Brian Leung, Ph.D.
Associate Professor


Lab members


Graduate Students


    Emma Hudgins

    Emma Hudgins, PhD Student

    The objective of my PhD research is to advance predictive invasion ecology by creating multispecies models for various stages of the invasion process. The phases of invasion include transport to a site, establishment at that site, and subsequent spread.

    It is of fundamental interest in ecology to determine whether general rules govern invasions sufficiently to make predictions across species using a common model. Such general rules also have considerable applied value in allowing new pests to be predicted a priori.

    Firstly, I will build general models for invasive pest spread and establishment in the United States. I will then incorporate the invasive species detection process, and will build a joint model of transport, establishment, and detection for freshwater invasive plants in Ontario. A final component to these general models will be examining the role of political boundaries on the invasion process. I hypothesize that invasions proceed more slowly across borders than within borders due to decreased travel and due to legislation at these borders. Predictive models of each phase of invasion allow managers to take the most effective pest control actions. The development of these tools will increase the ability of pest managers to accurately forecast future species invasions and reduce their impacts.

    Andrew Sellers
    Andrew Sellers, PhD Student

    Temporal Fluxes in Nutrient Subsidy Supply: Effects of Seasonal Upwelling on Algal-Herbivore Interactions
    Seemingly discrete ecosystems are often connected by spatial flows of materials and organisms that represent important resource subsidies for species in recipient systems, and may strongly influence community structure and trophic interactions. Early studies in tropical rocky intertidal habitats highlighted the role of top-down processes and local scale interactions in regulating community structure and dynamics, but ignored the potential influence of large scale oceanographic processes that deliver nutrient rich water to coastal ecosystems (i.e. marine upwelling). For my dissertation I will examine how nutrient subsidies from tropical upwelling events influence producer-herbivore interactions in rocky intertidal communities in the Pacific coast of Panama. The Pacific coast of Panama is divided into two broad regions: the upwelling Gulf of Panama in the east, and the non-upwelling Gulf of Chiriqui in the west. Such variation in exposure to seasonal upwelling events represents an ideal setting to examine how large scale oceanographic processes influence intertidal community structure and algal-herbivore interactions in the tropics. My research will shed new light on the processes that shape community structure and influence trophic interactions on tropical coasts.

    Lidia Della Venezia

    Lidia Della Venezia, PhD Student

    Predicting invasive species impact under limited data availability: single and multispecies risk assessment.

    My research will focus on the evaluation of the impact of aquatic non-indigenous species through the development of a toolbox for quantitative risk assessment, which will integrate a variety of methodologies that address and incorporate uncertainty, in order to make use of all the available information.

    This framework will be applied to the invasive species Bythotrephes longimanus as a case study, to evaluate its impact on pelagic crustacean zooplankton biodiversity in Ontario lakes. Consequently, I will apply this toolbox to other invasive species in different freshwater and marine ecosystems in order to validate it, evaluate its generalizability, and assess the improvements as more information is made available.

    Finally, I will incorporate invasive species interactions for a comprehensive multispecies risk assessment.

    Natalie Richards

    Natalie Richards, MSc Student

    My research takes place in the context of how sustainable transformation is informed by the scientific and public spheres. I have been working with a range of communities in Canada to help them articulate key characteristics of their ideals for the future through participatory techniques of visioning an pathway designing.
    Additionally, I am currently employing meta-analytics to investigate how the priorities of sustainability scientists have changed over time since the launch of the Intergovernmental Panel on Climate Change.

    Victoria Reed

    Victoria Reed, MSc Student

    In 2011 the world's largest roller-compacted concrete arch-gravity dam completed construction and was put in operation on the Changuinola River in Bocas del Toro province, Panama. The dam is under the operation and ownership of AES Changuinola, a subsidiary of AES Corporation. As a result of the dam operation, more than 1000 people, including the indigenous Ngäbe people, were re-settled.

    The dam itself is located inside a protected forest area, the Bosque Protector de Palo Seco (BPPS), and while residents were relocated, they were allowed to remain within the BPPS (AES Changuinola, 2013).

    I will be working with Dr. Brian Leung and Dr. Hector Guzman, and we will be evaluating the impacts of the Changuinola I Dam on the local watershed and manatee population. The project is divided into three main components; the first is to establish the current state of the river, using the information that is publicly available (e.g. land use, rainfall, soil type, land slope, etc.) and the Environmental Impact Assessment conducted prior to construction. We hope to create a snapshot of the watershed prior to the dam construction, and at present by comparing historical remote sensing imagery. The second step of our research will be to develop a watershed model of the Changuinola River using the Soil and Water Assessment Tool. The models developed will inform the last phase of the project, which is a manatee population model. This last analysis will involve the monitoring of the local manatee population and habitat to establish the effects of modifying the watershed.


    Anthony Sardain

    Anthony Sardain, MSc Student

    Risk assessments (RAs) are a common and relatively well-developed method to predict the occurrence and impact of non-indigenous species. However, a majority of RAs have been conducted assuming the past will predict the future, despite evidence of continuing, global changes in environmental conditions. Climate change is one such global environmental process that is expected to have far-reaching ecological consequences, including to the spread of non-indigenous species.

    Although some RA models have incorporated climate change, most of these have been species-specific, rather than general pathway-level models that consider all non-indigenous species that could be associated with a specific invasion pathway. And none of these models have focused on shipping ballast water, which is thought to be the world's largest invasion vector. This is problematic as climate change is expected to affect all phases of the ballast-mediated invasion process, from the opening of new shipping routes to the removal of physiological barriers for potential invaders.

    My research is focused on filling this void by creating a vector-based model of ballast-mediated invasion in the context of global climate change at a more global scale. Specifically, I focus on the uptake, introduction, and establishment stages of invasion, making use of various quantitative modelLing techniques such as species distribution models, probabilistic models, and propagule pressure-establishment models. This final product of this will provide a more accurate forecast of species invasion in the context of global climate change, potentially allowing for timelier and more effective preventative measures to combat an urgent global problem.


Previous Grad Students

Johanna Bradie PhD Student
Project Title: Using genetic and population characteristics to predict establishment success of NIS
Andrew Sellers M.Sc. student
Project Title: Higher ectoparasite richness and abundance in introduced red lionfish (Pterois volitans) at low latitudes: implications for biotic resistance and enemy release.
Published in: Sellers, A. J., Ruiz, G. M., Leung, B., & Torchin, M. E. (2015). Regional Variation in Parasite Species Richness and Abundance in the Introduced Range of the Invasive Lionfish, Pterois volitans. PloS one, 10(6), e0131075
Corey Chivers PhD Student
Project Title: Predictive invasion ecology and decisions under uncertainty.
Paul Edwards PhD Student
Project title: Optimizing monitoring and eradication of
invasive species: new frameworks and applications.
Ayaz Hyder PhD Student
Project title: Influenza spread models: integrating epidemiological and dynamic simulation approaches.
Stefanie Kulhanek M.Sc. Student.
Project title: Investigating the use of invasion history, meta-analysis and niche-based models as tools for predicting the ecological impact of introduced aquatic species.
Erin Gertzen M.Sc. Student.
Project title:Assessing the relationship between propagule pressure and probability of establishment for aquatic invasive species using two novel approaches .
David Delaney Ph.D. Student
Project title: Monitoring, managing and modeling the spread of marine invasive species
Dominique Roche M.Sc. Student.
Enemy release and biological invasions: a community study on Nile Tilapia
Discovery, distribution, and eradication potential of the introduced mud crab, Rhithropanopeus harrisii, in the Panama Canal

Previous Undergraduate Students

Kanako Hasegawa Undergraduate student.
Project title: Is there consistency in ecological impacts by invasive species?
Brooke Wilson Undergraduate student.
Project title: The importance of epistemic uncertainty for non-indigenous species management
Jillian Cohen Undergraduate student.
Project title: Quantifying and identifying aquatic plants sold in the aquarium trade in Montreal.
Erin Gertzen Undergraduate student.
Project title: Quantifying and identifying fish sold in the aquarium trade in Montreal.
Oriana Familiar Undergraduate student.
Project title: Estimating propagule pressure of fish from the aquarium trade to the St Lawrence.
Nick Mirotchnick Undergraduate student.
Project title: Surveys of customer pathways of plants from the aquarium trade to the St Lawrence