155 research outputs found
Microbial communities in dark oligotrophic volcanic ice cave ecosystems of Mt. Erebus, Antarctica.
The Earth's crust hosts a subsurface, dark, and oligotrophic biosphere that is poorly understood in terms of the energy supporting its biomass production and impact on food webs at the Earth's surface. Dark oligotrophic volcanic ecosystems (DOVEs) are good environments for investigations of life in the absence of sunlight as they are poor in organics, rich in chemical reactants and well known for chemical exchange with Earth's surface systems. Ice caves near the summit of Mt. Erebus (Antarctica) offer DOVEs in a polar alpine environment that is starved in organics and with oxygenated hydrothermal circulation in highly reducing host rock. We surveyed the microbial communities using PCR, cloning, sequencing and analysis of the small subunit (16S) ribosomal and Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (RubisCO) genes in sediment samples from three different caves, two that are completely dark and one that receives snow-filtered sunlight seasonally. The microbial communities in all three caves are composed primarily of Bacteria and fungi; Archaea were not detected. The bacterial communities from these ice caves display low phylogenetic diversity, but with a remarkable diversity of RubisCO genes including new deeply branching Form I clades, implicating the Calvin-Benson-Bassham (CBB) cycle as a pathway of CO2 fixation. The microbial communities in one of the dark caves, Warren Cave, which has a remarkably low phylogenetic diversity, were analyzed in more detail to gain a possible perspective on the energetic basis of the microbial ecosystem in the cave. Atmospheric carbon (CO2 and CO), including from volcanic emissions, likely supplies carbon and/or some of the energy requirements of chemoautotrophic microbial communities in Warren Cave and probably other Mt. Erebus ice caves. Our work casts a first glimpse at Mt. Erebus ice caves as natural laboratories for exploring carbon, energy and nutrient sources in the subsurface biosphere and the nutritional limits on life
Defining the word āseamountā
Author Posting. Ā© Oceanography Society, 2010. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 23, 1 (2010): 20-21.The term seamount has been
defined many times (e.g., Menard, 1964; Wessel, 2001; Schmidt and
Schmincke, 2000; Pitcher et al., 2007; International Hydrographic
Organization, 2008; Wessel et al., 2010) but there is no āgenerally
acceptedā definition. Instead, most definitions serve the particular
needs of a discipline or a specific paper
Recommended from our members
Seamount Catalong: Seamount Morphology, Maps, and Data Files
Seamount research, more often than not,
is carried out by highly specialized science
teams with narrowly focused science objectives.
As a result, different seamount science
disciplines often do not collaborate or are
not even aware of each other. However, it is
obvious that interdisciplinary collaboration
is the most successful approach to help
understand the integrated chemical, physical,
and biological systems at seamounts.
The Seamount Biogeoscience Network
(SBN) was founded to promote the necessary
cooperation through workshops, publications,
and the development of a database
that allows all seamount sciences to share
data. Among such data, bathymetric maps
are the most fundamental to all disciplines
Vailuluāu Seamount
Author Posting. Ā© Oceanography Society, 2010. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 23, 1 (2010): 164-165.Vailuluāu seamount is an active underwater
volcano that marks the end of
the Samoan hotspot trail
Recommended from our members
Scalable models of data sharing in Earth sciences
Many Earth science disciplines are currently experiencing the emergence of new ways of data
publication and the establishment of an information technology infrastructure for data archiving and
exchange. Building on efforts to standardize data and metadata publication in geochemistry [Staudigel et
al., 2002], here we discuss options for data publication, archiving and exchange. All of these options have
to be structured to meet some minimum requirements of scholarly publication, in particular reliability of
archival, reproducibility and falsifiability. All data publication and archival methods should strive to
produce databases that are fully interoperable and this requires an appropriate data and metadata
interchange protocol. To accomplish the latter we propose a new Metadata Interchange Format (.mif ) that
can be used for more effective sharing of data and metadata across digital libraries, data archives, and
research projects. This is not a proposal for a particular set of metadata parameters but rather of a
methodology that will enable metadata parameter sets to be easily developed and interchanged between
research organizations. Examples are provided for geochemical data as well as map images to illustrate the
flexibility of the approach.Keywords: geosciences, metadata, publication, interdisciplinary, data management, data sharingKeywords: geosciences, metadata, publication, interdisciplinary, data management, data sharin
Seamount sciences : quo vadis?
Author Posting. Ā© Oceanography Society, 2010. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 23, 1 (2010): 212-213.Seamounts are fascinating natural
ocean laboratories that inform us about
fundamental planetary and ocean
processes, ocean ecology and fisheries,
and hazards and metal resources. The
more than 100,000 large seamounts
are a defining structure of global
ocean topography and biogeography,
and hundreds of thousands of smaller
ones are distributed throughout every
ocean on Earth
Recommended from our members
High-resolution ā“ā°Ar/Ā³ā¹Ar dating of the oldest oceanic basement basalts in the western Pacific basin
We report new ā“ā°Ar/Ā³ā¹Ar ages for the oldest Pacific oceanic floor at Ocean Drilling Program Site 801C in the Pigafetta basin and Site 1149D close to the Izu-Bonin subduction zone in the Nadezhda basin. These ages were determined by applying high-resolution incremental heating experiments (including 15ā30 heating steps) to better resolve the primary argon signal from interfering alteration signatures in these low-potassium ocean crust basalts. Combined with previous results from Pringle [1992] for Site 801B and 801C, we arrive at a multistage history for the formation of the Pigafetta ocean crust. The oldest part of the Pacific plate was formed at the spreading ridges at 167.4 Ā± 1.4/3.4 Ma (n = 2, 2Ļ internal/absolute error), offering an important calibration point on the Geological Reversal Timescale (GRTS) since it represents the old end of the Mesozoic magnetic anomalies. This mid-ocean ridge basalt sequence, however, is overlain by more tholeiites and alkali basalts that were formed 7.3 Ā± 1.5 Myr later around 160.1 Ā± 0.6 Ma (n = 7, 2Ļ internal error). The older age group is confirmed independently by radiolarian ages ranging from Late Bajocian to Middle Bathonian (167ā173 Ma [Bartolini and Larson, 2001]) and by profound differences in the structural characteristics of this basement section [Pockalny and Larson, 2003]. Thin layers comprising hydrothermal deposits separate these sequences, which in addition to the difference in isotopic age show distinct major and trace element compositions. This indicates that key volcanic and hydrothermal activity took place 400ā600 km away from the spreading ridges, on the basis of a Jurassic ~66 km/Myr half spreading rate in the Pacific. It remains unclear if these processes were active continuously after the initial formation of the Pacific oceanic crust, but all our observations seem to point to an episodic history. Site 1149D gives another important calibration point on the GRTS of 127.0 Ā± 1.5/3.6 Ma (n = 1, 2Ļ internal/absolute error) for anomaly M12 that is slightly younger when compared to current timescale compilations (134.2 Ā± 2.1 Ma [Gradstein et al., 1995]). This might suggest that the dated basalt from Site 1149D does not represent the age of the ocean crust formed at its ridge axis; it may also be part of the Early Cretaceous intraplate events that have produced dolerite sills in the Pacific crust at Sites 800 and 802 around 114ā126 Ma
- ā¦