Michel Aidoo

Chemistry major, CUNY Bronx Community College
CEOAS mentor: Rick Collwell

Investigating the structure of microbial communities in freshwater and sediments where salmon spawn

Salmon in the oceans migrate to freshwater streams to spawn in the sediments. The female salmon pass on vitamins to their eggs, including thiamine (vitamin B1). As the fry emerge and grow, they need more thiamine to perform their metabolic activities and facilitate their growth and development. Because virtually all living organisms on Earth require thiamin, it is already in high demand, so unfavorable factors that affect the production and distribution of the vitamin in the freshwater ecosystem can have severe consequences on the developing fish and the entire ecosystem. The Sacramento River in California, a site where Chinook salmon spawn, experienced severe thiamine deficiency, causing increased mortality of the juvenile fishes in the river (California Salmon Deaths Traced to Thiamine Deficiency - Los Angeles Times, n.d.). Even though the staff at the National Oceanic and Atmospheric Administration (NOAA) mitigated the immediate problem by injecting the female salmon with thiamine boosters before they spawned, there is an underlying concern of inadequate or no thiamine production by the microbes in the river. Because thiamine is created at the base of the food web (microorganisms) and is generally acquired by salmon through the food they consume, we wanted to know the types of microbes in the environments where salmon spawn and where young salmon develop to determine whether stream microbiomes play a role in the provision of thiamine to juvenile fish.

Demetria L. Eves

Geology major, California State University Long Beach
CEOAS mentor: Ed Brook

Allan Hills ablation zone ice core glacial cycle pacing

Currently, the highest resolution continuous ice core climate data extends back 800,000 years. Continuous records are ideally obtained from ice cores drilled in regions where ice is relatively stagnant with regular accumulation and as much of its in-situ stratigraphic orientation preserved as possible. Even under ideal surface conditions, stratigraphic integrity within deeply buried ice can be compromised, presenting unique challenges in analyzing significantly old ice for accurate paleoclimate reconstructions (Higgins, J. A. et al., 2015). An ice core (CMC1) drilled in 2019 from the Allan Hills Blue Ice Area in East Antarctica was dated using the 40Ar dating method and contains stratigraphically disturbed ice from 500 ka to 2.7 Ma (Yan, Y. et al., 2019; Kehrl, L. et al., 2018) The discrete greenhouse gas measurements currently taken from CMC1 show less variability across the glacial-interglacial cycles than we see in records from other cores, such as EPICA Dome C (EDC) (Bauska, T. K. et al., 2018; Chappellaz, J., Brook, E., Blunier, T. and Malaizé, B., 1997). The combination of stratigraphic uncertainty and the large sample size required for 40Ar dating makes examining small-scale stratigraphy a challenge. To gain a higher resolution picture of both the horizontal and vertical variations in ice properties in the core, we propose to analyze multiple small samples for carbon dioxide (CO2) concentrations, methane (CH4) concentrations and stable oxygen isotope ratios (d18O) in the lateral and vertical dimensions of select pieces of CMC1 ice. This study will focus on the section of CMC1 that overlaps with published records from other Antarctic cores, such as EDC, which contain ice up to 800 ka.

Susannah C. Herz

Geology major, Allegheny College
CEOAS mentor: JC Creveling

Refining the timing of the Cambrian Explosion of life through dynamic time warping of carbon isotope curves

The Cambrian explosion of life describes a roughly 30 million year period in which animal life evolved at an extraordinary rate. The evidence of this event exists in carbonate strata located around the world. Unfortunately, many of those deposits are not able to be radiometrically dated which would allow for a more precise age to be assigned to them and an overall better understanding of the Cambrian explosion. The solution to this challenge may be found through a technique called dynamic time warping.  In this application of dynamic time warping, a sequence of stable carbon isotope data from a precisely-dated Moroccan outcrop is compared to the equivalent curve from South China. A computer program uses an algorithm to decide which possible alignments of the curves works the best mathematically, and other knowledge of the area is used to select one. This process is first used to create a more complete picture of all of the stratigraphic sections from South China and then compare that to Morocco. This results in a more refined understanding of South China’s Cambrian strata and serves as a test for a new method that has rarely been used in the geosciences.

Riley Jones

Zoology major, Oregon State University
CEOAS mentor: JC Creveling

Employing dynamic time warping to refine the age of the Cambrian Explosion through regional and global δ13Ccarb composites

The Cambrian “Explosion” is a defining event for all of the animal life that is alive today, because it is the period in which all of the phyla alive today appeared. New data from Morocco will allow for a more detailed account of the timing of events within this Period. However, because this data is lacking in the biostratigraphy that is required for dating diversification events. Therefore, data from regions across the globe such as Australia, China, Mongolia, and Siberia must be included and compared because of their biostratigraphic records to come to a more concise conclusion. This conclusion will be drawn using composites of the multiple regions that will be compared to each other and the new Moroccan chronology.

Jennifer Kosty

Atmospheric and Ocean Sciences and Mathematics major, University of California – Los Angeles
CEOAS mentor: Jim Lerczak

Evaluating the influence of coastal ocean waters on the Yaquina Bay estuary

Estuaries are heavily influenced by coastal ocean waters that are brought in during flooding tides. We seek to characterize the seawater that enters the Yaquina Bay estuary from the Pacific Ocean. This water is crucial to quantify as its properties may affect vulnerable organisms and the overall health of ecosystems within Yaquina Bay. We will conduct a correlation analysis on temperature and salinity time series collected within the Bay and the nearby coastal ocean. We will then quantify the concentrations of dissolved oxygen and carbon dioxide that enter the Bay from the ocean and identify potential drivers of changes in these concentrations. These efforts will allow us to better understand the properties of the seawater entering Yaquina Bay and the potential impacts of these waters.

Sarah Leibovitz

Geology and Environmental Studies major, Amherst College
CEOAS mentors: Maureen Walczak, Alan Mix, Joe Stoner

Understanding Holocene freshwater fluxes from the Columbia River basin through salinity proxies in marine sediment cores

Anthropogenic climate change will cause changes in precipitation in the Pacific Northwest, but there is uncertainty about whether the regional climate will become wetter or drier as it warms. We would like to reconstruct a history of freshwater flux from the Columbia River throughout the Holocene. This reconstruction will provide insight into past changes in the quantity and seasonality of precipitation in the PNW during periods of warmer climate. We will use stable isotope analysis (δ18O) of foraminifera from marine sediment core  OC2006A-10JC, collected just north of Astoria Canyon, as a proxy for salinity. Oxygen isotope data from foraminifera that live in different seasons will provide insight into changes in the seasonality of precipitation in the PNW over time.

Aaron Martin

Geology major, California State University Long Beach
CEOAS mentor: JC Creveling

Refining the tempo of the Cambrian Explosion by using dynamic time warping on the regional and global scale

There have been some difficulties assigning absolute ages to fossil first appearances in the early Cambrian Period. Through the use of Dynamic Time Warping (DTW), we hope to assign ages to fossil first appearances by using δ13C isotope data processed from particularly fossil rich paleo sedimentary basins in the following countries: Australia, China, Mongolia, and Siberia. Each of these paleo-basins has a varying amount of information on the lithostratigraphy and biostratigraphy that can guide chemostratigraphic correlation. We will use DTW to create δ13C data alignments between various stratigraphic columns within a region. Once completed, all δ13C alignments will be plotted into one regional composite; each regional composite can be compared to the composite of the remaining regions to produce a global δ13C isotope composite that will be used to assign ages to fossil first appearances on a global scale.

Farhana Mederbel

Chemistry and Physics major, Paris Saclay University
CEOAS mentor: Christo Buizert

Study of methane in ice cores during the Holocene

It is more important than ever to understand what we are going to have to face during the future years and decades. To better understand these challenges, we need to understand the past climate. In order to do that, researchers and scientists from all around the world utilize ice cores to access data of gas composition of the atmosphere back in time, which permits us to reconstruct past climate and gain information about the temperature in the past. In 1998, scientists extracted ice cores from the Vostok station in Antarctica, giving access to 420,000 years old ice at a depth of 3,623 meters. Therefore, analysis of ice cores from Antarctica and Greenland allow us to know the evolution of climate and the composition of the global atmosphere. During my work with Kaden this summer, we tend to focus on a “small” specific period from the Holocene to look at the methane concentration there. Indeed, methane is a gas present everywhere in the atmosphere that is directly related to the global temperature of the planet.  Therefore, when we have the methane concentration we are going to be able to get information about temperature and accumulation during the Holocene (11650 years ago to present). For the first part of this proposal we are going to see to what extent the ice core gives us data on the gas concentration and what is the gas entrapment process. Then, we will talk about the measurement process in order to get the gas concentration. Finally, the last part will explain the use of a proxy known as Δage, (age difference), to reconstruct past climate.

Brooke Newell

Earth Systems Science major, Texas Christian University
CEOAS mentor: Rene Boiteau

The impact of phycosphere bacteria on diatom growth under iron-limiting conditions

In an overwhelmingly iron-deficient ocean, competition for this scarce resource has resulted in marine organisms evolving ingenious methods for iron acquisition, including the creation and use of specialized iron binding molecules. These molecules, known as siderophores, play a critical role in maintaining the health of organisms in low iron environments. We seek to develop a greater understanding of the role of bacteria in promoting algal growth under low iron conditions through investigating the effects of co-culturing diatoms and bacterial partners with a form of strongly bound iron in high and low concentrations. Examination of co-culture dynamics is essential in order to develop strategies to further microalgae biofuel production through controlling the iron dynamics of algal ponds. Through growing our diatom of interest both alone and with bacterial partners, we will be able to track the growth, siderophore production, and iron uptake in each culture through the utilization of cell counts, solid phase extraction, and inductively coupled plasma mass spectrometry. The information gathered from these methods will help to build a greater understanding of the relationship between diatoms and bacterial partners and the suitability of the bacteria that produce them for protective use in microalgae biofuel production.

Antonio Ortiz Laboy

Chemistry major, Pontifical Catholic University of Puerto Rico
CEOAS mentor: George Waldbusser

Measurements of chlorophyll A through space and time in Yaquina Bay

Chlorophyll a is a compound that can be classified as a fluorophore. These types of compounds have the property that when they are irradiated with light at a certain wavelength, they absorb it and emit it as a photon at a longer wavelength. Analyzing these compounds via fluorescent spectroscopy is highly convenient due to the high sensitivity and selectivity that this technique provides. As with UV-Visible spectroscopy, fluorescent spectroscopy can allow us to determine the concentration of a fluorophore, in the case of this research, chlorophyll a. The development of a method through fluorescent spectroscopy to measure concentrations of chlorophyll a confidently, with precision and accuracy, can ultimately let us measure the levels of chlorophyll a in the estuary in Yaquina Bay to evaluate how to the change of tides can affect the variation of chlorophyll levels in the waters of Yaquina Bay.

Adalia Xiony Rodriguez

Geology major, Bryn Mawr College
CEOAS mentors: Maureen Walczak, Alan Mix, Joe Stoner

Lithostratigraphic boundaries of the retreat recording the Cordilleran Ice Sheet in the Northern Washington Margin

Located in the Pacific Northwest, the Cordilleran ice sheet is one of the most poorly understood deglaciation events in recent geological time. Observing and interpreting when and where the ice sheet began to destabilize- whether the destabilization first began on the western coast or more eastern into the ice sheet- will eventually help comprehend how large land masses lose their ice, the constraints of deglaciation and will help predict future models of ice sheet destabilization in places such as Greenland and Antarctica. The data that will be collected is a sediment core that comes from the Astoria Canyon off the coast of Washington which has multiple drainage sources, carrying thousands of years of sediment from the eastern and western part of the continent. Sediment core OC2006A-10JC will be sampled and washed for planktic foraminifera and radiocarbon dating tests be performed to get a chronology of the major lithostratigraphic boundaries. Furthermore, previous XRF data will be looked at to understand the elements making up the core and from there an interpretation of the possible source rocks can be. This information will be compared with other sediment cores in the surrounding areas to figure out the full timeline of the deglaciation.

Nicholas C. Romero

Marine Science major, California State University Monterrey Bay
CEOAS mentor: Ed Dever

Analysis of AC-S (spectrophotometer) proxies for ecosystem variables using the OOI Endurance Array off the coasts of Oregon and Washington

Phytoplankton communities are the base of the ocean web because of their ability to carry out photosynthesis with chlorophyll pigments. This research aims to calculate, form, and estimate proxies for chlorophyll fluorescence and Particulate Organic Carbon (POC) using a WET Lab's Spectral Absorption and Attenuation Sensor (AC-S) and comparing the data to proxies gathered from fluorescence-based measurements. We will do this by accessing the Ocean Observatories Initiatives (OOI)  AC-S and fluorometer data from 2015 to present time to create a time series analysis using Python. This research will help us understand the quality of AC-S data and will allow the scientific community to more confidently use the data for a multitude of purposes. This includes observing absorption and attenuation as a function of wavelength giving an insight into phytoplankton communities and understanding the ecological applicability of the data retaining to phytoplankton biogeography.

Melanie Schwarz

Geology major, Oregon State University
CEOAS mentor: JC Creveling

Using dynamic time warping to align δ13C isotope data in Siberia to refine the timing of the Cambrian Explosion

The Cambrian "explosion" is an important interval in time during which modern-day phyla evolved, however, the absolute timing of these fossils are unknown. Morocco contains absolute dates from stratigraphy deposited during the Cambrian, but it does not contain any fossils; Siberia contains an abundance of small shelly fossils, but no absolute dates. The two regions contain δ13Ccarb data, which can be used in a technique called dynamic time warping; this technique creates different alignment possibilities between two curves of δ13Ccarb data. A regional composite of Siberia will establish relative dates of fossils, which will then be compared to Morocco's composite. Aligning the two regions will establish absolute dates of fossil appearances, meaning evolutionary rates can be calculated.

Elijah Stahr

Mathematics major, Texas Tech University
CEOAS mentor: Andreas Schmittner

Reconstructing Atlantic Meridional Overturning Circulation during Heinrich Stadial 1 using carbon isotopes

The formation of deep water masses in the North Atlantic has seen great and sometimes abrupt change throughout the history of the ocean. In order to better understand the behavior of ocean circulation, we seek to reconstruct the Atlantic Meridional Overturning Circulation (AMOC) during Heinrich Stadial 1. Gaining greater insight into the behavior of deep ocean circulation in Earth’s past is vital for understanding variability in climate and ocean circulation. We will employ a coupled circulation biogeochemical model to investigate the impacts of varied AMOC strengths and depths on carbon isotope ratios. By comparing this model data to real world data from ocean sediment cores, we expect to test the hypothesis that the AMOC during HS1 was in a collapsed state.

Josh Vazquez

Environmental Sciences major, University of Texas
CEOAS mentor: Alyssa Shiel

Reconstruction of ancient lead pollution in Lake Erhai, China

Application of isotopic geochemistry methods onto a sediment core from Lake Erhai, Yunnan, China, allows for a reconstruction of a 4500 year record of lead (Pb) pollution. Currently, the exact sources of the elevated lead pollution levels during the Mongol Era are unknown, but are linked to mining and smelting. Measuring Pb isotopic values assists in pinpointing the source of lead pollution, whether natural or anthropogenic. Sediment samples come from a Lake Erhai sediment core known as Core C12, where the application of isotopic geochemistry methods will result in lead isotope values over time. If we measure Pb isotopic values from the Lake Erhai sediment cores, then we pinpoint the source of the lead being deposited into the lake during the Mongol Era.

Sarah Villhauer

Atmospheric and Ocean Sciences and Mathematics major, University of California – Los Angeles
CEOAS mentors: Ken Zhao and Erin Pettit

Do ocean currents accelerate or decelerate the disintegration of ice shelves?

Petermann Gletscher’s ice shelf (PGIS), located in Northwest Greenland, has experienced significant thinning and calving within the past two decades, however, little is known on how specific basal geometries, including channels, crevasses, and terraces, impact the basal melt rates of PGIS. Our project will investigate whether ocean currents accelerate or decelerate the melting, and relatedly the disintegration, of PGIS as well as other floating ice shelves in Northern Greenland and around the Antarctic Ice Sheet. Ice shelves act as a stabilizing influence on grounded ice, therefore the melting and disintegration of ice shelves increases flow of grounded ice into the ocean, which leads to rise in sea levels; understanding how different basal geometries influence melt rates can allow us to make more accurate sea level predictions in the future. We will develop and analyze a z-coordinate model of ocean circulation within channels, crevasses, and terraces motivated by the parameters of PGIS as well as those representative of other ice-shelf cavities. This will allow us to observe the behavior of ocean circulation within our designated basal geometries—including the mean 3D velocity, temperature, salinity, and the corresponding turbulent momentum, heat, and salt fluxes—and therefore provide insight on how these geometries impact melting of ice shelves in general.

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