Bacterial Mats Research Articles

High-frequency study of megafaunal communities on whale bone, wood and carbonate in hypoxic Barkley Canyon

Organic-rich whale bones and wood falls occur widely in the deep sea and support diverse faunal communities, contributing to seafloor habitat diversity. Changes in community structure through succession on deep-sea bone/wood substrates are modulated by ecosystem engineers, i.e., bone-eating Osedax annelids, and wood-boring Xylophaga bivalves. Here, we use a comparative experimental approach and Ocean Networks Canada’s (ONC) cabled observatory in hypoxic Barkley Canyon to study, at high temporal resolution, colonization and succession on whale-bone, Douglas fir wood, and control carbonate rock over 8.3 mo. Experimental substrates were similar in size and mounted on PVC plates near the seafloor at 890 m depth and monitored by high-definition video camera for 5-min intervals every 6-12 h over a period of 8.3 mo. A broad range of seafloor and sea-surface environmental variables were also monitored at this site over the 8.3 mo to account for environmental variability and food input. Following loss of the high-definition camera, substrates were surveyed approximately annually with lower resolution ROV video for an additional 8.5 y. We find that megafaunal abundances, species diversity, and community structure varied substantially over 8.3 mo on each substrate, with markedly different patterns on whale bones due to the development of extensive white bacterial mats. A combination of seafloor and sea surface variables explained < 35% of bone/wood community variation. Bone-eating Osedax annelids failed to colonize whale bones even after 9.2 years, and boring Xylophaga bivalves colonized the wood at much lower rates than in better oxygenated deep-sea locations. Species diversity on whale-bone and wood substrates appeared to be substantially reduced due to the absence of ecosystem engineers and the low oxygen concentrations. We hypothesize that Osedax/Xylophaga colonization, bone/wood degradation, and bone/wood community development may be limited by oxygen concentrations of 0.22 - 0.33 ml.l on the NE Pacific margin, and that OMZ expansion due to climate change will reduce whale-bone and wood degradation, and the contribution of whale falls and wood falls to beta diversity, on the NE Pacific margin.

New cold seep sites on the continental slope southwest to Svalbard

We discovered seafloor features such as bacterial mats and carbonate crusts typical for active methane seeps on the continental slope southwest of Svalbard. These features are associated with two main northwest-southeast trending morphological structures that are oriented parallel to the regional continental slope. Both structures occur at c. 800 m water depth, at the boundary between the Storfjorden trough mouth fan to the south and the Hornsund trough mouth fan to the north, which suggests a loading related fluid seepage. The main structure displays depressions and ridges forming a crater in its center. Other occurring features include small sediment mounds, domes often covered by bacterial mats, and hummocky seafloor colonized by siboglinid tubeworms. Free gas bubbles were spotted close to the centre and plumes along the rims of the structure. Thick carbonate crusts indicate a long seepage history in the center of the structure and on top of the ridges. The sources of the seeps are likely to be Miocene old organic-rich deposits, or Paleocene hydrocarbon reservoirs.

Adaptation of Fildes Peninsula Lakes (King George Island, East Antarctica) to climate change and anthropogenic impacts

The load on the Antarctic oases has been recently increasing, with intensive research carried out by various countries and ecological tourism developing. This leads to an increase in the impact on the aquatic ecosystems of the lakes and streams in addition to the warming climate and glacier melting. This paper presents findings from a study of the Fildes Peninsula (King George Island) lakes’ aquatic ecosystems in the summer period of January–February 2020. In addition to results of hydrological and hydrochemical studies, the paper provides data from measurements of the self-cleaning ability of representative oasis lakes, as well as greenhouse gas fluxes from the lakes surface. The water level of the streams decreased 5 times over the summer season, and the water discharge — 10 times. The streams flowing from the glacier have the fullest water. The lakes have a neutral reaction, sometimes weakly alkaline; they are well aerated: the average value of dissolved oxygen in water is 85 %, occasionally supersaturation of up to 137% was observed. The concentration of nutrients in the water has amplitudes that are considerable for Antarctic oases lakes. A significant correlation can only be observed between nitrates and phosphates, and also between the water turbidity and the nutrients’ concentration. Maximum turbidity is observed in lakes with abundant content of bacterial mats. Most of the lakes have hydrochemical type II sodium chloride waters. The assessment of the lake self-cleaning ability using the ratio of destruction and organic matter production showed the general ability of ecosystems to cope with external (natural) pressures on ecosystems, but not in all cases. Eutrophication of the lakes and stream valleys is also noted. Carbon dioxide (CO2) absorption was observed in most of the streams and lakes, in some of them — methane (CH4) absorption as well. However, CH4 is generally emitted from the surface of the lakes. The largest values are recorded for small lakes located on glacial moraines and in places where ornithosoils are present. The agreement of the findings from the hydroecological studies of the Fildes peninsula lakes with those presented earlier by other authors makes it possible to conclude that there is a certain resistance of the lakes to climatic changes, but one can already talk about a significant anthropogenic impact on the freshwater oasis ecosystems.

Heavy metal movement through insect food chains in pristine thermal springs of Yellowstone National Park.

Yellowstone National Park thermal features regularly discharge various heavy metals and metalloids. These metals are taken up by microorganisms that often form mats in thermal springs. These microbial mats also serve as food sources for invertebrate assemblages. To examine how heavy metals move through insect food webs associated with hot springs, two sites were selected for this study. Dragon-Beowulf Hot Springs, acid-sulfate chloride springs, have a pH of 2.9, water temperatures above 70°C, and populations of thermophilic bacterial, archaeal, and algal mats. Rabbit Creek Hot Springs, alkaline springs, have a pH of up to 9, some water temperatures in excess of 60°C, and are populated with thermophilic and phototrophic bacterial mats. Mats in both hydrothermal systems form the trophic base and support active metal transfer to terrestrial food chains. In both types of springs, invertebrates bioaccumulated heavy metals including chromium, manganese, cobalt, nickel, copper, cadmium, mercury, tin and lead, and the metalloids arsenic, selenium, and antimony resulting from consuming the algal and bacterial mat biomass. At least two orders of magnitude increase in concentrations were observed in the ephydrid shore fly Paracoenia turbida, as compared to the mats for all metals except antimony, mercury, and lead. The highest bioaccumulation factor (BAF) of 729 was observed for chromium. At the other end of the food web, the invertebrate apex predator, Cicindelidia haemorrhagica, had at least a 10-fold BAF for all metals at some location-year combinations, except with antimony. Of other taxa, high BAFs were observed with zinc for Nebria sp. (2180) and for Salda littoralis (1080). This accumulation, occurring between primary producer and primary consumer trophic levels at both springs, is biomagnified through the trophic web. These observations suggest trace metals enter the geothermal food web through the microbial mat community and are then transferred through the food chain. Also, while bioaccumulation of arsenic is uncommon, we observed five instances of increases near or exceeding 10-fold: Odontomyia sp. larvae (13.6), P. turbida (34.8), C. haemorrhagica (9.7), Rhagovelia distincta (16.3), and Ambrysus mormon (42.8).

Lithological features of the uryuk formation in the tolparovo section of the vendian (Southern Urals)

New results of lithological structural and textural observations and petrographic study of rocks of the Uryuk formation exposed in the basin of the Maly Tolpar River in the Bashkir meganticlinory are presented. For the first time, a wide development of consedimentary underwater landslide folds in the Uryuk deposits has been established, the sizes of which vary from the first tens of centimeters to the first meters. In sandstones, the presence of oblique, wavy, flasery and horizontal, with a dual character of thin clay layers, layering, as well as structureless layers with a massive texture, is recorded. Signs of shallow wave ripples have been established. Mechanoglyphs and textures similar to Arumberia banksi have been found, which presumably represent the lithified structures of bacterial mats that existed under certain conditions – shallow-sea environments and conditions of sandy-clay sedimentation. It is concluded that the Uryuk deposits, despite the absence of direct lithological signs of diamictites in them, form a single sedimentary sequence with the underlying Tolparov-Suirovsky marine glacial deposits, in which a shallow-sea sedimentation regime is established by the end of the Uryuk time. It is shown that the presence of ferruginous minerals in sandstone cement is secondary in nature and is associated with their epigenetic transformations. It is concluded that the red-colored color of the rocks of the Uryuk formation cannot be used for stratification of its sections and reconstruction of sedimentation conditions in the Uryuk time.

Marine anoxia initiates giant sulfur-oxidizing bacterial mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland

Abstract. The Santa Barbara Basin naturally experiences transient deoxygenation due to its unique geological setting in the southern California Borderland and seasonal changes in ocean currents. Long-term measurements of the basin showed that anoxic events and subsequent nitrate exhaustion in the bottom waters have been occurring more frequently and lasting longer over the past decade. One characteristic of the Santa Barbara Basin is the seasonal development of extensive mats of benthic nitrate-reducing sulfur-oxidizing bacteria, which are found at the sediment–water interface when the basin's bottom waters reach anoxia but still provide some nitrate. To assess the mat's impact on the benthic and pelagic redox environment, we collected biogeochemical sediment and benthic flux data in November 2019, after anoxia developed in the deepest waters of the basin and dissolved nitrate was depleted (down to 9.9 µM). We found that the development of mats was associated with a shift from denitrification to dissimilatory nitrate reduction to ammonium. The zone of sulfate reduction appeared near the sediment–water interface in sediment hosting these ephemeral white mats. We found that an exhaustion of iron oxides in the surface sediment was an additional prerequisite for mat proliferation. Our research further suggests that cycles of deoxygenation and reoxygenation of the benthic environment result in extremely high benthic fluxes of dissolved iron from the basin's sediment. This work expands our understanding of nitrate-reducing sulfur-oxidizing mats and their role in sustaining and potentially expanding marine anoxia.

Active prokaryotic and eukaryotic viral ecology across spatial scale in a deep-sea brine pool.

Deep-sea brine pools represent rare, extreme environments, providing unique insight into the limits of life on Earth, and by analogy, the plausibility of life beyond it. A distinguishing feature of many brine pools is presence of thick microbial mats that develop at the brine-seawater interface. While these bacterial and archaeal communities have received moderate attention, viruses and their host interactions in these environments remain underexplored. To bridge this knowledge gap, we leveraged metagenomic and metatranscriptomic data from three distinct zones within the NEOM brine pool system (Gulf of Aqaba) to reveal the active viral ecology around the pools. We report a remarkable diversity and activity of viruses infecting microbial hosts in this environment, including giant viruses, RNA viruses, jumbo phages, and Polinton-like viruses. Many of these form distinct clades-suggesting presence of untapped viral diversity in this ecosystem. Brine pool viral communities exhibit zone-specific differences in infection strategy-with lysogeny dominating the bacterial mat further away from the pool's center. We linked viruses to metabolically important prokaryotes-including association between a jumbo phage and a key manganese-oxidizing and arsenic-metabolizing bacterium. These foundational results illuminate the role of viruses in modulating brine pool microbial communities and biogeochemistry through revealing novel viral diversity, host associations, and spatial heterogeneity in viral dynamics.

Characterizing Håkon Mosby Mud Volcano (Barents Sea) cold seep systems by combining ROV-based acoustic data and underwater photogrammetry

Cold-seeps have a unique geo-ecological significance in the deep-sea environment. They impact the variability of present-day submarine sedimentary environments, affecting the evolution of the landscape over time and creating a variety of submarine landforms, one of which is Mud Volcanoes (MVs). MVs form due to the extrusion of mud, fluids, and gas, mainly methane, from deeper sedimentary layers. These natural gas seepage systems could significantly affect climate change and the global carbon cycle. We present a comprehensive method that combines ROV-based multibeam mapping and underwater photogrammetry to enhance the understanding of the physical relationships between geomorphic units characterizing the Håkon Mosby Mud Volcano (HMMV) and the distribution of associated habitats. HMMV is indeed characterized by high thermal and geochemical gradients from its center to the margins resulting in a clear zonation of chemosynthetic communities. Our approach integrates multi-resolutions and multi-sources data acquired using a work-class ROV. The ROV-based microbathymetry data helped to identify the different types of fine-scale submarine landforms in the central part of HMMV. This revealed three distinct geomorphic units, with the central hummocky region being the most complex. To further study this area, ROV images were analyzed using a defined Structure from Motion workflow producing millimetric resolution 2D and 3D models. Object-Based Image Analysis (OBIA), applied on orthomosaics, allowed us to obtain a fine classification of main benthic communities covering a total area of 940m2, including the active seepage area of the hummocky rim. Four major substrate types were identified in these regions: uncovered mud, bacterial mats high-density, bacterial mats low-density, sediments and tubeworms. Their relationship with terrain morphology and seepage activity were investigated at different spatial scales, contributing to a deeper understanding the ecological functioning of cold seep ecosystems in MVs. The applied workflow is proposed as an innovative processing technique for future studies on cold-seep systems. Geomorphic and ecological processes in extreme environments are inherently linked and marked by spatial patterns typifying associated habitats and sedimentary environments. This is poorly investigated in previous studies, leaving a substantial gap in the geomorphological drivers responsible for habitat distribution and extent in cold seep systems.

GEOCHEMICAL CONDITIONS OF SULLAR SPRING: FORMATION OF AUTHIGENIC MINERALS AND METHANE FLUXES

Link for citation: Soldatova E.A., Sidkina E.S., Kiriukhin B.A., Maximov P.N., Krivenok L.A., Ivanov V., Tananaev N.I. Geochemical conditions of Sullar spring: formation of authigenic minerals and methane fluxes. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 16-33. In Rus. Relevance and the research object. Interpermafrost aquifers and areas of their discharge with seasonal ice covers are special permafrost-hydrogeological and hydrochemical systems that are not typical for the thick continuous permafrost zone of Central Yakutia. Differences in chlorofluorocarbon content indicate the anaerobic conditions of some springs suggesting microbial degradation of these compounds by methanogenic bacteria. In the discharge area of such springs, a sharp change in the geochemical conditions takes place leading to a transformation in the water chemical composition and boosting the processes of authigenic mineral formation in this buffer area. In current work we considered the geochemical system of the Sullar spring – the most northern and the least studied among interpermafrost groundwater discharge zones of the Lena River right bank. Intensive accumulation of authigenic minerals was found in the Sullar discharge area during field research. It was Fe compounds with bacterial mats as an opalescent film. Some researchers state the connection between the transformation of Fe compounds during permafrost melting and the migration and transformation of organic matter, including its consumption by microorganisms with further methane emission. We assumed that there is a relationship between the authigenic mineral formation and the content and emission of methane in the discharge area of the spring. This research is the first comprehensive description of the hydrochemistry of the interpermafrost water of the Sullar spring. The aim of the research was to explore influence of geochemical conditions and microbial communities on formation of authigenic minerals and methane fluxes, in particular the effect of the change of geochemical conditions due to groundwater discharge on Fe precipitation and to analyze the relation of that process with methane fluxes. For this purpose, we study water chemical composition of the Sullar spring, measure methane fluxes from water surface and analyze mineral and microbial composition of secondary mineral crusts and bottom eluvium collected near water sampling points. Methods. The main element content was determined by ion chromatography. The concentrations of the bicarbonate ion and dissolved carbon dioxide were calculated by the equilibrium modeling method based on the pH and Eh values of the system. The content of trace elements was measured by mass spectrometry with inductively coupled plasma. To identify seasonal and annual variability, a retrospective analysis of the water chemical composition of the Sullar spring for the period from 1962 to 2020 was carried out. Methane fluxes were measured using the chamber method. The methane concentration was determined by gas chromatography with a flame ionization detector. The features of the secondary mineral crusts and bottom eluvium were determined using a petrographic microscope. The chemical composition of individual mineral phases was evaluated using a scanning electron microscope equipped with a detector for energy dispersive X-ray spectral microanalysis. The DNA concentration was measured on a fluorimeter. Amplicon libraries were generated by polymer chain reaction with universal primers for the V4 region. Equilibrium modeling was carried out using the HCh software.

Metagenomics Revealed a New Genus 'Candidatus Thiocaldithrix dubininis' gen. nov., sp. nov. and a New Species 'Candidatus Thiothrix putei' sp. nov. in the Family Thiotrichaceae, Some Members of Which Have Traits of Both Na+- and H+-Motive Energetics.

Two metagenome-assembled genomes (MAGs), GKL-01 and GKL-02, related to the family Thiotrichaceae have been assembled from the metagenome of bacterial mat obtained from a sulfide-rich thermal spring in the North Caucasus. Based on average amino acid identity (AAI) values and genome-based phylogeny, MAG GKL-01 represented a new genus within the Thiotrichaceae family. The GC content of the GKL-01 DNA (44%) differed significantly from that of other known members of the genus Thiothrix (50.1-55.6%). We proposed to assign GKL-01 to a new species and genus 'Candidatus Thiocaldithrix dubininis' gen. nov., sp. nov. GKL-01. The phylogenetic analysis and estimated distances between MAG GKL-02 and the genomes of the previously described species of the genus Thiothrix allowed assigning GKL-02 to a new species with the proposed name 'Candidatus Thiothrix putei' sp. nov. GKL-02 within the genus Thiothrix. Genome data first revealed the presence of both Na+-ATPases and H+-ATPases in several Thiothrix species. According to genomic analysis, bacteria GKL-01 and GKL-02 are metabolically versatile facultative aerobes capable of growing either chemolithoautotrophically or chemolithoheterotrophically in the presence of hydrogen sulfide and/or thiosulfate or chemoorganoheterotrophically.

TYMKIVIA PRIMITIVA GEN. NOV. SP. NOV., A NEW TYPE OF FOSSILS FROM THE LATE EDIACARAN (VENDIAN) KANYLIVKA GROUP IN PODOLIA, UKRAINE

A thick sequence of Ediacaran (Vendian) deposits is exposed in the southwestern part of Ukraine along the valley of the Dniester River and its left tributaries. The stratigraphy and lithology of these deposits have been studied in some detail, but information on the fossil record is still very scarce. The Kanilovka Group sedimentary sequence has the lowest level of exploration. Tymkivia primitiva gen. nov. sp. nov. is described from Late Ediacaran shallow-water marine rocks of the Podolia region. The fossils are casts of the inner surface and imprints on the surface of bacterial mats (“death masks”) of small, sedentary sac-like organisms. Numerous imprints on the surface of mudstone and siltstone slabs testify to the existence of mass settlements of these organisms in the Volyn-Podilsky sedimentary basin in the Late Ediacaran. Morphological details that could be interpreted as a mouth, anus, and internal organs are not found in the fossils. Tymkivia was found in association with bacterial mat remains and the carbonaceous compressions of Vendotaenia, Kanilovia, and the problematic rod-shaped Harlaniella. Tymkivia is interpreted as possible remains of benthic plants; it is morphologically similar to some modern green algae. The option of interpretation as a fossilized record of the polyp stage of Medusozoa (Cnidaria) cannot be ruled out either. The appearance and disappearance of these organisms are the benchmarks of the stage of sedimentation of the Kanylivka Group.

Environment-Forming Effect of Bubble Gas Emissions in the Golubaya Bay, Black Sea: Oxygen Regime and Bacterial Mats

Gas seep and fluid flows from the seabed are an environment-forming factor of the aquatic environment, mainly due to their influence on the dissolved gases in the water, including dissolved oxygen. During the summer seasons from 2019 to 2021 in the area of shallow water gas emission site off the southern coast of the Heracles Peninsula, series of vertical probing profiles were carried out to determine hydrological parameters of the water: dissolved oxygen concentration (O2), temperature (T), salinity (S), and flow velocity (U). The study area is an underwater ledge with faults in the form of three canyons composed of dense limestones, two of which contained bubble gas emissions. Significant variability in O2 was identified in canyons where gas emissions are observed: from 1 to 80% saturation in the bottom layer, in contrast to normoxia at the background sites. Hypoxia was observed in the bottom layer above the emission sites in the absence of turbulence at temperature stratification. The values S decreased with depth, and the maximum difference reached 0.4‰. The bubble gas was dominated by methane (68.5–75.5%), and the carbon isotope composition of the bubble methane gas varied from –67.9 to –59.8‰ VPDB in 2019 and 2020, respectively. This generally indicates that the CH4 is of predominantly microbial genesis, was formed under different conditions, and matured in various periods of research during the monitoring period. Bacterial mats (mostly sulfur-oxidizing bacteria) were found in the areas of gas emissions.

Environment-Forming Effect of Bubble Gas Emissions in the Golubaya Bay, Black Sea: Oxygen Regime and Bacterial Mats

Environment-Forming Effect of Bubble Gas Emissions in the Golubaya Bay, Black Sea: Oxygen Regime and Bacterial Mats

Cruise report CAGE15-3

The cruise had two main objectives: Deployment of the two CAGE ocean floor observatories (OS1 and OS2) at shallow PKF site and deeper PKF site; CAGE ocean floor observatories were designed and build as collaborative work of CAGE scientists with Kongsberg engineers. Observatories have identical set up except that only one of them have side looking multibeam. The set up is: Seabed Platform/seabed lander/mooring frame (x2) – OS1 has black mooring frame, OS2 has grey mooring frame, CTD (x2), Oxygen sensor (x2), CH4 sensor (x2), CO2 sensor (x2), pH sensor (x1), Fluorometer (x2), ADCP (x2), Current profiler (x1), Multibeam echosounder (x1) – grey lander, OS2, Broadband Hydrophone (x2), Flowmeter (x2) For specific description of each lander, please refer to ‘taking over’ documents (WP4 team leader). Landers and sensors arrived to Tromsø with a track from Hamburg, A. Silyakova was a reference person to receive goods and shipping documents. Time period between 24 and 26 of June was the assemblage of observatories and tests of telemetry/communication/camera on a launcher. Pär Jeanson (PhD student WP4) and Reidar Kaasa (substitute engineer instead of Anoop in WP4) from CAGE were assigned to receive training on observatory assemblage/communication. 26 of June – taking over procedure. Sites for the deployment were discussed during preparatory phase. Water depth at the sites could not exceed 500 meters due to restrictions in relation to the recovery rope, which is only 500 meters long. Photographs from the tow cam used during CAGE 15-2 cruise (chief scientist on the cruise G. Panieri) revealed sites with bacterial mats on the ocean floor. Prior each deployment we did echosounder and multibeam survey to know where flares are highly concentrated. Information from the survey was mapped instantly. Target spots for both observatories were chosen based on all this combined information. Oceanographic survey in the area of shallow PKF methane flares; From the “Testing seep fertilization hypothesis” proposal:‘ During cruise CAGE 14-1 the USGS-GAS system detected elevated methane fluxes near the coast and over the shelf seep site in ca. 90m water depth. Methane fluxes above the 240 and 400m site are much less, although slightly elevated with respect to the open ocean (e.g. Vestnesa). Unexpectedly, high methane concentrations (up to 20nM) are often accompanied by low CO2 concentrations. Initial estimates of the total CO2 budget show that under those conditions seep areas are CO2 sinks. What are the biological, geochemical and hydrographic conditions that made these seeps a CO2 sink? Are the observations from CAGE 14-1 repeatable? And ultimately, what are the processes causing the strong CO2 consumption.’It was decided to test seep fertilization hypothesis during CAGE 15-3 cruise by conducting comprehensive water sampling for biogeochemical environment in the entire water column above the area of methane flares. At the same time, USGS-GAS system was onboard allowing to simultaneously measuring surface water/lower atmosphere gas concentrations. This potentially allows calculating vertical gas flux from one realm to another. Depending on available time, collaborators equipment and human resources, water from 64 CTD stations was samples for following parameters: CH4 concentration; discrete sampling to introduce into CDRS system – 13C CH4, CO2; pH; DIC and 13C DIC; DOC; MOx; FISH; DNA; DMSP; CDOM; Nutrients (nitrate, silicate, phosphate). The cruise may be known as: CAGE15_3

CAGE16-4 Cruise Report: Recovery of observatories and water column survey offshore Svalbard

The cruise occurred from May 1st to May 9th 2016 and was part of the Centre of Excellence for Arctic Gas Hydrate, Environment and Climate (CAGE) at UiT – The Arctic of Norway. The main goal of the cruise was to recover two observatories that were deployed on June 30th and July 2nd 2015 during CAGE 15-3 (chief scientist Anna Silyakova). The sites were selected according to pictures taken during CAGE 15-2 cruise (chief scientist Giuliana Panieri) illustrating bacterial mats on the sea floor. The exact locations were decided just prior to deployment according to flare locations. The present cruise also aimed at investigating an area of extensive flares western Svalbard, particularly the shallow shelf and shelf edge. The addressed scientific topics include quantification of methane concentration in the water column, dissolved inorganic carbon, pH, microbial activity and identification, nutrients, DMSP, CDOM and current amplitude and direction. The cruise may be known as: CAGE16_4

Mega- and macrofauna of the hydrothermally active submarine Piip Volcano (the southwestern Bering Sea)

Benthic communities of the hydrothermally active submarine Piip Volcano (55°445 N, 167°263 E, 368–495 m, the southwestern Bering Sea) were explored during the 75th and 82nd cruises of the RV Akademik M.A. Lavrentyev using the ROV Comanche 18. The Piip Volcano is the northernmost hydrothermal region in the Pacific. Macrofauna composition and community structure were investigated based on qualitative and relative abundance samples along with still images and video records. In total, 130 species of macro- and megafauna were found, of which ∼25% are new to science. Of the fauna, 9 species (7%) are obligate or potentially obligate to environments with access to reduced chemicals. These species are the bivalve Calyptogena pacifica (Vesicomyidae: Pliocardiinae), the gastropods Parvaplustrum wareni (Parvaplustridae) and Provanna sp. (Provannidae), the amphipod Onesimoides sp. (Tryphosidae), the leptostracan Nebalia piipensis (Nebaliidae), the isopod Eurycope andreyi (Munnopsidae), and the polychaetes Neosabellides uschakovi (Ampharetidae), Ophryotrocha beringiana (Dorvilleidae) and Harmothoe globosa (Polynoidae).The total species richness of the Northern and Southern summits was almost identical (90 species and 85 spp respectively), but the number of species on sites without bacterial mats on the Northern Summit (81 spp) was almost 1.5 times higher than on the Southern Summit (57 spp). At the same time the species richness was almost twice higher in habitats with bacterial mats and/or clam beds on the Southern Summit (58 spp) compared to the Northern one (32 spp). The main faunal difference was the absence of Calyptogena pacifica on the Northern Summit. The factors that may explain differences of the faunal communities of the Northern and Southern summits are discussed.The distinctive features of macro- and megafaunal communities of the Piip Volcano were the significant number of taxa, obligate for reducing habitats, of different taxonomic levels including family and subfamily levels and plentiful abundances of sedentary organisms, including the sea anemone Corallimorphus cf. pilatus, the demosponge Vulcanella koltuni, calcareous sponges and benthopelagic Trachimedusa, all of them presumably utilizing the rich food resources of reducing habitats.

A new species of the genus Nebalia (Crustacea: Phyllocarida: Leptostraca) from hydrothermal vent fields of the submarine Piip Volcano (the southwestern Bering Sea) described through molecular and morphological analysis

A new leptostracan species, Nebalia piipensis sp. nov., collected during the 82nd cruise of the RV Akademik M.A. Lavrentyev on the submarine Piip Volcano (the southwestern Bering Sea) at depths of 400–472 m, has been described. These leptostracans were abundant at bacterial mats and in assemblages of chemosymbiotrophic bivalves Calyptogena pacifica (Pliocardiinae). Nebalia piipensis sp. nov. differs from the known Nebalia species by a set of features including a distally tapering eye-stalk mostly covered by an ommatidial part; a rostrum with the length 2.5 times the width; an article 2 of mandibular palps bearing three thin plumose and one thin simple seta; an article 1 of the second maxilla endopod 1.8 times longer than an article 2; furcal rami longer than the combined length of the pleonite 7 and telson; rounded denticles of pleonites 6 and 7; an indistinct anal-plates ‘shoulder’. Nebalia piipensis sp. nov. is the second species of the genus Nebalia reported from hydrothermal vent fields after N. tagiri, described from hydrothermal vents in Kagoshima Bay, at 200 m. The sequences of COI barcoding region, 16S and Histon H3 loci for the new species were obtained. The phylogenetic analysis based on COI sequence showed that all the northwestern Pacific species, including N. tagiri and N. piipensis sp. nov. are clustering together. However, N. piipensis sp. nov. is genetically closer to N. dolsandoensis from regular habitats than to the vent species N. tagiri. A preliminary examination of the body surface of the new leptostracan species using scanning electronic microscopy revealed a variety of epibiotic bacteria.

Methane seep communities on the Koryak slope in the Bering Sea

Methane seep communities on the Koryak slope in the Bering Sea were discovered in 2018 during the 82nd cruise of the RV Akademik M.A. Lavrentyev using ROV Comanche 18. Methane seeps found between 400 m and 695 m depth are the northernmost chemosynthesis-based habitats (∼61°N) known to date in the Pacific. Macrofauna species composition and community structure of methane seep and background benthic communities were investigated at three depth horizons: 400–402 m, 417–429 m and 647–695 m.A total of 335 macrofaunal species were identified. At the depth 647–695 m the species richness in the methane seep communities was 265 species and 72 species in the background. The deepest seep communities were characterized by the highest species richness, relatively high evenness and strong variations in the composition and structure. At shallower depths the species richness was low: 33–34 species at methane seeps and 66–71 in the background. The methane seep communities at shallow depths showed relatively low evenness and low diversity of community structure. The highest species richness at the greatest depth can be related in part to increased habitat heterogeneity associated with carbonate crusts and vesicomyid clam beds occurring only at deeper methane seeps. The deepest methane seep communities were dominated by the chemosymbiotrophic pliocardiine Calyptogena pacifica; dominant in the background was the ophiuroid Ophiophthalmus normani. At shallower methane seeps only single specimens of C. pacifica were found. The shallower methane seeps were dominated by the background species despite numerous extensive bacterial mats and high potential toxicity of the environment. The seep community at 417–429 m was dominated by the echinoid Brisaster latifrons with population density on the bacterial mat four times higher than in the background. Four chemosymbiotrophic species were recorded at 647–695 m and only one was found at shallower depths. Potentially obligate to reducing habitats polychaetes of the genus Neosabellides and Ophryotrocha occurred in methane seep communities at all depths. Further geochemical, geological and microbiological studies are required to better characterize differences of methane seeps at different depths and reasons of these differences.

Unexpected diversity found within benthic microbial mats at hydrothermal springs in Crater Lake, Oregon.

Crater Lake, Oregon is an oligotrophic freshwater caldera lake fed by thermally and chemically enriched hydrothermal springs. These vents distinguish Crater Lake from other freshwater systems and provide a unique ecosystem for study. This study examines the community structure of benthic microbial mats occurring with Crater Lake hydrothermal springs. Small subunit rRNA gene amplicon sequencing from eight bacterial mats was used to assess community structure. These revealed a relatively homogeneous, yet diverse bacterial community. High alpha diversity and low beta diversity indicate that these communities are likely fueled by homogeneous hydrothermal fluids. An examination of autotrophic taxa abundance indicates the potential importance of iron and sulfur inputs to the primary productivity of these mats. Chemoautotrophic potential within the mats was dominated by iron oxidation from Gallionella and Mariprofundus and by sulfur oxidation from Sulfuricurvum and Thiobacillus with an additional contribution of nitrite oxidation from Nitrospira. Metagenomic analysis showed that cbbM genes were identified as Gallionella and that aclB genes were identified as Nitrospira, further supporting these taxa as autotrophic drivers of the community. The detection of several taxa containing arsC and nirK genes suggests that arsenic detoxification and denitrification processes are likely co-occurring in addition to at least two modes of carbon fixation. These data link the importance of the detected autotrophic metabolisms driven by fluids derived from benthic hydrothermal springs to Crater Lake’s entire lentic ecosystem.

Hot Springs, Tigers, and Bears … Oh My!

The old expression “chance favors the prepared mind” and the word “serendipity” perfectly fit this case. In the summer of 2006, my former major professor, Leon Higley, traveled to Bozeman, Montana, to attend a surprise party to celebrate my tenure at Montana State University. Like any self-respecting person who finds himself in the Bozeman area, he made the 90-minute drive south to Yellowstone National Park. What he observed there by chance would ultimately lead to some amazing discoveries. While shuffling along the boardwalk trails with thousands of other tourists at Mammoth Hot Springs, he saw something surprising. No, surprising doesn’t do it justice; it was amazing. The tiger beetle Cicindelidia haemorrhagica (LeConte) (Coleoptera: Carabidae) was hunting on a hot, wet bacterial mat (Fig. 1). The beetle remained for long periods, not only under the hot sun, but also lingering on the bacterial mat, which was at least 42ºC. This was incredible because unlike what is known for other tiger beetles, it made no attempt to behaviorally cool itself by seeking shade, dipping its body in water for evaporative cooling, or stilting its body to reduce insolation. Leon knew this was not normal because of his experiences studying other tiger beetle species (Brosius and Higley 2013). Other tiger beetles—especially those that are warm-adapted and hunt and forage in open, sparsely vegetated areas—can spend more than 50% of each diurnal period behaviorally cooling themselves or completely avoiding activity during the midday. They simply don’t linger in hot areas.