Hydroclimate of Southern Greenland during interglacials of the past 600,000 years based on terrestrial leaf wax biomarker isotopes preserved in ocean sediments

Abstract
The Greenland Ice Sheet has the potential to contribute significantly to sea level rise in response to anthropogenic warming in the coming centuries. However, the long-term stability of the Greenland ice Sheet in response to warm climate conditions is poorly understood, in part due to a lack of records of terrestrial Arctic climate conditions during previous interglacials. I propose to analyze hydrogen isotopesof terrestrial vegetation biomarkers preserved in marine sediments during interglacials of the past 600,000 years (Marine Isotope Stages (MIS) 1, 5e, 7, 9, 11, and 13), to test the hypothesis that the greatest enrichment of precipitation isotopes, and thus greatest warmth, occurred during the last interglacial, MIS 5e.

Biography
As an undergraduate geology-chemistry student in the Brown University geosciences department, I became fascinated by the application of the analytical approach of chemistry to decode signals of change in Earth’s history. I was especially drawn to study biogeochemical proxies and their inherently interdisciplinary nature, as they are produced by ecology, studied on chemical scale, and record climate processes. I am currently pursuing a Ph.D. at the University at Buffalo, where my research has focused on understanding past hydroclimate change in western Greenland through the Holocene based on the analysis of organic geochemical proxies in lacustrine sediments. With the Schlanger fellowship, I will analyze the hydrogen isotopes of terrestrial biomarkers in ocean sediments to compare climate variability on much longer timescales, between Late Quaternary interglacials.

Oceanographic controls on mid-Holocene nutrient consumption at Palmer Deep, West Antarctic Peninsula

Abstract
Carbon drawdown in Southern Ocean coastal systems is a function of productivity and nutrient  supply,which are regulated by nutrient input from deep water masses, vertical mixing, and springtime
stratification associated with sea ice retreat. Variation in sea surface temperature (SST), the abundance ofstratification-related Chaetoceros resting spores, and a decrease in warm water forms of Eucampia antarctica along the West Antarctic Peninsula (WAP) between 5-7 ka indicate possible water mass and nutrient delivery changes on both millennial and sub-millennial time scales. Here, I propose to examine sub-millennial scale variability of deep water intrusion and surface stratification as related to surface ocean nutrient dynamics by a generating a diatom-bound nitrogen isotope (δ15Ndb) record from the ultrahigh-resolution Southern Ocean ODP Site 1098. These data will be further used to understand potential future nutrient dynamic changes associated with warming of the WAP linked to the disintegration of ice shelves and potentially large fluctuations in ecological zones.

Biography

During my undergraduate chemistry degree, I found that the most compelling applications of what I learned were climate, biochemistry, and marine systems. The combination of academic interest and living in an era when climate news has dominated headlines and politics put further study of climate and the oceans squarely in my crosshairs. I currently work with Dr. Rebecca Robinson at the University of Rhode Island’s Graduate School of Oceanography examining how changing ocean conditions over time have shaped the role of biology in controlling climate. My PhD has focused on validation of the diatom-bound nitrogen isotope proxy (δ¹⁵N_db), which can record downcore nutrient dynamics, by examining the relationship between cultured diatoms, sinking particles, and sediment records. The Schlanger Fellowship will allow me to add an additional component to my research – a new mid-Holocene downcore record of δ¹⁵N_db from IODP Site 1090 off the West Antarctic Peninsula that will help address key questions relating deep-water intrusion onto the shelf, productivity cycles, and biologically mediated CO₂ drawdown.

Active microbial community survival in Mariana Forarc sediments

Abstract
The marine deep subsurface is one of the largest unexplored biomes on the planet. Subsurface sediment from International Ocean Discovery Program Expedition 366 to the Mariana Forearc serves as an ideal location to explore microbial community structure, function, and methods for survival. Mariana Forearc includes serpentine mud volcanoes along a ridge that were characterized as methanogenic, sulfidic, and high pH. The objectives of this expedition were to analyze the sedimentary microbial populations and evaluate their contribution to the surrounding geochemistry. This project addresses these objectives while providing insight into survival within this extreme environment.

Biography

My interest in microbial competition and survival began as an undergraduate at the University of Southern Mississippi. I studied marine biology and conducted research in Dr. Mohamed Elasri’s lab. My research focused on Staphylococcus aureus and its ability to persist against antimicrobial compounds. This foundation led me to pursue my PhD with Dr. Brandi Kiel Reese at Texas A&M University – Corpus Christi. I am generally interested in microbial community function and survival mechanisms within natural environments. My project focuses on the serpentinizing seamounts of the Mariana Convergent Margin from the International Ocean Discovery Program Expedition 366. I will be using culture dependent and culture independent analyses using sediment across the ridge and the flank of the seamounts to determine how and which microbes survive within subduction zones.

What drives plankton evolution? : An investigation of the paleoenvironmental impacts on radiolarian macroevolution using the constrasting histories of tropical and polar Neogene oceans

Abstract
Despite the crucial role of plankton in ocean ecosystems, geochemical cycling, and regulating Earth’s climate, specific environmental impacts on their biodiversity remain poorly
understood. Radiolarians are siliceous zooplankton that are globally abundant and speciose across latitudes throughout the Neogene. This study will document radiolarian biodiversity and turnover from 23-1 Ma in the Eastern Equatorial Pacific (EEP) for comparison to a similar Southern Ocean dataset and regional paleoenvironmental proxies. Understudied relative to other plankton, radiolarians provide an opportunity to examine potential driving factors (i.e. ocean temperature, watermass structure, and nutrient availability) that manifest themselves differently at low and high latitudes.

Biography

The relationship between evolution and environment is what fascinates me most about the natural world.  Inspired by my time as a ranger, exploring the parklands of Oregon and California, I decided to shift academic focus from literary studies to geology upon entering graduate school.  For my MS, I worked with Alycia Stigall at Ohio University to constrain the timing of the Great Ordovician Biodiversification Event using brachiopods from North America.  This experience was not only vital to my development as a researcher, but also gave me an appreciation for the quality, sample sizes, and continuous nature of the fossil record preserved in deep-sea sediment cores.  Now at the University of Nevada with Paula Noble and Dave Lazarus, my goal is to characterize radiolarian evolutionary patterns in the context of paleoclimate.  I look forward to examining the potential impacts of multiple environmental factors on biodiversity, community structure, and turnover rates throughout the Neogene.  I hope this will better establish the controls on plankton evolution, and contribute to our understanding of how ocean ecosystems respond to climate change.