My research aims to understand the effects of human and natural stressors on aquatic environments, focusing on community and ecosystem-level dynamics over various temporal and spatial scales. I use a variety of ecological and paleolimnological techniques to address various research questions relating to natural dynamics of freshwater systems, environmental contaminants, and ecological response to environmental change.
Ongoing work falls into several themes:
Primary producer community dynamics
Primary producers play a key role in ecosystem structure and function, and can be influenced by a multitude of top-down and bottom-up processes. Most aquatic systems are now multi-stressor systems. At the community level, multiple stressors may act synergistically to produce profound responses from algal communities, including shifts in dominant algal groups, significant species turnover, and novel community composition. It remains uncertain how stressors may interact to affect ecological communities on long-time scales, and how novel communities will impact ecosystem functioning. Addressing these knowledge gaps are crucial in order to undertake proper restoration or management of aquatic systems. This research uses diatom assemblages and photosynthetic pigment analyses to assess drivers of primary producer communities and responses to natural and anthropogenic stressors on various temporal and spatial scales.
Long-term environmental change in freshwater wetlands
Freshwater wetlands have historically been some of the most vulnerable landscapes to human-induced destruction and land conversion. Wetlands are naturally dynamic landscapes, constantly evolving and changing on both long and short timescales. Long-term investigations are crucial to understanding ecosystem dynamics and resiliency to human and natural perturbations in wetland environments, and elucidate drivers of change which occur over longer time scales, such as climate and hydrological change. As hydrological fluctuations are key drivers of ecosystem dynamics in wetland systems, long-term studies are required in order to fully understand the role of natural hydrological variability in wetland systems, and to discern the effects of anthropogenic perturbations. For sites which lack such long-term data, paleolimnology can be used to determine natural variability of systems, assess long-term ecological response to stressors, and address questions related to ecosystem processes and recovery over long timescales.
Contamination histories of freshwater systems
Global industrialization and development have led to long histories of increasing contaminant deposition to aquatic systems. As a result of atmospheric transportation, contaminants may travel long distances before being deposited, in addition to having regional and local sources. Long-term studies of contaminant dynamics using paleolimnological methods may be used to determine spatial and temporal variations in the extent and dynamics of contamination of freshwater systems. My research uses lake sediment cores to analyze deposition histories of mercury and other metals, persistent organic pollutants, and spheroidal carbonaceous particles to aquatic systems.
Emerging contaminants of concern in aquatic systems
Microplastics are an emerging contaminant of concern, ubiquitous in aquatic systems. The use of plastics in society has increased exponentially since the mid-20th century, with an estimated 8300 million tonnes of plastic manufactured by 2016, of which 6300 million tonnes is estimated to have ended up as waste. Microplastics are <5 mm in size, and can be either fragmented or degraded pieces of larger plastic materials, or manufactured for industrial purposes. When microplastics enter the aquatic environment, the threat to aquatic organisms may be through ingestion or entanglement, causing effects to physiololgical systems, reproduction, and feeding, among others. My research aims to better understand the current and past threat of microplastic pollution to Canadian aquatic systems, employing aquatic ecological and paleolimnological methods, and includes urban and remote freshwater, and remote marine systems, and examines sources, transport, and fate of microplastics within Canada.