Zachary Allen
Computer Science major, Oregon State University
CEOAS mentors: Scott Durski, Jenny Hutchings
Exploring Improved Computational Performance of a Discrete Element Sea Ice Model Using GPU Parallelization
The Siku model is a discrete element model that simulates sea ice dynamics and mechanics, highlighting the cohesive yet divisible nature of sea ice. Improved methods of optimizing the model increase the scale and possibilities for application of this discrete element model and others like it. The model has the potential for increased performance using parallelization methods in individual processes and the code's overall framework. Here we show the benefits an expensive process receives from the integration of parallelization methods utilizing a graphical processing unit (GPU). The process of identifying overlapping edges of elements (responsible for at least 24.5% of computing time in the model) is extracted, refactored, and analyzed to focus on the direct response that the process exhibits harnessing the proposed optimization. Leveraging the GPU, the increase in calculation time in relation to the number of elements being evaluated demonstrated logarithmic growth, compared to the current implementation’s linear growth. The GPU begins to outperform the current method around 2000 elements, where a modest regional application of the model would include 5000 to 100000 elements. Although these results are derived from a refactored representation of the process and the actual benefits possible for the Siku model are yet to be determined, these results lay the groundwork for navigating the best path forward in further optimization of the code using GPU parallelization. Discrete element models like the Siku model are fundamentally constrained in scalability by the computational cost of processes that can be minimized using GPU parallelization.
Matthew Boling
Physics major, Brigham Young University – Idaho
CEOAS mentor: Andreas Schmittner
Modeling Effects of AMOC Variations on Carbon and Carbon Isotopes Components
The Atlantic Meridonal Overturning Circulation (AMOC) is responsible for transporting heat and nutrients in and between ocean basins, and affects carbon distributions in the ocean as indicated by paleoclimate data. That data shows correlations between atmospheric CO2, δ13C, and AMOC. However, carbon and δ13C cycling is complex, and not well understood why these relationships exist. In this study, we used a climate model that included diagnostic tracers, allowing for a decomposition of carbon and δ13C, improving our mechanistic understanding of the effect of AMOC changes on carbon and carbon isotope components. Both positive and negative freshwater fluxes were applied to the Atlantic Ocean, simulating various changes in the strength of AMOC. The carbon was decomposed into Dissolved Organic Carbon, Dissolved Inorganic Carbon, and δ13C components, among other things, and studied to determine the relationship between each component, and changes in the strength of AMOC. One of the primary findings of this study showed that when AMOC collapses, carbon components take a while to find their new equilibrium, whereas when AMOC was temporarily strengthened via a negative freshwater flux, the various carbon components tended to respond much more quickly, and approach approximately the equilibrium value that they started out with. This is significant because it informs our understanding of how the ocean will absorb CO2 in the event of either an AMOC collapse or strengthening, and we will have a better understanding of the processes that impact the carbon distributions within the ocean.
Michael Clark
Mechanical Engineering major, Linn-Benton Community College
CEOAS mentors: Emily Eidam and Molly Keogh
Analysis of Sediment Accretion Rates Across the Arctic
The Arctic Ocean is extremely valuable for the collection of data for the use of quantifying the impact of humanity on the environment, due to the phenomenon known as Arctic amplification, which describes the Arctic’s tendency to display environmental change more rapidly than that of lower latitudes. This sensitivity to environmental change and the use of isotopic geochronology can be very effective for determining regional change on a human time scale. With the use of sediment cores stored in the OSU Marine and Geology Repository, we can use isotopic analysis as a means of determining sediment accretion rates, which are heavily impacted by the environmental conditions in a region, to measure how these regions are changing over time. In addition to previously collected data, the primary methods that we plan to employ for this research are 210Pb isotopic analysis, grain size, and organic content as a means of determining changes in sediment accretion across the Arctic. We also aim to determine if regions that have high sediment accretion rates may lend themselves to be ideal for core collection for the construction of high-resolution records of sedimentation.
Oona LaLuna Clark
Climate Science major, Oregon State University
CEOAS mentors: Alyssa Shiel and Lourdes Moreu
An Investigation into Lead Contamination in Soils and Moss from Lead-sheathed Telecom Cables in Corvallis, Oregon
Lead pollution is a significant issue that continues to plague cities across the United States of America, even decades after leaded gasoline was phased out for use in automobiles. Because lead poisoning can pose devastating consequences to human health especially in young, developing children, understanding the sources and spread of environmental lead in populated urban areas is of great importance. This geochemical study will assess the impact of lead-sheathed aerial telecom cables on environmental lead levels in Corvallis, Oregon by measuring the lead concentrations and isotopic compositions of moss and soils. This study builds on previous work by measuring lead levels in soils near these cables, comparing lead levels of co-located moss and soils, and assessing the reach of lead emissions from these cables. Lead concentrations above the EPA limit for residential soil lead levels (200 ppm) were found in two co-located soil samples and one moss sample of sites tested, with soil levels ranging from 8 to 318 ppm, and moss ranging from 1.5 to 260 ppm. Isotopic signatures were also tested to verify common sources of lead between co-located soil and moss samples.
Katelyn Coates
Wildlife Biology major, University of Montana
CEOAS mentors: Kim Bernard and Rachel Kaplan
Exploring Interannual Variability and Environmental Impacts on the Reproductive Fitness of Mature Female Antarctic Krill
Antarctic krill, Euphausia superba (referred to as "krill" hereafter), are vital to the Antarctic pelagic ecosystem. They serve as primary consumers of phytoplankton, a key food source for apex predators such as blue whales, and play a significant role in carbon sequestration in the Southern Ocean. Additionally, krill are economically important, as they are the target of the largest fishery in the Southern Ocean. However, the Antarctic Peninsula (AP), one of the fastest warming regions in the world, is experiencing substantial changes in its pelagic ecosystem. The impact of this warming on krill population dynamics and reproductive success remains unclear. To address this, we analyzed historical krill population data from the AP (January 1999–2011, Palmer Antarctica Long Term Ecological Research) to examine interannual variability in the timing and duration of the spawning season and to identify environmental drivers. We also developed a pregnancy index to quickly assess the sexual development stage of female krill in the field. Our findings showed that both the timing of spawning initiation and the spawning season duration varied annually. Linear mixed-effects models indicated that neither could be directly explained by environmental conditions at the time of sampling. It appears that oceanographic and climatological conditions in the months preceding the spawning season may significantly influence the reproductive output of mature female krill. These factors will be incorporated into future models, with results shared with the SCAR Krill Expert Group to enhance krill fishery management.
Abigail Gaddis
Geology & Geophysics major, Purdue University
CEOAS mentors: Emily Eidam and Molly Keogh
Coastal sediment deposition in the western Ross Sea
Climate change is being accelerated during the Anthropocene. Sediment records around the world display anthropogenic influences, partly through engineering environments and directly altering where sediment flows, and these changes in the sediment records help to share important information about how humans are changing the environment. Sediment cores contain timelines of sediment accretion rates over the years, and within these cores, a naturally occurring radioisotope provides a valuable way to establish a geochronological record. This study aims to utilize 210Pb dating to understand how sediment accretion rates have changed in the Ross Sea, located in the Antarctic, which is fed by major ice streams. Additionally, variables like organic content and particle size will be measured in each sample to understand the environmental conditions when the sediment was deposited. The focus of this study is on sediment accretion rates, inferred by a combination of grain size data and 210Pb analyses, and the location of the cores in proximity to large glacial output locations. The results of this study indicate that sediment accretion occurs at higher rates in the western Ross Sea due to the presence of large ice streams. Those in eastern Antarctica indicate slower accretion rates due to the presence of smaller ice streams.
Jamie George
Marine Science major, Coastal Carolina University
CEOAS mentor: Astrid Leitner
Canyon Edge Community Composition and Dynamics in relation to Oceanographic Drivers in Monterey Submarine Canyon
The Monterey submarine canyon is a biological hotspot located off the Pacific coast of California in a region defined by strong seasonal upwelling. The drivers responsible for sustaining the high biological activity associated with the canyon are still an ongoing topic of research. Here we analyze the composition, abundance, and ecological interactions of the benthic, benthopelagic, and pelagic communities at 200 meters depth on the canyon shelf break with a benthic time lapse camera. A total of 353 videos from four deployments were annotated on a two hour interval using the Video Analysis and Reference System (VARS) software. The potential impact of topographic blockage on the abundances of the canyon edge community was investigated by looking at diel patterns in abundances. Additionally, the influence of upwelling strength and current velocity were assessed. Across the deployments, 31 predatory interactions were observed between benthic and pelagic animals supporting the idea that abrupt bathymetric features are hot spots for benthopelagic interactions. Using generalized additive models (GAM) we found that time of day, current velocity, and oceanographic season are all important drivers of abundances for euphausiids, mesopelagic fishes, and planktonic organisms at the canyon edge. Patterns associated with time of day and onshore current velocities were consistent with the topographic blocking hypothesis. This provides evidence that topographic blocking may be an additional mechanism supporting high biological activity in submarine canyons.
Alayna Kisiday
Chemistry major, Willamette University
CEOAS mentors: Kristen Buck, Laura Moore and Leo Mahieu
Quantifying electroactive iron binding humic-like substances in the Southern Ocean
Iron is an essential nutrient for all cell growth, metabolism, and function. In over 35% of the world's surface ocean, iron is the limiting nutrient for the primary producers in the ocean, phytoplankton. Organically complexed iron accounts for over 99% of dissolved iron (DFe), but largely these organic ligands are unknown. Humic-like substances (HS) are dissolved organic matter that complex iron to form an electroactive compound (eHS), which we can measure directly using cathodic stripping voltammetry. It has been reported that in some regions of the world, 20-60% of the iron binding, organic ligand pool can consist of HS. Though, the study of eHS is a novel area of research, resulting in a limited body of knowledge surrounding the role HS ligands play in iron cycling across the world. Here we show that HS ligands are not only present in the Southern Ocean, but they are a substantial portion of the organic ligand pool; up to 97% of DFe was found to be complexed by humic-like ligands. Additionally, at a depth of 25m, spatial correlations between HS ligands and chlorophyll concentrations were found across all stations. This suggests a biologically controlled source of eHS at the surface. The finding of ambiently occurring eHS in this study expands previous knowledge surrounding the importance of humic ligands, and confirms they are present and active in cycling iron in the Southern Ocean.
Matthew Koteskey
Chemistry major, Oregon State University
CEOAS mentors: Kristen Buck, Laura Moore and Leo Mahieu
Effects of Ocean Acidification on Nickel Speciation and Phytoplankton Uptake in the Northeastern Pacific
Nickel (Ni) is an important micronutrient for many species of phytoplankton in the ocean. Ocean acidification due to increases in anthropogenic CO2 can possibly have effects on Ni speciation, including its dissolved fraction (DNi). DNi comes in inorganic and organic forms where the inorganic forms are bioavailable, and the rest is bound to organic ligands which may be affected by pH and potentially impact their ability to bind DNi. To test this idea, seawater was collected at different locations during a cruise in the Eastern Pacific and the pH adjusted to correspond to future climate change scenarios. The seawater samples were incubated over 4-6 days with additions of iron to half of the samples and nitrogen to all the samples to facilitate phytoplankton growth. Samples were taken from before and after the incubations and then analyzed using an electrochemical technique allowing for the determination of labile dissolved Ni (labile DNi) which reflects how much Ni is bioavailable. A change in initial Ni lability was observed in two of the three regions surveyed. Differences in how the pH changed the lability of Ni across the incubations suggest the presence of different nickel binding ligands that are differently impacted by the change in pH. Aside from the incubation in the coastal upwelling system, there did not appear to be a correlation between pH and Ni uptake from the phytoplankton in the samples. However, the variations in labile DNi observed in this study suggests an impact of ocean acidification on DNi speciation and bioavailability for phytoplankton.
Nina Mahalingam
Biochemistry and Molecular Biology major, University of California Davis
CEOAS mentors: Kim Bernard and Rachel Kaplan
Analyzing the Caloric Content of Krill in New Zealand: Implications for Whale Energetics
In the South Taranaki Bight (STB) of New Zealand, persistent upwelling conditions foster a highly productive ecosystem characterized by substantial phytoplankton biomass, which sustains high densities of the euphausiid (krill) Nyctiphanes australis. N. australis serves as the primary prey for numerous higher trophic-level species, including jack mackerel and a culturally significant and genetically distinct resident blue whale (Balaenoptera musculus brevicauda) population. Marine heatwaves (MHW) in the STB have been shown to cause decreased whale feeding and breeding activities, as well as less frequent and more sparsely distributed krill aggregations. This work prompted the development of Project SAPPHIRE (Synthesis of Acoustics, Physiology, Prey, and Habitat in a Rapidly changing Environment), which aims to understand the impact of climate change – in particular, MHW events – on blue whale and krill populations in the STB. We are interested in how warming events, which cause shifts in metabolic processes, affect energetic availability within predator-prey relationships. We determined the caloric content of krill as a means to assess their health and nutritional quality, thereby offering a valuable new insight into the health of the resident blue whale population. Average length, wet mass, dry mass, and energetic value of individual krill were established to be: 15.07 mm, 11.50 mg, 3.31 mg, and 0.048 kJ, respectively. These metrics are examined within the framework of blue whale energetics, as extracted from existing literature, to estimate the biomass of krill required to sustain the New Zealand blue whale population.
Grace Miller
Biochemistry & Molecular Biology and Neuroscience & Physiology major, Wright State University
CEOAS mentors: Kristen Buck, Laura Moore and Leo Mahieu
Nickel Speciation in the Southern Ocean
Nickel (Ni) is an important micronutrient for many marine species, including phytoplankton. In the Southern Ocean, which has a major influence on global circulation and water masses composition, Ni speciation has yet to be investigated. Profile samples for metal speciation were collected in September and October 2016 in open ocean and coastal waters surrounding the West Antarctic Peninsula. Dissolved Ni (DNi) profiles were analyzed for labile DNi in depths ranging from 20 m to 3500 m. Results from DNi profiles and humic-like substances were compared to provide new insight on the cycling of Ni in the Southern Ocean. Electrochemical techniques and linear regression of peak heights recorded were used to determine the total labile DNi. Surface DNi was found to be stable while surface labile DNi showed great variation between organic and inorganic Ni. Across all depths, labile DNi was inconsistent; labile DNi ranging anywhere from 12-85% offshore and inshore. A depletion of surface chlorophyll inshore and a depletion of surface phaeophytin offshore of the studied area was observed, suggesting labile DNi as a source of cell death. These results are the first Ni speciation depth profiles in the Southern Ocean and provide a baseline of the biogeochemistry of Ni in the West Antarctic Peninsula.
Carly Otto
Climate Science major, Oregon State University
CEOAS mentors: Andreas Schmittner and Jenny Hutchings
Model Validation Study: Fixing Southern Ocean Sea Ice Bias in the UVic ECSM
The University of Victoria Earth System Climate Model (UVic ESCM) is a tool for advancing our understanding of long-term climate and carbon cycle dynamics including paleo-climate. Here, we assess the model's representation of Southern Ocean sea ice by comparing it with passive microwave satellite data from National Snow and Ice Data Center (NSIDC) and National Ocean and Atmospheric Administration (NOAA). Forced with climatological (monthly-mean) atmospheric wind stress, the model overestimates sea ice concentration. Whereas the observations show a gradual decrease in concentration with distance from Antarctica, the model shows close to 100% ice cover from the Antarctic margin to almost the sea ice edge. As a result, the UVic model overestimates sea ice area by as much as 4 million square kilometers. The model additionally shows a persistent, large polynya in the center of the Weddell Sea, which is not seen in the observations. Two hypotheses are tested that can explain these model biases: (1) missing wind stress variability, and (2) missing variable ice thickness classes. To test hypothesis (1), wind forcings are adjusted to include high-frequency and interannual variability. High-frequency wind variability is introduced by extracting anomalies from ERA5 daily wind reanalysis data for the year 1990. Hypothesis (2) is tested through sensitivity experiments with variable numbers of sea ice thickness categories. We theorize that implementing wind stress variability induces more accurate shear stress, therefore resulting in more realistic ice motion. This also applies to the implemented ice thickness classes, where lower varying thicknesses show improved model results compared to observations.
Kaley Peterson
Environmental Science, Oregon State University
CEOAS mentor: Andrea Jenney
Forecasting Subseasonal Near-Surface Ocean Chlorophyll Variability: Insights from the Madden-Julian Oscillation
Analysis of satellite derived ocean color data indicates that the Madden-Julian Oscillation (MJO) produces prominent fluctuations in near-surface ocean chlorophyll. We have developed an investigation to explore the connection between the Madden-Julian Oscillation (MJO) and variations in near-surface chlorophyll levels. Specifically, the “Sensitivity to the Remote Influence of Periodic EventS (STRIPES)” index will allow us to quantify the ‘fingerprint’ of MJO variability on global satellite-derived surface concentrations, from 2002 to 2023. This analysis demonstrates that the Madden-Julian Oscillation (MJO) causes substantial variations in near-surface ocean chlorophyll around the equator. Given that the MJO can be forecasted with a lead of two weeks or more, we may be able to begin predicting chlorophyll concentrations.
Samantha Quinones
Physics and Astronomy major, University of Texas San Antonio
CEOAS mentor: Erin McParland
Dissolved Metabolites in Microbial Communities at Hydrothermal Vents
Carbon dioxide is a greenhouse gas that is absorbed by the oceans and knowing its fate is critical to understanding Earth’s climate. Marine microbes, such as phytoplankton, take up carbon dioxide for photosynthesis, and in the process release fixed carbon as dissolved organic matter (DOM). DOM plays an important role in the global carbon cycle, yet it is still not completely understood. One factor that could help bridge a better understanding of DOM distribution relies on analyzing the quality and quantity of DOM. When microbes process these compounds, they produce labile DOM. Labile DOM is thought to be comprised of molecules exuded as by-products of biological metabolism. These molecules are referred to as metabolites, which microbial communities use for energy and cellular functions. Recent work has quantified dissolved metabolites in the surface ocean, but, to our knowledge, these molecules have not been quantified in the deep ocean at hydrothermal vents. However, hydrothermal vents within the deep host active microbial systems, and presumably these communities also rely on dissolved metabolites to function. To learn more about the deep sea carbon cycle, we measured dissolved metabolites at three hydrothermal vent sites from the Axial Seamount, and compared their composition and concentration to dissolved metabolites in the surface ocean. Many of the detected molecules produced by microbes at the hydrothermal vents were also found to be produced by microbes in the surface ocean. Interestingly, some of the concentrations of dissolved metabolites exceeded surface ocean values by an order of magnitude. By identifying and quantifying labile DOC in the deep ocean, we can start to develop a better understanding of organic carbon cycling and the crucial roles hydrothermal vents play in deep marine ecosystems.
Matoska Silva
Biology major, Oregon State University
CEOAS mentors: Kim Bernard and Rachel Kaplan
Interactions of climate variability and krill spatial distribution in the Northern California Current region
The Northern California Current (NCC) ecosystem exhibits changes in response to climatic processes that drive variability in circulation and temperature, as well as warming anomalies including marine heat waves. Climatically driven shifts in the lower trophic levels of the NCC ecosystem, such as changes in nutrient content and spatial distribution of zooplankton communities, may result in more widespread ecosystem-level disturbances. Krill are among the most vital zooplankton conveying energy from primary producers to secondary consumers in the NCC, and their potential for dramatic decline in size and abundance in response to warming events makes them important organisms to study in the context of both established climate variability and novel responses to climate change. To assess how recent climate variability has impacted the spatial distribution of krill in the NCC, we investigated acoustically detected krill aggregations from April 2023 (neutral conditions, post-La Niña) and April 2024 (El Niño). We detected krill aggregations both north and south of Cape Blanco and east and west of the 200-m isobath in both 2023 and 2024. We also found a decrease in the acoustic catch per unit effort (CPUE) of krill aggregations based on nautical area scattering coefficient (NASC) in regions west of the 200-m isobath between 2023 and 2024. Our findings suggest a decrease in the abundance of krill in offshore regions of the NCC during the 2024 El Niño, but this interpretation may be complicated by technological limitations.
Lauren Stalford
Environmental Science major, Oregon State University
CEOAS mentors: Alyssa Shiel and Lourdes Moreu
Using Isotopes to Fingerprint Sources of Lead Pollution in Western Oregon
Environmental lead levels have been decreasing since the phase out of leaded gasoline, however, current sources of lead emissions (e.g., smelters, lead ammunition, airports, metal recyclers) can contaminate local or regional areas. Lead isotopes can be used to identify original ore deposits, but mixed inputs can muddy these characteristic fingerprints. Contemporary isotope studies have measured the individual isotope fingerprints of Pb sources, but no known work has been done to characterize Pb sources by emission type or industry. This study measured Pb concentrations and isotopes around 3 types of Pb sources in Western Oregon: airports, paper and pulp mills, and gun ranges, and compared them with previous isotope studies of urban and industrial areas as well as signatures from Pb mines. Pb concentrations encompassed a wide range, from 0.40ppm to 1,065ppm. The highest levels were found in and around shooting ranges, particularly a BLM-owned quarry near Marys Peak with no known lead management policy in place. Isotope analysis is ongoing, but preliminary results suggest at least one distinct fingerprint for airports, and weak or nonexistent fingerprints for paper mills and gun ranges. The high rate of recycling for lead metal products may contribute to the similarity between isotope ratios of these sectors.
Noel Wang
Physics major, Carleton College
CEOAS mentors: Jenny Hutchings and Mackenzie Jewell
Investigating causes of an unusual 2024 Beaufort Shelf polynya
The formation of polynyas, openings in continuous sea ice, depends on winds, ocean heating, or a combination arising from complicated regional atmospheric and oceanic dynamics. Coastal polynyas serve as windows into ice conditions and play important roles in biological and human activities. In January 2024, an unusually large and persistent polynya developed westward from Herschel Island along the Arctic Ocean’s Beaufort Shelf, extending 500 km and lasting nearly two weeks. This polynya’s unprecedented occurrence in 2024 motivates our study of its causes. We examined how wind and sea ice drift affected the 2024 polynya event and compared it with others over the past 20 years. Remote sensing data and atmospheric reanalyses show that 5-10 m/s east-southeasterly alongshore winds correspond with polynya opening, indicating a primarily wind-driven mechanism associated with high-pressure systems over the Beaufort Sea. However, while historically precedent winds occurred during the 2024 event, the polynya grew twice as large as in the past. We hypothesize that warm coastal upwelling in the region, previously observed near local moorings in 2017-2019, may have contributed to the 2024 event. The extent to which sensible heating or an increasing dynamic sensitivity of sea ice to wind affects the polynya is unknown. Our initial results demonstrate that wind forcing plays a leading role in controlling the Herschel Island polynya in the Beaufort Shelf. We also underscore the need for more in situ moorings to collect oceanographic data in the region to improve our understanding of the role of ocean heat.
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