Microbial Mat Research Papers - Academia.edu (original) (raw)

2025, Scientific Reports

Fossilization processes and especially the role of bacterial activity during the preservation of organic material has not yet been well understood. Here, we report the results of controlled taphonomic experiments with crayfish in freshwater and sediment. 16S rRNA amplicon analyzes showed that the development of the bacterial community composition over time was correlated with different stages of decay and preservation. Three dominating genera, Aeromonas, Clostridium and Acetobacteroides were identified as the main drivers in the decomposition of crayfish in freshwater. Using micro-computed tomography (µ-CT), scanning electron microscopy (SEM) and confocal Raman spectroscopy (CRS), calcite clusters were detected after 3–4 days inside crayfish carcasses during their decomposition in freshwater at 24 °C. The precipitation of calcite clusters during the decomposition process was increased in the presence of the bacterial genus Proteocatella. Consequently, Proteocatella might be one of t...

2025, Goldschmidt2022 abstracts

2025, Scientific Reports

Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating...

2025, Geochimica et Cosmochimica Acta

The multiple sulfur isotope composition of porewater sulfate from the anoxic marine sapropel of Mangrove Lake, Bermuda was measured in order to establish how multiple sulfur isotopes are fractionated during reoxidative sulfur cycling. The porewater-sulfate d 34 S and D 33 S dataset exhibits the distinct isotopic signatures of microbial sulfate reduction and sulfur reoxidation. We reproduced the measurements with a simple diagenetic model that yielded fractionation factors for net sulfate removal of between À29.2& and À32.5&. A new approach to isotopic modeling of the sulfate profiles, informed by the chemistry of sulfur intermediate compounds in Mangrove Lake, reveals that sulfate reduction produces a relatively small intrinsic fractionation and that an active reoxidative sulfur cycle increases the fractionation of the measured values. Based on the model results, the reoxidative cycle of Mangrove Lake appears to include sulfide oxidation to elemental sulfur followed by the disproportionation of the elemental sulfur to sulfate and sulfide. This model also indicates that the reoxidative sulfur cycle of Mangrove Lake turns over from 50 to 80% of the sulfide produced by microbial sulfate reduction. The Mangrove Lake case study shows how sulfur isotope fractionations can be separated into three different "domains" in D 33 S-d 34 S space based on their ability to resolve reductive and reoxidative sulfur transformations. The first domain that differentiates reductive and reoxidative sulfur cycling is well illustrated by previous studies and requires 34 S-32 S fractionations more negative than %À70&, beyond the fractionation limit of microbial sulfate reduction at earth surface temperatures. The second domain that distinguishes reductive and reoxidative processes is between 34 S-32 S fractionations of À40& and 0&, where the 33 S-32 S fractionations of sulfate reduction and reoxidation are significantly different. In the remaining domain (between 34 S-32 S fractionations À70& and À40&), the similarity of the multiple sulfur isotope signals from microbial sulfate reduction and disproportionation means that the two processes cannot be discriminated from each other.

2025, Frontiers in microbiology

The Yellowstone geothermal complex contains over 10,000 diverse geothermal features that host numerous phylogenetically deeply rooted and poorly understood archaea, bacteria, and viruses. Microbial communities in high-temperature environments are generally less diverse than soil, marine, sediment, or lake habitats and therefore offer a tremendous opportunity for studying the structure and function of different model microbial communities using environmental metagenomics. One of the broader goals of this study was to establish linkages among microbial distribution, metabolic potential, and environmental variables. Twenty geochemically distinct geothermal ecosystems representing a broad spectrum of Yellowstone hot-spring environments were used for metagenomic and geochemical analysis and included approximately equal numbers of: (1) phototrophic mats, (2) "filamentous streamer" communities, and (3) archaeal-dominated sediments. The metagenomes were analyzed using a suite of c...

2025, Frontiers in microbiology

Six phototrophic microbial mat communities from different geothermal springs (YNP) were studied using metagenome sequencing and geochemical analyses. The primary goals of this work were to determine differences in community composition of high-temperature phototrophic mats distributed across the Yellowstone geothermal ecosystem, and to identify metabolic attributes of predominant organisms present in these communities that may correlate with environmental attributes important in niche differentiation. Random shotgun metagenome sequences from six phototrophic communities (average ∼53 Mbp/site) were subjected to multiple taxonomic, phylogenetic, and functional analyses. All methods, including G + C content distribution, MEGAN analyses, and oligonucleotide frequency-based clustering, provided strong support for the dominant community members present in each site. Cyanobacteria were only observed in non-sulfidic sites; de novo assemblies were obtained for Synechococcus-like populations ...

2025, International Journal of Astrobiology

In this work, we address the difficulty of reliably identifying traces of life on Mars. Several independent lines of evidence are required to build a compelling body of proof. In particular, we underline the importance of correctly interpreting the geological and mineralogical context of the sites to be explored for the presence of biosignatures. We use as examples to illustrate this, ALH84001 (where knowledge of the geological context was very limited) and other terrestrial deposits, for which this could be properly established. We also discuss promising locations and formations to be explored by ongoing and future rover missions, including Oxia Planum, which, dated at 4.0 Ga, is the most ancient Mars location targeted for investigation yet.

2025, Environmental Microbiology

Shallow thermokarst ponds are a conspicuous land-scape element of the Arctic Siberian tundra with high biogeochemical variability. Little is known about how microbes from the regional species pool assemble into local pond communities and how the resulting patterns affect functional properties such as dissolved organic carbon (DOC) remineralization and greenhouse gas (GHG) turnover. We analysed the pelagic microbiomes of 20 ponds in north-eastern Siberia in the context of their physico-chemical properties. Ponds were categorized as polygonal or trough according to their geomorphological origin.The diversity of bacteria and eukaryotic microbes was assessed by ribosomal gene tag sequencing. Null model analysis revealed an important role of stochastic assembly processes within ponds of identical origin, in particular for genotypes only occurring in few systems. Nevertheless, the two pond types clearly represented distinct niches for both the bacterial and eukaryotic microbial communities. Carbondioxide concentration, indicative of heterotrophic microbial processes, varied greatly, especially in the trough ponds. Methane concentrations were lower in polygonal ponds and were correlated with the estimated abundance of methanotrophs. Thus, the overall functional variability of Arctic ponds reflects the stochastic assembly of their microbial communities. Distinct functional subcommunities can, nevertheless, be related to GHG concentrations.

2025, Journal of Bacteriology

Exiguobacterium antarcticum is a psychotropic bacterium isolated for the first time from microbial mats of Lake Fryxell in Antarctica. Many organisms of the genus Exiguobacterium are extremophiles and have properties of biotechnological interest, e.g., the capacity to adapt to cold, which make this genus a target for discovering new enzymes, such as lipases and proteases, in addition to improving our understanding of the mechanisms of adaptation and survival at low temperatures. This study presents the genome of E. antarcticum B7, isolated from a biofilm sample of Ginger Lake on King George Island, Antarctic peninsula.

2025, Proceedings of SPIE

Analog examples of what primeval oceans might have looked in the Precambrian are probably extant in various regions and at various size scales in present day oceans albeit they have not been sufficiently recognized and/or studied. The Eastern Boundary Current Ecosystems (EBCEs), with their characteristic high productivity-inducing coastal upwelling events, their extensive and intensive anoxic/hypoxic water column and methane and sulfide-rich benthic environment, appear to represent such analogs. Moreover, recent studies have shown that they possess diverse anaerobic prokaryotic communities of mat-forming large multi-cellular filamentous bacteria similar to fossils found in Archean and Proterozoic rocks. Observations in the Bay of Concepcion, central Chile (~36°S), inserted in the second most productive EBCE of the world, suggests that given similar oceanographic dynamics, past oceans may have presented different predominant colorations after the first probable "red" color of the reduced iron-rich Archean ocean and prior to the present day "blue" color. In this coastal ecosystem a "black" coloration has been observed to form as the result of the floating to the surface layer of sulfide-blackened benthic detritus together with chunks of microbial mats, and a "milky to turquoise" coloration resulting from different concentrations of colloidal, nano-sized particles which may include elemental sulfur and/or microorganisms. If the present is the key to the past we posit that "black" color oceans could have existed during the Proterozoic "Canfield sulfidic ocean" followed by "milky to turquoise" colored oceans during later stages of the Proterozoic. Meso-scale examples of "milky" and "turquoise" portions of oceans, caused by elemental sulfur from oxidized hydrogen sulfide eruptions, have been described from off Namibia and there appear to also exist elsewhere. Examples of "black" oceans have apparently not been reported but the name of the Black Sea, the largest permanent anoxic basin on Earth, suggests that at some point in time it may have been black, at least locally and/or for short periods, prompting the name. We conclude suggesting that analogous to the present "Blue Planet" denomination, in the past our Earth could possibly have deserved the successive names of "Red", "Black" and "Milky-Turquoise" Planet.

2025, PubMed

New complex communities of morphologically diverse and sometimes abundant large, multicellular, filamentous bacteria were discovered in the oxygen-deficient, organically laden, shelf sediments under the oxygen minimum zone off the coast of the eastern Pacific, i.e., off the coasts of central and northern Chile; central and northern Perú; Roca Redonda, Galápagos Archipielago, Ecuador; and off the Pacific coasts of Panamá and Costa Rica. Similar microbial communities were also observed in the reduced layer of a muddy-sand beach adjacent to a mangrove swamp on Coiba Island, Pacific Panamá, and in the organically laden bottom underneath a salmon culture pen in southern Chile (region X). Of varying morphology, the diameters of the bacteria range from 1 to 10 mum, and their lengths from around 10 mum to usually several hundreds but at times several thousands of micrometers. The new filamentous bacterial component is at least one order of magnitude smaller than the also multicellular "megabacteria" Thioploca spp. and Beggiatoa spp., and is collectively referred to as "macrobacteria". A recent review only mentioned a few of these free-living filamentous bacteria, remarking on their scarcity despite the obvious advantages of a large size. This prokaryote size-window has been rarely investigated optically by researchers; thus, assemblages that appear to have had world-wide distribution probably since pre-Cambrian times have been overlooked.

2025, Deep Sea Research Part I: Oceanographic Research Papers

A brackish-water cold seep on the North Anatolian Fault (NAF) in the Marmara Sea was investigated with the Nautile submersible during the MarNaut cruise in 2007. This active zone has already been surveyed and revealed evidence of active seeping on the seafloor, such as bubble emissions, patches of reduced sediments, microbial mats and authigenic carbonate crusts. MarNaut was the first opportunity to sample benthic communities in the three most common microhabitats (bioturbated and reduced sediments, carbonate crust) and to examine their relationships with environmental conditions. To do so, faunal communities were sampled and chemical measurements were taken close to the organisms. According to diversity indices, the bioturbated microhabitat exhibited the highest taxonomic diversity and evenness despite a lower number of samples. Conversely, the reduced sediment microhabitat exhibited the lowest taxonomic diversity and evenness. The carbonate crust microhabitat was intermediate although it had the highest biomass. Multivariate analyses showed that (1) fauna were relatively similar within a single microhabitat; (2) faunal community structure varied greatly between the different microhabitats; (3) there was a link between faunal distribution and the type of substratum; and (4) chemical gradients (i.e. methane, oxygen and probably sulphides) may influence faunal distribution. The estimated fluid flow velocity (0.4-0.8 m/yr) confirmed the presence of fluid emission and provided evidence of seawater convection in the two soft-sediment microhabitats. Our results suggest that the reduced sediments may represent a harsher environment with high upward fluid flow, which restrains seawater from penetrating the sediments and inhibits sulphide production, whereas bioturbated sediments can be viewed as a bio-irrigated system with sulphide production occurring at greater depths. Therefore, the environmental conditions in reduced sediments appear to prevent the colonization of symbiont-bearing fauna, such as vesicomyid bivalves, which are more often found in bioturbated sediments. Fluid flow appears to control sulphide availability, which in turn influences the horizontal and vertical distribution patterns of fauna at small spatial scales as observed at other seep sites

2025, Limnology and Oceanography

We investigated the hypothesis that sulfate reduction rather than oxygenic photosynthesis promotes calcification in a hypersaline microbial mat by increasing the ion concentration product: ICP ϭ [Ca 2ϩ ] ϫ [CO ]. Pore-water 2Ϫ 3

2025, Geosciences

Hamelin Pool, Shark Bay, Western Australia, is home to the largest and most diverse assemblage of living marine stromatolites, with shapes and sizes comparable to ancient structures. A recent field-intensive program revealed seasonally ephemeral occurrences of modern dendrolitic microbial mats forming in intertidal, low energy settings. Dominated by filamentous cyanobacteria, dendrolitic microbial mats are formed when filaments provide a supporting framework as a result of gliding mobility, to build a shrubby morphology. Dendrolites, known throughout the rock record, refer to macroscopic microbialites with mesostuctures composed of unlaminated arborescent structures called shrubs. In these modern examples, thick filaments of Lyngbya aestuarii form the "trunk" of the bush, with finer filaments of Lyngbya fragilis, Phormidium sp. and Schizothrix sp. forming the "branches" These biologically-influenced dendrolitic structures provide insight into the complex interplay of microbial communities and the environment, broadening our understanding of shrub and dendrolite formation throughout the rock record.

2025, Astrobiology

Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai'i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai'i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai'i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies.

2025, HAL (Le Centre pour la Communication Scientifique Directe)

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2025, Iraqi Geological Journal

Al-Kuwaizi Sabkha exists 21 km south of Al-Hodeidah City, occupying a low topographic region along the Red Sea coast of Yemen. It is secluded from the sea by sand dunes. This study aims to investigate the microbial-induced sedimentary structures and sediment characteristics of the sabkha in this unique coastal environment. The findings will contribute to a better understanding of the geological processes shaping this area and provide insights into microbial activity in an extremely arid climate. The sabkha sediments are texturally classified as slightly gravelly sand and muddy sand, generally polymodal with dominant fine sand, nearly symmetrical, and very leptokurtic. Field investigation of the evaporite-siliciclastic sabkha environment revealed microbially induced surface sedimentary structures such as petee structures, mat chips, tufts, reticulates, jelly rolls, sieve-like surfaces, and wrinkle structures. This sabkha environment provides a good model for studying the potential preservation of life signatures and understanding the depositional environments of ancient evaporite sequences influenced by microbial structures.

2025, PLoS ONE

The Paleoproterozoic Era witnessed crucial steps in the evolution of Earth's surface environments following the first appreciable rise of free atmospheric oxygen concentrations ,2.3 to 2.1 Ga ago, and concomitant shallow ocean oxygenation. While most sedimentary successions deposited during this time interval have experienced thermal overprinting from burial diagenesis and metamorphism, the ca. 2.1 Ga black shales of the Francevillian B Formation (FB2) cropping out in southeastern Gabon have not. The Francevillian Formation contains centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Here, new material from the FB2 black shales is presented and analyzed to further explore its biogenicity and taphonomy. Our extended record comprises variably sized, shaped, and structured pyritized macrofossils of lobate, elongated, and rodshaped morphologies as well as abundant non-pyritized disk-shaped macrofossils and organic-walled acritarchs. Combined microtomography, geochemistry, and sedimentary analysis suggest a biota fossilized during early diagenesis. The emergence of this biota follows a rise in atmospheric oxygen, which is consistent with the idea that surface oxygenation allowed the evolution and ecological expansion of complex megascopic life.

2025, FEMS Microbiology Ecology

A photosynthetic microbial mat was investigated in a large pond of a Mediterranean saltern (Salins-de-Giraud, Camargue, France) having water salinity from 70& to 150& (w/v). Analysis of characteristic biomarkers (e.g., major microbial fatty acids, hydrocarbons, alcohols and alkenones) revealed that cyanobacteria were the major component of the pond, in addition to diatoms and other algae. Functional bacterial groups involved in the sulfur cycle could be correlated to these biomarkers, i.e. sulfate-reducing, sulfur-oxidizing and anoxygenic phototrophic bacteria. In the first 0.5 mm of the mat, a high rate of photosynthesis showed the activity of oxygenic phototrophs in the surface layer. Ten different cyanobacterial populations were detected with confocal laser scanning microscopy: six filamentous species, with Microcoleus chthonoplastes and Halomicronema excentricum as dominant (73% of total counts); and four unicellular types affiliated to Microcystis, Chroococcus, Gloeocapsa, and Synechocystis (27% of total counts). Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments confirmed the presence of Microcoleus, Oscillatoria, and Leptolyngbya strains (Halomicronema was not detected here) and revealed additional presence of Phormidium, Pleurocapsa and Calotrix types. Spectral scalar irradiance measurements did not reveal a particular zonation of cyanobacteria, purple or green bacteria in the first millimeter of the mat. Terminal-restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA gene fragments of bacteria depicted the community composition and a fine-scale depth-distribution of at least five different populations of anoxygenic phototrophs and at least three types of sulfate-reducing bacteria along the microgradients of oxygen and light inside the microbial mat.

2025

The Purgatoire Valley dinosaur tracksite ('Dinosaur Lake') is North America's largest assemblage of Late Jurassic dinosaur tracks. Roughly 1,300 tracks representing ~100 trackways were reported from a 5,600 m 2 area in 1986. Extensive new excavations have revealed more than 800 additional tracks in a 2,600 m 2 area. Less abraded tracks farther from the river channel, excavated below bed rock not alluvium, provide highquality-of-preservation morphometric data. Sauropod (Parabrontopodus) trackways up to 88 m long, some with over 100 successive pes prints, comprise nearly 500 manus and pes tracks. Parallel sauropod trackways confirm previous interpretations of gregarious behaviour, now including a mixed herd of subadult and adult individuals. A preferred westward trackway progression trend likely suggests a single or short-lived episode of gregarious movement along a lake shoreline. Nearly 300 newly recorded tridactyl (theropod) tracks range from 25 to 40 cm in length, with several trackways exceeding 25 or more successive steps. Theropod tracks are assigned to ichnogenus Megalosauripus, also known from the Late Jurassic of Utah, Europe, Central Asia and North Africa. Other theropodan ichnogenera (Hispanosauropus and Therangospodus) from this epoch and region have not been identified. Cross-cutting (over-printing) trackway relationships help constrain the sequence of track registration events.

2025

2025, International Journal of Speleology

Sulfur Cave (Puturosu Mountain, Romania) is an extreme environment, unique for displaying life in a gas chemocline. The lower part of the cave is filled with CO 2 , CH 4 , and H 2 S of mofettic origin, while the upper part contains air that floats above the heavier volcanic gasses. S° and H 2 SO 4 (from sulfur-oxidation) cover the cave wall at and below the CO 2 -H 2 S:O 2 gas/gas interface. On the cave wall, near the interface the pH is <1 and unusual microbial biofilms occur on the rock's surface. We provide context information on the geology, mineralogy, chemistry and biology to better understand this unique environment. We have used X-ray diffraction, optical microscopy, scanning electron microscopy with EDAX capabilities, stable isotope analysis and 16S and 18S rDNA amplicon sequencing. The most common taxa in the microbial biofilms are Mycobacteria, Acidithiobacillus and Ferroplasmaceae. Liquid water in this system originates solely from condensation of water vapor onto the cave walls making inflow of organic carbon from outside unlikely. The most likely primary source of energy for this microbial community is sulfur oxidation with H 2 S and S° as main reductants and atmospheric O 2 as the main oxidant. Ferric iron from the rock surface is another potential oxidant. In Sulfur Cave, gaseous CO 2 (from mofettic emission) maintains the stability of the gas chemocline. Sulfur Cave biofilms can help the search for extreme life in the subsurface, near volcanic systems on Earth and Mars. The Sulfur Cave example shows that a habitable environment can be established underground in gas chemoclines near CO 2 -dominated gas discharge zones, where it can have a steady supply of water and energy.

2025, Aquatic Microbial Ecology

A unique chemoautotrophic system of floating microbial mats was examined in a subterranean cave in southern Romania. Oxygen measurements were made with a recently developed technique applying micro-optodes. The oxygen uptake rate of the anoxic and sulfidic cave waters over the atmosphere/water interface was as high as 103.3 i 9.1 mm01 O2 m-2 d-l. Floating microbial mats consisting primarily of sulfide oxidizers and fungal mycelia were found to be adapted to reduced oxygen supply and thrived even under strict anoxia. These 2 mm thick mats were inhabited by 5 different species of nematodes, reaching densities of 9.8 X 106 ind. m-2 Possible alternative pathways for growth of the mats and also for the persistence and reproduction of nematodes under strict anoxic conditions are discussed.

2025, Annales Societatis Geologorum Poloniae

The major constituent of Upper Jurassic limestones which build Brama Bolechowicka (Bolechowice Gate, a group o f valley-wall limestone rocks near Kraków) is massive limestone representing a complex of cyanobacterial-sponge carbonate buildups. Talus sediments of the buildup are present as clastic limestones exposed in isolated crags. Apparent bedding planes visible in the massive limestones are dissolution-widened fractures, fault joints and gently inclined shearing fractures in fault-related flexures. Limestones exposed ESE from Brama Bolechowicka represent interbiohermal facies and clastic sediments of variable age and origin. The Jurassic strata exposed ESE from Brama Bolechowicka lie within a wide fault zone which separates the Ojców Block from the Krzeszowice Graben. The variable dipping directions of these strata are caused mainly by the presence of hinge faults within this fault zone. A bstrakt. Zasadniczą część górnojurajskich wapieni tworzących Bramę Bolechowicką stanowi kompleks cyjanobakteryjno-gąbkowych budowli węglanowych wykształconych jako wapienie masywne. Osady talusa budowli są reprezentowane przez wapienie detrytyczne budujące pojedyncze skałki Bramy Bolechowickiej. Powierzchnie nieciągłości w wapieniach masywnych są spękaniami ciosowymi, szczelinami uskokowymi i połogimi ścięciami tektonicznymi w obrębie fleksury przyuskokowej. Osady odsłaniające się na ESE od Bramy Bolechowickiej reprezentują facje międzybiohermalne oraz osady detrytyczne o zróżnicowanym wieku i genezie. Występowanie na ESE od Bramy Bolechowickiej utworów jurajskich o zróżnicowanym wykształceniu, ale generalnie młodszych od facji obserwowanych w Dolinie Bolechowickiej ma przyczyny tektoniczne, a nie sedymentacyjne. Zmienne kierunki nachyleń tych utworów są spowodowane głównie obecnością uskoków zawiasowych w rozleglej strefie uskokowej oddzielającej płytę ojcowską od rowu krzeszowickiego.

2025, Heredity

A microbial species concept is crucial for interpreting the variation detected by genomics and environmental genomics among cultivated microorganisms and within natural microbial populations. Comparative genomic analyses of prokaryotic species as they are presently described and named have led to the provocative idea that prokaryotes may not form species as we think about them for plants and animals. There are good reasons to doubt whether presently recognized prokaryotic species are truly species. To achieve a better understanding of microbial species, we believe it is necessary to (i) re-evaluate traditional approaches in light of evolutionary and ecological theory, (ii) consider that different microbial species may have evolved in different ways and (iii) integrate genomic, metagenomic and genome-wide expression approaches with ecological and evolutionary theory. Here, we outline how we are using genomic methods to (i) identify ecologically distinct populations (ecotypes) predicted by theory to be species-like fundamental units of microbial communities, and (ii) test their species-like character through in situ distribution and gene expression studies. By comparing metagenomic sequences obtained from well-studied hot spring cyanobacterial mats with genomic sequences of two cultivated cyanobacterial ecotypes, closely related to predominant native populations, we can conduct in situ population genetics studies that identify putative ecotypes and functional genes that determine the ecotypes' ecological distinctness. If individuals within microbial communities are found to be grouped into ecologically distinct, species-like populations, knowing about such populations should guide us to a better understanding of how genomic variation is linked to community function.

2025, International Symposium on Artificial Intelligence

The ExoMars rover will make heavy use of machine vision algorithms for autonomous navigation. To support the validation of these algorithms, a visual simulation capable of generating realistic simulated images of a Mars-like virtual environment has been developed. This is an enhancement of the University of Dundee's PANGU planet surface simulation tool. The simulation is based on data from the planetary science literature and validated using images from the Mars Exploration Rovers. It includes models of rocks, surface reflectance, atmospheric dust, a rover vehicle and dynamically computed shadows. It provides a straightforward way for autonomy researchers to generate high-quality images for testing, and has potential to be used as a more general rover simulation visualisation tool.

2025

2025, Applied and Environmental Microbiology

Microbial communities in cores obtained from methane hydrate-bearing deep marine sediments (down to more than 300 m below the seafloor) in the forearc basin of the Nankai Trough near Japan were characterized with cultivation-dependent and -independent techniques. Acridine orange direct count data indicated that cell numbers generally decreased with sediment depth. Lipid biomarker analyses indicated the presence of viable biomass at concentrations greater than previously reported for terrestrial subsurface environments at similar depths. Archaeal lipids were more abundant than bacterial lipids. Methane was produced from both acetate and hydrogen in enrichments inoculated with sediment from all depths evaluated, at both 10 and 35°C. Characterization of 16S rRNA genes amplified from the sediments indicated that archaeal clones could be discretely grouped within the Euryarchaeota and Crenarchaeota domains. The bacterial clones exhibited greater overall diversity than the archaeal clones...

2025, Extremophiles

have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms. Communicated by A. Oren.

2025, Water, Air, & Soil Pollution

The aim of this study is to describe general features of sediment, primary producers and both benthic and planktonic consumers in two shallow saline lakes (Salada de La Muerte and Salada de Pifiol) in order to detect main factors influencing food web structure. The lakes are located in Los Monegros district, in the central area of the Ebro River catchment, NE Spain. Both lakes are temporary with salinity well above 30 g L". Although they are situated close to each other (distance: 300 m), their communities of primary producers differ dramatically. One lake (La Muerte) is dominated by microbial malt and seems to function through the benthic pathway. The other (Pifiol) has some macrophytes but phytoplankton is the main source of primary production. Two cycles (1994/95 and 1995/1996), quite different in their hydrological characteristics, have been studied. PCA demonstrated the major influence of hydrologic features (e.g. water level) over biotic and abiotic parameters. The presence of microbial mats in La Muerte played a key role in stabilizing the sediments. A comparison of food web structure and dynamics in both lakes has been performed and the influence of sediment features is discussed.

2025, Acta Botánica Malacitana

Antarctica.The current study describes the biodiversity and distribution of cyanobacteria from the natural habitats of Schirmacher land, East Antarctica surveyed during 23 rd Indian Antarctic Expedition (2003)(2004). Cyanobacteria were mapped using the Global Positioning System (GPS). A total of 109 species (91 species were non-heterocystous and 18 species were heterocystous) from 30 genera and 9 families were recorded; 67, 86 and 14 species of cyanobacteria were identified at altitudes of sea level >100 m, 101-150 m and 398-461 m, respectively. The relative frequency and relative density of cyanobacterial populations in the microbial mats showed that 11 species from 8 genera were abundant and 6 species (Phormidium angustissimum, P. tenue, P. uncinatum Schizothrix vaginata, Nostoc kihlmanii and Plectonema terebrans) could be considered as dominant species in the study area. Key words. Antarctic, cyanobacteria, biodiversity, blue-green algae, Schirmacher oasis, Species distribution. Oriental. En este estudio se describe la biodiversidad y distribución de las cianobacterias presentes en los hábitats naturales de Schirmacher, Antártida Oriental, muestreados durante la 23ª Expedición India a la Antártida (2003Antártida ( -2004)). Las muestras de cianobacterias fueron georreferenciadas mediante un GPS. Se identificaron 109 especies (91 no heterocistadas y 18 provistas de heterocistes) de 30 géneros y 9 familias; en los tramos de altitud sobre el nivel del mar >100 m, 101-150 m y 398-461 m se detectaron 67, 86 y 14 especies, respectivamente. La frecuencia y densidad relativas de las poblaciones de cianobacterias en los tapices microbianos mostraron que 11 especies de 8 géneros eran abundantes y que 6 especies (Phormidium angustissimum, P. tenue, P. uncinatum, Schizothrix vaginata, Nostoc kihlmanii y Plectonema terebrans) se pueden considerar como dominantes en el área de estudio. Palabras clave. Algas verde-azuladas, Antártida, cianobacterias, distribución de especies, oasis de Schirmacher.

2025, Journal of Earth Science

The microbial dolomite model has been used to interpret the origin of sedimentary dolomite. In this model, the formation of low-temperature protodolomite, an important precursor to sedimentary dolomite, can be facilitated either by actively metabolizing cells of anaerobic microbes and aerobic halophilic archaea or by their inactive biomass. Aerobic halophilic bacteria are widely distributed in (proto-)dolomite-depositing evaporitic environments and their biomass might serve as a template for the crystallization of protodolomite. To test this hypothesis, carbonation experiments were conducted using dead biomass of an aerobic halophilic bacterium (Exiguobacterium sp. strain JBHLT-3). Our results show that dead biomass of JBHLT-3 can accelerate Mg 2+ uptake in carbonate mineral precipitates. In addition, the amount of Mg incorporated into Ca-Mg carbonates is proportional to the concentration of biomass. High Mg-calcite is produced with 0.25 or 0.5 g/L biomass, whereas protodolomite forms with 1 g/L biomass. This is confirmed by the main Raman peak of Ca-Mg carbonates, which shifts towards higher wavenumbers with increased Mg substitution. Microbial cells and their imprints are preserved on the surface of high Mg-calcite and protodolomite. Hence, this study furthers our understanding of the dolomitization within buried and dead microbial mats, which provides useful insights into the origin of ancient dolomite.

2025, Geomicrobiology Journal

Modern hydrated Mg rich stromatolites are actively growing along the shallow shorelines of Lake Salda (SW Turkey). An integrated approach involving isotopic, mineralogical, microscopic, and organic/geochemical techniques along with culture-independent molecular methods were applied to various lake samples to assess the role of microbial processes on stromatolite formation. This study further explores the biosignature preservation potential of fossil stromatolites by comparing with textures, lipid profiles and isotopic composition of the modern stromatolites. Similar lipid profile and d 13 C isotope values in active and fossil stromatolites argue that CO 2 cycling delicately balanced between photosynthetic and heterotrophic (aerobic) activity as in the active ones may have regulated stromatolite formation in the lake. A decrease in the exopolymeric substances (EPS) profile of the mat and concurrent hydromagnesite precipitation imply a critical role for EPS in the formation of stromatolite. Consistently, a discrete, discontinuous lamination and clotted micropeloidal textures with cyanobacterial remnants in the fossil stromatolites likely refer to partial degradation of EPS, creating local nucleation sites and allowing precipitation of hydrated Mg minerals and provide a link to the active microbial mat in the modern stromatolites. Our results for the first time provide strong evidence for close coupling of cyanobacterial photosynthesis and aerobic heterotrophic respiration on hydromagnesite textures involved in the stromatolite formation of Lake Salda. The creation of photosynthesis induced high-pH conditions combined with a change in the amount and properties of the EPS and the repetition of these processes over time seems to be a possible pathway for stromatolite growth in the lake. Understanding these microbial symbioses and their mineralized records may provide new insights on the formation mechanism of Mg-rich carbonates not only for terrestrial geological records but also for planetary bodies like Mars, where hydrated Mg-carbonate deposits have been identified in possible paleolake deposits at Jezero crater, the landing site of the NASA Mars 2020 rover.

2025, Marine Ecology

The Eiffel Tower edifice is situated in the Lucky Strike hydrothermal vent field at a mean depth of 1690 m on the Mid-Atlantic Ridge (MAR). At this 11-m-high hydrothermal structure, different faunal assemblages, varying in visibly dominant species (mussels and shrimp), in mussel size and in density of mussel coverage, were sampled biologically and chemically. Temperature and sulphide (∑S) were measured on the different types of mussel-based assemblages and on a shrimp-dominated assemblage. Temperature was used as a proxy for calculating total concentrations of CH 4 . Based on the physico-chemical measurements, two microhabitats were identified, corresponding to (i) a more variable habitat featuring the greatest fluctuations in environmental variables and (ii) a second, more stable, habitat. The highest temperature variability and the highest maximum recorded temperatures were found in the assemblages visibly inhabited by alvinocaridid shrimp and dense mussel beds of large Bathymodiolus azoricus, whereas the less variable habitats were inhabited by smaller-sized mussels with increasing bare surface in between. Larger mussels appeared to consume more ∑S compared with smaller-sized (<1 cm) individuals and thus had a greater influence on the local chemistry. In addition, the mussel size was shown to be significantly positively correlated to temperature and negatively to the richness of the associated macrofauna. The presence of microbial mats was not linked to specific environmental conditions, but had a negative effect on the presence and abundance of macro-fauna, notably gastropods. Whereas some taxa or species are found in only one of the two microhabitats, others, such as polychaetes and Mirocaris shrimp, cross the different microhabitats. Temperature was proposed to be a more limiting factor in species distribution than ∑S.

2025, PeerJ

The production of hydrogen and methane by geochemical reactions associated with the serpentinization of ultramafic rocks can potentially support subsurface microbial ecosystems independent of the photosynthetic biosphere. Methanogenic and methanotrophic microorganisms are abundant in marine hydrothermal systems heavily influenced by serpentinization, but evidence for methane-cycling archaea and bacteria in continental serpentinite springs has been limited. This report provides metagenomic and experimental evidence for active methanogenesis and methanotrophy by microbial communities in serpentinite springs of the Voltri Massif, Italy. Methanogens belonging to family Methanobacteriaceae and methanotrophic bacteria belonging to family Methylococcaceae were heavily enriched in three ultrabasic springs (pH 12). Metagenomic data also suggest the potential for hydrogen oxidation, hydrogen production, carbon fixation, fermentation, and organic acid metabolism in the ultrabasic springs. The ...

2025

Salt pans or playas, which are saline-rich springs surrounded by halite evaporates in arid environments, have played an essential role in landscape erosion during the formation of the Namib Desert and are numerous in its central region. In this study, we used shotgun metagenomics to investigate the phylogenetic and functional capacities of the microbial communities from two salt pans (namely, Eisefeld and Hosabes) located in the Central Namib Desert, located in Southwest Africa. We studied the source and sink sediment mat communities of the saline streams, as well as those from two halites (crystallized structures on the stream margins). The microbial assemblages and potential functions were distinct in both niches. Independently from their localization (Eisfeld vs Hosabes and source vs sink), the sediment mat communities were dominated by members of the Alpha- and Gamma-proteobacteria classes, while halites were Archaea-dominated and also contained high abundances of the extremely ...

2025, Annals of Microbiology

A bacterial strain (DE2008) was isolated from a consortium of microorganisms living in the microbial mats of the Ebro Delta with the ability to grow under conditions of high concentrations of lead and copper. Strain DE2008 has been characterized by microscopic and metabolic techniques and identified by sequencing of PCR-amplified 16S rRNA gene fragments as Micrococcus luteus. The strain is highly resistant to lead and copper. Micrococcus luteus DE2008 grew optimally until levels of 1 mM of Pb (NO 3 ) 2 and CuSO 4 , respectively, and was completely inhibited at 3 mM Pb(NO 3 ) 2 and at 1.5 mM CuSO 4 . Elemental analysis determined by energy-dispersive X-ray spectroscopy (EDX) coupled with scanning electron microscopy and transmission electron microscopy from polluted cultures of DE2008 show that this microorganism can biosorpt Pb and Cu in exopolysaccharide envelopes, without accumulating them inside the cells.

2025, Facies

The structure, mineralogy, and accretion processes of the modern and subfossil cyanobacterial microbialites from the alkaline crater lake Alchichica (Puebla, Mexico) were studied, along the lake's bathymetry and hydrochemistry. The recent lowering of the lake level had exposed microbialitic carbonate mounds and crusts, which emerged up to 2 m above the water surface, while accreting cyanobacterial microbialites were present down to a depth of *15 m. Morphological and molecular analysis found that the living cyanobacterial mats were composed of diverse filamentous and coccoid cyanobacteria (Nostocales, Chroococcales, Oscillatoriales, and Pleurocapsales). The emerged subfossil microbialites comprised two generations: ''white'' (domes and crusts composed mainly of hydromagnesite with an admixture of huntite and calcite, 238 U/ 230 Th age of *2.8 ka BP), and ''brown'' (chimneys, columns and laminated crusts composed of aragonite with an admixture of Mg-calcite, 238 U/ 230 Th age of *1.1 ka BP). The significant age, structural, mineralogical, and isotopic differences suggest that the two generations were formed in different environmental conditions: the ''white'' during a dry period, and the ''brown'' in wet climate associated with high water level and intense inflow of ground water, which lowered the Mg/Ca ratio resulting in formation of aragonite instead of hydromagnesite. The hydromagnesite, replacing the primary aragonite precipitated in the living cyanobacterial biofilm, frequently undergoes silicification, which obliterates both the primary structure of the carbonate and the enclosed remains of cyanobacterial microbiota. This process helps to explain the abundant formation of dolomites and cherts in an allegedly highly alkaline Early Precambrian ocean. Thus, Lake Alchichica represents a modern alkaline environment where biosedimentary structures resembling Precambrian deposits are generated.

2025, Applied and Environmental Microbiology

The distribution and abundance of sulfate-reducing bacteria (SRB) and eukaryotes within the upper 4 mm of a hypersaline cyanobacterial mat community were characterized at high resolution with group-specific hybridization probes to quantify 16S rRNA extracted from 100-μm depth intervals. This revealed a preferential localization of SRB within the region defined by the oxygen chemocline. Among the different groups of SRB quantified, including members of the provisional families “ Desulfovibrionaceae ” and “ Desulfobacteriaceae ,” Desulfonema -like populations dominated and accounted for up to 30% of total rRNA extracted from certain depth intervals of the chemocline. These data suggest that recognized genera of SRB are not necessarily restricted by high levels of oxygen in this mat community and the possibility of significant sulfur cycling within the chemocline. In marked contrast, eukaryotic populations in this community demonstrated a preference for regions of anoxia.

2025, Nature

Viruses, and more particularly phages (viruses that infect bacteria), represent one of the most abundant living entities in aquatic and terrestrial environments. The biogeography of phages has only recently been investigated and so far reveals a cosmopolitan distribution of phage genetic material (or genotypes) 1-4 . Here we address this cosmopolitan distribution through the analysis of phage communities in modern microbialites, the living representatives of one of the most ancient life forms on Earth. On the basis of a comparative metagenomic analysis of viral communities associated with marine (Highborne Cay, Bahamas) and freshwater (Pozas Azules II and Rio Mesquites, Mexico) microbialites, we show that some phage genotypes are geographically restricted. The high percentage of unknown sequences recovered from the three metagenomes (.97%), the low percentage similarities with sequences from other environmental viral (n 5 42) and microbial (n 5 36) metagenomes, and the absence of viral genotypes shared among microbialites indicate that viruses are genetically unique in these environments. Identifiable sequences in the Highborne Cay metagenome were dominated by single-stranded DNA microphages that were not detected in any other samples examined, including sea water, fresh water, sediment, terrestrial, extreme, metazoan-associated and marine microbial mats. Finally, a marine signature was present in the phage community of the Pozas Azules II microbialites, even though this environment has not been in contact with the ocean for tens of millions of years. Taken together, these results prove that viruses in modern microbialites display biogeographical variability and suggest that they may be derived from an ancient community. Microbialites are organosedimentary structures accreted by sediment trapping, binding and in situ precipitation due to the growth and metabolic activities of microorganisms 5 . Stromatolites and thrombolites are morphological types of microbialites classified by their internal mesostructure: layered and clotted, respectively 5 . Microbialites first appeared in the geological record ,3.5 billion years ago, and for more than 2 billion years they are the main evidence of life on Earth 6,7 . Whether modern microbialites are proxies of ancient ecosystems is a major outstanding question 6 . Viruses, and more specifically phages, are the most abundant biological entities in the world's oceans 8 . Phages influence microbial growth rates, genetic exchange, diversity and adaptation, and thus evolution 8 . Current biogeographical studies of phages suggest that they are cosmopolitan in distribution, unlike some examples of

2025

The physicochemistry, hydrology and invertebrate fauna are described for an unusual wetland, EPP 173, in Melaleuca Park, near Perth, Western Australia. EPP 173 is important as the site for a northern outlier population of the Black-stripe minnow, Galaxiella nigrostriata (Shipway), a fish endemic to southwestern Australia. EPP 173 is an acid (pH <5.5, typically pH 3.3 to 3.9), seasonal wetland with unusually dark water (TCU >1200). The colour of the water together with the surrounding forest and wetland vegetation facilitate the establishment and persistence of strong thermal stratification of the wetland in spring and summer. The invertebrate fauna comprises 41 species with a substantial benthic cladoceran component, including at least one species previously known only from southern wetlands between Augusta and Albany. The wetland is of high conservation value, containing no exotic species and low concentrations of nutrientsaccompanied by the absence of algal blooms. However, encroaching urban development is likely to alter the limnology of EPP 173, threatening the survival of the resident G. nigrostriata population.

2025, Palaeogeography, Palaeoclimatology, Palaeoecology

The carbonaceous compression fossils Protoarenicola baiguashanensis , Pararenicola huaiyuanensis Wang, 1982, and Sinosabellidites huainanensis Zheng, 1980, from the early Neoproterozoic Liulaobei and Jiuliqiao formations in northern Anhui, North China, were previously interpreted as worm-like metazoans, largely on the basis of transverse annulations and purported proboscis structures. If correct, these would be some of the earliest known bilaterian animals and would provide a key paleontological calibration to molecular clock analyses. In this study, we examine a large population of these carbonaceous fossils, clarify their taxonomy, and provide new insights into their morphological, paleoecological, and phylogenetic interpretations. Although all three species are characterized by annulated tubes, P. baiguashanensis bears a bulbous terminal structure at one end of its tube. P. huaiyuanensis is characterized by a constricted opening at one end and a closed termination at the other. The two ends of S. huainanensis tubes are both closed and round. The bulbous terminal structure in P. baiguashanensis was previously interpreted as an animal proboscis, but new observations suggest that it was more likely a holdfast structure analogous to discoidal holdfast structures of the Mesoproterozoic Tawuia-like fossil Radhakrishnania Kumar, 2001, and the frondose Ediacara fossil Charniodiscus Ford, 1958. Furthermore, it is possible that at least P. baiguashanensis and P. huaiyuanensis may represent reproductive or taphonomic fragments of the same organism. This reinterpretation weakens the previous interpretation that P. baiguashanensis and P. huaiyuanensis were worm-like bilaterian animals. Instead, they can be alternatively interpreted as erect epibenthic organisms, possibly coenocytic algae reaching a tiering height of 30 mm. The predominance of discoidal holdfasts, as opposed to rhizoidal holdfasts, in pre-Ediacaran epibenthic organisms was probably related to more stable substrates in the presence of microbial mats and in the absence of bioturbating animals.

2025, Canadian Journal of Fisheries and Aquatic Sciences

Arctic warming has recently accelerated, triggering the formation of thaw ponds and the mobilization of a carbon pool that has accumulated over thousands of years. A survey of 46 thaw ponds in the Canadian arctic and subarctic regions showed that these ecosystems have high concentrations of dissolved organic matter (DOM) and nutrients and are relatively productive. This activity was reflected in the optical properties of DOM that indicated a dominance of allochthonous sources but a significant contribution of low molecular weight compounds. Several subarctic ponds were stratified in summer, resulting in a hypoxic hypolimnion. Most ponds were supersaturated in CO2 and CH4, with higher gas concentrations in bottom waters. However, arctic thaw ponds colonized by benthic microbial mats showed lower CO2 concentrations, likely caused by active photosynthesis. CO2 was correlated with both the quantity and the optical properties of DOM, suggesting the significant role of dissolved compounds...

2025, Geobiology

Microbialite-forming microbial mats in a hypersaline lake on the atoll of Kiritimati were investigated with respect to microgradients, bulk water chemistry, and microbial community composition. O2 , H2 S, and pH microgradients show patterns as commonly observed for phototrophic mats with cyanobacteria-dominated primary production in upper layers, an intermediate purple layer with sulfide oxidation, and anaerobic bottom layers with sulfate reduction. Ca(2+) profiles, however, measured in daylight showed an increase of Ca(2+) with depth in the oxic zone, followed by a sharp decline and low concentrations in anaerobic mat layers. In contrast, dark measurements show a constant Ca(2+) concentration throughout the entire measured depth. This is explained by an oxygen-dependent heterotrophic decomposition of Ca(2+) -binding exopolymers. Strikingly, the daylight maximum in Ca(2+) and subsequent drop coincides with a major zone of aragonite and gypsum precipitation at the transition from the...

2025, Australian Journal of Earth Sciences

Apart from within the Arumbera Sandstone that spans the Ediacaran-Cambrian boundary, the entire Neoproterozoic succession of the Amadeus Basin has been generally believed to be devoid of metazoan fossils, despite features of possible biogenic origin having been described in the earliest geological mapping reports. Herein are described a suite of curious, rounded impressions preserved upon the surface of a sandstone bed from the basal Neoproterozoic unit, the quartzitic Heavitree Formation that dates to ca 850 Ma. Compared with rounded structures of both organic and inorganic origin, these features resemble fossils of stranded medusae, both modern and ancient, and thereby add a potentially pelagic lifeform to previously described burrowing and sessile forms of likely metazoans, which are preserved as fossils/trace fossils within the Tonian period of the Neoproterozoic elsewhere in the basin. An organic origin for these features would support the contention that the Amadeus Basin harbours the earliest evidence that macroscopic life flourished, albeit briefly, some 215 million years prior to the start of the Ediacaran period and 250 million years before metazoans successfully colonised the late Ediacaran seas. KEY POINTS 1. Curious rounded impressions upon a scree sample of Heavitree Formation (ca 850 Ma) are best compared with fossils of stranded jellyfish, both modern and ancient. 2. Such impressions add to the phyla seemingly extant within the Amadeus Basin during the Tonian Period (early Neoproterozoic). 3. Such phyla suggest that metazoan life evolved some 250 Ma earlier than generally believed, although became extinct locally some 10 Ma later. 4. Extinction occurred at ca 840 Ma when changing climate caused the enclosed Amadeus Basin to evolve from conducive shallow aquatic conditions to a harsh evaporitic salt pan. 5. Two later forays into metazoan evolution within the basin are evidenced by burrow-like tubular structures at ca 720 Ma and the Arumberia fossils at ca 560 Ma.

2025, Australian Journal of Earth Sciences

The mid-Tonian-aged Heavitree Formation, the basal unit of the Amadeus Basin succession, has long been believed to be devoid of metazoan fossils. Since a recent review of isolated occurrences of purported metazoan traces and remains within the formation's upper unit, however, that conclusion has been questioned and led to the identification of new fossil remains, including imprints of Aspidella reported herein. Previously, organic-looking structures encountered in rocks older than mid-Ediacaran (ca 580 Ma) were commonly interpreted as originating inorganically, primarily through water escape, but a recently examined outcrop of the upper unit of the Heavitree Formation revealed a variety of water escape structures in association with, but structurally distinct from, a suite of organic impressions. KEY POINTS 1. Both biogenic Aspidella and abiogenic water escape structures occur within the upper member of the Tonian Heavitree Formation in the Amadeus Basin. 2. The Aspidella are structurally distinct from the water escape structures. 3. The presence of Aspidella adds to a growing list of phyla seemingly extant within the Amadeus Basin during the early Neoproterozoic. 4. Extinction of this Amadeus 'biota' occurred at ca 840 Ma when climatic conditions changed the basin from a conducive shallow aquatic environment to a harsh evaporitic salt pan.