The Aquatic Microbial Ecology Research Group at the University of Tennessee



Steven W. Wilhelm, Ph.D. (Western Ontario)

Professor of Microbiology and benevolent dictator

Professor Wilhelm is the laboratory PI and responsible for herding cats, chaos control, wine selection and middle relief.

Steven Wilhelm is the Kenneth and Blaire Mossman Professor of the Department of Microbiology.  Professor Wilhelm is a Fellow of the American Academy of Microbiology as well as a Sustaining Fellow of the Association for the Sciences of Limnology and Oceanography (ASLO). In June of 2021 he was named the winner (along with Curtis Suttle) of the John H Martin Award from ASLO for their initial description of  the viral shunt. In 2022 he was named a fellow of the American Association for the Advancement of Science (AAAS).

Gary LeCleir, Ph.D. (Georgia)  

Research Assistant Professor, REU Director

Dr LeCleir came to Knoxville in 2006 after completing his PhD at the University of Georgia.  He is our in house statistical guru, field deployment leader and reigning karaoke champion. 

Along with teaching in the Departmental core curriculum, Dr LeCleir also serves as  the director of the NSF-FUNDED REU site run by the department.

Robbie Martin, Ph.D. (Tennessee)     


Postdoctoral Associate


Robbie joined the lab in late 2012 as a PhD student and has been a virtual Jack-of-all-trades.  After completing his PhD he accepted our offer to stay on to continue to work on our toxic cyanobacterial projects.  Presently Robbie is setting running chemostat studies of Microcystis gene regulation and physiology that will feed into modeling studies by collaborators at  the Technical University of Berlin.

Emily Chase, Ph.D. (Aix-Marseille University)       

Postdoctoral Associate

Emily joined the lab in early 2022 after completing her doctoral work in France as well as a MSc and BSc at Acadia (Canada).  She has joined the group to work on our AaV genetics team, seeking to develop tools to make the genome of this virus tractable.


Brittany Zepernick,  Ph.D. (Tennessee)       

SEC Postdoctoral Associate

Brittany joined the lab in fall 2018 as part of our harmful algal blooms team and defend her PhD in Spring 2023. Recently she was awarded a prestigious SEC Postdoctoral Fellowship to continue her investigations on pH effects on plankton communities. She will be working on our collaborations with researchers in Ohio, Michigan and NC to examine factors that drive Microcystis success and ecological outcomes in large lakes with a focus on competition with diatoms.  Along with being a NSF-GRFP winner, she held a Tennessee Fellowship for Graduate Excellence.  Most recently she has jumped deeper into the world of freshwater diatoms to try and understand how they bloom in winter months.

Liz Denison,  M.Sc. (UNC Wilmington)       

Doctoral Candidate, Microbiology

Liz joined the lab in fall 2019 after completing a MSc project looking at cetacean microbiomes.  Currently she is working with our collaborators at ORNL and Duke on a project to examine virus activity in Sphagnum bogs that are part of the DOE Project Spruce initiative.   Along with examining the effects of temperature on virus infection, Liz is becoming our in-house expert on all-things mitovirus. Currently she holds a UT GATE Fellowship for her work.


Gwendolyn Stark,  B.Sc. (SUNY ESF)       

Doctoral Candidate, Microbiology

Gwen came to the lab in fall 2019 with an interest in toxic cyanobacteria and fresh waters.   Presently she is working with Robbie Martin on the cold temperature phenotype in Microcystis as well as resolving strain variability that we see between different Microcystis isolates.

Alex Truchon,  M.Sc. (U Mass Amherst)       

Doctoral Candidate, Microbiology

Alex joined the lab in the fall of 2020 where he is working as part of the Aureococcus team.  Along with working on resequencing the virus and some hosts, he will be continuing our efforts to make the AaV virus-host system genetically tractable. Alex was awarded a Tennessee Fellowship for Graduate Excellence when he joined UT.

Katelyn Hougton,  M.Sc. (U West Florida)       

Doctoral Candidate, Microbiology

Katelyn joined the lab in late 2021 to work with us on our projects examining virus - host interactions.  She will be using single-celled approaches to transcriptomics and samples from the Sargasso Sea to tease apart "who infects who".


Ashton Stark, B. Sc.   (James Madison) 

Doctoral Candidate, Microbiology

Ashton is a JMU alum and former NSF REU student from the UTK program in Microbiology.

Presently a graduate student rotator, she is splitting her time between Aureococcus and our new interests in the role of fungi in carbon cycling in large lakes.


David Niknejad, B. Sc.  (Tennessee)  

Masters Candidate, Microbiology

David was a UTK Microbiology major who worked with Brittany on her efforts to examine competition between Microcystis and diatoms.   He has also participated  - along with Robbie Martin - in our collaborations with the Hans Paerl lab to examine the effects of nutrient reduction on microbial communities and Microcystis in Lake Erie.

Now he has moved onto a graduate project where he is collaborating with a local citizens group to establish a baseline understanding of the plankton of the Tennessee River.

Laura Smith, M.Sc. (Delaware)

Research Associate

With a BSc from The Ohio State University and a MSc from Delaware, Laura has joined the lab in early 2021 to help our team working on all thing Microcystis. Along with maintaining culture stocks she will be helping to get our various chemostats up and running (and keep them that way) for experiments ranging from long term evolution influences to the effects of episodic events.



Graduate student alumni


Brittany Zepernick

Investigating drivers of algal bloom succession in Lake Erie  (Ph.D. 2023)

Naomi Gilbert

Constraints on microbial variability in the open ocean (Ph.D. 2022)

Helena Pound

Microbial Community Dynamics of a Microcystis Bloom (Ph.D. 2021)

Eric Gann

Physiological and ecological characterization of the Aureococcus anophagefferens virus host system (Ph.D. 2020)

Samantha Coy

Tool development for model studies on the interactions between a eukaryotic algae and a giant virus (Ph.D. 2019)

Robbie Martin

Ecological constraints of toxic cyanobacterial blooms (Ph.D. 2018)

Lauren Krausfeldt

Molecular characterization of factors constraining the success and toxicity of Microcystis blooms (Ph.D. 2018)

P. Jackson Gainer

Microbial interactions in the North Pacific Ocean (Ph. D. 2018)

Joshua Stough

Prediction of host-microbe interactions from community high-throughput sequencing data (Ph.D. 2017)

Mohammad Moniruzzaman

Molecular and ecological aspects of interactions between Aureococcus anophagefferens and its giant virus (Ph.D. 2016)

Morgan Steffen 

Systems biology of Microcystis blooms (Ph.D. 2014)

Shafer Belisle 

Urea as a nutrient source for Lake Erie blooms (M.Sc. 2014)

Tiana Pimentel 

Environmental constraints on cyanomyophage in the Pacific Ocean (M.Sc. 2013)

Claire Campbell

The effects of nutrient limitation and cyanophage on heterotrophic microbial diversity (M.Sc. 2012)

Audrey Matteson

Quantification and ecological perspectives on cyanophage and aquatic viruses (Ph.D. 2011)

Matthew Saxton   

Constraints on primary production in Lake Erie (Ph.D. 2011)

Star Loar  

Seasonal Variation in Lake Erie picoplankton (M.Sc. 2009)

Janet Rowe 

Ecological aspects of viruses in marine systems (Ph.D. 2008)

Johanna Rinta-Kanto

Biogeography and genetic diversity of toxin producing cyanobacteria in a Laurentian Great Lake (PhD. 2006)

Leo Poorvin

The role of viruses in Fe cycling in the World's oceans (Ph.D. 2005)

Julie L. Higgins

Virus dynamics in high nutrient - low chlorophyll marine surface waters (M.Sc. 2005)

Cecile E. Mioni

Using a bioluminescent bacterial bioreporter to assess iron bioavailability in the ocean (Ph.D. 2004)

Melanie Eldridge

The effects of Fe on plankton in HNLC regions of the world's oceans (Ph.D. 2004)

Amanda L. Dean

The dynamics, distribution, and activity of viruses in Lake Erie (M.Sc. 2004)

Shannon Pedigo-Eftland

The effects of iron on growth and physiology of the cyanobacterium Microcystis aeruginosa (M.Sc. 2004)

Johanna Rinta-Kanto


The effects of viral size class enrichments on microbial communities in marine systems   (M.Sc. 2001)



updated 11/09/2023