Research

What we do in the Joye Research Group

Biogeochemistry is an interdisciplinary science that examines how biological processes mediate the geological and chemical dynamics of the Earth's hydrosphere and lithosphere. The integrative nature of biogeochemical research requires application of tools from different disciplines, including: microbiology, biochemistry, analytical chemistry, geochemistry, ecology, hydrology, mathematics, physics, and many others.

Molecular Biological studies of microbial communities using DNA, RNA, or protein based approaches reveal information about microbial community structure and potential metabolic activity.

By combining biogeochemistry and molecular biological data sets, we can document the microbial community composition (which microbes are there?) and elucidate their metabolic potential (what processes can they mediate?) as well as their actual activity (what processes are they mediating?).

A fundamental challenge for environmental scientists is to identify and understand the factors that regulate rates of biogeochemical processes. This requires that we understand the factors that regulate microbial community composition and microbial activity, as the latter reflects the active portion of the total microbial community. Evaluating variations in microbial community structure and in rates of biogeochemical processes provides the information needed to begin to identify links between environmental forcing functions, microbial structure, and microbial community function. Such information will permit us to begin to develop mechanistic models of how biogeochemical cycles will respond to global change.

The Joye Group research examines the biogeochemical cycling of nutrients (nitrogen and phosphorus), dissolved gases (dinitrogen, nitrous oxide, oxygen, methane, carbon dioxide, and hydrogen), trace metals (iron and manganese), carbon, and sulfur in a variety of systems, ranging from saline lakes to temperate and tropical coastal environments to deep ocean sediments and brines to Antarctic lakes and Arctic seas. Several projects include parallel studies of biogeochemical and molecular ecological dynamics with the aim of identifying fundamental feedbacks between environmental variables, microbial community composition, and microbial activity.

Areas of focus include coastal ecology and the study of microbial metabolism in and adaptation to “extreme” environments. Our study areas cover deep sea extreme environments, including hydrothermal vents, colds seeps, and gas hydrates; natural and accidental hydrocarbon discharges; coastal biogeochemistry, including salt marshes, mangroves, and groundwater; climate change in temperate coastal and arctic ecosystems; and surficial extreme environments, including polar and temperate salt lakes. Detailed information on these study areas are provided in the links below.

Brief Overview of the Research Areas

Coastal Biogeochemistry

We strive to identify and understand the environmental and physiological controls on elemental cycling (e. g., N, P, C, O, S, Fe, Mn ...) and ecosystem metabolism in coastal regions. A primary goal of this work is to identify how coastal ecosystems respond to global change and various natural and anthropogenic forcing functions.

We utilize a broad, cross-disciplinary approach to address biogeochemical research questions. We value innovative technologies and incorporate new methodologies and approaches into our research program as they become available. Our work exploits traditional biogeochemical (e.g., radio- and stable- isotopic tracers, physiological inhibitor-based studies), microbiological (e.g., enrichment culture work, microbial isolations), molecular biological (e.g., PCR, cloning and sequencing), and geochemical (e.g., rate measurements, stable isotopes, and constituent concentration profiles) to examine rates of individual processes at local and system-wide scales. Significant effort is put towards developing novel approaches and techniques to address research questions.

We have worked or are working in a variety of coastal environments, including salt marshes along the coast of Georgia, South Carolina, Louisiana, and Massachusetts, and mangrove forests in Florida, Belize, and Panama.
Coastal Biogeochemistry- Mangrove Biogeochemistry

Coastal Biogeochemistry- Groundwater Biogeochemistry

Coastal Biogeochemistry- Sediments

Extreme Environments

Examining the interrelationships between organisms and the environments in which they exist is a basic goal of biogeochemistry. When such studies focus on life-supporting environments that exist near the extremes of planetary conditions, new insight can be obtained regarding the evolution of life on Earth and the ability of microorganisms to adapt to a variety of physiological extremes, e.g., temperature, salinity, pressure, etc. The study of extreme environments is often referred to as "Astrobiology.”

Our research in extreme environments examines chemoautotrophic processes (methane oxidation and nitrification) as well as heterotrophic processes (carbon oxidation, sulfate and metal oxide reduction and denitrification). We use traditional biogeochemical approaches and molecular biological and organic geochemical methods to quantify rates of specific processes, access microbial diversity and genetic potential, and to identify novel microorganisms with unique physiologies.

This research is supported by the National Science Foundation, the National Institute for Undersea Science and Technology, by the American Chemical Society's Petroleum Research Fund, and the Gulf of Mexico Research Initiative.
Deep Sea Extreme Environments

Surficial Extreme Environments- Biotic and Abiotic nitrous oxide sources

Surficial Extreme Environments- Mono Lake

Surficial Extreme Environments- Microbially Mediated Anaerobic Carbon Cycling

Accidental Hydrocarbon Discharges in Marine Environments

Our research of accidental discharges of oil and gas into marine environments seeks to understand the rates of degradation by microbial and geochemical processes as well as the ultimate fate of these influxes. Our work thus far has focused on the 2010 Gulf of Mexico Macondo Well Blowout (Deepwater Horizon) incident but will include future deepwater drilling accidental discharges.
Hydrocarbon Discharge in Marine Environments

Climate Change

The effects of climate change on the environments we study pervade our research, but we are specifically looking at the consequences of climate change in temperate coastal and arctic ecosystems.
Climate Change- Degrading Offshore Permafrost

Climate Change- Temperature Changes

Climate Change- Salinization of Freshwater Coastal Wetlands