Autochthonous production sustains food webs in large perialpine lakes, independent of trophic status: Evidence from amino acid stable isotopes

Saboret, Grégoire; Stalder, Dominique; Matthews, Blake; Brodersen, Jakob; Schubert, Carsten J.

doi:10.1111/fwb.14071

Cited by 5 publications

(5 citation statements)

References 164 publications

(216 reference statements)

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“…Notably, blue sources were characterised by lighter Phenylalanine values, consistent with algae fingerprinting (Saboret et al, 2023), while brown sources exhibited heavier Isoleucine and Leucine values, likely influenced by bacterial de novo synthesis that results in relative 13 C-enrichment of those EAAs (Larsen et al, 2013).…”

Section: Primary Consumers Of Blue Green and Brown Integrate Distinct...mentioning

confidence: 52%

“…We hydrolysed the pellets and subsequently derivatized the free AAs to N-acetyl methyl ester (NACME-AA) derivatives following previous protocols (Corr et al, 2007;Larsen et al, 2013). A full description of the protocol can be found in Saboret et al (2023). We measured AA mass fractions (see Protocol B, Data S1), and isotopes of carbon (see Protocol C, Data S1).…”

Section: Sample Analysismentioning

confidence: 99%

“…Another notable advancement lies in the capacity to differentiate primary producers from various phyla based on the relative difference between EAA δ 13 C, an approach commonly referred to as fingerprinting (Larsen et al, 2009). Based on the fingerprinting, studies have estimated the relative importance of producers as food source of several consumers (Arsenault et al, 2022;Liew et al, 2019;Manlick et al, 2024;Manlick & Newsome, 2022;Saboret et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

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Quantifying the utilisation of blue, green and brown resources by riparian predators: A combined use of amino acid isotopes and fatty acids

Saboret,

Drost,

Kowarik

et al. 2024

Methods Ecol Evol

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Global change drives multiple facets of biodiversity including interaction diversity, which is fundamental for ecosystem functioning. However, studying trophic interactions is challenging in meta‐ecosystems, that is ecosystems connected by spatial flows of energy, materials and organisms across ecosystem boundaries. While analytical methods based on abundances of polyunsaturated fatty acids (PUFAs) and stable isotopes of amino acids (AAs) are being increasingly used, it has never been explored if both approaches could be: (i) combined in mixing models to enhance precision in dietary inference (ii) compared to disentangle transfers of various PUFAs and proteins in food webs in the wild. We explore the utility of analytical approaches based on PUFA abundances and AA isotopes to resolve resource transfers in a natural riparian food web. We focus on spiders and their potential prey from blue, green and brown sources to address three important and persisting methodological issues in food‐web ecology, namely whether (i) essential AA carbon isotopes can resolve protein origin from blue, green and brown resources, (ii) PUFA relative abundance and AA isotopes can be combined in a mixing model to provide higher precision estimates (i.e. narrower intervals) and (iii) combining the two approaches can unveil the coupling of protein and PUFA transfers in food webs. Our research demonstrates the power of AA isotopes and PUFAs to distinguish blue, green, and brown sources and their transfer up to consumers. We show that combining PUFA relative abundance and AA isotopes in a mixing model provides overall estimates similar to the individual estimates but significantly increases precision. In addition, we showcase how combining approaches unveil the coupling of protein and PUFA transfers. For instance, we show that most PUFAs are less concentrated from prey to predators, relative to proteins, highlighting uncoupling of PUFAs and protein transfer along food chains. We show for the first time the effectiveness of combining AA isotopes and PUFA abundances, particularly relevant for complex trophic interactions in a meta‐ecosystem context. Our study illustrates the trophic uncoupling of proteins and PUFAs, highlighting the necessity in combining both approaches.

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Section: Primary Consumers Of Blue Green and Brown Integrate Distinct...mentioning

confidence: 52%

Section: Sample Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantifying the utilisation of blue, green and brown resources by riparian predators: A combined use of amino acid isotopes and fatty acids

Saboret,

Drost,

Kowarik

et al. 2024

Methods Ecol Evol

Self Cite

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“…This general problem can often be masked by LDA dimensionality reduction, but is likely more noticeable when implementing Bayesian mixing models. Recent simulations on lake ecosystem data highlight that significant bias can occur between known basal resource contributions and those estimated using the LDA approach (Saboret et al 2023). Moreover, we argue that the perceived limitations of mixing models should be considered a strength in that they require adequate prior understanding of the system (Makarewicz and Sealy 2015) for robust proportional estimates.…”

Section: Conceptualising the Quantification Of Basal Resource Eaa Usementioning

confidence: 89%

The power and pitfalls of amino acid carbon stable isotopes for tracing the use and fate of basal resources in food webs

Vane¹,

Cobain²,

Larsen³

2023

Preprint

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Natural and anthropogenic stressors are spatiotemporally complex, having indirect effects on the composition and biomass of organisms at the base of a food web, and their availability and nutritional quality. Because basal organisms synthesise the biomolecules essential for metazoan growth and survival (i.e. basal resources), understanding the connections between basal resources and consumers across diverse time scales is needed to fully comprehend their impact on food webs. Traditional approaches using bulk stable isotope ratios have provided insight into basal resource use, but lack specificity in identifying multiple basal resources and their transfer through ecosystems. The development of compound-specific stable isotope analyses now allows researchers to trace the trophic transfer of specific biomolecules. This paper provides an overview of the advances and challenges associated with tracing basal resources with carbon stable isotopes in amino acids (δ13C-AA). We develop a conceptual framework for understanding the mechanistic underpinning of δ13C-AA values. Subsequently, formal definitions of associated terminologies that have so far been lacking in the literature are proposed. We empirically highlight the diagnostic ability of the relative offsets between δ13C values of essential amino acids, termed δ13C-EAA patterns. As these offsets remain largely unaltered during trophic transfer and across varying environments, they can be used as fingerprints to trace spatiotemporal shifts in basal resource use within food webs. Given the stable preservation of amino acids in many metazoan tissues, δ13C-EAA fingerprints can provide insights into basal resource use in food webs from geological history through to the contemporary. The added value of non-essential amino acids as metabolic biomarkers are explored and demonstrated in an archaeological context. We provide thorough overviews of the analytical and statistical methodologies involved in making robust inferences in food web studies. The constraints and pitfalls of δ13C-AA data are discussed, such as issues with basal resource specificity, de novo synthesis, and problems with large compilation datasets. Taken together, δ13C-AA values provide a powerful tool for understanding the specific use of basal resources in food webs on various spatiotemporal scales, but careful consideration and characterization of basal resources is necessary to ensure accurate estimations of proportional use.

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“…Instead, we propose that greater use of bacterially derived energy, channelled through the microbial loop (i.e., slow energy) may improve reproductive fitness in lake trout-this is especially evident for males (Figure 2). Although they may not provide omega-3 polyunsaturated fatty acids like algae, bacteria are still likely to provide key macronutrients such as protein and fat, and are becoming an increasingly recognised source of energy supporting lake biomass (Saboret et al, 2023). In this case, differences in energy channelling among individuals could be mediated by diet diversity (Weisse et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

Energy channelling, food chain length and body condition in a northern lake predator

Shipley,

McMeans,

Besser

et al. 2023

Freshwater Biology

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Identifying potential links between food web structure and animal body condition is fundamental for predicting the long‐term persistence of populations under rapidly changing environments. Northern lakes, and the cold‐water adapted species that inhabit them, are particularly vulnerable to a warming climate. We explored relationships among body condition and energy channel use in lake trout (Salvelinus namaycush) and seasonal variation in food‐chain length in the Lake of Two Rivers, Ontario, Canada. Bayesian mixing models using carbon isotope values (δ13C) of essential amino acids showed that individuals utilising multiple energy channels had higher gonad mass, suggesting that dietary diversity has reproductive fitness benefits. Amino acid nitrogen isotope (δ15N) analysis revealed seasonal variation in food chain length, with extension of the food web during winter and spring and truncation of the food web during summer. Although these findings illustrate increased omnivory of lake trout during summer, there was no clear evidence that seasonal changes in food chain length had an impact on trout condition. These findings provide new insight into potential relationships between food web structure, energy flow and consumer condition in freshwater ecosystems, thereby revealing potential responses of species to shifting ecosystem states under intensifying climate change at high latitudes.

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Autochthonous production sustains food webs in large perialpine lakes, independent of trophic status: Evidence from amino acid stable isotopes

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 5 publications

References 164 publications

Quantifying the utilisation of blue, green and brown resources by riparian predators: A combined use of amino acid isotopes and fatty acids

Quantifying the utilisation of blue, green and brown resources by riparian predators: A combined use of amino acid isotopes and fatty acids

The power and pitfalls of amino acid carbon stable isotopes for tracing the use and fate of basal resources in food webs

Energy channelling, food chain length and body condition in a northern lake predator

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