Current Projects

Linking microbial community composition to ecosystem function:

• Lead PI, 2022-2025, National Science Foundation, Molecular and Cellular Biosciences (MCB-2153767), $687,229; Transitions: Metagenomics of aquatic biofilms: evaluating linkages between autotrophic and heterotrophic microbial diversity and function.
  
• Lead PI, 2023-2026, Department of Energy (DOE) Joint Genome Institute (JGI) New Investigator Community Sequencing Program (CSP) (DOE-509684), value of services from JGI: $50,000. Using metatransciptomics to link aquatic biofilm microbial diversity and function.
  

The overarching goal of this research is to use molecular techniques to bridge the gap between microbial community composition and functioning within natural environments. Boreal peatlands provide a model ecosystem to examine relationships between microbial structure and function owing to their role in global carbon storage. Many ecosystem processes (e.g., carbon cycling) are mediated by microorganisms and understanding how microbial functions scale up to the ecosystem level is an important goal in ecology. Therefore, my students and I are examining both the eukaryotic (algae) and prokaryotic (bacteria) diversity of the biofilm microbiome (i.e., who is there?) and identify functional traits (i.e., what do they do?) with the goal of relating changes in microbiome structure and function to peatland carbon dioxide emissions.

Plant-microbial interactions in northern wetlands:

• Co-PI, 2022-2025, National Science Foundation, Division of Environmental Biology (DEB-2141285). $199,895; RUI: Source or sink: Does plant-microbial interactions determine the direction of carbon flux during the wet phase of northern peatlands?
  

The goal of this project is to examine the extent to which plant subsidies govern ecosystem carbon emissions by regulating the composition of microbial biofilms. Compared to our understanding of biofilm ecology in most other environments, our knowledge of microbial interactions within wetlands is lacking. This knowledge gap is particularly evident in peatlands, a common landscape feature at northern latitudes. In peatland ecosystems, vascular plants and mosses have the potential to shift the metabolic balance of the microbial biofilm in favor of heterotrophy by providing carbon subsidies that allow heterotrophs to outcompete autotrophs for available nutrients. Given that some plant subsidies are more labile than others, the ability for plants to facilitate microbial activity may depend on plant community composition. However, the impact of plant community structure on microbial biofilms has not been widely studied in peatlands. As a result, it is difficult to predict how shifts in plant functional groups, such as those occurring with climate change, influence the carbon balance of northern peatlands.

Aquatic-terrestrial linkages in boreal peatlands regulate ecosystem processes:

• Co-PI, 2020-2025, National Science Foundation, Division of Environmental Biology (DEB-2011286) Long Term Research in Environmental Biology (LTREB) Program. $600,000; LTREB: Collaborative Research: Long-term changes in peatland C fluxes and the interactive role of altered hydrology, vegetation, and redox supply in a changing climate.

Northern peatlands are a critical component of the global carbon cycle and their response to climate change will play a key role in determining future concentrations of atmospheric carbon dioxide. Hydroperiods of northern peatlands are becoming increasingly variable with climate change and it has become apparent that flooded conditions are now a common characteristic of the landscape and need to be considered with respect to carbon storage. Recent studies have shown that elevated carbon dioxide emissions associated with enhanced decomposition during flooded conditions can be offset by autotrophic biofilm development. However, altered hydrologic regimes are also causing shifts in plant functional groups which have the potential to influence biofilm development by altering the amount and composition of organic matter available for heterotrophic microorganisms. The goal of this project is to examine the effects of hydrologic regime on the relationship between algal production and carbon dioxide emissions.

Trophic interactions regulate carbon dioxide emissions from boreal peatland ecosystems:

• Co-PI, 2017-2021, National Science Foundation, Division of Environmental Biology (DEB-1651195). $297,879; EAGER: Assessing the role of trophic interactions on peatland carbon cycling under varied nutrient availability.
  

The exchange of carbon between organisms and the environment regulates the fate of atmospheric carbon dioxide within globally important reservoirs. Species interactions mediate the exchange of carbon by altering the balance between photosynthetic carbon fixation (i.e., uptake of carbon dioxide from the atmosphere) and heterotrophic respiration (i.e., emit carbon dioxide to the atmosphere). For instance, predators can influence ecosystem carbon storage by regulating the density of prey, and in doing so, induce a trophic cascade that affects the biomass of lower trophic levels and thereby the amount of carbon fixed by primary producers. However, no efforts to date have evaluated the role of animals in mediating carbon storage through trophic interactions in peatlands, which are a critical component of the global carbon cycle. This research evaluated how interactions between nutrient availability (bottom-up effects) and predation (top-down effects) interact to control food web structure and carbon cycling in northern peatlands.

Environmental controls on toxic cyanobacteria:

• Lead PI, 2016-2017, Indiana Water Resources Research Consortium, U.S. Geological Survey (G11AP20078). $49,856; Predicting toxic cyanobacteria blooms in the Wabash River Watershed.
  

We are interested in the influence of environmental degradation on the occurrence of harmful algal blooms (HABs). Harmful algal blooms have been widely attributed to anthropogenic nutrient inputs and increasing water temperatures, which promote nuisance growth of toxin-producing cyanobacteria. Despite considerable research examining the environmental controls on toxin-producing cyanobacteria, little is known about the factors that regulate the release of toxins from cyanobacterial cells or degradation of cyanotoxins by heterotrophic bacteria following release. Understanding when cyanotoxins are present and the environmental factors associated with toxicity is critical to effective water quality management and the reduction of health risks associated with cyanotoxin exposure.