Montana State University

Priscu Research Group

Department of Land Resources
and Environmental Sciences

334 Leon Johnson Hall
Bozeman, MT 59717

Tel: (406) 994-3250
Fax: (406) 994-5863

Graduate Student Research Projects

Trista Vick-Majors, PhD Student:

Trista's dissertation work aims to answer the question, “how does the ensemble of environmentally imposed energetic constraints impact nutrient cycling in microbially dominated systems?”, through the following projects:

Physiological ecology of microorganisms in the water column of Subglacial Lake Whillans, Antarctica (Geomicrobiology of Subglacial Environments, GBASE):
Recent recognition of the widespread nature of liquid water beneath the Antarctic ice sheet has generated new interest in subglacial aquatic environments as microbial habitats. These environments have been hypothesized to contain active ecosystems and encompass stores of organic matter and nutrients of unquantified significance to Earth’s biogeochemical cycles. Subglacial Lake Whillans lies 800 m beneath the surface of Whillans Ice Stream, West Antarctica. Remote sensing data indicate that the lake lies near the end of a hydrological flow-path and periodically flushes into the sea under the Ross Ice Shelf. Trista used radiolabeled substrates to measure rates of microbial activity (heterotrophy and chemolithoautotrophy) and nutrient transformations in Subglacial Lake Whillans, and plans to repeat these experiments at the Whillans Ice Stream grounding zone where the water from Subglacial Lake Whillans is predicted to enter the ocean and create an ice-covered estuary.
--The WISSARD project is funded by the NSF Office of Polar Programs through the American Recovery and Reinvestment Act, NOAA, NASA, and the Gordon and Betty Moore Foundation.

Microbial assemblages during the Polar Night transition (MIRADA LTERs):
High latitude environments, such as the McMurdo Dry Valley lakes, are subject to seasonally segregated light/dark cycles, which have important consequences for microbial diversity and function on an annual basis. To determine community-level responses to a changing energy regime, Trista worked with the MIRADA LTERs (http://amarallab.mbl.edu/mirada/mirada.html) to use 454-based rRNA gene tag sequencing to sample archaeal, bacterial, and eukaryal microbial assemblages in McMurdo Dry Valley lakes Fryxell and Bonney during the height of photosynthetic primary production during the Austral summer, and as photosynthesis shut down during the autumn sun-set. She used network analysis to look for inter- and intra-domain interactions indicative of adaptation to the loss of photosynthetic carbon.
--This project is funded by a NSF IPY grant from the Office of Polar Programs and by the NSF through the LTER network.

Biogeochemical characteristics of sub-Ross Ice Shelf waters near McMurdo Sound, Antarctica:
The McMurdo Ice Shelf lies off of the Victoria Coast of Antarctica, and comprises the northwest corner of the Ross Ice Shelf. The underlying water is mainly sourced from McMurdo Sound via a channel to the Ross Sea. In December 2012, as a test of WISSARD instrumentation, the WISSARD team penetrated the McMurdo Ice Shelf with a hot water drill. Water samples were collected with Niskin bottles deployed to 30 m and 850 m below the ice water interface and an in situ water filtration unit deployed to 850 m was used to collect samples for DNA extraction. Trista is analyzing the biogeochemical characteristics of this permanently ice-covered oceanic environment, in collaboration with members of the WISSARD team. She is using fluorescence analysis of dissolved organic matter (EEMs) to compare dissolved organic matter in the deep and shallow water samples, along with measurements of bacterial activity, geochemical parameters, and microbial community composition data provided by collaborators at Louisiana State University to provide insights into this under-sampled oceanic environment.
--The WISSARD project is funded by the NSF Office of Polar Programs through the American Recovery and Reinvestment Act, NOAA, NASA, and the Gordon and Betty Moore Foundation.

Alex Michaud, PhD Student:

Geomicrobiology of Subglacial Antarctic Subglacial Environments (GBASE) (2010-present):
As part of the GBASE component of the WISSARD (Whillians Ice Stream Subglacial Access Research Drilling) project, Alex will be studying .

Ice nucleation bacteria in hailstones (2010-present):
The discovery of ice nucleation active bacteria has had broader implications than previously realized.  Study of these bacteria has been confined to snow and rain, but a recent hailstorm in Bozeman has stimulated the hypothesis that they may play a role in nucleating hailstones.  Graduate student Alex Michaud is conducting investigations on this hypothesis, which will help in further understanding of the role of hailstones in the world's hydrologic cycle.
--Work on this project is being conducted in MSU's Subzero Science and Engineering Facility.
--This project is funded by an NSF IGERT Fellowship.

Cyanobacteria in the McMurdo Dry Valleys (2009-present):
The McMurdo Dry Valleys (MCM) have been the focus of study for many years as a model system for understanding ecosystem dynamics and life at the extremes.  The study of Cyanobacteria has revealed insight to these questions and continues to be valuable for investigation, as Cyanobacteria occur in very diverse ecological niches.  Graduate student Alex Michaud is conducting a study that probes the diversity of Cyanobacteria present at several habitats throughout the cold, dry habitat of Taylor Valley, Antarctica.  Using the 16S rRNA gene sequence and the 16S-23S internal transcribed spacer (ITS), Alex compares the diversity of genera detected using each of these phylogenetic markers, and draws conclusions regarding dispersal and distribution of Cyanobacteria in Taylor Valley.  A solid understand of how Cyanobacteria disperse will lend insight into how bacteria are transported in the Dry Valleys of Antarctica.
--This project is funded by the National Science Foundation, Office of Polar Programs, and an NSF IGERT Fellowship.

Pamela Santibanez Avila, PhD Student (Fulbright- CONICYT Scholarship from Chile)

Biological measurements in West Antarctic Ice Sheet (WAIS) Divide ice core (2010-present):
West Antarctic Ice Sheet (WAIS) Divide is a U.S. deep ice coring project funded by the NSF as a component of the larger WAISCORES initiative.  WAIS Divide is collecting a deep ice core from the flow divide in central West Antarctica in order to develop a unique series of interrelated climate, ice dynamics, and biologic records focused on understanding interactions among global Earth systems during the Last Deglaciation (LD). As part of this collaborative project to generate high-resolution chemical and biological records from the WAIS Divide ice core, Pamela will work with a Microcyte flow cytometer, epifluorescence microscopy and scanning electron microscopy to detect and determine bacterial density and viability, and characterize biological markers in ice cores. Biological data can provide new, novel and corroborative information that will allow a full interpretation and reconstruction of paleoclimate and paleoatmospheric composition in ice-cores from cold and temperate glaciers.
--This project is funded by the National Science Foundation, Office of Polar Programs.

She is also collaborating on a project in Barrow, Alaska. This project examines microbial life in seasonally ice covered lakes and is funded by the NASA Astrobiology Institute (NAI).

Jeff Patriarche, M. Sc. Student

Long-Term changes in phytoplankton diversity in McMurdo Dry Valley lakes:
Jeff is working as part of the Longterm Ecological Research (LTER) project in the McMurdo Dry Valley lakes. He is analyzing data from the bbe Fluoroprobe, a submersible spectrofluorometer which differentiates the following groups of phytoplankton: Cyanobacteria, Chlorophyta, Chrysophyta, Cryptophyta. He will look at changes in spring/summer diversity from 2004-2014, and at changes in diversity over the Polar Night period (November - April 2007). He will also work with data collected as part of the NASA project that currently has a bbe Fluoroprobe profiling every day in West Lake Bonney.
--This project is funded by the National Science Foundation, Office of Polar Programs.

Priyanka Kudalkar, M.Sc. Student

The role of fungi in the permanent ice covers of lakes in the McMurdo Dry Valleys (2013-present):
The permanently ice covered lakes of Antarctica harbor a diverse group of microbes that live in unique liquid water habitats. Priyanka's research focuses on the functional role offungi in the permanent ice covers of lakes in the McMurdo Dry Valleys. Genomic methods to screen for functional genes are used to identify novel fungal types unique to this region of Antarctica. Results from the study will be the first to address the structure and function of fungi in these subzero habitats and the potential for eukaryotic life to exist in icy worlds beyond Earth.
--This project is funded by the National Science Foundation, Office of Polar Programs.