The main thrust of my research programme is creating an “ecology of material conditions”. Ecosystems are awash with various substances that can act as energy, materials and/or information for organisms, but we currently lack many of the tools integrate these various ecological currencies in a coherent matter. To tackle this problem, I participate in numerous research collaborations with field, experimental and theoretical ecologists and evolutionary biologists to build analytical tools, theory and models to apply to constructed and natural ecosystems. This research can be divided up into three main axes, though I generally view them as overlapping significantly as results from one area feed into others: 1) determining the impacts of the diversity of spatial flows across ecosystem boundaries, 2) linking ecophysiology to ecosystem functioning through material flows and 3) understanding the impacts of non-resource effects of matter in time and space.
Impacts of the diversity of spatial flows across ecosystem boundaries
Ecosystems do not exist in isolation. In many cases, fluxes of energy, materials and organisms between habitats could be larger than those generated locally. However, these fluxes can be of variable quality and the flows can be unidirectional, bidirectional or part of a complicated, connected network of different habitats like streams, lakes and forests. The primary focus of my work has been to explore how differences in the movement rates of nutrients and of organisms in different spatial arrangements can impact community structure and ecosystem functioning.
However, with environmental conditions like temperature and precipitation changing, the connectivity of our ecosystems change with it. I am currently collaborating on work led by Dr. Ridouan Bani that examines how the properties of connectivity (i.e. its mean, variance, covariance) change for a metapopulation with climate change and its implications for marine protected areas. To extend this work beyond populations to metacommunities, I am working with a group of professors led by Dr. Eric Pedersen of Concordia University to create a working group on the diversity of flows in metacommunities.
Another approach is to connectivity is to imagine how different organisms perceive their landscape structure, such as when adjacent ecosystems are very different from one another (e.g. forest and a lake). With the Canadian Institute for Ecology and Evolution working group led by Professor Eric Harvey of Université de Montréal and Professor Marie-Josée Fortin of the University of Toronto, we developed a conceptual framework to capture how spatial fluxes from heterogeneous ecosystems can impact both local and regional ecosystem functioning in ways that cannot be capture by current meta-ecosystem models.
However, with environmental conditions like temperature and precipitation changing, the connectivity of our ecosystems change with it. I am currently collaborating on work led by Dr. Ridouan Bani that examines how the properties of connectivity (i.e. its mean, variance, covariance) change for a metapopulation with climate change and its implications for marine protected areas. To extend this work beyond populations to metacommunities, I am working with a group of professors led by Dr. Eric Pedersen of Concordia University to create a working group on the diversity of flows in metacommunities.
Another approach is to connectivity is to imagine how different organisms perceive their landscape structure, such as when adjacent ecosystems are very different from one another (e.g. forest and a lake). With the Canadian Institute for Ecology and Evolution working group led by Professor Eric Harvey of Université de Montréal and Professor Marie-Josée Fortin of the University of Toronto, we developed a conceptual framework to capture how spatial fluxes from heterogeneous ecosystems can impact both local and regional ecosystem functioning in ways that cannot be capture by current meta-ecosystem models.
Linking ecophysiology to ecosystem functioning through material flows
Communities and ecosystems are at the top of the hierarchical scale of biological organization, but their mechanisms and processes have their roots in the ecophysiology of the organisms that compose them. To do so, we need to use life history traits like nutrient uptake rates and organism stoichiometry that help us track material flows between organisms and ecosystem compartments. By using common currencies like materials and energy in combination with these traits can allow us to predict the outcome of community dynamics and ecosystem functioning. For example, I have used data from various early successional species on Mount St. Helens in order to explore both the possibility that ecological stoichiometry can explain observed paters of successional dynamics. We can also investigate how the concentrations of materials within organisms can lead to alter expectations, such as plants with high N:P tissue ratios can still respond positively to increases in nitrogen in the soil.
We are using this approach to examine the impacts of stressors such as acidification and herbicides on aquatic communities as part of the Large Experimental Array of Ponds (LEAP) project led by Professor Andrew Gonzalez of McGill University. We derived a meta-ecosystem model that utilizes parameterized life history traits that capture the transfer of limiting nutrients between trophic levels in order to develop a priori predictions for the experiments. This work has shown that various mechanisms like ecological sorting and evolutionary rescue can explain why phytoplankton can recover from severe acidification, and that dispersal between mesocosms was unlikely to impact the overall dynamics of the system. This model will serve as the basis for future experiments in the LEAP project, which are being done as part of the Food From Thought research program, to explore how agricultural contaminants and spatial connectivity impact the recovery of aquatic communities.
We are using this approach to examine the impacts of stressors such as acidification and herbicides on aquatic communities as part of the Large Experimental Array of Ponds (LEAP) project led by Professor Andrew Gonzalez of McGill University. We derived a meta-ecosystem model that utilizes parameterized life history traits that capture the transfer of limiting nutrients between trophic levels in order to develop a priori predictions for the experiments. This work has shown that various mechanisms like ecological sorting and evolutionary rescue can explain why phytoplankton can recover from severe acidification, and that dispersal between mesocosms was unlikely to impact the overall dynamics of the system. This model will serve as the basis for future experiments in the LEAP project, which are being done as part of the Food From Thought research program, to explore how agricultural contaminants and spatial connectivity impact the recovery of aquatic communities.
Understanding the impacts of non-resource effects of matter in time and space
Ecosystems are awash in different kinds of substances, yet our best theories focus on a privileged few that serve as our main currencies: energy (e.g. carbon biomass) and resource materials (e.g. phosphorus). However, many substances do not act as resources for organisms in ecosystems. The ‘non-resource effects’ of these substances can be highly varied, from a volatile organic compound acting as information for gastropods while acting as noxious poison for copepods. How a substance is distributed in space and time plays a key role in determining its effects and recognizing the role organisms play in the substance’s distribution is vital for our ecological understanding.
At LEAP, we examined the key role of non-resource effects of acidity in the 2018 experiment. Our major treatment was to see how pre-exposure to mild acidification could help spur community reassembly that would allow for evolutionary rescue in the face of severe acidification. Instead, we found that pre-exposure had no final impact on phytoplankton recovery. Instead, we discovered through careful time-series analysis that ecosystem function was completely disrupted initially in non-exposed mesocosms, while it persisted in pre-exposed ones. However, the rate of recovery was much faster in the non-exposed mesocosms, resulting in relatively similar functioning at the end of the experiment. We currently do not understand why this pattern of recovery occurs, but it shows that better understanding of how acidification impacts multiple ecosystem properties is required to advance our theories.
At LEAP, we examined the key role of non-resource effects of acidity in the 2018 experiment. Our major treatment was to see how pre-exposure to mild acidification could help spur community reassembly that would allow for evolutionary rescue in the face of severe acidification. Instead, we found that pre-exposure had no final impact on phytoplankton recovery. Instead, we discovered through careful time-series analysis that ecosystem function was completely disrupted initially in non-exposed mesocosms, while it persisted in pre-exposed ones. However, the rate of recovery was much faster in the non-exposed mesocosms, resulting in relatively similar functioning at the end of the experiment. We currently do not understand why this pattern of recovery occurs, but it shows that better understanding of how acidification impacts multiple ecosystem properties is required to advance our theories.