Trophic compression of lake food webs under hydrologic disturbance

Hansen, Adam G.; Gardner, Jennifer R.; Connelly, Kristin A.; Polacek, Matt; Beauchamp, David A.

doi:10.1002/ecs2.2304

Cited by 11 publications

(15 citation statements)

References 42 publications

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“…Species with a broad trophic niche are successful in invading endemic communities or surviving disturbance (Bommarco et al 2010, Dammhahn et al 2017. Most empirical studies on the trophic-niche shifts in disturbed habitats have focused on the responses of individual species, while changes in trophic-niche structure at the community level have been studied only in aquatic systems (di Lascio et al 2013, Hansen et al 2018.…”

Section: Introductionmentioning

confidence: 99%

Collapse of trophic‐niche structure in belowground communities under anthropogenic disturbance

et al. 2018

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The niche concept is a central paradigm in ecology, but empirical evidence on how the niche structure of belowground communities is affected by ecosystem disturbance is lacking. Niche differentiation evolves due to stable coexistence of species in a community, suggesting that in unstable communities, the niches of species should largely overlap. Here, we test this prediction using empirical data on the trophic‐niche structure of several belowground collembolan communities of natural (forest and meadow) and disturbed (pasture and urban lawn) habitats. Scaled stable isotope compositions of carbon and nitrogen were used to reveal the trophic specialization of species. In full agreement with the theoretical predictions, trophic‐niche structure collapsed in disturbed habitats, which was illustrated by decreased interspecific and increased intraspecific variation in the stable isotope compositions. In stable natural habitats, different trophic niches are occupied by different collembolan species, but in disturbed habitats, poor niche specialization is partly compensated for by intraspecific trophic flexibility. The simplification of food‐web structure was in line with the evidence coming from disturbed aquatic ecosystems, suggesting that the collapse of trophic‐niche structure may be a common feature of disturbed communities across biomes.

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Section: Introductionmentioning

confidence: 99%

Collapse of trophic‐niche structure in belowground communities under anthropogenic disturbance

et al. 2018

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“…The observed shift in feeding behaviour, the act of flushing invasive piscivores out of the reservoir and improved smolt outmigration together demonstrated the potential of this extreme water management scenario for conferring survival benefits to future cohorts of juvenile salmon without compromising other requirements for the reservoir such as winter flood control (Murphy et al, 2019). These alternative outcomes between Washington and Oregon show how detrimental or advantageous consequences for ecosystem function and species of concern can manifest in complex ways over a continuum of water use intensity as mediated by the social‐ecological context driving requirements for threatened species recovery and water delivery or storage for human benefit (Hansen et al, 2018; McMeans et al, 2016; Zohary & Ostrovsky, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Studies evaluating patterns of resource use among top‐level piscivores in freshwater lakes have generally documented significant levels of trophic and or spatial‐habitat partitioning thought to reduce competition and bolster coexistence (Guzzo et al, 2016; Herwig et al, 2021; Hodgson et al, 1997). However, these patterns may be less pronounced in regulated systems such as reservoirs where human‐driven water manipulation can compress habitat availability and trophic diversity (Hansen et al, 2018; Murphy et al, 2019). Studies in regulated systems are rare, but needed for identifying processes that limit or promote coexistence amid expanding human‐induced disturbance, environmental change and water use (Hansen et al, 2018; Westrelin et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Resource use among top‐level piscivores in a temperate reservoir: implications for a threatened coldwater specialist

Hansen

Gardner

Connelly

et al. 2021

Ecology of Freshwater Fish

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Evaluations of resource use among native piscivores in natural lakes have consistently documented significant partitioning that supports coexistence. Partitioning may be less prominent in reservoirs where water‐level fluctuations can compress habitat and trophic diversity, but studies are lacking. Stable isotopes and bioenergetic models were used to quantify trophic interactions within a native piscivore assemblage inhabiting a temperate irrigation reservoir and explore implications for coexistence with a focus on threatened bull trout (Salvelinus confluentus). As hypothesised, adult bull trout exhibited the greatest degree of trophic specialisation by consuming mostly coldwater pelagic forage fish, which were consumed seasonally by the more abundant burbot (Lota lota) and northern pikeminnow (Ptychocheilus oregonensis). Numerous trophic niche overlap probabilities exceeded 70%, were as high as 93% and greatest between bull trout and burbot. Bioenergetics simulations demonstrated the high seasonal consumption capacity of burbot relative to northern pikeminnow. As a result, threefold to fourfold fewer burbot were required to consume the annual productivity of coldwater prey important for bull trout, particularly in the absence of small‐bodied mesothermic or eurythermal fish as a buffer. Collectively, our analysis elucidated relatively strong trophic niche overlap among similarly sized piscivores, the importance of maintaining a diverse forage fish community for promoting coexistence and the greatest potential for competitive interactions between adult bull trout and burbot if key prey were limited or less diverse. More studies in regulated systems are needed to test for consistent patterns and identify mechanisms that limit or promote coexistence amid growing human‐induced environmental change and demands on freshwater.

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“…The stable isotope samples were crushed to a fine homogeneous powder using a ball mill. Subsamples were then pressed into ultra-pure tin capsules and analyzed using an Elementar Vario Micro-Cube elemental analyzer (Flash EA1112; Thermo Scientific, Monza, Italy) coupled with a continuous-flow isotope-ratio mass spectrometer (Delta V Advantage, Thermo Scientific, Dreieich, Germany) (Careddu et al, 2015;Hansen et al, 2018). The elemental analyzer and spectrometer were recalibrated after every 10 measurements following the manufacturer's directions.…”

Section: Stable Isotope Analysis and Bayesian Isotope Mixing Modelmentioning

confidence: 99%

Temporal changes of the food web structure and function driven by changes in hydrological regimes and water quality in a large shallow lake

Yang

Fu²,

Li³

et al. 2022

Front. Environ. Sci.

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Assessing food web structural properties and energy fluxes under changing hydrological regimes and water quality reveals the temporal patterns of ecosystem dynamics in shallow lakes. Here, we studied northern China’s largest shallow lake (Lake Baiyangdian) using quantitative food web models for five representative years (1958, 1980, 1993, 2009, and 2019). We analyzed the temporal patterns of food web structure and function by combining a Bayesian isotope mixing model with a food web energetics model. We further examined the temporal changes of unweighted and weighted food web topological attributes. Lake Baiyangdian changed from a detritus-based into a phytoplankton-based food web based on the relative contributions of basal food sources and energy flux distributions. The trophic position of fingerlings, large omnivorous fish, and carnivorous fish decreased with increasing eutrophication. The highest energy fluxes were from detritus to zooplankton and mollusks in 1958, from detritus and phytoplankton to zooplankton in 1980, 1993, and 2009, and from phytoplankton to zooplankton and detritus to mollusks in 2019. The highest total energy flux was in 1993, followed by 2019, with the lowest value in 1958. Unweighted food web metrics showed similar patterns. We observed more pronounced temporal variability in the node- and link-weighted food web metrics than in the unweighted metrics. In addition, hydrological factors (threshold, duration, reversals between high, and low water levels), eutrophication, and some water quality factors (chemical oxygen demand, dissolved oxygen, and pH) played important roles in the temporal changes of food web dynamics in Lake Baiyangdian. Our findings demonstrate the importance of integrating unweighted and weighted indicators to holistically comprehend how highly aggregated food webs respond to changing hydrological regimes and water quality, thereby improving management and restoration of shallow lake ecosystems.

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Trophic compression of lake food webs under hydrologic disturbance

Cited by 11 publications

References 42 publications

Collapse of trophic‐niche structure in belowground communities under anthropogenic disturbance

Collapse of trophic‐niche structure in belowground communities under anthropogenic disturbance

Resource use among top‐level piscivores in a temperate reservoir: implications for a threatened coldwater specialist

Temporal changes of the food web structure and function driven by changes in hydrological regimes and water quality in a large shallow lake

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