Marilyn L. Fogel

Marilyn L. Fogel (September 19, 1952 – May 11, 2022) was an American geo-ecologist and Professor of Geo-ecology at UC Riverside in Riverside, California. She is known for her research using stable isotope mass spectrometry to study a variety of subjects including ancient climates, biogeochemical cycles, animal behavior, ecology, and astrobiology. Fogel served in many leadership roles, including Program Director at the National Science Foundation in geobiology and low-temperature geochemistry.

She was the second female staff scientist at the Carnegie Institution for Science's Geophysical Laboratory and the first female recipient of the Alfred Treibs Medal from the Geochemical Society for her achievements in the field of organic geochemistry.

Early life Fogel was born on September 19, 1952, in Moorestown, New Jersey.

In 1970 she enrolled at Pennsylvania State University, where she majored in biology, graduating in 1973 with a BS in biology with honors. She graduated in 1977 with a PhD in Botany and Marine Sciences, There, she taught courses on the fundamentals of ecology, biogeochemistry, stable isotope ecology, field ecology, and the anthropocene.

In 2016, she relocated to UC Riverside in Riverside, California, where she assumed several leadership roles: inaugural holder of the Wilbur Mayhew Endowed Chair in Geo-Ecology (2017), first director of the new EDGE Institute (Environmental Dynamics & Geo-Ecology), and professor of Geo-ecology in the Earth and Environmental Sciences Department. Her research there focused on geo-ecology, astrobiology, paleontology, and anthropology. She also supervised two PhD students and served on the committees of other graduate students.

Research

Paleo-ecology and climate change Fogel used isotope ratios in ancient sediments and fossils to trace climate, diet, and species presence over time.

In one study, she and collaborators used eggshell fragments from Genyornis newtoni (a large, extinct flightless bird) in Australia that ranged in age from 100,000 to 50,000 years to show that the bird's extinction 50,000 years ago was likely due to human impact rather than climate changes. 40,000 years ago, Australia went through a dry period, as recorded in Emu (Dromaius novaehollandiae) egg shells, but the extinction of Genyornis 50,000 years ago rather than 40,000 suggests that their extinction was likely unrelated to the drying. Using stable carbon isotopes, her group determined that Genyornis consumed nearly exclusively C3 plants, and that their cranial morphology indicated a browser reliant upon shrubland. Because it seems that the Genyornis diet is fairly restrictive, it is likely that the arrival of humans around 55,000 years ago and their burning of land may have caused some megafauna extinction as it changed the vegetation. Because the Paleozoic Era was one of drastic organismal shift, and the origin of vascular plants, it was previously unclear if Prototaxites were vascular plants or fungal species. However, a team of researchers, including Fogel, found the 𝛿13C of the species to be as much as 13‰ different from contemporaneous vascular plants, suggesting that Prototaxites are in fact heterotrophs, and more likely a fungus.

Using carbon isotope ratios in prehistoric human bone collagen, Fogel was able to study the diet of ancient humans. North American humans were either primarily maize eaters, which is a C4 plant, or primarily hunter-gatherers, which contains more C3 plants. Using this knowledge, Fogel measured the 𝛿13C values of essential amino acids to indicate whether the ancient human populations consumed primarily maize or were hunter-gatherers. Similarly, she was able to measure the marine nitrogen presence in human skeletons on Easter Island to establish that they consumed large amounts of marine food, and used the 15N enrichment in infants to determine the length of nursing in prehistoric populations.

Modern ecosystems Isotopic ratios are often used to trace the flow of certain elements through environmental systems. "Tagging" a molecule with an unusual isotope can allow a researcher to study a specific molecule and follow it in ecosystems, a technique known as using environmental tracers. Beyond human tagged compounds, natural isotope abnormalities occur as a result of various biotic and abiotic processes, and can often be found to vary across regions and species. Fogel has used these variations as natural ways to track animal movements, diets, and environmental shifts, and has also investigated the specific mechanisms that lead to environmental isotope fractionation.

As an example of a biotic fractionation event, respiration has led to an enrichment of 18O in the atmosphere relative to 16O. The isotopic ratio of 18O/16O is +23.5‰ relative to V-SMOW, and this ratio should also be observed in oxygen's consumption ratios. In one of the first major studies of plant oxygen consumption and fractionation, Guy, Fogel, and Berry defined the oxygen fractionation effects of various plant functions. They found that plants do not fraction oxygen isotopes in the photolysis of water in spinach thylakoids, but that they did discriminate against 18O during oxygen uptake by 21.3‰ during the oxygenation of Rubisco in spinach and by 22.7‰ during the photorespiration of phosphoglycate by glycate oxidase. Lignin, the main structural polymer in plants, was found to be depleted in 13C by 2–6‰ relative to the whole plant, and by 4–7‰ relative to the cellulose in saltwater cordgrass. diet and habitat use in the Amboseli Park in Kenya. Carbon isotope ratios vary by plant type, and so a change in carbon ratio of an elephant can indicate a shift in diet from trees to grasses. Strontium isotope ratios are reflected in the geologic age of bedrock, and so can be used as a tracer of the concentration of elephants within the park. Stable isotope ratios can also reveal diet specialization and shifts as specific carbon and nitrogen ratios are often indicative of groups of organisms. Using these ratios, Fogel has worked on diet studies on California sea otters, butterflies, blue crabs, killer whales, San Joaquin kit foxes, and bald eagles.

These same techniques of isotope fractionation investigations have also been used to study human environmental impacts. Because organic sewage outflow is enriched in 15N, she and her collaborators have been able to study the impacts of human sewage on coral reef systems by drawing a correlation between the 15N/14N ratio and the percentage of diseased coral species, as well as the impacts of chicken houses on nearby ecosystems. First, to make sure that the amino acids were extraterrestrial in origin, they measured the 𝛿13C values of the amino acids in the meteorites, which turned out to be significantly higher than the 𝛿13C value of amino acids on Earth, confirming that they were not contamination from Earth (+31.6‰ to +50.5‰ in the meteorites relative to −70‰ to 11.25‰ present on Earth). These results supported an idea initially postulated by Hirshmann and Withers that the martian atmosphere was formed from a reduced mantle. The reducing conditions indicated by the meterotic carbon content tentatively supports abiotic production of methane on Mars. and given the Sigma Xi Distinguished Scientist Award from the UC Merced Chapter. Also in 2013, she was awarded the Alfred Treibs Medal in the Organic Geochemistry Division from the Geochemical Society, which recognizes major achievements over a career in organic geochemistry. She was the first woman to win this prize. and became the Wilbur W. Mayhew Endowed Professor of Geo-Ecology at UC Riverside in 2017. The University of Oslo, where Fogel spent her Fulbright grant.

Fogel served on numerous committees, including the Scientific Advisory Committee for the Jug Bay Wetlands Sanctuary from 1992 to 2005, the Committee on Origin and Evolution of Life for the Space Studies Board, National Research Council 2000–2002, the Advisory Committee for the Carnegie Institution Department of Global Ecology from 2003 to 2005, and the AGU Biogeosciences Fellows Selection Committee in 2013 and 2014. In 2003, she was elected a Fellow of the Geochemical Society and European Association of Geochemistry. She was a Fulbright Scholar to Norway in 2006, and awarded the Jubilee Medal of the Geological Society of South Africa in 2006. She served as the National Science Foundation Director of Geobiology and Low Temperature Geochemistry from 2009 to 2010.

As a member of the NASA Astrobiology Institute from 1998 to 2010, she served on the Management Team (2004 to 2008) and then as chief scientist (2008) of the Arctic Mars Analog Svalbard Expedition (AMASE).

Legacy

Marilyn Fogel and her husband, Christopher Swarth, created several endowments to support high school and undergraduate college students. The Marilyn Fogel Endowment Fund for Internships, which is geared towards providing support for young scientists to experience research for the first time, allows high school and undergraduate students to conduct mentored internships at Carnegie's Geophysical Lab, and at the Department of Terrestrial Magnetism in Washington DC. They also endowed scholarships for undergrads at Penn State University and at the University of California, Merced.