YELLOWSTONE NATIONAL PARK HYDROTHERMAL SYSTEMS
A slide show of some hydrothermal areas that can be viewed by the public from boardwalks (all photos by Jeff Havig). The majority of the work we do is in hydrothermal areas that are closed to the public (due to public safety concerns). Yellowstone National Park takes public safety extremely seriously, and anyone without special training and granted special access to back country hydrothermal areas to conduct scientific research (through the Permit Office) can be cited by Park Rangers (a felony), with a mandatory court appearance in Mammoth Village. A misstep in these hydrothermal areas can lead to serious injury or death. Death following submersion in boiling water (if one is able to get out) will take about two to three days as your body dehydrates, unable to retain moisture due to the flash boiling of all of your skin. Nothing can be done for you, and if you are lucky you might be able to say goodbye to your loved ones before you perish.
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Hydrothermal systems in Yellowstone National Park present an amazing array of physical and geochemical parameters, affording us the opportunity to ask as many questions as we can imagine. One can find hot springs with pH values from 9.5 to nearly zero, temperatures that range from above boiling (which is around 93°C for the elevation of YNP, which is typically between 7000 to 8000 feet/2200 to 2500 meters for the sites we collect from) to ambient, that undergo regular periods of interrupted flow, and that have concentrations of major and trace constituents that span many orders of magnitude. Much of this is driven by subsurface processes, including phase separation resulting from subsurface boiling of hydrothermal fluids. How those phases reach the surface and interact with local groundwater influence the surface expression of a hot spring. This is an excellent place to explore the relationship between geochemical environments and microbial communities.
We are particularly interested in the microbial communities that are found in hydrothermal systems at YNP. Microbial communities can take the forms of filaments or streamers (long, feathery string-like forms that maximize surface area exposure in flowing water), mats (layered, with potentially dramatic differences in geochemistry and community composition across millimeters of depth), and stromatolites (layered, often growing at the air-water interface). These macroscopic forms are similar to what is found in the rock record from 3.5 billion years ago to the present day. Furthermore, the higher temperatures and extreme geochemistry in these hot spring environments often exclude Eukaryotes, providing microbial community composition makeup that is exclusively Archaea and Bacteria, similar to what was found on earth prior to the evolution of Eukarya (around 1.5 billion years ago). Exploring and characterizing these microbial communities may provide a glimpse at what life was like on the early Earth, and potentially what life may have looked like on Mars. |
For some of the papers published from our hot spring research, scroll down! They are listed from most recent to older. Also, scroll to the bottom for bonus images from exploring hydrothermal systems in New Zealand's Taupo Volcanic Zone.
A circum-neutral hot spring in the Upper Geyser Basin, YNP. Temperature of source is near boiling (which is ~93°C at the high elevations of YNP), and the pH is ~8. Note the orange to red photosynthetic mats, denoting where the temperature is below 72°C. Pink filaments can be found in the outflow channel of some of these types of springs (where the temperature is ~85°C), and were taken as signs of hydrothermal microbial life by the Hayden Expedition of 1871, and are the source of taq polymerase which allowed the recent revolution in molecular research. Photo by Jeff Havig.
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Cartoon representation of the subsurface processes that drive geochemistry in Yellowstone hot springs. The typical hot springs in the Lower, Midway, and Upper Geyser Basins are fed by hydrothermal water that has undergone minimal subsurface boiling and phase separation. Hot springs in other areas (like the Mud Volcano Area, Norris Geyser Basin, and the Gibbon Geyser Basin) are fed by water that has undergone subsurface boiling and phase separation, and mixing with local groundwater. Based on Figure 1 from Havig et al. (2021) (discussed below).
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Dragon's Mouth Spring is an acidic spring (pH ~2) at the Mud Volcano Area, YNP. These vapor phase-dominant springs typically have high sulfide concentrations, and low water outflow (if any). Behind the steam is a lush mat of algae, likely Cyanidium, which thrive in acidic areas in Yellowstone. Photo by Jeff Havig.
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Above: Filaments similar to those found in Lower Geyser Basin hot springs, YNP.
Below: Stromatolites forming in the photic zone of an outflow from a circum-neutral hot spring in the Upper Geyser Basin, YNP. Photos by Jeff Havig. |
Closeup of a microbial mat sample. Note the changes in color from the top to the bottom of the mat. The total cross sectional depth is about 1.5 centimeters. The sample was collected in accordance with Yellowstone science permit rules. Photo by Jeff Havig.
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Outcrop of siliceous sinter deposit from a circum-neutral hot spring. The layers were likely deposited by microbial mats. What biosignatures are locked inside? (Photo by Jeff Havig.)
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Meet me in the middle: Median temperature controls on phototrophic microbial communities in eruptive hot springs
In this work lead by Dr. Trinity Hamilton of the Fringe Lab, we sampled phototrophic microbial communities in two eruptive hot springs in the Lower Geyser Basin in Yellowstone National Park. The microbial communities saw temperature swings of up to 40 C, depending on where in outflow channel they were. We conducted carbon uptake experiments and evaluated the community compositions. The results of this work suggest that rather than the high temperature, the median temperature was a key driver for the evolution of the community members.
Right: Google Earth images for the sampling locations for this work (from the Supplemental Online Material for the published paper. Below: A link to the paper
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Below: The two eruptive sites that we worked at were Flat Cone and an unnamed hot spring we dubbed The 'Jolly Jelly'. The 'Jolly Jelly' exhibits a fairly regular eruptive periodicity while Flat Cone is erratic in the length between eruptions.
Figure 1: Site photos and temperature variation. (Top) Temperature measured over a 4-h window near the FC source and two outflow locations: FC hot (where phototrophs were first visible in the center of the outflow channel) and FC cool. (Bottom) Temperature measured over a 4-h window near the JJ source and two outflow locations: JJ hot (where phototrophs were first visible in the center of the outflow channel) and JJ cool.
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Below: Results of molecular work (16S rRNA analyses for community composition) and carbon uptake experiments for phototrophic communities in the outflow channels of Flat Cone and 'Jolly Jelly'.
Figure 2: Diversity, phototroph community composition, and C assimilation rates. (A) Richness and Shannon diversity indices calculated for the 16S rRNA amplicons. (B) Heatmap of the relative abundance of OTUs assigned to putative bacterial phototrophs according to the work of Hamilton et al. (14). (C) Heatmap of the relative abundance of cyanobacterial ASVs. (D) Rates of C assimilation in microcosm assay performed in the dark (wrapped in foil) and light. Error bars from triplicate measurements. In all light versus-dark comparisons, the rates are statistically different (P , 0.05).
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Hot spring microbial community elemental compositions, geochemical environments, and retention of elements during the transition to siliceous sinter
The work presented in this paper published in the journal Astrobiology represents over ten years of research and work by myself and a wonderfully supportive group of collaborators. The results are based on the analyses of 16 elements binned as follows: major components of biomass - C (as DIC and DOC), N (as TDIN), P; trace biomass components essential for biological functions - Mg, V, Mn, Fe, Co, Ni, Cu, Zn, and Mo; and elements not known to play an important role in biological functions - Li, Al, Ga, and As. These analyses were conducted on water, biofilm, and siliceous sinter samples collected from 60 different hot springs across 8 different hydrothermal areas in Yellowstone National Park. This was then combined with literature data to present an overview of elemental uptake and sequestration by hot spring microbial communities and siliceous sinters.
We found evidence supporting biologically important elements were systematically retained in the siliceous sinters derived from microbial communities in both phase separation and minimal phase separation hydrothermal systems, suggesting elemental concentrations may serve as an additional biosignature that can be preserved in the rock record. |
Introducing a new term: Biocumulus
In this paper we propose the new term ‘‘biocumulus’’ (plural: ‘‘biocumuli’’) to describe these microbiological structures based on the combination of bio (latin for life) and cumulus (latin for heap, or pile), here defined as the sum of microbial community cellular biomass, EPS (e.g., polysaccharides, proteins, DNA), accumulated allochthonous material, and precipitated minerals that together form a distinctive mass that is ordered and not ascribed to sedimentary processes alone. Biocumulus would include all microbial community-associated structures (i.e., filaments, mats, and stromatolites), and it would encompass biofilms and microbialites. |
Figure 1: Map of YNP with hydrothermal sampling areas labeled. Areas shown include: AS, Amphitheater Springs; CHA, Crater Hills Area; GCA, Geyser Creek Area; GOPA, Greater Obsidian Pool Area, MVA; IGB, Imperial Geyser Basin; LGB, Lower Geyser Basin; MGB, Midway Geyser Basin; MVA, Mud Volcano Area; NGB, Norris Geyser Basin; NMC, Norris-Mammoth Corridor; RG, River Group, LGB; SM, Sentinel Meadows, LGB; SSA, Sylvan Spring Area; SVHS, Secret Valley Hot Springs; UGB, Upper Geyser Basin; WCA, White Creek Area, LGB. Large open circles indicate sites reported in previous work, small closed circles indicate sites reported in this study, and large open circles with inset small closed circles indicate sites reported in previous work and this study.
Figure 5 (right) shows that plotting hot springs by sulfate versus chloride concentration in log-log space breaks the hydrothermal systems down and makes it easier to tease apart the hydrothermal inputs feeding hot springs.
Here is a link to the paper:
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And here are the results of plotting the elemental concentrations in the hot spring waters - binned for simplicity into five categories from highest concentration range [largest circles in red] to lowest concentration range [smallest circles in black]. These are the environments that the microbial communities experience. The biggest take away is that the type of phase that is predominantly feeding a hot spring will determine whether that hot spring is relatively high or low in concentration for all elements shown.
Figure 6: SO4^2- versus Cl- plots with hot spring biologically non-essential (NON-BIO) element concentration bins overlain,
including (in increasing atomic weight) Li, Al, Ga, and As. Element ranges for bins given for each element. |
Figure 7: SO4^2- versus Cl- plots with hot spring major biologically relevant (BIO) element concentration bins overlain,
including (in increasing elemental atomic weight) DIC, DOC, TDIN [TDIN =NH4(T) + NO3- + NO2-], and total dissolved phosphorous (P). Element ranges for bins given for each element. DIC, dissolved inorganic carbon; DOC, dissolved organic carbon; TDIN, total dissolved inorganic nitrogen. |
Figure 8: SO4^2- versus Cl- plots with hot spring trace biologically relevant (BIO-TRACE) element concentration bins
overlain, including (in increasing elemental atomic weight) Mg, V, Mn, Fe, Co, Ni, Cu, Zn, and Mo. Element ranges for bins given for each element. |
For looking at the behavior of microbial communities in the different phase regimes (whether in mixed phase systems or minimal phase separation systems, described in detail in the paper), we found that there were differences in elemental sequestration, but some surprising similarities in retention of elements in the transition from biofilm to siliceous sinter.
Figure 9: Biocumulus concentration and median values by increasing atomic weight for elements that are grouped into one of three bins, including biologically non-essential (NON-BIO, including Li, Al, Ga, and As), major biologically essential elements (BIO, including C, N, and P), and trace biologically essential elements (BIO-TRACE, including Mg, V, Mn, Fe, Co, Ni, Zn, Mo). Biocumulus samples grouped as either no phase separation sites (royal blue left justified open circles and closed bar, n = 74) or phase separation sites (raspberry red right-justified open circles and closed bar, n = 39). Data from this study and literature (Havig, 2009; Havig et al., 2011; Schuler et al., 2017; Hamilton et al., 2019; Havig and Hamilton, 2019a, 2019b).
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Figure 12: Elemental compositions and median values for top: no phase separation area biocumulus and sinter, and bottom: phase separation area biocumulus and sinter, both plotted against element in increasing atomic weight. Elements binned as described in Section 3.2. Data from this study and literature (Havig, 2009; Havig et al., 2011; Schuler et al., 2017; Hamilton et al., 2019; Havig
and Hamilton, 2019a, 2019b). Percent retention between biocumulus median and sinter median given below each element column. |
We put together this conceptual model to help describe illustrate how the different types of elements move through the hydrothermal systems and eventually end up in siliceous sinters, which can then become part of the rock record.
Figure 13: Conceptual model for flow of elements into hot spring biocumulus systems and retention/loss through diagenesis to silica sinter. (1) Weathering of local rock and detritus from local biota contribute to local soil formation. (2) Primary inputs of elements into biocumulus from deposition of soil particulates via aeolian transport and hot spring water delivering elements for precipitation (Si as silica), fixation (C and N), and uptake/sequestration (N, P, trace elements). (3) Microbial communities grow and build structures from autochthonous accumulation of biomass, EPS, and precipitation of silica and allochthonous accumulation of soil particulates. Accumulation of BIO, BIO-TRACE, and NON-BIO elements occurs. Silica content increases with time, acting to dilute other elemental constituents. (4) Buildup of biocumulus leads to eventual outflow path avulsion, decreasing hot spring input/temperature and causing death of thermophilic microbial community; decomposition/breakdown drives loss of BIO and BIO-TRACE elements accumulated with biomass/EPS. (5) Complete outflow avulsion leads to desiccation of biocumulus and diagenesis from biocumulus to siliceous sinter. Retention of silica, systematic loss of BIO and BIO-TRACE elements, NON-BIO element loss (Li, Al), and retention (Ga, As). Biocumulus textures, BIO, and BIO-TRACE elements preserved through diagenesis by biocumulus co-precipitated silica and later infill of silica (lower right).
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Exploring hot spring siliceous sinter samples for possible trace element biosignatures - The work of Dr. Andrew Gangidine in collaboration with MAD EGG Lab
As part of his PhD research (which I was extremely fortunate to be a part of), now Dr. Andrew Gangidine used exciting new instrumentation (BIO-SIMS - and instrument that allows for the detection and mapping of most of the periodic table at super fine scale) to analyze siliceous sinters with microbial filaments preserved. His field site focused on Steep Cone - an alkaline (pH ~ 7.5) boiling (Temp ~ 93 C at the source) hot spring in the Sentinel Meadows area of the Lower Geyser Basin in Yellowstone National Park. Andrew sampled as part of our research group on multiple expeditions to YNP. Below is the first paper to come from his PhD work.
Above - The sample site, where Sentinel Creek has cut away part of the siliceous sinter mound that has built as a result of precipitation from the outflow of the Steep Cone source.
From Gangidine et al., 2021: FIG. 2. Steep Cone, Lower Geyser Basin, Yellowstone National Park, USA. (a) Layers of exposed strata and a modern spring discharge channel. (b) Hot spring located on the top of Steep Cone. The orange pigment in the discharge channels indicates the presence of photosynthetic microorganisms. (c) and (d) Photomicrographs of a Gram-negative filament illustrating a mucilaginous coating (panel c, scale bar = 20 μm) and cellular trichome (panel d, scale bar = 5 μm) collected from the discharge channel of Steep Cone (near the yellow arrow in panel a). Preserved microbial filaments are found throughout the deposit including in sinter (e) near the top of Steep Cone (yellow arrow in panel a) displaying orange pigment, and in (f) the lower strata of Steep Cone devoid of pigment (red arrow in panel a). Scale bars in (e) and (f) = 20 μm. Similarly, densely packed smaller filaments in microbial mats are found (g) near the top of Steep Cone (in a discharge channel, near the yellow arrow in panel a), and similar morphologies are preserved in sinter (h) at the base of the deposit (blue arrow in panel a). Scale bars in (g) and (h) = 200 μm.
From Gangidine et al., 2021: FIG. 2. Steep Cone, Lower Geyser Basin, Yellowstone National Park, USA. (a) Layers of exposed strata and a modern spring discharge channel. (b) Hot spring located on the top of Steep Cone. The orange pigment in the discharge channels indicates the presence of photosynthetic microorganisms. (c) and (d) Photomicrographs of a Gram-negative filament illustrating a mucilaginous coating (panel c, scale bar = 20 μm) and cellular trichome (panel d, scale bar = 5 μm) collected from the discharge channel of Steep Cone (near the yellow arrow in panel a). Preserved microbial filaments are found throughout the deposit including in sinter (e) near the top of Steep Cone (yellow arrow in panel a) displaying orange pigment, and in (f) the lower strata of Steep Cone devoid of pigment (red arrow in panel a). Scale bars in (e) and (f) = 20 μm. Similarly, densely packed smaller filaments in microbial mats are found (g) near the top of Steep Cone (in a discharge channel, near the yellow arrow in panel a), and similar morphologies are preserved in sinter (h) at the base of the deposit (blue arrow in panel a). Scale bars in (g) and (h) = 200 μm.
Right: A link to Andrew's paper
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Above - A high-resolution SEM (scanning electron microscope) image and spot analysis results for a living filament encrusted in siliceous sinter.
From Gangidine et al., 2021: FIG. 3. Filaments from Steep Cone, displaying a coating of silica. (a) Scanning electron microscope image of a recently living filament collected from a Steep Cone discharge channel (yellow arrow, Fig. 2a) showing the silica coating surrounding the filament. Scale bar = 10 μm. (b) High-magnification view of the silica coating surrounding the filament, showing characteristic botryoidal texture. Scale bar = 2 μm. Orange and blue X marks indicate location of point analyses of a silica coating and filament, respectively, by energy dispersive X-ray spectroscopy shown in (g) and (h). (c–f) A series of photomicrographs of progressively older filaments (i.e., from progressively deeper within the Steep Cone stratigraphy) displaying increasing levels of organic alteration but preservation of the silica coating. (c) A living filament collected from an active discharge channel of Steep Cone (cf. filament illustrated in panels a and b) subjected to a Gram stain highlighting biomass in red. Scale bar = 10 μm and applies to (c–f). (d) A recently silicified filament collected from the top of Steep Cone (yellow arrow, Fig. 2a) shows pigment retained within the silica coating. (e) A silicified filament located deeper within the sample taken from the top of Steep Cone (yellow arrow, Fig. 2a) shows a loss of pigment but retention of the filamentous morphology and silica coating after several years of diagenesis. (f) A silicified filament from sinter collected from halfway through the ∼14 ka deposit (red arrow, Fig. 2a), showing retention of the filamentous morphology and silica coating. (g) Silica spectrum from the spot marked with an orange X in (b). (h) Spectrum from the spot marked with a blue X in (b), showing the presence of organic C, and smaller amounts of Na and Cl.
From Gangidine et al., 2021: FIG. 3. Filaments from Steep Cone, displaying a coating of silica. (a) Scanning electron microscope image of a recently living filament collected from a Steep Cone discharge channel (yellow arrow, Fig. 2a) showing the silica coating surrounding the filament. Scale bar = 10 μm. (b) High-magnification view of the silica coating surrounding the filament, showing characteristic botryoidal texture. Scale bar = 2 μm. Orange and blue X marks indicate location of point analyses of a silica coating and filament, respectively, by energy dispersive X-ray spectroscopy shown in (g) and (h). (c–f) A series of photomicrographs of progressively older filaments (i.e., from progressively deeper within the Steep Cone stratigraphy) displaying increasing levels of organic alteration but preservation of the silica coating. (c) A living filament collected from an active discharge channel of Steep Cone (cf. filament illustrated in panels a and b) subjected to a Gram stain highlighting biomass in red. Scale bar = 10 μm and applies to (c–f). (d) A recently silicified filament collected from the top of Steep Cone (yellow arrow, Fig. 2a) shows pigment retained within the silica coating. (e) A silicified filament located deeper within the sample taken from the top of Steep Cone (yellow arrow, Fig. 2a) shows a loss of pigment but retention of the filamentous morphology and silica coating after several years of diagenesis. (f) A silicified filament from sinter collected from halfway through the ∼14 ka deposit (red arrow, Fig. 2a), showing retention of the filamentous morphology and silica coating. (g) Silica spectrum from the spot marked with an orange X in (b). (h) Spectrum from the spot marked with a blue X in (b), showing the presence of organic C, and smaller amounts of Na and Cl.
Left - in situ BIO-SIM analyses of different siliceous sinter samples from different layers of the cut face of Steep Cone. What stood out to us was how the trace element concentrations were highest in close proximity to the outside of the microbial filament.
From Gangidine et al., 2021: FIG. 5. Secondary ion mass spectrometry analyses of silicified microbial filaments from various levels of strata of Steep Cone. The first panel of each column shows a white light (W.L.) image of the silicified filaments with a white outline surrounding the area of the filament which has been bisected at the surface of the thin section (and thus analyzed via SIMS). Subsequent panels show the elemental maps for the area shown in the first panel for each element noted on the top row. The color bar on the right shows relative values from low (blue) to high (red). Scale bar = 20 μm and applies to all images. See Fig. 9 and the Supplementary Materials for quantified concentrations of trace elements and analyses of additional samples. C = carbon, Si = silicon, Fe = iron, Ga = gallium, Mn = manganese. |
Low biomass/high silica sites: Windows into the earliest microbial communities on Earth?
Some hot springs host microbial communities that depend solely on chemotrophy (use chemical reactions to gain energy and drive metabolic reactions such as carbon fixation). These types of environments and microbial communities may provide a window into what some of the earliest microbial communities on Earth may have looked like.
Figure 1 from our paper (Havig and Hamilton, 2019): The locations we sampled in Yellowstone National Park for the low biomass sites ranged in pH from ~3 to ~9, and included putative anoxygenic phototrophic communities as well as chemotrophic. All research conducted under Yellowstone Research Permit YELL-2017-SCI-7020/YELL-2018-SCI-7020.
While the low biomass sites we sampled may not immediately make one think of microbial communities in the way that the thick phototrophic mats, stromatolites, or lush filaments found in some hot springs do, we have found evidence for potentially complex microbial communities dependent upon chemicals provided by the hydrothermal waters. Sulfur, in particular, seems like an important energy source which may help 'feed' microbial communities that cycle the sulfur in situ. We suggest that studying these types of hydrothermal systems and better understanding the types of biosignatures they may produce may be important not only for better interpreting the presence of life in the early rock record on Earth, but may also have implications for what to look for in the search for life on other planets, especially Mars and the upcoming NASA Mars 2020 rover mission. Here is a link to the paper:
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Carbon uptake at low biomass sites was determined through mesocosm experiments as a way to estimate primary productivity. We measured carbon uptake at all sites, with all sites falling close to the same range of values except for one site with oxygenic phototrophs ('The Dryer'). The results of the carbon uptake experiments are shown below, along with the temperature and pH values for the sites. This is Figure 3 from the paper.
Above: From the paper's Fig 2, the molecular results showing the basic community composition breakdown for the sites we sampled. Crenarcheota were the predominant Archaeal sequences present across all sites, and Aquificae and Proteobateria found in most of recovered bacterial sequences. Many of the sequences recovered were unclassified/uncharacterized.
We were able to do a lot of imaging and characterization of the sediment/biomass samples collected from the sites. We used an Scanning Electron Microscope with an attached Emission Detection X-Ray Spectrometer located at the LacCore facility at UMN. This was crucial for determining that there was evidence for sulfur species being both reduced and oxidized at some of the sites. |
Above: From Figure 5 in the paper, SEM images of the biofilms and sediments in the outflow of Boulder Geyser in the Lower Geyser Basin. We found abundant evidence for iron sulfide mineral precipitation at the high temp (84.8 C) and high pH (8.6) site.
Above: Figure 7 from the paper, SEM images of sediments in Dante's Inferno, Gibbon Geyser Basin. Here we found evidence for elemental sulfur being oxidized (spheres) as well as iron sulfide minerals being precipitated (potentially from sulfur reduction), suggesting a complex sulfur cycle occurring in situ.
Above: Figure 8 from our paper, SEM images of an anoxygenic photosynthetic mat from 'Avocado Pool', Gibbon Geyser Basin. Here we found evidence for iron sulfide minerals precipitating in the phototrophic mat.
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Hypolithic microbial communities: Hints for life on the Archean continental surface?
Hydrothermal Areas Harbor Hypolithic Phototrophic Communities Which May Represent What Life On Archean Continental Land Surfaces Might have Looked Like Over 3 Billion Years Ago.
A footstep in loose silica sinter gravels uncovers the bright green cryptic phototrophic microbial community living underneath. Photo by Jeff Havig.
Lurking under bleached-white silica sinter surfaces in Yellowstone hydrothermal areas are lush green phototrophic microbial mats. Most of the time researchers just walk across these surfaces on their way to sample the more exciting hot springs, but we decided to stop and explore these cryptic systems. This resulted in a paper where we introduce these systems to the scientific community (Havig and Hamilton, 2019 - see below).
Our results indicate that the hypolithic (below-rock, or in this case, below-sinter) phototrophic microbial communities are as productive as subaerial and subaqueous phototrophic communities, suggesting the majority of primary productivity occurring in hydrothermal areas is not happening in the hot springs or their outflow channels, but actually in the distal loose sinter fields. The silica sinter gravels and sands acts as a mulch layer that traps moisture, protects the microbial communities from washing away during rain events, and protect them from UV radiation while allowing photosynthetically active radiation to pass through. We are currently working on a follow-up manuscript that will characterize a much wider array of hypolith sample sites in Yellowstone. |
Figure 2 from Havig and Hamilton (2019) showing molecular results (top), carbon uptake experiment results (middle), and cartoon sketches of the sampling sites from this project. All sites were predominantly phototrophs, and exhibited strong light-dependent carbon uptake (fixation of 13-C labeled dissolved inorganic carbon).
Supplementary Figure 3 from Havig and Hamilton, 2019 showing Google Earth images and pictures of the sites sampled for this work. Samples were collected from hypolith sites (sub-sinter, or ssint), subaqueous sites (saq), and subaerial sites (saer). All research conducted under Yellowstone Research Permit YELL-2016-SCI-7020.
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Supplementary Figure 4 from Havig and Hamilton, 2019 showing how the light passing through silica sinter sands and gravels preferentially attenuates the blue end of the light spectrum, helping block UV radiation.
Figure 3 from Havig and Hamilton, 2019 showing a conceptual model of how hypolithic oxygen-producing phototrophic microbial communities living on terrestrial surfaces could have played a significant role in driving oxidative weathering on Archean land surfaces before the Great Oxidation Event of 2.45 Ga.
These sorts of hypolithic communities are rare today, only found in areas where environmental conditions exclude plant life (such as extreme aridity in deserts). In hydrothermal areas, heat and/or volcanic gases from the ground act as inhibitors of plant growth, allowing hypolithic microbial communities to dominate. |
Here is a link to the paper:
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Carbon uptake in stromatolites, mats, and filaments
As part of a collaborative effort between MAD EGG Lab and The Fringe Lab (led by Prof. Trinity Hamilton), we looked at community composition and carbon uptake rates for stromatolites, microbial mats, and filaments at a hydrothermal site in Yellowstone. This resulted in a student-led paper (Schuler et al., 2017 - see below).
Our results indicate that mats and filaments have significantly higher carbon fixation rates than stromatolites, suggesting crediting stromatolites with driving oxygen production during the Archean and Paleoproterozoic may in fact under-represent the input from microbial features that are not as readily preserved in the rock record. |
Above: Fig 1 from Schuler et al. (2017): Map of locations sampled and images of the biofilms we sampled. All sampling was conducted under Yellowstone Research Permit YELL-2016-SCI-7020.
Right: Fig 2 from Schuler et al. (2017): Microbial community composition for bacteria and archea, measured via 16S rRNA analyses.
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Left: Fig 3 from Schuler et al. (2017): Carbon uptake rates measured by in situ mesocosm experiments. We sampled from phototrophic as well as chemotrophic microbial communities.
Below: Fig 5 from Schuler et al. (2017): A conceptual cartoon showing the inverse correlation between preservation potential and primary productivity for microbial biofilms in hot spring environments.
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Right: A link to the paper that Caleb published.
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Carbon and nitrogen isotopes in a hot spring's microbial communities
One project looked at the carbon and nitrogen isotope signatures of biofilms down an outflow channel of a boiling, circum-neutral hot spring (Rosette Geyser, aka 'Bison Pool') in the Lower Geyser Basin of Yellowstone. The study linked the presence of carbon fixation genes to carbon isotope signature and nitrogen isotope signature to presence of nitrogen fixation genes in the microbial communities present from the source and down the outflow channel. Carbon isotope fractionation factors (biomass - dissolved inorganic carbon values) ranged from less than five per mil to greater than 20 per mil. The following are some figures and the resulting paper:
Figure 5 from Havig et al. (2011):
Trends in biomass carbon isotope values indicate different fractionations by carbon-fixing organisms with decreasing temperatures, showing increasing fractionation with decreasing temperature. Below is a manuscript that we published based on work done by Dr. Havig as part of his dissertation at ASU.
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Figure 7 from Havig et al. (2011):
Compiled literature values (black bars) compared to biomass values for carbon isotopes for different temperature ranges. |
Figure 10 from Havig et al. (2011):
Trends in biomass nitrogen isotope values indicate uptake from a finite pool of fixed nitrogen in the chemotrophic zone, and then an increase in nitrogen fixation-sourced nitrogen in the phototrophic zone. |
TAUPO VOLCANIC ZONE (TVZ) HYDROTHERMAL SYSTEMS,
NEW ZEALAND
NEW ZEALAND
We have started a collaboration with Professor Kathy Campbell of the University of Auckland and Professor Martin Van Kranendonk of the University of New South Wales to work with them in several areas in the TVZ, with our initial collaborative sampling trip occurring February of 2019. There will be much more to come as I upload images and some related literature, so stay tuned! For now, please enjoy some short slide shows of images from the different areas.
Hell's Gate Area, TVZ, New Zealand (Spring, 2019). Photos by Jeff Havig.
Lake Rotokawa Area, TVZ, New Zealand (Spring, 2019). Photos by Jeff Havig.
Wai-O-Tapu, TVZ, New Zealand (Spring, 2019). Photos by Jeff Havig.
Orakei Korako, TVZ, New Zealand (Spring, 2019). Photos by Jeff Havig.
Waimangu, TVZ, New Zealand (Spring, 2019). Photos by Jeff Havig.