Refining trophic dynamics through multi‐factor Bayesian mixing models: A case study of subterranean beetles

Saccò, Mattia; Blyth, Alison J.; Humphreys, William F.; Cooper, Steven J.; Austin, Andrew D.; Hyde, Josephine; Mazumder, Debashish; Hua, Quan; White, Nicole E.; Grice, Kliti

doi:10.1002/ece3.6580

Cited by 15 publications

(6 citation statements)

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“…While comparable results were generated by both approaches under LR, once the system receives mixed terrestrially-derived inflows of OM during HR (see Saccò et al, 2020a), the outputs of the two models differed substantially. Further discussion on the cost-benefit evaluation of the different designs, including the potential incorporation of prior qualitative information in form of DNA metabarcoding data, can be found in Saccò et al (2020c). Interestingly, plant-derived OM incorporated by copepods during LR followed a slightly different trend.…”

Section: Discussionmentioning

confidence: 99%

“…These tests were performed at the Australian Nuclear Science and Technology Organisation (ANSTO, Sydney) (see Saccò et al, 2019b for further details). 14 C content of the same samples was determined using the accelerator mass spectrometry (AMS) STAR Facility at ANSTO (Sydney) (see Saccò et al, 2020cSaccò et al, , 2021a for further details).…”

Section: Stable Isotope and Radiocarbonmentioning

confidence: 99%

“…Relative contributions from dietary items were estimated using SIMM (Stable Isotope Mixing Models, R-package "simmr"). We used a triple proxy approach (δ 13 C, δ 15 N, and 14 C) as described in Saccò et al (2020c) coupled with carbon and nitrogen concentration data as priors (see Supplementary Table 1 for details). Specific trophic discrimination factors have not yet been determined for stygofauna.…”

Section: Statistical Analysesmentioning

confidence: 99%

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Getting to the Root of Organic Inputs in Groundwaters: Stygofaunal Plant Consumption in a Calcrete Aquifer

et al. 2022

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Groundwater environments interact with and support subterranean biota as well as superficial aquatic and terrestrial ecosystems. However, knowledge of subterranean energy flows remains incomplete. Cross-boundary investigations are needed to better understand the trophic structures of groundwater ecosystems and their reliance on carbon inputs from aboveground. In this study we used carbon and nitrogen stable isotope analyses combined with radiocarbon fingerprints to characterise organic flows in groundwater ecosystems. We coupled these data with DNA metabarcoding of the gut contents of stygofauna to further elucidate organic matter (OM) sources and shifts in diet preferences. Samples were collected from the arid zone Sturt Meadows calcrete aquifer under low rainfall (LR) and high rainfall (HR) conditions. Bayesian modelling of Δ14C, δ13C, and δ15N data indicated that primary consumers (copepods) incorporated mainly particulate organic carbon (POC) under LR but during HR shifted to root derived material (either exudates or direct root grazing). By contrast, diets of secondary consumers (amphipods) were dominated by root material under both LR and HR. Our DNA metabarcoding-based results indicate that amphipods relied primarily on root inputs from perennial trees (likely Eucalyptus and Callitris) during the dry season (LR). Under HR, diets of both amphipods and copepods also included organic material derived from a broad range of more shallow rooted shrubs, and ephemeral herbs and grasses. Our findings illustrate the complexity of functional linkages between groundwater biota and surface terrestrial ecosystems in environments where aboveground productivity, diversity and OM flux to groundwater are intimately linked to often episodic rainfall.

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Section: Discussionmentioning

confidence: 99%

Section: Stable Isotope and Radiocarbonmentioning

confidence: 99%

Section: Statistical Analysesmentioning

confidence: 99%

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Getting to the Root of Organic Inputs in Groundwaters: Stygofaunal Plant Consumption in a Calcrete Aquifer

et al. 2022

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“…Some studies have attempted to model groundwater ecosystem ecological functioning 76,77 , but none of them has focused on wide multidisciplinary designs. Here we combined information from previous food web investigation on stygofauna 7,78 and microbial patterns 22 with the information gathered via isotopic (carbon and nitrogen) and genetic data on stygofaunal gut biomes from this study (Fig. 5).…”

Section: Discussionmentioning

confidence: 99%

Rainfall as a trigger of ecological cascade effects in an Australian groundwater ecosystem

Saccò

Blyth

Humphreys

et al. 2021

Sci Rep

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Groundwaters host vital resources playing a key role in the near future. Subterranean fauna and microbes are crucial in regulating organic cycles in environments characterized by low energy and scarce carbon availability. However, our knowledge about the functioning of groundwater ecosystems is limited, despite being increasingly exposed to anthropic impacts and climate change-related processes. In this work we apply novel biochemical and genetic techniques to investigate the ecological dynamics of an Australian calcrete under two contrasting rainfall periods (LR—low rainfall and HR—high rainfall). Our results indicate that the microbial gut community of copepods and amphipods experienced a shift in taxonomic diversity and predicted organic functional metabolic pathways during HR. The HR regime triggered a cascade effect driven by microbes (OM processors) and exploited by copepods and amphipods (primary and secondary consumers), which was finally transferred to the aquatic beetles (top predators). Our findings highlight that rainfall triggers ecological shifts towards more deterministic dynamics, revealing a complex web of interactions in seemingly simple environmental settings. Here we show how a combined isotopic-molecular approach can untangle the mechanisms shaping a calcrete community. This design will help manage and preserve one of the most vital but underrated ecosystems worldwide.

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“…community species composition) such as DNA metabarcoding, have the potential to bring new light to our understanding of food‐web interactions (e.g. Saccò et al ., 2019, 2020, 2021 b ). Once applied to hypersaline biota, such interdisciplinary designs have the potential to provide insights on energy flows, diet preferences, prey–predator interactions and shifts in trophic niche occupations [Majdi et al .…”

Section: Future Research Avenuesmentioning

confidence: 99%

Salt to conserve: a review on the ecology and preservation of hypersaline ecosystems

et al. 2021

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When it comes to the investigation of key ecosystems in the world, we often omit salt from the ecological recipe. In fact, despite occupying almost half of the volume of inland waters and providing crucial services to humanity and nature, inland saline ecosystems are often overlooked in discussions regarding the preservation of global aquatic resources of our planet. As a result, our knowledge of the biological and geochemical dynamics shaping these environments remains incomplete and we are hesitant in framing effective protective strategies against the increasing natural and anthropogenic threats faced by such habitats. Hypersaline lakes, water bodies where the concentration of salt exceeds 35 g/l, occur mainly in arid and semiarid areas resulting from hydrological imbalances triggering the accumulation of salts over time. Often considered the ‘exotic siblings’ within the family of inland waters, these ecosystems host some of the most extremophile communities worldwide and provide essential habitats for waterbirds and many other organisms in already water‐stressed regions. These systems are often highlighted as natural laboratories, ideal for addressing central ecological questions due to their relatively low complexity and simple food web structures. However, recent studies on the biogeochemical mechanisms framing hypersaline communities have challenged this archetype, arguing that newly discovered highly diverse communities are characterised by specific trophic interactions shaped by high levels of specialisation. The main goal of this review is to explore our current understanding of the ecological dynamics of hypersaline ecosystems by addressing four main research questions: (i) why are hypersaline lakes unique from a biological and geochemical perspective; (ii) which biota inhabit these ecosystems and how have they adapted to the high salt conditions; (iii) how do we protect biodiversity from increasing natural and anthropogenic threats; and (iv) which scientific tools will help us preserve hypersaline ecosystems in the future? First, we focus on the ecological characterisation of hypersaline ecosystems, illustrate hydrogeochemical dynamics regulating such environments, and outline key ecoregions supporting hypersaline systems across the globe. Second, we depict the diversity and functional aspects of key taxa found in hypersaline lakes, from microorganisms to plants, invertebrates, waterbirds and upper trophic levels. Next, we describe ecosystem services and discuss possible conservation guidelines. Finally, we outline how cutting‐edge technologies can provide new insights into the study of hypersaline ecology. Overall, this review sheds further light onto these understudied ecosystems, largely unrecognised as important sources of unique biological and functional diversity. We provide perspectives for key future research avenues, and advocate that the conservation of hypersaline lakes should not be taken with ‘a grain of salt’.

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Refining trophic dynamics through multi‐factor Bayesian mixing models: A case study of subterranean beetles

Cited by 15 publications

References 84 publications

Getting to the Root of Organic Inputs in Groundwaters: Stygofaunal Plant Consumption in a Calcrete Aquifer

Getting to the Root of Organic Inputs in Groundwaters: Stygofaunal Plant Consumption in a Calcrete Aquifer

Rainfall as a trigger of ecological cascade effects in an Australian groundwater ecosystem

Salt to conserve: a review on the ecology and preservation of hypersaline ecosystems

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