Research

About My Research

Freshwater ecosystems have been increasingly threatened by human activities and my research aims to broadly understand these threats by way of examining the aquatic carbon cycle. My research program examines dissolved organic matter (DOM) primarily as well as nutrients in freshwater ecosystems.

My research links the physical, chemical, and biological components of aquatic ecosystems and addresses the consequences of global change drivers (e.g., climate change, land use change, flooding) on the structure and function of lakes and rivers. My long-term goals are to understand how DOM composition and its interactions with climate, landscape, and other ecosystem drivers (e.g., nutrients, temperature) affect the structure and function of aquatic ecosystems.

Despite their relatively small geographic footprints, freshwater ecosystems play an important role in the global carbon cycle. Dissolved organic matter is an important reason for this because it is one of the most active and mobile carbon pools. However, although we know that this matter is important for ecosystem processes, we don’t fully understand how human activity affects its composition in freshwater ecosystems.

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Current Projects

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1) Biogeochemistry of Dissolved Organic Carbon.

We have been working in this research area for almost two decades, funded primarily by the NSERC Discovery Program and Canada Research Chair. We have completed extensive research linking river and lake DOM dynamics to land use, climate and other human activities. We have found that anthropogenic land use modifies DOM quality in freshwater ecosystems, mobilizes fossil DOC, controls food webs (e.g., benthic diatom biodiversity and increases ecological functions such as microbial activity, community respiration, enzyme activity, and nutrient uptake. While our knowledge of DOM chemistry has progressed rapidly over the past decade, there remains a need, and with this CRC I propose, to better integrate this knowledge into an ecosystem-level understanding to better model both C fluxes across waterscapes and the ecological functioning of freshwater.

2) Non-Linear Changes, Regime Shifts and Early Warning Indicators.

There is now increasing evidence that non-linearity is a common response in ecological systems to pressures caused by human activities. Using long-term datasets we are focusing this research theme to:

1) better understand non-linearity in freshwaters and the environmental drivers that moderate non-linearity and

2) detect sudden transitions to find early-warning signals to better anticipate and manage regime changes. We are applying this framework to several systems including using RAEON high-frequency data collected using autonomous instruments for early indicators of algal blooms in Lake Erie and other long-term monitoring datasets to detect regime changes (e.g., Lake Simcoe).

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3) Climate Change and Floods: Understanding Biogeochemical, Ecosystem Services and Function

We are involved in a few projects to better understand how water levels, high flow events and floods affect river and lake ecosystem services and function. This is currently being completed under the funding of an NSERC Strategic Network Grant (FloodNet) focused on improving flood forecasting systems and management capacity in Canada. We are also characterizing natural water levels in lakes and rivers to explore the effects of dams as well as the used of concentration-discharge curves for ecosystem management.

4) Aquatic Carbon Budgets

Initially funded by an NSERC Strategic Project we are currently constructing a carbon balance of Lake Erie. With additional funding from the CRC program, we are now expanding this to include DOM composition into C-budgets as well as expanding these measurements to others lakes and rivers. To determine the quality of DOM exported by aquatic ecosystems and whether they act as a sink or source of carbon, we will incorporate DOM quality measurements into studies of short (e.g., storm events) and longer term (2-year field seasons) fluxes of DOC, inorganic carbon (DIC, CO2), particulate carbon and nutrients entering and leaving several streams and lakes of contrasting average DOM composition.

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What I Teach

I currently teach/have taught several classes in ecology:

  • BIOL 2260h/ERSC 2260h: Introductory Ecology
  • BIOL 3050h: Limnology
  • BIOL 3051h: River and Stream Biology
  • BIOL 4330h/ERSC 4330h: Global Change of Aquatic Ecosystems

Information for Prospective Students

My research is interdisciplinary and I expect students in my lab to master a range of numerical techniques and analytical chemistry skills (or be willing to learn them). Generally, students in my lab are encouraged to develop independent scientific research and be highly motivated. If you select a field of study that you are not really interested in, the temptation to drop out when things become difficult will be high. I welcome any inquiries from students with backgrounds in ecology, environmental sciences, environmental chemistry or geography. Students are encouraged to employ field, laboratory and theoretical approaches to their work.