Browsing by Author "Laini, A"

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    New light in the dark - a proposed multidisciplinary framework for studying functional ecology of groundwater fauna
    (Elsevier, 2019-04-20) Saccò, M; Blyth, AJ; Bateman, PW; Hua, Q; Mazumder, D; White, NE; Humphreys, WF; Laini, A; Griebler, C; Grice, K
    Groundwaters provide the vast majority of unfrozen freshwater resources on the planet, but our knowledge of subsurface ecosystems is surprisingly limited. Stygofauna, or stygobionts -subterranean obligate aquatic animals - provide ecosystem services such as grazing biofilms and maintaining water quality, but we know little about how their ecosystems function. The cryptic nature of groundwaters, together with the high degree of local endemism and stygofaunal site-specific adaptations, represent major obstacles for the field. To overcome these challenges, and integrate biodiversity and ecosystem function, requires a holistic design drawing on classical ecology, taxonomy, molecular ecology and geochemistry. This study presents an approach based on the integration of existing concepts in groundwater ecology with three more novel scientific techniques: compound specific stable isotope analysis (CSIA) of amino acids, radiocarbon analysis (14C) and DNA analyses of environmental samples, stygofauna and gut contents. The combination of these techniques allows elucidation of aspects of ecosystem function that are often obscured in small invertebrates and cryptic systems. Carbon (δ13C) and nitrogen (δ15N) CSIA provides a linkage between biogeochemical patterns and ecological dynamics. It allows the identification of stygofaunal food web structures and energy flows based on the metabolic pathway of specific amino groups. Concurrently, 14C provides complementary data on the carbon recycling and incorporation within the stygobiotic trophic webs. Changes in groundwater environmental conditions (e.g. aquifer recharge), and subsequent community adaptations, can be pinpointed via the measurement of the radiocarbon fingerprint of water, sediment and specimens. DNA analyses are a rapidly expanding approach in ecology. eDNA is mainly employed as a biomonitoring tool, while metabarcoding of individuals and/or gut contents provides insight into diet regimes. In all cases, the application of the approaches in combination provides more powerful data than any one alone. By combining quantitative (CSIA and 14C) and qualitative (eDNA and DNA metabarcoding) approaches via Bayesian Mixing Models (BMM), linkages can be made between community composition, energy and nutrient sources in the system, and trophic function. This suggested multidisciplinary design will contribute to a more thorough comprehension of the biogeochemical and ecological patterns within these undervalued but essential ecosystems. © 2019 Elsevier B.V.
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    Stygofaunal community trends along varied rainfall conditions: deciphering ecological niche dynamics of a shallow calcrete in Western Australia
    (John Wiley & Sons, Inc, 2019-09-16) Saccò, M; Blyth, AJ; Humphreys, WF; Karasiewicz, S; Meredith, KT; Laini, A; Cooper, SJB; Bateman, PW; Grice, K
    Groundwaters host highly adapted fauna, known as stygofauna, which play a key role in maintaining the functional integrity of subterranean ecosystems. Stygofaunal niche studies provide insights into the ecological dynamics shaping the delicate balance between the hydrological conditions and community diversity patterns. This work aims to unravel the ecological trends of a calcrete stygofaunal community, with special focus on niche dynamics through the Outlying Mean Index analysis (OMI) and additional calculation of Within Outlying Mean Indexes (WitOMI), under three rainfall regimes. Temperature and pH changed significantly among different rainfall conditions (P < .001), and together with salinity were the most influential drivers in shaping stygofaunal assemblages. These environmental conditions, linked with nutrient fluctuations in the groundwater, constrained changes in niche occupation for water mites, two species of beetles and juvenile amphipods (OMI analysis, P < .05). The WitOMI analysis revealed differential subniche breadths linked with taxa-specific adaptations after different rainfall conditions. Our results indicate that stygofaunal niches are closely linked to the hydrodynamic conditions influenced by different rainfall regimes. Further long-term investigations, incorporating broader ecological perspectives, will help to understand the impacts associated with climate change and anthropogenic pressures on one of the most threatened ecosystems in the world. © 2019 John Wiley & Sons, Ltd.
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    Tracking down carbon inputs underground from an arid zone Australian calcrete
    (Public Library of Science (PLOS), 2020-08-28) Saccò, M; Blyth, AJ; Humphreys, WF; Middleton, JA; White, NE; Campbell, M; Mousavi-Derazmahalleh, M; Laini, A; Hua, Q; Meredith, KT; Cooper, SJB; Griebler, C; Allard, S; Grierson, P; Grice, K
    Freshwater ecosystems play a key role in shaping the global carbon cycle and maintaining the ecological balance that sustains biodiversity worldwide. Surficial water bodies are often interconnected with groundwater, forming a physical continuum, and their interaction has been reported as a crucial driver for organic matter (OM) inputs in groundwater systems. However, despite the growing concerns related to increasing anthropogenic pressure and effects of global change to groundwater environments, our understanding of the dynamics regulating subterranean carbon flows is still sparse. We traced carbon composition and transformations in an arid zone calcrete aquifer using a novel multidisciplinary approach that combined isotopic analyses of dissolved organic carbon (DOC) and inorganic carbon (DIC) (δ13CDOC, δ13CDIC, 14CDOC and 14CDIC) with fluorescence spectroscopy (Chromophoric Dissolved OM (CDOM) characterisation) and metabarcoding analyses (taxonomic and functional genomics on bacterial 16S rRNA). To compare dynamics linked to potential aquifer recharge processes, water samples were collected from two boreholes under contrasting rainfall: low rainfall ((LR), dry season) and high rainfall ((HR), wet season). Our isotopic results indicate limited changes and dominance of modern terrestrial carbon in the upper part (northeast) of the bore field, but correlation between HR and increased old and 13C-enriched DOC in the lower area (southwest). CDOM results show a shift from terrestrially to microbially derived compounds after rainfall in the same lower field bore, which was also sampled for microbial genetics. Functional genomic results showed increased genes coding for degradative pathways—dominated by those related to aromatic compound metabolisms—during HR. Our results indicate that rainfall leads to different responses in different parts of the bore field, with an increase in old carbon sources and microbial processing in the lower part of the field. We hypothesise that this may be due to increasing salinity, either due to mobilisation of Cl- from the soil, or infiltration from the downstream salt lake during HR. This study is the first to use a multi-technique assessment using stable and radioactive isotopes together with functional genomics to probe the principal organic biogeochemical pathways regulating an arid zone calcrete system. Further investigations involving extensive sampling from diverse groundwater ecosystems will allow better understanding of the microbiological pathways sustaining the ecological functioning of subterranean biota. © 2020 Saccò et al