Tag Archive for Ellen Thomas

Thomas Awarded NSF Grant for Paleoceanographic Research

by Olivia Drake • September 14, 2017

Ellen Thomas

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 • January 18, 2017

Ellen Thomas holds two enlarged samples of microfossils in her lab at Wesleyan. Thomas was recently awarded a medal for her research efforts.

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 Brady Medal is cast in bronze.

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.

Thomas’s Research on Marine Biota during a Period of Rapid Global Warming Published

by Olivia Drake • January 18, 2017

Ellen Thomas

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.

Thomas Co-Authors 5 Papers in Academic Journals

by Andrew Logan ’18 • April 29, 2016

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.

Thomas’s Microfossil, Climate Change Research Published in 2 Journals

by Olivia Drake • October 1, 2015

Ellen Thomas

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.

NSF Supports Thomas’s Study on the Impact of Rapid Carbon Emissions on Global Climate

by Olivia Drake • August 20, 2015

Ellen Thomas

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.”

Thomas Authors 4 Papers on Environmental Change

by Olivia Drake • May 13, 2015

Ellen Thomas

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 • February 10, 2015

Ellen Thomas, research professor of earth and environmental science, holds two samples of microfossils that were printed on a 3-D printer at the University of Iowa. The printed fossil models are about 8,000 times bigger than the actual limestone fossils. These planktonic forms lived closer to the surface of the water. At left is Hantkenina alabamensis, which lived when the world was warm, and went extinct at the time of formation of the Antarctic ice cap about 33.7 million years ago. At right is Globigerinella siphonifera. It lives in the subtropics today, in open ocean. “When it’s alive, it has spines and protoplasm inside and along the spines,” she said. (Photos by Olivia Drake)

This slide contains more than 300 microfossil specimens from an ocean drilling site in the eastern Indian Ocean. These are estimated to be 55.8 millions years old, and lived during a period of extreme global warming with a duration of 170,000 years. At the beginning of this warm period, there was a mass extinction of deep-sea benthic foraminifera, which may have been caused by the rapid global warming and ocean acidification.

#THISISWHY

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,

by Olivia Drake • October 27, 2014

Joop Varekamp

Ellen Thomas

Wesleyan faculty Joop Varekamp and Ellen Thomas are among the authors of a paper on rates of sea-level rise along the eastern U.S. seaboard titled “Late Holocene sea level variability and Atlantic Meridional Overturning Circulation,” published in the journal Paleoceanography, Volume 29, Issue 8, pages 765–777 in August 2014. Varekamp is the Harold T. Stearns Professor of Earth Science, professor of earth and environmental sciences and professor of environmental studies. Thomas is research professor of earth and environmental sciences at Wesleyan, and also a senior research scientist in geology and geophysics at Yale University.

Ellen Thomas discovered that microfossils, such as this foraminifera fossil, reveal that warm oceans had less oxygen.

Pre-20th century sea level variability remains poorly understood due to limits of tide gauge records, low temporal resolution of tidal marsh records, and regional anomalies caused by dynamic ocean processes, notably multidecadal changes in Atlantic Meridional Overturning Circulation (AMOC). In the study, Varekamp and Thomas examined sea level and circulation variability along the eastern United States over the last 2,000 years, using a sea level curve constructed from proxy sea surface temperature records from Chesapeake Bay, and 20th century sea level-sea surface temperature relations derived from tide gauges and instrumental sea surface temperatures.

Thomas also is a co-author of a paper titled ‘I/Ca evidence for upper ocean deoxygenation during the PETM‘ published in the Paleoceanography, October 2014.

In this paper, Thomas suggests that the Paleocene-Eocene Thermal Maximum (PETM), a potential analog for present and future global warming, may help in such forecasting future deoxygenation and its effects on oceanic biota. Forecasting the geographical and bathymetric extent,

by Olivia Drake • June 4, 2014

The deep-sea benthic foram Aragonia velascoensis went extinct about 56 million years ago as the oceans rapidly acidified. (Photo by Ellen Thomas)

Ellen Thomas, research professor of earth and environmental sciences, is the author of a paper titled “Rapid and sustained surface ocean acidification during the Paleocene-Eocene Thermal Maximum,” published in Paleoceanography, May 2014.

In this paper Thomas and her colleagues document that ocean acidification of the surface ocean not only occurred during past times of global warming and high CO2 levels, but also by how much — about 0.3 pH units. The group studied planktic foraminifers from a drill site in the North Pacific.

Thomas’ study has been highlighted in a press release from Columbia University and also on Phys.org.

Thomas’s Paper Published in Nature Geoscience

by Olivia Drake • April 18, 2014

Ellen Thomas

Ellen Thomas, research professor of earth and environmental sciences, is the co-author of a paper titled “Carbon Sequestration during the Palaeocene–Eocene Thermal Maximum by an Efficient Biological Pump,” published in the April 2014 edition of Nature Geoscience.

In the paper, Thomas explains how ocean-dwelling bacteria may have vacuumed up carbon and halted a period of extreme warmth some 56 million years ago. The finding suggests how Earth might once have rapidly reversed a runaway greenhouse effect.

Its effect on global oceanic productivity is controversial. In the paper, Thomas and her colleagues present records of marine barite accumulation rates that show distinct peaks during this time interval, suggesting a general increase in export productivity. The authors propose that changes in marine ecosystems, resulting from high atmospheric partial pressure of CO2 and ocean acidification, led to enhanced carbon export from the photic zone to depth, thereby increasing the efficiency of the biological pump. Higher seawater temperatures at that time increased bacterial activity and organic matter regeneration.

Gabriel Popkin ’03 wrote about Thomas’s research in a April 2014 article titled “Ocean Bacteria May Have Shut Off Ancient Global Warming” in Science News.

Varekamp, Thomas Author Chapters on Long Island Sound Reference Volume

by Olivia Drake • December 6, 2013

Joop Varekamp and Ellen Thomas co-authored chapters in this new book on the Long Island Sound.

Joop Varekamp and Ellen Thomas are the authors of three chapters included in a reference volume for Long Island Sound. The book, Long Island Sound: Prospects for the Urban Sea, is published by Springer in 2013. Varekamp is the Harold T. Stearns Professor of Earth Science, professor of earth and environmental sciences, professor of environmental studies. Thomas is research professor of earth and environmental sciences.

Varekamp co-authored a chapter titled “Metals, Organic Compounds and Nutrients in Long Island Sound: Sources, Magnitudes, Trends and Impacts,” and another chapter titled “The Physical Oceanography of Long Island Sound.” Thomas co-authored a chapter titled “Biology and Ecology of the Long Island Sound.”

Varekamp and Thomas worked on the book for about six years. The last comprehensive Long Island Sound book was published in the early 1970s.

“We hope that it will be the reference volume for Long Island Sound for some decades to come,” Varekamp said.