Tag Archive for Ellen Thomas
by Olivia Drake •
Throughout time, rising oceanic and atmospheric oxygen levels have been crucial to the habitability of environments at the surface of the Earth.
“The Earth had no free oxygen gas in its atmosphere early on,” said Ellen Thomas, the Harold T. Stearns Professor of Integrative Sciences. “The oxygen has been provided over time by photosynthesis of algae followed by storage of organic matter in rocks.”
Thomas, who also is research professor of earth and environmental sciences, examines the timing of oxygen formation in Earth’s atmosphere and oceans over geological time in a study published in the May 2018 issue of Science.
The paper, titled “Late Inception of a Resiliently Oxygenated Upper Ocean,” stems from a multiyear, multinational, multiauthor research effort that explores the time trend and causes of increased oxygenation during the current Phanerozoic Eon, which began more than 542 million years ago. Thomas and her colleagues used iodine geochemistry to determine that the upper section of the ocean became rich in oxygen much later than previously predicted, linked to evolution of oceanic phytoplankton.
The research was supported by a National Science Foundation grant at Wesleyan and coauthored by scientists at Syracuse University and the University of California, Riverside.
by Olivia Drake •
For the past 60 years, a massive megafauna mammal thrived in crates buried in Wesleyan’s tunnels and attics. This month, the creature, known as a Glyptodon, has emerged in Exley Science Center for public viewing.
Although the armored armadillo-like animal became extinct more than 10,000 years ago, Wesleyan acquired a fossil cast in the 1870s, where it became a showpiece at the university’s Orange Judd Museum of Natural Sciences.
In 1957, the museum closed and thousands of artifacts, including the Glyptodon, were haphazardly stuffed into crates and boxes and hauled to multiple locations throughout campus.
“After the museum closed, everything was scattered all over, anywhere there was a place to put it,” said Ellen Thomas, the Harold T. Stearns Professor of Integrative Sciences and research professor of earth and environmental sciences. “Just recently, we’ve started to uncover all these lost treasures and we’re working to get them organized and cataloged. The Glyptodon is one of our major finds.”
Ellen Thomas, University Professor in the College of Integrative Sciences and research professor of earth and environmental sciences, is a co-author of a paper titled “Very Large Release of Mostly Volcanic Carbon During the Paleocene-Eocene Thermal Maximum,” published in the weekly science journal Nature on Aug. 31.
The study focused on Palaeocene–Eocene Thermal Maximum, a surface warming event associated with ecological disruption that occurred about 56 million years ago, releasing a large amount of carbon. The researchers combined boron and carbon isotope data in an Earth system model and found that the source of carbon was much larger than previously thought.
Most of the carbon, Thomas and her colleagues discovered, was probably released by volcanism during the opening of the North Atlantic Ocean when Greenland separated from Europe.
by Olivia Drake •
The availability of sufficient dissolved oxygen in seawater is critical for marine life, and places where oxygen falls below a critical concentration — or “dead zones” — are often associated with mass die-offs of fish, shrimp and other creatures.
With future global warming, the oceans are on course to see progressively less dissolved oxygen available. Scientists currently use often not well-tested computer models to predict the expansion of dead zones, but a team of researchers from Wesleyan, University California Riverside and Syracuse University are hoping to use oceanic sediment samples to better predict where die-offs may occur next.
Their study, titled “Refining Foraminifera I/Ca as a Paleoceanographic Proxy for the Glacial Atlantic Ocean” was funded by a National Science Foundation grant on Aug. 16. The award, worth $423,739, will be awarded to the three universities over three years.
Ellen Thomas, University Professor in the College of Integrative Sciences, research professor in earth and environmental sciences, will use her share of the funds to support undergraduate student summer research fellowships.
by Olivia Drake •
For her outstanding efforts in pioneering studies in micropalaeontology and natural history, The Micropalaeontological Society (TMS) awarded Wesleyan’s Ellen Thomas with the 2016 Brady Medal.
The Brady Medal is TMS’s most prestigious honor and is awarded to scientists who have had a major influence on micropalaeontology by means of a substantial body of research.
Thomas was honored for “communicating to an extremely broad audience fascinating, impactful and often thought-provoking research” and “academic encouragement of students and peers over the years with [her] generosity of time in a very busy and successful career,” noted TMS President F. John Gregory.
Thomas, research professor of earth and environmental sciences and the University Professor in the College of Integrative Sciences, investigates the impact of changes in environment and climate on living organisms on various time scales, with the common focal point of benthic foraminifera (eukaryotic unicellular organisms). She studies their assemblages, as well as trace element and isotope composition of their shells. Foraminifera live in salt or at least brackish water, so she concentrates her research on the oceans, from the deep sea up into tidal salt marshes.
The Micropalaeontological Society exists “to advance the education of the public in the study of Micropalaeontology” and is operated “exclusively for scientific and educational purposes and not for profit”. It was initiated as The British Micropalaeontological Group in 1970.
The Brady Medal is named in honor of George Stewardson Brady (1832-1921) and Henry Bowman Brady (1835-1891) in recognition of their outstanding pioneering studies in micropalaeontology.
Read more about Ellen Thomas in these past News @ Wesleyan articles.
by Olivia Drake •
Ellen Thomas, research professor of earth and environmental sciences, is the co-author of “Pteropoda (Mollusca, Gastropoda, Thecosomata) from the Paleocene-Eocene Thermal Maximum of the United States Atlantic Coastal Plain,” published in Palaeontologia Electronica, Article 19 (3) in October 2016.
The Paleocene Epoch lasted 65 to 54.8 million years ago and the Eocene Epoch lasted from 56 to 33.9 million years ago, and was a period of rapid global warming.
The response of many organisms to the Paleocene-Eocene Thermal Maximum (PETM) has been documented, but marine mollusks are not known from any deposits of that age. For the first time, Thomas and her co-authors describe a PETM assemblage of pteropods (planktic mollusks), consisting of six species representing three genera (Altaspiratella, Heliconoides and Limacina). Four species could be identified to species level, and one of these, Limacina novacaesarea sp. nov., is described as new. Only the genus Heliconoides was previously known from pre-Eocene sediments, with a single Campanian specimen and one latest Paleocene species.
by Andrew Logan ’18 •
Ellen Thomas, professor of earth and environmental sciences and University Professor in the College of Integrative Sciences, recently co-authored five papers in academic journals.
Her first paper, “Jianshuiite in Oceanic Manganese Nodules” co-authored with Jeffery Post and Peter Heaney, appeared within American Mineralogist. Deviating from her usual research, Thomas focused on mineralogy and, in particular, the crystal structure of a rare mineral found in sediments during an ancient counterpart of future global warming.
Thomas co-authored “Variability in Climate and Productivity during the Paleocene-Eocene Thermal Maximum in the Western Tethys,” with Flavia Boscolo-Galazzo and Luca Giusberti, both of the University of Padova. This paper, more in line with her usual research, examines unicellular organisms of the deep sea floor that suffered extinction due to a prior period of global warming. It appeared in Climate of the Past.
Working once again with Boscolo-Galazzo and Giusberti and several other scholars, Thomas co-authored, “The Planktic Foraminifer Planorotalites in the Tethyan Middle Eocene” in the Journal of Micropaleontology. This paper describes the researchers’ use of stable isotope analysis to distinguish between floating planktonic matter from bottom-dwelling foraminifera. Through this analysis, they discuss environmental changes during a relatively period of global warming that took place between approximately 9 and 40 million years ago.
“Late Paleocene-Middle Eocene Benthic Foraminifera on a Pacific Seamount (Allison Guyot, ODP Site 865):Greenhouse Climate and Superimposed Hyperthermal Events,” appeared in Paleoceanography. It discusses deep-sea faunas during the same period in the article from the paragraph above. The two other authors of the paper were mentored by Thomas and briefly visited Wesleyan while under her supervision.
The final paper, “Oxygen depletion recorded in upper waters of the glacial Southern Ocean,” appeared in Nature Communications. This paper documents Thomas’s collaborative research with several scholars and PhD students on Antarctic environments during the last few ice ages. In particular, their work focuses on benthic foraminifera, and chemical analysis of their shells.
by Olivia Drake •
Ellen Thomas, the University Professor in the College of Integrative Sciences, research professor of earth and environmental science, is the co-author of two recently published papers. They include:
“Microfossil evidence for trophic changes during the Eocene–Oligocene transition in the South Atlantic (ODP Site 1263, Walvis Ridge),” published in Climate of the Past, Volume 11, pages 1249–1270 in September 2015 and “Changes in benthic ecosystems and ocean circulation in the Southeast Atlantic across Eocene Thermal Maximum 2,” published in the journal Paleoceanography, Volume 30, pages 1059-1077 in August 2015.
“Microfossil evidence” describes changes in organisms living in the oceans during a major change in the earth’s climate, a period of global cooling about 33.7 million years ago, when the Antarctic ice sheet first became established. The seven co-authors are all women, including former Wesleyan graduate student Raquel Fenero.
The researchers examined the biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene–Oligocene transition at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, southeast Atlantic Ocean). During this time interval, global climate, which had been warm under high levels of atmospheric CO2 during the Eocene, transitioned into the cooler climate of the Oligocene.
In the Paleoceanography article, Thomas and her co-authors describe changes in benthic ecosystems in the oceans during a short period of global warming about 53.7 million years ago, and the effects of loss of oxygen and ocean acidification. The researchers include climate and geochemical modeling to indicate that changes in ocean circulation due to warming triggered more profound effects on living organisms at some depths than at other depths, and that the response of life forms to global warming (including feedback effects) thus may be complex. This article is the result of research done during Thomas’s stay as Leverhulme Visiting Professor at the University of Bristol in the United Kingdom, where she co-supervised graduate student Suzy Jennions.
“Our combined ecological and modeling analysis illustrates the potential role of ocean circulation changes in amplifying local environmental changes and driving temporary, but drastic, loss of benthic biodiversity and abundance,” Thomas said.
by Olivia Drake •
Ellen Thomas, the University Professor in the College of Integrative Sciences, received a grant in August from the National Science Foundation to support her research on “Evaluating Deep-Sea Ventilation and the Global Carbon Cycle during early Paleocene Hyperthemals.”
The $105,000 award is part of a combined $619,000 grant shared with Yale University and the University of Texas at Arlington.
Rapid, short-term global warming events in the Early Paleogene (~65-45 million years ago) were caused by massive greenhouse gas release into the ocean-atmosphere system. These warming events, called hyperthermals, had far-reaching effects on the evolution of life on Earth, ecosystems and the carbon cycle. The most extreme of these events was the Paleocene-Eocene Thermal Maximum (~55.5 million years ago). Hyperthermals resemble what could happen during anthropogenic climate change, and provide analogs for the effects of greenhouse gas emissions and their long-term effects on life on Earth.
By testing earth system interactions during the Paleogene hyperthermals, this interdisciplinary project will provide new insight into the impact of rapid carbon emissions on global climate—carbon cycle feedbacks and extremes in climate.
In this three-year collaborative project, new biotic, isotopic and trace element proxies will be integrated with existing data into a state-of-the-art, high-resolution, comprehensive earth system model to test the hypothesis that deep-sea ventilation released a massive amount of carbon from the refractory dissolved organic matter (DOM) pool during hyperthermal events, increasing atmospheric CO2 levels, thus amplifying climate change through carbon-cycle feedback.
“We will investigate the environmental response (e.g., ocean acidification and deoxygenation) and its impact on pelagic ecosystem structure for three Paleogene hyperthermals with different magnitude and duration,” Thomas explained. “The project will focus on a key mechanism involving remineralization of organic matter and oxidation of the DOM pool in the ocean, with potentially major implications for future climate evolution.”
by Olivia Drake •
Ellen Thomas, research professor of earth and environmental sciences, is the co-author of four recenty-published papers. They include:
“Deep-sea benthic foraminiferal turnover during the early middle Eocene transition at Walvis Ridge (SE Atlantic),” published in Palaeogeography, Palaeoclimatology, Palaeoecology, Issue 417: pages 126-136, January 2015. The paper’s co-author, Silvia Ortiz, was a PhD student at the University of Zaragoza, and spent several months at Wesleyan working with Thomas.
by Olivia Drake •
Research Professor Ellen Thomas grasps a glass-enclosed sample of hundreds of microfossils, each a white fleck of limestone barely visible to the human eye.
“The first time students look at these they say, ‘they all look the same to me,’ but in reality, they are all have very different shapes,” Thomas says. “Even under a microscope, it can be difficult for a new eye to see the differences, but each species has its own shape; some have a much more open, light structure because they lived floating in the oceans close to the surface. Others have denser shells and lived on the bottom of the ocean, or within the mud. And each one can tell us, in its chemical make up, what the environmental conditions were like at the time that they lived and built their shells.”
By studying and analyzing microfossils, Thomas and fellow scientists are able to explore aspects of climate change on a variety of timescales,