People

Jessica Balerna – Ph.D. student
Jessica studies how outcomes of aquifer hydrology management alter surface-water and wetland ecology in ways that feed back on human perceptions of environmental change and management. Jessica is broadly interested in urban aquatic ecology and codetermination of integrated human and natural systems.

Cassie Campbell – Ph.D. student
Cassie studies ecological and biogeochemical drivers and outcomes of mangrove distribution, with particular interest factors that may facilitate or constrain mangrove range adjustments in response to climate change.

Carley Defillips – M.S. student and Nitrogen S-STEM scholar
My professional goal is to improve the stormwater system to prevent pollution associated with urban run-off. Stormwater run-off often directly flows into greater water bodies such as lakes, rivers, or oceans. Urban pollutants such as excess nutrients, toxic chemicals, and plastics negatively impact their recipient ecosystems by degrading habitat quality and lowering biodiversity.

Sarita Emmanuel – Ph.D. student
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David Lewis – Associate Professor
I am interested in understanding controls on the flux and storage of nutrients and energy in ecosystems, human-environment interactions, and their implications for ecosystem structure and function. My research presently focuses on freshwater wetlands and intertidal habitats in mixed-use landscapes. I also study soil biogeochemistry in managed landscapes ranging from urban yards to farms and forests. I collaborate with natural and social scientists and environmental managers to better understand the dynamics of coupled natural-human socioecosystems. My teaching program includes graduate and undergraduate courses on various areas of ecology and environmental science.
orcid.org/0000-0002-8094-1577

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Alumni

Bert Anderson – M.S. 2019
Master’s thesis: The distribution and biogeochemistry of algal mats of the coastal salt pans of west central Florida

My research focused on describing the spatial arrangements of coastal salt pans within their landscape. Scattered throughout these rare and understudied unvegetated patches are mats of algae and microbes. Where these microbial mats occur and the nature of their biogeochemical consequences on surface soils were central to my master’s thesis research.

Sandra Voors – M.S. 2018, B.S. 2015
Master’s thesis: Ecosystem Function and Phenotypic Variation in Spartina Alterniflora Salt Marshes

My thesis research investigates the relationship between plant functional traits and nutrient cycling dynamics in tidal salt marshes. I am interested in exploring the feedbacks that drive the cycling and storage of carbon and nitrogen in marsh soils, and the corresponding phenotypic variation in smooth cordgrass, Spartina alterniflora.

Sandy is twice a lab alum! She did an undergraduate honors thesis in the lab. See her undergraduate research poster.

Kristen Langanke – M.S. 2017
Master’s thesis: Response to nitrogen and salinity conditions in Rhizophora mangle seedlings varies by site of origin

Using a common garden experiment, Kristen investigated differences among sites (plausibly, populations) and maternal lineages in the growth responses and survivorship of red mangrove (R. mangle) seedlings to manipulations of salinity and nutrient (specifically, nitrogen) supply. The research sheds light the scope for plasticity and the importance of within-species diversity in coping with expected coastal environmental change such as sea level rise and eutrophication. Kristen was primarily advised by Dr. Christina Richards, while also being a member of the Lewis Lab.

Annie Majette – lab manager and technician
Annie is also a lab alumnus! She conducted her undergraduate honors thesis research in the lab, graduating in 2018. Her thesis examined the possible adjustment of soil microbial function to long-term exposure to elevated temperatures. Working in intertidal sediments, she studied thermal effects on nutrient storage and mineralization along temperature gradients. Now as a technician, her interests lie in applications of pXRF technology for soil elemental analysis.

Andres Santini Laabes – Undergraduate & Post-Bacc researcher
Andres’ research examines longitudinal and temporal variation in a nutrient and organic carbon concentrations in a stream as it moves through a variety of urban and riparian forest land use types and past potential point sources of pollution.

Kirsti Martinez – B.S. 2014, Honors, Goldwater Scholar
Undergraduate honors thesis: “Lateral and vertical components of leaf litter inputs to mesic flatwood and floodplain swamp ecosystems on a subtropical toposequence”

Soil properties are strongly shaped by plants, as plants are the principal source of organic matter to soil, and shape the physical and chemical environment through shading, root growth, and a host of other mechanisms. Yet, soils do not always “match” the plants they are found beneath. Kirsti explored a possible mechanism for this mismatch to investigating the magnitude and lateral redistribution of plant leaf litter across an quintessential Florida landscape.

Viviana Penuela – M.S. 2014
Master’s thesis: “Influences of yard management intensity on urban soil biogeochemistry”

Viviana investigated how lawn management practices give rise to soil biogeochemical differences among lawns that are located on the same soil types. She was particularly interested in examining the practice of irrigating lawns with reclaimed water, and investigating whether the chemistry of reclaimed water rendered it a stressor or a nutrient subsidy for soil microbial communities. Viviana is now an Environmental Specialist for the FL Dept of Environmental Protection

Sharon Feit – M.S. 2012
Masters thesis: “Variability in hydrology and ecosystem properties and their role in regulating soil organic matter stability in wetlands of west-central Florida.”

Sharon now works for Barr, an engineering and environmental consulting firm in Minnesota, where she works on endangered species, habitat assessments, wetland/waterbody surveys, and regulatory permitting.

Kristine Jimenez
Lab Manager and Research Technician, 2011-13
Kristine spearheaded a project using the rare stable isotope  of nitrogen (15N) to investigate rapid storage of N into stable organic forms in coastal wetland soils, focusing on salt marsh and mangrove forest habitats. She also managed our lab, from coordinating schedules and budgets to maintaining highly specialized instrumentation. Finally, while here at USF, she participated in outreach by using soils to explore sustainability themes with Native American students at the College of Menominee Nation, in Wisconsin. After departing from the lab, Kristine was first a technician and manager in the Univ. of Cincinnati Stable Isotope Biogeochemistry facility, and then moved on to a technician/scientist position at Cincinnati Children’s Hospital.

Jewel Brown – B.S. 2012, Honors
Undergraduate honors thesis: Interactive effects of simulated sea-level rise and warming on microbial carbon and nitrogen cycling in mangrove and salt marsh soils.

Selected for presentation at the USF Undergraduate Research and Arts Colloquium. Jewel went on from the lab to medical school at the Univ. of South Florida, from which she graduated in 2017.