Connect Knowledge with Action
2023 Research Colloquium
CVC hosts a Research Colloquium every two years, with the theme Connecting Knowledge with Action. We invite students, professors, and environmental professionals to join us to share and learn about the research that is being carried out in the Credit River Watershed.
This event is cohosted by the Centre for Urban Environments, University of Toronto Mississauga.
Our aim is to facilitate
- The incorporation of findings from research in our jurisdiction into CVC’s work
- Enable networking and mentoring
- Help to build and strengthen collaborations
- Provide an opportunity for direct feedback from applied practitioners to researchers
We welcome attendance from all members of our research community. The event is an opportunity to learn more about the watershed and what is happening in it. The program includes presentations from both external researchers and CVC staff, as well as opportunities for networking.
December 6, 2023
2021 Research Colloquium Program
Decisions determine destiny: Together we can create a resilient future
Kata Bavrlic and Christine Zimmer, Credit Valley Conservation
The Credit River Watershed has undergone dramatic change since the arrival of European settlers. A landscape that was historically dominated by mature old growth forests and wetlands (~ 90 per cent), now has roughly equal parts of natural, agricultural and urban cover. As land was cleared and surfaces were hardened, habitat loss and fragmentation changed the structure and function of natural heritage features, including the important flood mitigation and water cleansing services they provide. In this modified landscape, storm events create surface runoff that can result in flooding and erosive damage to streams and infrastructure. In order to mitigate the cumulative impacts associated with landcover and landuse change, we need to engage and collaborate with local thought leaders as we face threats such as climate change and invasive species. Most importantly, we must acknowledge that the decisions we made in the past have consequences for today, and that the decisions we make today will impact future generations. The first part of this presentation will provide an overview of what types of information and expertise CVC has to offer as we partner with others to fill research gaps. We will then demonstrate how we’re using lessons learned from the past to support research and decisions to protect our natural heritage system for future generations.
Trends and legacy of freshwater salinization: untangling over 50 years of stream chloride monitoring
Bhaswati Mazumder, Claire Oswald, Christopher Wellen, Georgina Kaltenecker, and Ryan Sorichetti, Ryerson University
Long-term increasing stream chloride (Cl) trends are generally attributed to road salts and increases in urban land cover over the past few decades, however recent research shows that even relatively rural streams can retain Cl and exceed water quality guidelines in summer after road salting has stopped. Untangling the relative influences of long-term changes in streamflow & urban growth on Cl trends is critical for making informed decisions about road salt management. The portion of Cl trends not explained by changes in streamflow or urban growth could be due to changes in road salt application rates and/or legacy Cl in groundwater slowly making its way to streams. This study assessed seasonal, long-term stream Cl trends across Ontario, where urbanization accelerated and road salt management plans started to develop since early 2000s. We compared trends over winter salting & summer non-salting seasons with urban growth estimates from two independent time periods, 1965–1995 & 2002–2018. For a subset of sites with sufficient flow data in these periods, we parsed the seasonal trends into flow & management trend components (QTC & MTC). We found that most of the variance in MTC in the winter could be explained by urbanization, while about half of it could be explained in summer. We analyzed Cl estimates in low-flow conditions to explore the extent of subsurface contributions to Cl trends, and concluded with a summary of challenges & recommendations for future studies on road salt legacy in streams.
Nutrient concentration-discharge patterns across the Great Lakes Basin
Nandita Basu and Kimberly Van Meter, University of Waterloo
Changes in seasonal nutrient dynamics are occurring across a range of climates and land use types. In the present study, we have used concentration and discharge data from more than 200 stations across U.S. and Canadian watersheds to identify (1) archetypal seasonal concentration regimes for nitrate, soluble reactive phosphorus (SRP), and total phosphorus, and (2) dominant watershed controls on these regimes across a gradient of climate, land use, and topography. Our analysis shows that less impacted watersheds, with more forested and wetland area, most commonly exhibit concentration regimes that are in phase with discharge, with concentration lows occurring during summer low-flow periods. Agricultural watersheds also commonly exhibit in-phase behavior, though the seasonality is usually muted compared to that seen in less impacted areas. With increasing urban area, however, nutrient concentrations frequently become essentially a-seasonal or even exhibit clearly out-of-phase behavior. In addition, our data indicate that seasonal SRP concentration patterns may be strongly influenced by proximal controls such as the presence of dams and reservoirs. In all, these results suggest that human activity is significantly altering nutrient concentration-discharge regimes
Can the Morphological Quality Index (MQI) be used to determine the ecological status of lowland rivers?
Johnathan Lemay, Pascale Biron, Maxime Boivin, Nicolas Stampfli and Kyleisha Foote, Concordia University
Stream assessment indices have become increasingly important in quantifying the overall status of river networks to define specific targets for restoration initiatives. However, some of these evaluation tools, for instance the Qualitative Habitat Evaluation Index (QHEI), are resource intensive since they are field based. Indices that are less dependent on field observations, such as the Morphological Quality Index (MQI), can provide a greater spatial coverage at a lower cost. The objectives of this study are to (1) verify whether a river’s morphological quality, using the MQI, can predict the fish habitat quality of a stream determined with the QHEI, (2) compare the morphological quality, estimated solely from remotely sensed data (RMQI), to the standard MQI, (3) test whether a modified MQI (MMQI) is more appropriate for the eastern Canadian landscape, and (4) considering the near absence of dams in lowland eastern Canadian streams, compare an MQI where dam-related indicators are optional (MQI-OD) with the QHEI. The geomorphological and ecological conditions of 118 stream reaches, including 97 in agricultural areas, were assessed across Quebec and southern Ontario. A strong correlation was observed at the reach scale between the MQI and QHEI (r = 0.81) and the MQI and RMQI (r = 0.95). Both modified MQI (MMQI and MQI-OD) showed a stronger correlation than the standard MQI with the QHEI (r = 0.87). These results demonstrate that the MQI can be used to provide an assessment of fish habitat quality, while the remote MQI (RMQI) can estimate the overall status of river networks.
Phosphorus accumulation in a bioretention cell in Mississauga, Ontario: Insights from data analysis and process-based modeling
Bowen Zhou, Ariel Lisogorsky, Mahyar Shafii, Chris Parsons, Elodie Passeport, Fereidoun Rezanezhad, and Philippe Van Cappellen, University of Waterloo
Bioretention cells are a Low Impact Development (LID) technology that is being promoted as a green solution to attenuate urban stormwater nutrient loadings. Despite extensive implementation of bioretention cells in Canada, the mechanistic understanding of phosphorus (P) cycling in bioretention cells is still limited. We conducted detailed analyses of (geo)chemical and hydrological data coupled to numerical reactive transport modeling to simulate the fate and transport of P in a bioretention cell located in Mississauga (Ontario, Canada) within the Credit River watershed. Our objective is to utilize the model to predictively understand the accumulation and speciation of P in the bioretention cell under long-term field operation. Unlike existing bioretention models, our model incorporates a detailed representation of the biogeochemical processes that control P cycling in the bioretention cell. We further compare the model predictions with data from sequential chemical extractions of P from soil samples taken from the bioretention cell. The model correctly estimates the cumulative TP (total P) and SRP (soluble reactive P) outflow loadings from the bioretention cell, as well as the TP accumulation rate and observed partitioning of P over the different pools in the bioretention cell. The relative importance of various processes controlling P retention are assessed using mass balance calculations and sensitivity analyses of the model. The results show that filtration of fine P-containing particles and slow sorption are the main processes retaining P in the bioretention cell.
Design limitations to low impact development: Observing the site conditions that lead to stormwater bypass
Alex Fitzgerald, Credit Valley Conservation
Low impact development (LID)/green infrastructure is crucial for water quality protection by limiting pollutant loading and stream protection by reducing peak flows and erosion. Many types of LID features, such as bioretention, rely on infiltration for stormwater treatment. Under certain conditions, stormwater cannot infiltrate quickly enough and will pond on the bioretention surface, and will either enter an overflow system or bypass the system entirely. When these overflow events occur, stormwater runoff is not being treated and is not receiving any of the volume reduction or quality improvements that LIDs provide. Understanding the types of events that produce overflow, and the impact this has on water quality and quantity performance is vital for planning and designing LIDs. Monitoring overflow events can also be used to inform the type and frequency of maintenance activities. The parking lot at IMAX’s head office in Mississauga contains three bioretention swales that were each monitored from 2014 to 2019. Performance data will be presented reviewing the factors that cause overflow events and comparing water quality and quantity results between overflow and non-overflow events.
Stream fish community temperature preferences in watersheds across the Greater Golden Horseshoe
McKayla Jarvie, University of Toronto
Freshwater fish species require, and compete for, specific water temperatures and thermal regimes to maximize various physiological and behavioral processes. Yet, the thermal habitat on which they rely is being modified by localized human activities and global climate change. This study examined site-level changes in stream fish communities from numerous watersheds in southern Ontario over two decades, assessed the use of a weighted species association tolerance index with respect to water temperature (WSATI-WT) to track changes in community temperature preferences, and examined the effects of sampling variability on this index. While all communities showed evidence of compositional change over time, this did not always equate to changes in community temperature preference. Within-site temporal differences in the WSATI-WT ranged from -5.04 °C to 9.43 °C, 68% of which were positive and 32% negative, indicating both increases and decreases in temperature preferences occurred. Due to sampling error, WSATI-WT values had the potential to change by up to 9.8 °C (average = 1.57 °C), indicating that uncommon or underrepresented species have the potential to largely influence this index depending on their specific temperature preferences. While community rather than single-species responses to warming temperatures will provide better overall measures to protect and manage watersheds, more robust methods of tracking these responses are required.
Temperature tolerance of the invasive Round Goby, Neogobius melanostomus, in the Credit River
Kyla Greenham, University of Toronto
The Credit River has a unique situation where two separate populations of invasive Round Goby, Neogobius melanostomus, have established, at the mouth of the River and in the headwaters. The tolerance of Round Goby to wide ranges of environmental conditions, including temperature, suggests that Round Goby will likely find other suitable habitats to colonize in the Credit River. Understanding the impact of Round Goby on the native fish community and how warming temperatures affect the invasiveness of Round Goby is critical to establish management practices to protect native fish populations. Using Critical Thermal Maxima (CTmax) experiments, the CTmax for the two populations, exposed to differing thermal regimes in the Credit River, were compared to that of two native co-occurring benthic fishes, Longnose Dace (Rhinichthys cataractae) and Western Blacknose Dace (Rhinichthys obtusus). Both Round Goby populations exhibited similar temperature tolerances to the co-occurring Western Blacknose Dace population. Within sites, CTmax was only significantly higher for Round Goby compared to Longnose Dace at the Mississauga site. Between sites, all three species from the Mississauga site have a significantly higher CTmax than their conspecifics from Hillsburgh. When acclimated to the temperature of the other location, the CTmax for all three species significantly for fish from Mississauga, but not for Hillsburgh. The higher temperature regime in the lower reaches of the Credit River may better prepare Round Goby to being more resilient to temperature increases related to climate change.
A look at an ongoing research program to develop a captive breeding program for endangered Redside Dace
Ashley Watt and Trevor Pitcher, University of Windsor
Hatchery-based breeding programs often struggle with producing offspring that are suited to survive in the wild and this deficiency can be attributed (in part) to a poor understanding of natural mating dynamics and evolutionary consequences of breeding scheme choices. An example of a flawed breeding design includes the random use of mates which occurs at the expense of eco-evolutionary forces (e.g., sexual selection), which includes both selection before and after spawning occurs. These forms of selection have been found to increase the fitness of offspring in the wild; so, it is surprising that they have not been considered more readily in captive breeding programs. Here, my research will address this gap and explore the potential benefit(s) of including sexual selection to enhance the fitness of offspring produced as part of breeding research programs focused on endangered freshwater fish. The focal species of my PhD research is the endangered Redside Dace (Clinostomus elongatus), a small, cool-water cyprinid. Due to declining numbers in the wild and ongoing reintroduction efforts underway, captive breeding is becoming more important. My research has documented wild spawning behavior and determined two males’ mate with a female on average. Using this behavioral data, I will split batches of female’s eggs in half and fertilize half with sperm from one male and half with sperm from another male to examine the potential offspring quality (i.e., fitness related measures). This research will help identify suitable captive breeding techniques for endangered freshwater fish.
Assessing the impacts of urban development on Ambystoma jeffersonianum habitat in southern Ontario
Patricia Huynh, University of Waterloo
Jefferson Salamander (Ambystoma jeffersonianum) is an endangered salamander found in southern Ontario. It is suggested that Jefferson Salamander have specific habitat requirements of water quality, hydroperiod, and adjacent land uses for successful recruitment. Jefferson Salamander breed in vernal pools, and it is likely that urban development led to the rapid decline of these populations. In this study, the hydroperiod and water quality of vernal pools along a gradient of urban development were compared. Nine vernal pools in the City of Mississauga and Halton Region were compared. Of the 9 pools studied, 6 pools had Jefferson Salamander populations present in 2018. All the vernal pools in Halton Region that had Jefferson Salamander present dried up early summer, whereas the vernal pools in Mississauga that had salamanders present did not all dry up. Additionally, the ponds in Mississauga had higher densities of Jefferson Salamander (LJJ) whereas Halton Region had higher proportions of pure Jefferson Salamander (JJ). Lastly, the water quality between ponds were similar, suggesting that water quality may not be a strong indicator of suitable habitat. From these results, it appears that Jefferson Salamander may be able to tolerate a wider variety of conditions. However, urban development can cause habitat fragmentation and impact hydroperiod, leading to increased densities of salamanders per pond, more competition, and less successful breeding.
Bioacoustic surveys show distinct anuran communities between urban and rural landscapes
Claudia Lacroix and Donald Jackson, University of Toronto; Zach Kahn, Kelsey McNeill, and Kata Bavrlic, Credit Valley Conservation
Amphibians are globally imperilled due to numerous interacting factors such as habitat loss, pollutants, invasive species, disease and urbanisation, where a greater understanding of these factors is needed. Here, we use bioacoustics surveys to understand how anuran communities correspond to disturbances in the surrounding landscape. In 2018 and 2019, we used automated recording units to record the maximum call code observed at 30 sites across the Credit River watershed and used land-use surveys to quantify the percent landcover type (i.e., urban, agricultural, natural) within a 2km radius. Assuming that the maximum call code reflects relative abundance, we show that urbanisation negatively affects anuran communities by reducing species diversity and promoting toad dominated communities. Predominantly urban sites have lower taxonomic diversity and a higher proportion of American Toads, whereas natural sites have higher taxonomic diversity and a higher proportion of Spring Peepers, Wood Frogs, and Gray treefrogs. We hypothesize that differences may be, in part, due to habitat loss, environmental contaminants, noise pollution, non-native fish or a combination of these factors.
Stress relief for the Credit: From monitoring to aquatic and wetland restoration
Adrienne Ockenden and Sherwin Watson-Leung; Credit Valley Conservation
The Credit River Watershed faces numerous stressors such as climate change, land use change, and invasive species. Credit Valley Conservation monitors how ecosystems of the watershed are responding to these stressors. We use our monitoring data to inform and prioritize restoration actions in stream, wetland and terrestrial ecosystems. We will provide a whirlwind overview of how CVC transforms monitoring data, links them to stressors impacting aquatic and wetland ecosystems and turns them into meaningful ecosystem restoration projects.
City of Mississauga Natural Heritage System
Paul Tripodo and Sarah Piett; City of Mississauga
The City of Mississauga’s Natural Heritage System covers approximately 9.14% of the city and contains records of 1225 species of flora and 502 species of fauna. Since the mid-1990s, city staff, consultants and partners have been collecting data on these species and the habitats they are found in across the city. Join Sarah Piett, Supervisor of Woodlands & Natural Areas and Paul Tripodo, Natural Heritage Coordinator as they review the various ecological datasets available to researchers wishing to study the relationships among plants, wildlife, humans and the environment here in Mississauga. Their objective is to highlight some of the key data gaps and questions to help guide the management and stewardship of the city’s natural areas for generations to come.
Identifying forests with old growth potential in the Credit River Watershed
Zoe Bedford and Jay Malcolm, University of Toronto; Laura Timms, Credit Valley Conservation
Old growth forests provide important ecological services including carbon storage and habitat for a diverse array of species, yet they are often rare across the landscape. These forests are challenging to identify in part because of a lack of consensus on what constitutes old growth. The most commonly identified characteristics include trees older than 120 years, uneven age structure, gap-phase dynamics, an abundance of standing dead trees and downed wood, and the presence of tip-up mounds. In addition to their rarity and complex definition, there is a lack of research on old growth in southern Ontario. To address this gap we measured the following forest characteristics at potential old growth sites: 1) diameter and decay class of downed woody debris and standing deadwood; 2) pit-mound microtopography; 3) stand basal area and density; as well as 4) tree age. In total, 14 sites were surveyed, and 275 tree cores were collected. The collected data will be paired with LiDAR to evaluate if distinct structural characteristics are present in potential old growth forests. Finally, the results will be used to develop a suite of indicator values to identify potential old growth sites.
A regeneration monitoring protocol for the restoration of coniferous plantations to hardwood forests in southern Ontario
Bridget Trerise and Ben Kuttner, University of Toronto; Aaron Day, Credit Valley Conservation
A monitoring protocol for assessing hardwood regeneration in thinned coniferous plantations was developed and tested in the Credit Valley watershed. Restoration of hardwood forests is a common management objective for coniferous plantations in southern Ontario. However, there have previously not been any guides or standards for monitoring this restoration process. Therefore, a literature review was conducted to inform a silvicultural effectiveness monitoring protocol. The resulting protocol includes minimum regeneration standards, a survey procedure, and a data analysis system. Three overlapping regeneration standards were identified to account for the various height classes of regenerating trees associated with different stages of restoration. The protocol was tested in a coniferous plantation with several distinct compartments and a management history of thinning. The results of the survey will be used to discuss the suitability of the regeneration standards and the practicality of the data collection system. The results will also be used to present examples of ways in which the system can inform management actions. Future surveys in forests at earlier and later stages of restoration than the initial survey site can help to further test the regeneration monitoring protocol.
Translocating topsoil and woody debris from a mature ‘donor’ forest can rapidly advance understorey succession at plantations
Paul Richardson, Stephen Murphy and Jonas Hamberg; University of Waterloo
Major institutions are motivated to expand land covered by forests to combat climate change and biodiversity loss, but critics point to planted stands that exacerbate both crises. Improving afforestation by directing plantations towards high ecological similarity with outcomes of natural succession faces challenges, including management preferences for planting coniferous stands in otherwise deciduous ecoregions. We tested the hypothesis that vegetation communities resembling the understorey of old natural deciduous stands can quickly assemble at locations of younger successional age, provided managers distribute topsoil extracted from a suitable ‘donor’ stand experiencing advanced succession then replicate habitats using imported woody debris and ground-shading techniques. We conducted experimental translocations in Clearview Township, Ontario, applying donor materials from mature Acer saccharum forest that an aggregates producer must clear to prepare for their licensed quarry expansion.
Four years after translocation, recipient sites exhibited remarkable community similarity to the reference forest under some experimental conditions but not others. Understorey composition within treated ≈40-80-year-old coniferous plantations – especially where proximate to woody debris – was nearly indistinguishable from the donor forest. Following treatment at a gravel pit undergoing succession, and farmland recently planted with diverse native hardwoods, typical forest understorey herbs contributed to a low ground-layer that persisted beneath a taller layer of typical ‘old field’ vegetation. Strategically reusing forest topsoil that is an occasional by-product of extractive industries can therefore help realize valuable opportunities for enhancing the biodiversity and functioning of middle-aged coniferous plantations presently occupying the landscape, as well as at planned future afforestation sites.
Strategies for forest management of Credit Valley Conservation’s conservation areas impacted by Emerald Ash Borer
Monique Dosanjh, Sandy Smith, and Danijela Puric-Mladenovic, University of Toronto; Alana Svilans and Freyja Whitten, Credit Valley Conservation
Forests of the Credit Valley watershed in Ontario have a significant component of ash, and as a result have been significantly impacted by the emerald ash borer (EAB). EAB-induced ash mortality has resulted in the removal of 12,955 ash trees since 2014 in the Credit Valley watershed (Credit Valley Conservation, n.d.b.), and this has led to significant negative ecological effects. One of the main changes has been in the forest structure and composition as a result of the proliferation of invasive plants and an increase in ash regeneration.
Using Credit Valley Conservation’s (CVC) lands as a case study, the high-level objective of my study is to determine effective forest management strategies that can be used to restore areas impacted by EAB. It is expected that the recommendations from this study will be applicable to other areas impacted by EAB throughout North America. By identifying management strategies through a literature review and the prioritization of CVC restoration sites using GIS, I will prioritize management options for EAB-impacted areas. The focus will be on actions to mitigate invasive plants’ negative impacts and promote uneven-aged and limited ash regeneration.
Plant functional traits as measures of ecosystem service provision
Liane Miedema Brown, University of Guelph
Despite the relevance of ecosystem services (ES) to society and modern ecological research, current methods of measurement and mapping remain inconsistent and often lack primary data in estimating and modeling ES. A key player in our understanding of ES and their measurements are plant functional traits – chemical and physical aspects of plants – which are often cited as one of the drivers of ecosystem processes and functions. In order to better quantify the ES-plant functional trait indicators, we outline existing evidence of this relationship, and identify gaps between the best predicted ES and the most valued ES. This study offers an up-to-date review of plant functional traits’ direct or indirect relationships with ecosystem service provision and discusses the quantitative evidence these traits might hold as indicators. With this review we seek to a) offer a current summary of the quantitative evidence on ecosystem service-plant functional trait relationships, b) identify which traits have been used to successfully indicate ecosystem services and c) identify research gaps, and ecosystem services or traits that receive little attention or have weak criteria as indicators. We found that functional traits showed varying relationships to ES, with some depending on the ecosystem type they were found in, while others appeared to remain consistent across ecosystems and conditions. This indicates that there could exist a subset of traits that are ‘universal’ indicators across all ecosystem types, while others are ecosystem dependent.
The carbon sequestration and storage framework: guiding the use of measurement tools in the “carbon calculator toolbox”
Lauren Moretto and Tatiana Koveshnikova, Credit Valley Conservation
Rates of urbanization and climate change concerns are increasing in southern Ontario, which has fostered interest in the capacity of natural assets to sequester and store carbon, and by extension, mitigate carbon emissions. To achieve this, carbon sequestered and stored by natural assets needs to be quantified and valued. A variety of tools, methods, and resources for estimating carbon sequestration and storage are being developed in response to these interests. However, as the library of available tools increases, so too will the variation in carbon sequestration and storage estimates produced from these tools (which may rely on different base models), along with the possibility of incorrect tool use, and/ or questioning of the reliability and accuracy of estimates. In response to this concern, Credit Valley Conservation, Toronto and Region Conservation Authority, and Lake Simcoe Region Conservation Authority have developed guidelines to use existing methods, tools, and resources to achieve standardized carbon sequestration and storage estimations. This carbon framework includes: 1) a table of locally applicable, per hectare, land cover-based carbon sequestration and storage rates to conduct a baseline assessment across a landscape, and 2) guidance on the use of both internally-developed and publicly-accessible tools and resources for different natural assets, spatial scales, and project objectives and scenarios.
Evaluating the eco-health value of tree canopy cover scenarios in Brampton Ontario
Jeff Wilson, University of Waterloo; Umberto Berardi, Ryerson University; Mohamed Dardir, EcoHealth Ontario
This case study estimates the monetary value of health benefits that would result from increasing tree canopy cover under two scenarios in a Brampton, Ontario, neighbourhood. The study adopts an eco-health economic valuation framework to quantify the return on investments in urban greenspace and infrastructure in terms of improved population health, avoided health systems costs, and increased productivity. The project supports the Green Natural Infrastructure Strategy goal to increase tree canopy to mitigate very hot temperatures and associated negative health outcomes in high priority neighbourhoods in Peel Region.
Shaping the neighbourhood urban forest: Characterizing resident association roles and knowledge
Sadia Butt, University of Toronto
Humans influence the physical environment around them by their ability to steer decision-making at various levels, such as policy, neighbourhood and household. Urban forests are important to people as it is the near-nature opportunity at the local level. People in cities understand how important trees are to the environment and have knowledge about the risks and vulnerabilities that can impact the canopy cover.
At the neighbourhood level, resident associations are one type of community group that impacts urban forest governance. Even though urban forests are traditionally under the jurisdiction of the municipality for management, these groups can be highly motivated and have influence on both the governance and even the day to day management of urban forests.
My research investigates the role of resident associations in urban forest governance, in Mississauga, Ontario, Canada. Using a case study approach, I found that resident associations are highly motivated, develop strategies, engage in knowledge building and navigate the power dynamics to have their say in shaping their neighbourhood urban forest. I interviewed executive members of 9 resident associations that ranged from new to well-established areas across the City of Mississauga. Residents association roles are shaped by the need to share information with their neighbours and communicate with decision makers. The result is that they impact the shape of their neighbourhood urban forest.
A second wave of earthworm invasion: the arrival of pheretimoid “jumping worms” in southern Ontario
Michael McTavish, Esther Tang, and Sandy Smith, University of Toronto; Rob Bourchier, Agriculture and Agri-Food Canada
The introduction of a group of pheretimoid earthworms from Asia colloquially referred to as “jumping worms” into North America has been called a second wave of earthworm invasion. Jumping worms pose a serious threat to forest ecosystems as ecosystem engineers capable of rapidly removing leaf litter and reducing vegetation diversity and cover. Previously documented only in the northeast and midwest United States and once in Ontario in 2014, new observations from 2021 indicate the arrival of at least four species (Amynthas agrestis, A. hilgendorfi, A. tokioensis, and Pithemera bicincta) in southern Ontario. This study provides preliminary findings from community science reports of jumping worms across southern Ontario and a systematic survey of semi-natural ravines throughout the Greater Toronto Area (GTA). The purpose of this study is to determine what species are present and the current extent of their spread, and to investigate patterns between jumping worm presence and density, vegetation cover, and the community composition of other non-native earthworms. This preliminary research will inform initial assessments of the ecological impacts on jumping worms, guide efforts to limit further spread, and provide a baseline for monitoring future invasion in southern Ontario.
Thermal imaging to measure and monitor ecological issues
Jonas Hamberg and Patrick James, University of Toronto; Jonathan Ruppert, TRCA
We are using thermal imagers on satellites, the International Space Station and drones to monitor and measure the effect of restoration and ecological issues.
Using the ECOSTRESS thermal imager on the ISS we measured the effect of forest restoration on surface temperature at different times of the day and night. For NCC land in Norfolk County and TRCA land in the Humber River watershed we found a 4-7 C° difference in the afternoon between forest restoration and agriculture and suburban areas and significant cooling over time since restoration.
We will also present ongoing research using thermal cameras on drones (RPAS) to measure and monitor the thermal effect of LDD moth defoliation around the TRCA watersheds and the cooling effect of meadow restoration on the Meadoway project in eastern GTA.
On a more general note, we wish to discuss the cooling effect from restoration, how it can be measured as an ecosystem service, how it affects habitat and human wellbeing, as well as what it says about ecological change.
Monitoring forest change across the Credit River Watershed with tree-rings and satellite imagery time-series
Mitchell Bonney and Yuhong He, University of Toronto
In a recently published paper (Temporal connections between long-term Landsat time-series and tree-rings in an urban–rural temperate forest), we compared time-series of satellite-derived vegetation proxies and tree-ring widths. We found stronger connections at coniferous forest sites, potentially driven by differential response to summer temperature change. Although this study focused on the mechanisms behind the relationships between tree-rings and remote sensing time-series, all forest sites sampled are in the Credit River Watershed (CRW). There are thus interesting local stories to tell about the history of these forests dating back to the early 1970s (with remote sensing) and 1890s (with tree-rings). An example of an important event that impacts both tree-rings and remote sensing observations across the CRW is the 2013 ice storm, when many sites enter a period of recent decline. Further exploration into these valuable historical records of CRW’s forests reveal other periods of growth and decline that may be connected to historical events. We hope that Credit Valley Conservation and others interested in the history and health of our local forests will benefit from a look into the past with these exciting datasets. We thank Credit Valley Conservation for their help, especially during the planning stages of this project. Without your support and permission this research would not have been possible!
The great urban shift: climate change drives species turnover in cities
Alessandro Filazzola, Marc Johnson and Scott MacIvor University of Toronto; Laura Timms, CVC; Kimberly Barrett, Conservation Halton; Sue Hayes and Namrata Shrestha, TRCA
Nature is an integral element of cities globally. For many urban dwellers, the wildlife experienced in their city represents the only species with which they have familiarity. Iconic species are also emblematic of cities, for example many are characterized on sports team logos or on government flags. However, the species currently found in cities are not permanent fixtures, and anthropogenic impacts such as climate change, could threaten their presence and generational experience with them (e.g., ‘shifting-baseline syndrome’).
We modelled the distribution of over 1,800 species common in 60 North American cities to determine the predicted change in range that may occur with climate change. We found evidence of a “great urban shift” where resident urban species will become between 25 and 50 percent less common, either replaced by new species or not replaced at all. Among some of the most significantly impacted taxa include amphibians (-28%), true bugs (-36%), and waterfowl (-21%). Not all species were equally affected, but we predicted that over 51 million city residents will experience some decline in the presence of urban wildlife. These patterns were found irrespective of scenarios for greenhouse gas emissions. However, we did identify that the severity of great urban shifts will be defined by the magnitude our action (or inaction) on climate change. An impending massive change in the composition of urban biodiversity will impact the cultural identity of human residents, the delivery of ecosystem services, and our collective relationship to nature itself.
Identifying woodlands with high vulnerability to climate change in the Credit River Watershed
Laura Timms, Credit Valley Conservation
Climate change is affecting the natural systems of the Credit River Watershed, but not all areas are affected equally. Understanding which habitats are the most vulnerable will allow Credit Valley Conservation (CVC) to guide targets for management action to increase long term resilience and ecosystem health. This project builds on previous work at CVC, which assigned climate change vulnerability scores to 55 tree species using the NatureServe Climate Change Vulnerability Index tool. We combined these individual species vulnerability scores with Ecological Land Classification inventory data to calculate cumulative vulnerability scores for 3,928 treed polygons in the watershed. Cumulative scores were calculated based on the composition and dominance of tree species in the canopy and subcanopy of each polygon. About half (~51%) of the assessed area was scored as less vulnerable or moderately vulnerable, with another large portion (~43%) assessed as highly vulnerable. A relatively small portion of the assessed area (~6%) was identified as extremely vulnerable to climate change, including swamps, fens, and forests dominated by some coniferous species. Many of the patches of extremely vulnerable treed areas coincide with ecologically significant areas in the watershed. This work is being used by CVC as we plan for the future of the watershed and consider how best to implement mitigation and adaptation actions in the changing climate.
2019 Research Colloquium Program
Jim Bogart, University of Guelph
Unisexual Salamanders in Hilton Falls
Unisexual Ambystoma are the oldest known unisexual vertebrates and comprise a lineage of eastern North American all female salamanders that reproduce by stealing sperm from as many as five normally bisexual congeneric species. The sperm may be used to only stimulate egg development by gynogenesis but can be incorporated in the zygote to elevate the ploidy level or to replace one of the female’s haploid genomes. This flexible and unique reproductive system, termed kleptogenesis, is investigated using a microsatellite examination of 988 offspring from 14 unisexual mothers. All mothers produced clonal as well as ploidy-elevated offspring. Genome replacement and multiple paternity are confirmed for the first time in unisexual Ambystoma at Hilton Falls Conservation area. Microsatellite mutations were found in all five microsatellite loci and the estimated microsatellite mutation rate varied by locus and by genome. Clonal variation is attributed to the inclusion of sperm donors’ haploid genomes for ploidy elevation, genome replacement, mutations, and natural selection.
Junaid Khan & Chris Lovell, York University
Understanding the impacts of European Fire Ants (EFA’s; Myrmica rubra) on anuran populations in wetland habitats
There is a paucity of data on how invasive species may impact anuran populations (Beebee and Griffiths, 2005; Gibbon et al., 2000; Riley et al., 2005). A prolific invasive species – a small (approx. 3mm) red ant native to the Palearctic regions of Europe – Myrmica rubra (GISD, 2018) is largely unstudied for its potential impacts on anurans. The species was first identified in the Credit River watershed in 2001. Our study created a framework based on anuran and M. rubra life history traits to identify any overlap in niche, and potential interspecies competition. We quantified M. rubra abundance at seven CVC wetlands that also had between 12 and 15 years of anuran trends from Frog Watch efforts. Using presence/absence trends for six anuran species, we predicted that wetlands with high M. rubra abundance would show fewer years of a species being present compared to wetlands with low M. rubra abundance. The presence of one of the seven tested anuran species, Spring Peeper (Pseudacris crucifer) was negatively associated with M. rubra abundance (p = 0.002). A follow-up in 2018 attempted to find empirical evidence of interactions between American Toad (Bufo americanus) and M. rubra at Rattray Marsh. Although no direct interactions were found, more surveys are needed to determine the anuran-ant interspecies interactions within CVC wetlands.
Kirsten Burling, Bird Studies Canada
2016-2019 Great Lakes Marsh Monitoring Program Amphibian Survey of Rattray Marsh and Turtle Creek
In 2016 Kirsten Burling began Bird Studies Canada’s Great Lakes Marsh Monitoring Program’s amphibian survey which is night monitoring of calling frogs and toads. Three stations were set up: Station A on Turtle Creek in Jack Darling Memorial Park, Stations B and C on the knoll in Rattray Marsh Conservation Area, with B facing southward and C facing northward. The monitoring protocol for the programme was followed, involving three visits through spring and early summer to record early, mid and late breeding anurans. Credit Valley Conservation added Stonehaven Creek Bridge to the surveys, as Spring Peepers had been reported from this forested area. Over the four years of monitoring there was no evidence of Pickerel, Mink or Chorus Frog. A possible Wood Frog and possible Spring Peeper were heard the first year. Northern Leopard Frog was heard at all three marsh stations but not every year. American Toad and Green Frog were present at all three marsh stations every year. In the last two years, American Toad has been heard from the Stonehaven Creek Bridge. Finally, in 2919 a Gray Tree Frog was heard high on the hill between Turtle Creek and Rattray Marsh. Recommendations are made with regard to controlling phragmites at Stations S & B; bringing a halt to park refuse dumping into Turtle Creek; maintaining a corridor between Birchwood Park, Jack Darling & Rattray; reducing trail toad mortality with signage and education; maintaining access to the knoll lookout & boardwalk to Stations B & C for required monitoring April, May & June; and controlling water levels, especially after amphibian eggs are laid.
Mitchell Bonney, University of Toronto Mississauga
Insight on long-term forest change in the Credit Valley Watershed: Connecting satellites and field data.
In the Credit Valley Watershed, which has been under environmental pressure due to urbanization since the mid-1900s, protecting and maintaining the health of remaining forest communities is vitally important. To better understand what might influence these forests in the future, it is crucial to understand how past policies, actions and events may have influenced forests in the past. The Landsat satellite archive is uniquely positioned to monitor past changes across the entire watershed since 1972 at a spatial resolution capable of quantifying change even in small forest stands. However, changes observed by stacks of these satellite images through time are quantified as spectral reflectance variables. These variables are not ideal for conservation agencies and other organizations that make decisions and create policies based on information related to on-the-ground variables such as canopy cover and forest productivity. To combat this issue and through collaboration with Credit Valley Conservation, we have spent the last two summers collecting field data, including hemispherical photographs, forest inventories and tree cores, at dozens of forest sites across the watershed. These data are being compared with Landsat time-series data over the same locations to understand the relationship between on-the-ground variables and satellite reflectance. With these connections we can transform our Landsat time-series data from long-term change in reflectance to change in, for example, canopy cover. This transformation allows our dataset to be used with confidence in the decision and policymaking process.
Milena Rosenfield, University of Guelph
Estimates of ecosystem services in mosaic landscapes in Southern Ontario: influence of land cover and plant traits
Land use intensity and plant functional traits associated with ecosystem functions can influence the functioning of ecosystems and the potential to provide goods and services beneficial to humans. In mosaic landscapes, such as those encompassing agricultural, urban and natural areas, the potential of an ecosystem to provide a broad range of ecosystem services is vital to human well-being. The University of Guelph has been working with the CVC on several projects to explore the provision of multiple ecosystem services by natural ecosystems in the Credit River Watershed and evaluate the effect of landscape (land use) and plant characteristics (functional traits) on these services. A recently published study analyzed how landscape variables affect community assembly patterns, finding that landscape variables result in significant trait-divergence assembly patterns in different spatial scales. This study discusses the implications of trait divergence as well as the mechanisms through which landscape metrics might be responsible for these patterns. Our current project has two main objectives: the first is to assess the provision of multiple ecosystem services by different natural ecosystems (forests, riparian forests and wetlands) and to evaluate the impact of surrounding land cover on these ecosystem services. The second objective is to identify indicators for ecosystem services in forests using plant functional traits. This study highlights the importance of conserving natural ecosystems and preserving the provision of services that benefit human well-being, with implications for landscape management.
Hossam Abdel Moniem, University of Toronto Mississauga
Modeling and evaluating connectivity networks for the Credit valley watershed
The Provincial Policy Statement 2014 mandates planning and development of natural heritage systems in order to maintain, restore, or improve biodiversity and connectivity of natural heritage systems. Credit Valley Conservation authority (CVC) works with municipalities to develop and manage natural heritage systems within the Credit river watershed. Therefore, there is an important demand to modeling connectivity and evaluating the importance of natural heritage features within the CVC jurisdiction to optimize and prioritize their conservation efforts. In collaboration with the CVC, we used a Circuit Theory approach to model a wall-to-wall, high-resolution current density map to characterize the important connectivity pathways that facilitate the flow of biodiversity in the CVC landscape. We then analyzed the importance of each natural heritage feature for maintaining the connectivity network using a weighted least cost path, and four critical Euclidian dispersal thresholds identified by the CVC with insight into their biodiversity data. Our results illustrate the importance of natural heritage features within the CVC jurisdiction in maintaining the connectivity network within the Credit river watershed, which has been underestimated when modeled, previously, at the provincial scale. The implementation of this approach contributes to the CVC efforts towards prioritizing conservation decisions.
Zoe Bedford & Monique Dosanjh, University of Toronto Mississauga
Mapping Spatial and Temporal Trends in Lake Bathymetry in the Credit Valley Watershed Using Landsat Images
Bathymetry is the study and measurement of the depth of water bodies, and is an essential parameter to understand trends in the water volume and water variability in lakes. Accurate and detailed knowledge of lake depth in urban and suburban landscapes is important for a variety of applications including managing and maintaining aquatic ecosystem functioning in the context of rapid urbanization and climate change. Remote sensing technologies have been demonstrated to be time efficient and cost-effective in deriving lake bathymetry data and monitoring the spatial and temporal status of lake depth through their large geographical coverage and long history of image acquisition. One method is the SPEAR Relative Water Depth tool, an algorithm created to estimate the relative and absolute depth of water bodies from optical satellite imagery. Through the use of Landsat 8 imagery and the SPEAR Relative Water Depth tool in ENVI, this study derived the absolute depth for the lakes in the Credit Valley Watershed, and evaluated the accuracy of satellite-derived depth using ground depth data collected from three lakes. In addition, this study also investigated the ability of satellite-derived bathymetry to monitor spatial and temporal changes in lake depth between a wet and a dry year. Our work not only gains a comprehensive view of the current bathymetry of lakes in the Credit Valley Watershed, but also provides insights on how lakes have changed annually.
Meagan Kindree, University of Toronto Scarborough
Interactive Effects of Climate Change and Invasive Species
Climate change is a principal threat to freshwater biodiversity and to the structure and functioning of ecosystems. Freshwater fishes are particularly vulnerable to climate change due to their ectothermy and constrained dispersal ability within dendritic networks. Global climate change will alter thermal habitat availability for native and non-native invasive species, leading to changes in distribution and, potentially, negative impacts on ecosystem function. Synergies with invasive species, could amplify the effects of climate change on ecosystems and their communities. Native White Sucker (Catostomus commersonii) and invasive Round Goby (Neogobius melanostomus) were chosen as candidate species to examine how increases in temperature may influence native fish’s distribution and competition. This research completed in the Credit River has two main objectives. Firstly, to examine the response of these native and invasive fishes to increasing water temperature by measuring their agitation temperature and critical thermal maximum (CtMax) to predict their potential future interactions under a warming climate. Secondarily, to examine the trophic level and diet breadth of a native species when an invader of a similar fundamental niche is present. In collaboration with Credit Valley Conservation fish crews, I investigated the CtMAx of the two species to quantify differences in thermal tolerance in a natural system. Preliminary analysis suggests that CtMax and agitation temperature are significantly higher in Round Goby. In addition, the location along the river gradient is a significant driver of CtMax, suggesting some level of phenotypic plasticity in thermal tolerance of both species.
Lauren Lawson, University of Toronto
Road salt as a stressor to aquatic species at risk in Southern Ontario
The Golden Horseshoe region of southern Ontario is one of the most rapidly growing areas in North America, and with this growth comes an increase in impermeable surfaces including roads, parking lots, and sidewalks. In winter climates particularly, increases in road density leads to increases in the use of road salt. Road salt then enters waterbodies and groundwater through road runoff leading to increases in water salinity, with some locations having winter chloride concentrations comparable to brackish estuaries and even some concentrations similar to seawater. Our results show influxes of chloride in winter can persist year-round and lead to chronically high chloride concentrations, even in summertime when more natural background levels might be expected. Elevated chloride concentrations can be lethal for freshwater organisms and have been found to alter organismal behaviour and community dynamics at sublethal concentrations. As the distribution of many aquatic species at risk in Canada is concentrated in southern Ontario, an area with high application rates of road salt, increasingly elevated levels of chloride may represent a significant factor contributing to the decline of various species at risk. The initial phase of our research seeks to determine if chloride is contributing to the decline of Redside Dace. To accomplish this, we are studying exposure of Redside Dace to chloride in currently known sites as well as historic sites where extirpation is believed to have occurred.
Anna Marie O’Brien, University of Toronto
Urban runoff and the evolutionary ecology of aquatic plant-microbiome interactions
Plant-microbiome interactions are ubiquitous and provide critical support of plant growth both in natural and agricultural systems. Urbanization of landscapes brings previously un-encountered stressors, from urban heat islands to chemical-laden surface runoff, and such novelty may perturb plant-microbe interactions. Runoff contaminants disproportionately affect freshwater species, so we focus on a floating plant Lemna minor (duckweed) and its microbiome. Duckweed is tiny (fronds 2-5 mm) and reproduces rapidly (clonal generations in 3 days), making it highly amenable to experimentation. Duckweed hosts a mutualistic and diverse microbiome, of which many species can be lab-cultured, facilitating microbiome manipulation. We found that contaminant stressors (metals, salt, and anti-corrosives), and the origin of duckweed and its microbiome from across the Greater Toronto Area (including the Credit Valley watershed) can interactively alter plant traits. In fact, microbes favor biotransformation of some runoff contaminants to less stressful or growth-promoting compounds, and urban duckweed better tolerate chemical inputs. In progress work will test whether global change stressors in concert (CO2, temperature, and road runoff) predictably affect plant microbial communities.
Rosalind Murray, University of Toronto Mississauga
The effect of deicing road salt on dragonfly growth, survival and performance
The salinization of freshwater habitats is causing decreases in aquatic biodiversity on a global scale. Deicing road salt is a major contributor to increased salt pollution in cold climates, particularly in road-adjacent freshwater environments. Using a mesocosm experimental set up, we investigated the effect of environmentally relevant levels of road salt exposure on larval dragonflies from a CVC stormwater pond. Dragonfly larvae are important predators in freshwater environments and can shape aquatic communities. Moreover, adult dragonflies prey on human disease vectors (e.g. mosquitoes) and provide an important resource for higher predators such as birds and fish. Determining how dragonflies persist in the increasing salinity they experience in urban environments can be broadly applied to understanding how increased application of deicing road salt will influence both aquatic and terrestrial communities as a whole. We did not see any difference in growth rate and survival across salt treatments; however, we did find several sub-lethal effects of salt pollution on dragonfly performance. Salt-exposed dragonfly larvae decreased their foraging rate (consumed fewer mosquitoes) compared to control larvae. We also observed carryover effects; dragonflies exposed to road salt as larvae were less able to mount an effective immune response as adults. We suggest that road salt pollution in freshwater habitats is likely impacting organisms in subtle and sub-lethal ways that will accumulate quickly to influence community structure (e.g. more mosquitoes and vulnerable dragonflies) in both aquatic and terrestrial environments.
Chris MacQuarrie, Canadian Forest Service
Update on biological control of the emerald ash borer
A summary of the releases to date of the three species of parasitoids across eastern Canada and an update on research to assess establishment, impact and spread.
Amanda Liczner, York University
Using detection dogs to locate bumble bee nests: Lessons learned
Habitat loss is one of the main threats to bumble bees yet our understanding of bumble bee habitat is limited. This is especially true for the nesting habitat of bumble bees. The difficulty in locating bumble bee nests, which are often underground, may be contributing to our lack of knowledge of this critical resource. To address this important knowledge gap, we deployed detection dogs that were trained on the scent of bumble bee nests to three sites: Terra Cotta and Silver Creek Conservation Area and Scotsdale Farm. Although the dogs can detect the scent of bumble bee nests there were a number of challenges that may limit the applicability of this technique. These challenges include: humans are required to find confirmed wild nests, the search strategy, scent differences between nests, and site considerations.
Kayla Mundy-Heisz, University of Guelph
A comparison of bumble bees in farms and natural areas
Bumble bees (Bombus sp.) are generalist pollinators supporting a wide array of flora within the Northern Hemisphere. These bees also contribute to agricultural production of many fruits, berries and vegetables. Bumble bees are facing a myriad of risks which vary in intensity of interaction across space and time, including habitat loss, disease, invasive species, climate change, and pesticides. To understand the impact of farming on bumble bees, particularly queens, field studies comparing natural areas and farms in South Central Ontario were conducted over the past two years. Caught bumble bee queens were identified and marked before being released at the end of each sampling session. The abundance and diversity of bumble bee queens within natural areas and farms was compared. Further, the behaviour of the queen at the time of capture was recorded to examine any behavioural differences between natural areas and farms. If queens were foraging, the flower being used was recorded, allowing for comparison of foraging choice between natural areas and farms. This work is crucial to determine the number and diversity of bumble bee queens that may be exposed to pesticides from fields and if farms can also be used to promote the conservation of a wide range of bumble bee diversity.