697
1879-1026
1879-1026
DOI:10.1016/j.scitotenv.2020.143642