C-DEBI Newsletter – December 16, 2019

Publications & Press

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Nature Communications
New isotope constraints on the Mg oceanic budget point to cryptic modern dolomite formation – NEW!
Netta Shalev, Tomaso R. R. Bontognali, Charles Geoffrey Wheat*, Derek Vance
*C-DEBI Contribution 516

The oceanic magnesium budget is important to our understanding of Earth’s carbon cycle, because similar processes control both (e.g., weathering, volcanism, and carbonate precipitation). However, dolomite sedimentation and low-temperature hydrothermal circulation remain enigmatic oceanic Mg sinks. In recent years, magnesium isotopes (δ²⁶Mg) have provided new constraints on the Mg cycle, but the lack of data for the low-temperature hydrothermal isotope fractionation has hindered this approach. Here we present new δ²⁶Mg data for low-temperature hydrothermal fluids, demonstrating preferential ²⁶Mg incorporation into the oceanic crust, on average by ε_solid-fluid ≈ 1.6‰. These new data, along with the constant seawater δ²⁶Mg over the past ~20 Myr, require a significant dolomitic sink (estimated to be 1.5–2.9 Tmol yr⁻¹; 40–60% of the oceanic Mg outputs). This estimate argues strongly against the conventional view that dolomite formation has been negligible in the Neogene and points to the existence of significant hidden dolomite formation.

Environmental Microbiology
Energy flux controls tetraether lipid cyclization in Sulfolobus acidocaldarius – NEW!
Alice Zhou, Yuki Weber, Beverly K. Chiu, Felix J. Elling, Alec B. Cobban, Ann Pearson, William D. Leavitt

Microorganisms regulate the composition of their membranes in response to environmental cues. Many Archaea maintain the fluidity and permeability of their membranes by adjusting the number of cyclic moieties within the cores of their glycerol dibiphytanyl glycerol tetraether (GDGT) lipids. Cyclized GDGTs increase membrane packing and stability, which has been shown to help cells survive shifts in temperature and pH. However, the extent of this cyclization also varies with growth phase and electron acceptor or donor limitation. These observations indicate a relationship between energy metabolism and membrane composition. Here we show that the average degree of GDGT cyclization increases with doubling time in continuous cultures of the thermoacidophile Sulfolobus acidocaldarius (DSM 639). This is consistent with the behavior of a mesoneutrophile, Nitrosopumilus maritimus SCM1. Together, these results demonstrate that archaeal GDGT distributions can shift in response to electron donor flux and energy availability, independent of pH or temperature. Paleoenvironmental reconstructions based on GDGTs thus capture the energy available to microbes, which encompasses fluctuations in temperature and pH, as well as electron donor and acceptor availability. The ability of Archaea to adjust membrane composition and packing may be an important strategy that enables survival during episodes of energy stress.
 

Have an upcoming manuscript about the deep subseafloor biosphere and want to increase your press coverage? NSF's Office of Legislative and Public Affairs is looking to coordinate press releases between your home institution and the NSF to coincide with the date of publication. Please contact us as soon as your publication is accepted!

ASM Announces New President-Elect and Leadership – NEW!
A hearty congratulations to C-DEBI Senior Scientist Steve Finkel on his election to President of the American Society for Microbiology!

 

Meetings & Activities

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Data Labs: Using Ocean Observatory Initiative (OOI) Data to Engage Students in Oceanography @ AGU Ocean Sciences 2020 – NEW!
Join us for a National Science Foundation (NSF) sponsored workshop focused on the integration of Ocean Observing Initiative (OOI) data into undergraduate teaching of oceanography themes and concepts. Participants will explore a collection of Data Labs created by oceanography professors who attended the 2019 OOI Data Lab summer workshops. Learn from your peers lessons learned on how to effectively teach with data. Participants will share new teaching resources and brainstorm new ideas for how to integrate OOI data into introductory oceanography and Earth and environmental science courses. Professors who teach introductory (100 and 200 level) oceanography courses are encouraged to attend. Participants will receive a $300 stipend (issued post-workshop) along with complimentary light breakfast and lunch. Attendance is limited to 35 people. We will accept online submissions until January 15, 2020 or capacity is reached, whichever is sooner.

EGU General Assembly 2020: Submit your abstracts to session on scientific drilling
The deadline for abstract submission is January 15, 2020.

Goldschmidt: Hawai'i 2020, June 21-26
Abstract submission deadline: February 14, 2020.

AGU: Nominate Your Peers for 2020 Honors
Nominations are now open for 2020 AGU honors, including the Asahiko Taira International Scientific Ocean Drilling Research Prize. Deadline: March 15, 2020.

GRC: Exploring Fluxes, Forms and Origins of Deep Carbon in Earth and Other Terrestrial Planets, June 28-July 3, 2020, Lewiston, ME, USA
Applications for this meeting must be submitted by May 31, 2020.

Serpentine Days: 5th Workshop, September 21-24, Sestri Levante (Genova, Italy)
Registration will close June 30, 2020.

Ongoing Activities:

• C-DEBI: Rolling call for Community Workshop support
• C-DEBI: Protocols.io Group Page
• C-DEBI: Subseafloor Cultures Database
• C-DEBI: Join us on LinkedIn

Education & Outreach

 

Best, 

 

Matt

 

— 

Matthew Janicak

Data Manager

Center for Dark Energy Biosphere Investigations (C-DEBI)

Exploring life beneath the seafloor and making transformative discoveries that advance science, benefit society, and inspire people of all ages and origins.

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