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New Paper Update: Vital effects in bivalves, rebranded

A new paper out of the SCIPP Lab investigates isotopic differences between the inner and outer shell layers of bivalve shells. In this paper, PhD student Allison Curley and coauthors show that differences between inner shell layer (ISL) and outer shell layer (OSL) carbonate is conserved within a species but differs between species. We suggest this ISL-OSL difference is a proxy for physiology of the organism – how it grows its shell.

These particular samples represent 6 extinct bivalve species from Seymour Island, Antarctica. Some species show one direction of isotopic offset (d18O and d13C higher in ISL and D47 lower in ISL than OSL), others show the opposite direction offset, and a third group show no difference between the ISL and OSL. Tantalizingly, of the 6 species studied, the two that survive the KPg mass extinction show the largest magnitude offsets, potentially indicating an ability to regulate their internal body chemistry, even in the face of adverse external conditions.

This paper defines a framework for how ISL-OSL differences could be interpreted in other species and opens the door to a wide range of new research directions. Very exciting!

LINK TO PAPER: https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12940

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Clumped isotopes in the news

Prof Petersen was quoted in a science journalism piece in Ars Tecnica covering a recent high profile paper involving clumped isotopes by Meckler and coauthors published in Science Magazine. In that study, Meckler et al applied the clumped isotope paleothermometer to benthic forams from a sediment core in the Atlantic, taking the first steps towards recreating the iconic “Zachos curve” using this improved paleothermometer.

The Zachos curve has been used by many to describe global trends in climate over the Cenozoic (last ~66 million years). However, this curve is based on the d18O paleothermometer, which combines the influences of changing bottom water temperature (a proxy for global temperature) and changing global ice volume. If ice gets trapped on land in ice sheets and glaciers, the remaining seawater gets isotopically enriched, changing d18O values in benthic forams even with no temperature change. From just d18O measurements, it is impossible to separate the contributions of changing temperature and ice volume.

Meckler et al found bottom water temperatures during peak greenhouse periods were much warmer than previously determined. This is a very exciting result and shows the power and promise of using this improved paleothermometry technique for paleoceanography, especially during periods of changing or unknown global ice volume.

We hope that this work will continue and more similar records will be produced for sediment cores around the world, building a picture of global bottom water temperatures through the Cenozoic, unencumbered by uncertainties in ice volume.

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MGU Conference 2022

MGU (Michigan Geophysical Union) is a 1-day conference completely run by UM students, bringing together students studying earth sciences in the Earth and Environmental Science, Chemistry, and Climate and Space Sciences and Engineering departments across campus. This has historically just been a poster session, but this year a few live talks were held as well.

The SCIPP Lab had a very strong representation at MGU 2022! ALL members of the SCIPP Lab presented (4 grad, 4 undergrad posters) and Sierra volunteered as a judge. Two of our group members (Alex and Allison) were also on the organizing committee! Everyone did an awesome job creating their posters and presenting their results. Two of our undergrads were awarded “best undergrad presentation” awards! Congratulations Cecilie and Samantha!

1st Yr PhD student Alex Quizon presents modern gastropod clumped isotope calibration data to fellow graduate student. Of all the mollusks that have been calibrated and studied for clumped isotopes, marine gastropods have been largely left out. Preliminary work shows some species may have vital effects, but others do not. Identifying good target species can open up more fossil applications. Nice work Alex!
Junior UG Samantha Davies presents her work reconstructing paleo-ocean temperatures at a new KPg boundary section in Mississippi to Professor Jenan Kharbush. She must have impressed Professor Kharbush, because she was chosen as one of the “best undergrad posters”!! We are thrilled that Samantha will be continuing this research at more Gulf Coastal Plain sites as part of her senior thesis research in the SCIPP lab next year.
Freshman UG Manmeet Singh presents his work reconstructing paleo-ocean temperatures in the Maastrichtian Gulf Coastal Plain to Iso-Paleo-Lab grad student Nick Ellis (Passey Group). Amazing job Manmeet!
4th year PhD student Jade Zhang presents her work to lab neighbor Cameron Trip (Cole group). Jade is trying to figure out the best sampling and data processing strategy to extract temperature seasonality using D47. She is testing modern bivalves from the Atlantic/Caribbean where true seasonality is known. Then she hopes to apply these methods to fossils from Bermuda from the Last Interglacial to determine past seasonality.
Freshman Cecilie Phillips presents her work to an Earth graduate student. Cecilie is working with PhD student Alex Quizon to reconstruct past ocean temperatures and seasonalities up and down the US East Coast during the Last Interglacial. Cecilie analyzed fossil clams of the genus Mercenaria at subannual resolution and found growth shut offs at colder temperatures in the high latitude sites. We are excited that Cecilie will be staying on to work in the SCIPP Lab next year to continue this project!
Junior Sabrina Lanker explains her poster to SCIPP Lab grad student Lucas Gomes. Sabrina has been working with PhD student Jade Zhang to look at seasonality in fossil bivalves from Bermuda dating to the Last Interglacial. Nice work Sabrina!
1st YR PhD student Lucas Gomes presents his work on climate in the early Pleistocene of Florida. Lucas is using high resolution (subannual) clumped isotope sampling to reconstruct mean annual conditions, and seasonality of temperature and d18Owater from a Plio-Pleistocene section in central Florida. This preliminary data will be leading to new field work in early May to collect more samples from this site. Can’t wait to continue and grow this project!
3rd Yr PhD student Allison Curley explains her work on isotopic vital effects in bivalves to Professor Jena Johnson. Allison is studying mechanisms that produce different isotopic signatures in bivalve shells and how they can tell us about physiology, potentially in extinct taxa! Can’t wait to see this work published (soon!). Nice job Allison.
SCIPP Lab represents! Left to right: Professor Sierra Petersen, Manmeet Singh (fr), Samantha Davies (soph/jr), Allison Curley (3rd yr PhD), Cecilie Philips (fr), Lucas Gomes (1st yr PhD), Sabrina Lanker (jr), Jade Zhang (4th yr PhD). Not pictured: Alex Quizon (1st yr PhD). So proud of the awesome SCIPP Lab representation!! You guys did great!
And a silly one too 🙂

Photo credit for all photos (except the selfie) goes to MGU Photographer and Earth PhD student, Mike Machesky.

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SCIPP Lab welcomes two new members!

We are very excited to welcome our two newest members, Lucas Gomes and Alex Quizon, both PhD students. Lucas will be working on reconstructing paleoceangraphic conditions in the Pliocene of Florida looking at extremely fossil-dense beds of the Tamiami Fm./Pinecrest beds and Caloosahatchee Formation. Alex will be working on fossil seashells from South Carolina dating to the Last Interglacial and calibrating the clumped isotope paleothermometer in modern marine gastropods. Welcome welcome!

We are also sad to (sort of) say goodbye to our postdoc Matt Jones, who has left us for a fancy postdoc fellowship at the Smithsonian Institute in Washington DC (congrats Matt!). We will still be collaborating closely with Matt in our efforts to reconstruct Cretaceous paleotemperatures, especially in the Western Interior Seaway. He plans to leverage the extensive Cretaceous fossil collections of the Smithsonian and send us samples to analyze for clumped isotopes.

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Heidi submits her thesis and manuscript!

Despite setbacks due to COVID, our very own Heidi O’Hora submitted her masters thesis this week to graduate end-of-summer, and then turned around and submitted her manuscript to a top-tier journal for peer review and (hopefully) eventual publication in the scientific literature. Congratulations Heidi, you did it! We are so proud of the progress you’ve made over the past 2 years, especially considering it was such an unusual time.

Heidi’s thesis project involved reconstructing Late Cretaceous ocean temperatures in the modern-day region of Maastricht, the Netherlands. Her samples come from the type section of the Maastrichtian (ENCI quarry) among other locations. She found that temperatures in that area were much warmer than they are today (as expected for the greenhouse world of the Cretaceous) and that interactions between different water masses had a strong control on local ocean temperature and salinity.

Stay tuned for publication announcement later on!

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Sierra awarded the Sloan Research Fellowship

SCIPP Lab is excited to announce that Sierra has been selected as a 2021 Sloan Research Fellowship.

Paraphrasing from the Sloan website…

The Sloan Research Fellowship seeks to stimulate fundamental research by early-career scientists and scholars of outstanding promise. These two-year, $75,000 fellowships are awarded yearly to 128 researchers in recognition of distinguished performance and a unique potential to make substantial contributions to their field. Their achievements and potential place them among the next generation of scientific leaders in the U.S. and Canada. 

Sierra plans to use the funds to push forward our paleo-seasonality projects in the Pliocene and elsewhere.

Department Announcement

UM Record Article

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New Paper Update: Community-Wide Clumped Calibration Efforts

Sierra wrapped up a community-wide effort to reprocess and update clumped isotope calibration data from 11 different laboratories, including over 1200 individual replicates, to bring it into the same framework. This involved updating the fundamental parameters R13_VPDB, R17_VSMOW, R18_VSMOW, and λ used to calculate raw D47, using a consistent and updated set of theoretical equilibrium values (D47_TE) to tie things into the absolute reference frame, and applying a single set of acid fractionation factors (D*90-25) across all studies. We found that agreement is quite good between labs, once all the data processing is done uniformly and the “two-slope” or “multi-slope” problem that plagued the clumped community in the early days has all but disappeared in more recent studies.

Link to paper here

 

As part of this effort, we also developed a data template and began a relationship with the EarthChem database to house future clumped isotope datasets in a long-term storage location. For more information on that, see this page.

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Job Posting: Lab Manager for SCIPP Lab – FILLED

The SCIPP Lab is looking to hire a full-time lab manager to oversee daily operations, train students, and run samples. Our group works in a 3-PI shared lab space that was fully renovated in 2018-2019.

 

Day to day responsibilities include:

  • Oversee daily operations for a lab that operates two (2) mass spectrometers, including sample preparation and analysis, data quality control, instrument troubleshooting and repair, and compliance with safety standards.
  • Train and assist graduate and undergraduate students on the mass spectrometers including demonstrating various laboratory techniques and best practices for the instruments.
  • Prepare standard materials, maintaining supplies, and organize shared usage of equipment by lab members.

 

Required qualifications: Bachelor’s degree in a natural science discipline such as earth science, chemistry, or environmental sciences or engineering with secondary educational knowledge in geoscience as a plus. The candidate should have experience and expertise in stable isotopic analysis of carbonate materials, diagnosing and repairing lab equipment, laboratory management, and standard lab safety protocols. The ideal candidate is organized, have a strong attention to detail, with the ability to work well with others in a shared lab space environment.

Desired Qualifications: Master’s degree and/or previous working experience with Nu Perspective + NuCarb and Thermo MAT 253 instruments and/or the clumped isotope technique.

The salary range for this position is $37,600 – $47,000. Wage will be determined based on candidate qualifications.

 

TO APPLY:

Please contact Prof. Petersen by email at sierravp@umich.edu. Please provide a CV and a cover letter describing relevant prior experience and/or particular reason for interest in the position (if appropriate). We will begin reviewing applications August 1, 2019, continuing until the position is filled.

The University of Michigan is an equal opportunity/affirmative action employer.

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Our New Nu Instrument arrives in Michigan!

The SCIPP Lab has acquired a Nu Perspective + Nucarb to perform automated clumped isotope analyses (to the great happiness of everyone who has worked hours doing manual sample prep on our vacuum line). The crates arrived in Ann Arbor last week, and made it to our building today.

We had an exciting (and sometimes stressful) time welcoming our “new baby”.

 

At times, feet were up in the air…

(not pictured, these same feet teetering over the edge of the truck bed 4 feet off the ground, when “mama” Sierra almost had a heart attack)

…but “Midwife” Craig, our building manager, had steady hands, and with the help of many others…

 

…our baby girl landed safely in her new home! Waiting to be unpacked when the Nu Engineer arrives in a few weeks.

Weighing a few tons in total, mom and baby are both doing well now that all feet are safely on the ground. We still haven’t decided on a name…

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SCIPP Lab welcomes 4 new group members

The SCIPP Lab/Petersen Group is very excited to welcome four new members for the coming year. Julia Kelson will arrive as a postdoc under the NSF Postdoctoral Fellowship to study paleoclimate and paleohydrology using clumped and triple oxygen isotopes, in conjunction with the IsoPaleo Lab. Two incoming Masters students, Allison Curley and Heidi O’Hora, will be working on Cretaceous paleoclimate projects. Finally, undergraduate Steve Wedel will join our ranks to work on reconstructing climate during the Last Interglacial in Turks and Caicos.