Spherulitic microbialites from modern hypersaline lakes, Rottnest Island, Western Australia

Bischoff, Karl; Sirantoine, Eva; Wilson, Martha; George, Annette D.; Monteiro, Juliana Mendes; Saunders, Martin

doi:10.1111/gbi.12400

Cited by 22 publications

(21 citation statements)

References 53 publications

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“…In addition, the resultant [Ca]/[Alk] ratios shift between 5.2 and 76.8, while salinity contents can vary between 16.8 and 373 g/L. Carbonate products documented in these natural settings include micrite muds, peloids, microbialite/skeletal sands, thrombolite mounds and microbial mat‐related spherulites (Figure 9G) to spherulitic microbialites (Figure 9I; Arp et al, 2012; Bischoff et al, 2020; Burne & Moore, 1987; Burne et al, 2014; Moore, 1993).…”

Section: Resultsmentioning

confidence: 99%

“…Sediments constituted by authigenic polycrystalline spherulites are remarkably rare in Recent saline lacustrine environments, where mud‐size single crystals are volumetrically much more common. Some lacustrine evaporitic settings such as the Great Salt Lake, Kiritimati and Rottnest lagoons represent exquisite exceptions recording exotic Recent calcite spherulite sediments clearly occurring in association with microbial mat‐related structures or their exopolymers in highly saline settings (Arp et al, 2012; Bischoff et al, 2020; Chafetz et al, 2018; Chidsey et al, 2015; Kirkham & Tucker, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…As illustrated in their thermodynamic model (Figure 1C), Wright and Tosca (2016) assume that calcite/stevensite precipitation takes place in equilibrium during the evaporation trajectory while a progressive rise in sodium and chloride solute concentrations occurs (see Figure 1C). However, this model overlooks a finding of crystal engineering research that polycrystalline precipitation reflects kinetic rather than thermodynamic forcing (Sunagawa, 2005), and the repeated observation that the millimetre‐sized spherulites developing today are associated with biological influences (Bischoff et al, 2020; Chafetz et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Effects of salinity, organic acids and alkalinity on the growth of calcite spherulites: Implications for evaporitic lacustrine sedimentation

Mercedes‐Martín¹,

Rao

Rogerson

et al. 2021

The Depositional Record

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Lacustrine non‐skeletal carbonates exhibit a diversity of petrographies due to interactions between physico‐chemical and biologically influenced mechanisms. Despite the suggestion that evaporative concentration was involved in the formation of spherulite and shrubby‐bearing carbonate successions in the Pre‐Salt Cretaceous alkaline lakes of the South Atlantic, no consensus exists about the water chemistries promoting these exotic mineral textures. In this work, an experimental approach was developed to evaluate how changes in salinity (NaCl) and biopolymer concentrations (alginic acid) impact calcite growth dynamics from saline and alkaline synthetic solutions. Hydrochemical and petrographical data from selected modern saline/alkaline environments were compared with experimental datasets to further estimate how the underlying (bio)chemical conditions and lake locations probably converge to allow the formation of calcite spherulite grains in evaporitic settings. Spherulitic calcite from Recent saline lakes and experiments arise from waters with moderate to high [Calcium]/[Alkalinity] ratios ([Ca]/[Alk]) rather than in calcium‐depleted and alkaline‐rich environments which tend to produce single‐crystal calcites during abiotic water mixing or lake evaporation. This observation is consistent with the assembly of polycrystalline textures being a kinetically controlled feature, forced by remarkably high rates of nucleation. Also, the data analysed do not support a causative relationship between evaporite‐driven salinity fluctuations and the preferential formation of spherulites, shrubs or their intermediate textures. Ubiquitous in saline lakes, organic substances can lower the kinetic thresholds for spherulitic calcite aggregation while microbial photosynthesis can also raise pH, altogether enhancing calcite supersaturation and promoting spherulite formation in waters with moderate‐high [Ca]/[Alk] ratios and high salinities. Localised observations of abiotic spherulites in Recent soda lakes can occur in restricted mixing zones where [Ca]/[Alk] ratios are enhanced. This work highlights the roles of concentration regimes associated with biopolymers and microbial metabolism against the background salinity fluctuations in determining the morphological and textural transitions in lacustrine carbonate minerals.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of salinity, organic acids and alkalinity on the growth of calcite spherulites: Implications for evaporitic lacustrine sedimentation

Mercedes‐Martín¹,

Rao

Rogerson

et al. 2021

The Depositional Record

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“…Besides the lakes on the mainland of WA, Rottnest Island (30 km off the coast of Perth) hosts permanent hypersaline lakes once connected to the ocean and now closed to any marine influence (Bryan et al ., 2016). These wetlands host highly diverse aquatic microbial communities (Saccò et al ., 2021 a ) and lithifying and non‐lithifying microbial mats (Mendes Monteiro et al ., 2020) including conical spherulitic microbialites (Bischoff et al ., 2020), and a recorded presence of a novel halovirus (called SH1; Porter et al ., 2005). Large populations of trans‐equatorial wading species have been recorded making use of the hypersaline habitats over the last century (Saunders & De Rebeira, 2009), and positive trends in population growth have been found recently, highlighting the importance and conservation value of these unique systems (Mather, 2020).…”

Section: The (Concentrated) Salt Of the Earthmentioning

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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“…Here, groundwater lenses-generated by the high permeability of the widespread Tamala Limestone-are recharged via rainfall and discharge into some of the hypersaline lakes [29]. Recent molecular and biogeochemical investigations have indicated that the permanent hypersaline lakes at Rottnest Island host heterogeneous and delicate microbial communities including lithifying and non-lithifying microbial mats [30], together with spherulitic microbialites [31].…”

Section: Introductionmentioning

confidence: 99%

Metabarcoding under Brine: Microbial Ecology of Five Hypersaline Lakes at Rottnest Island (WA, Australia)

Saccò

White

Campbell

et al. 2021

Water

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Hypersaline ecosystems—aquatic environments where concentration of salt exceeds 35 g L−1—host microbial communities that are highly specialised to cope with these extreme conditions. However, our knowledge on the taxonomic diversity and functional metabolisms characterising microbial communities in the water columns of hypersaline ecosystems is still limited, and this may compromise the future preservation of these unique environments. DNA metabarcoding provides a reliable and affordable tool to investigate environmental dynamics of aquatic ecosystems, and its use in brine can be highly informative. Here, we make use of bacterial 16S metabarcoding techniques combined with hydrochemical analyses to investigate the microbial patterns (diversity and functions) from five hypersaline lakes located at Rottnest Island (WA). Our results indicate lake-driven microbial aquatic assemblages that are characterised by taxonomically and functionally moderately to extremely halophilic groups, with TDS (total dissolved solids) and alkalinity amongst the most influential parameters driving the community patterns. Overall, our findings suggest that DNA metabarcoding allows rapid but reliable ecological assessment of the hypersaline aquatic microbial communities at Rottnest Island. Further studies involving different hypersaline lakes across multiple seasons will help elucidate the full extent of the potential of this tool in brine.

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Spherulitic microbialites from modern hypersaline lakes, Rottnest Island, Western Australia

Cited by 22 publications

References 53 publications

Effects of salinity, organic acids and alkalinity on the growth of calcite spherulites: Implications for evaporitic lacustrine sedimentation

Effects of salinity, organic acids and alkalinity on the growth of calcite spherulites: Implications for evaporitic lacustrine sedimentation

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

Metabarcoding under Brine: Microbial Ecology of Five Hypersaline Lakes at Rottnest Island (WA, Australia)

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