1,721,037 research outputs found
Evaluating the Effectiveness of Restoration Activities for Freshwater Species at Risk in Ontario
Get PDFRestoration is the act of returning ecosystems to their historical trajectories to maximize ecosystem biodiversity, structure, and function. However, the effectiveness of aquatic restoration is often unknown due to gaps in knowledge associated with evaluating restoration. To overcome these gaps, evaluating the effectiveness of restoration for aquatic Species at Risk (SAR) using robust datasets and standardized monitoring are required. To assess whether the Canadian Habitat Stewardship Program (HSP) for the stewardship of aquatic SAR was effectively targeting aquatic SAR and to determine whether projects were achieving measurable conservation benefits, I analyzed 98 projects funded through the HSP in Ontario, 2006-2017. Although HSP-funded projects targeted areas of high SAR richness, many species-rich watersheds and widely distributed aquatic SAR were left untargeted. Lack of monitoring data prevented the evaluation of the effectiveness of these restoration projects. I addressed these shortcomings for one restoration project, habitat creation for spawning Spotted Gar in Rondeau Bay, Ontario, by monitoring and analyzing the fish assemblage – environment relationship of pre-monitoring data conducted for a Before-After-Control-Impact study evaluating the effectiveness of the project.M.Sc
Synergistic Impact of Climate Change and Aquatic Invasive Species on Native Fish Communities
Get PDFClimate change and invasive species are drivers of ecological disruption, fundamentally altering species distribution, community structures, and ecosystem functions. Climate change alters ecosystems by shifting temperature regimes, precipitation patterns, and seasonal cycles, influencing species distributions, ecological interactions, and survival. Invasive species threaten biodiversity by outcompeting native species for limited resources, disrupting established food-webs, and potentially leading to the decline or local extinction of native species. When combined, these stressors may amplify biodiversity loss and destabilize ecosystems through synergistic interactions. This thesis explores how climate change and invasive species interact to shape native fish communities in freshwater ecosystems. Using invasive Round Goby (Neogobius melanostomus) and two native benthic fish species, Longnose Dace (Rhinichthys cataractae) and Western Blacknose Dace (R. obtusus), in the Credit River, Ontario, Canada, I examine how thermal tolerance, feeding efficiency, and physiological responses to variable thermal environments influence competitive dynamics between invasive and native species. I test the hypothesis that Round Goby, due to its high thermal tolerance, will exhibit higher competitive performance, exerting greater competitive pressure on native fish species, which could potentially lead to significant ecological impacts. Functional-response experiments and thermal-tolerance trials demonstrate that Round Goby exhibits broader thermal tolerance and higher feeding efficiency than native species, particularly at elevated temperatures. These advantages may confer a competitive advantage over native species in warming environments, potentially contributing to shifts in local species composition and altering long-term community dynamics. The findings demonstrate how the combined effects of climate change and biological invasions can exacerbate ecological pressures, disrupting predator-prey dynamics, altering nutrient cycling, and reducing ecosystem resilience. To maintain biodiversity and ensure ecosystem stability in a warming world, a multifaceted approach that integrates habitat restoration, invasive-species management, and climate-adaptation strategies, is essential for reducing the compounded impacts of invasive species and climate change.Ph.D
Quantifying the Effect of Sampling Gear and Effort on the Index of Biotic Integrity in two Huron-Erie Corridor Areas of Concern
Get PDFThe Detroit and St. Clair rivers were identified as Areas of Concern (AOC) in response to losses in critical fish and wildlife habitat. Implementation of remedial action plans required aquatic monitoring of AOCs using the Index of Biotic Integrity (IBI), a multi-metric index for biological assessment. In this study, three methods of calculating the IBI were applied to fish communities sampled using two different gears to determine the influence of scoring and sampling methods on IBI scores. IBI score variance between sites was also examined to determine the influence of sample effort. The results revealed that the IBI was not sensitive to gear type in either rivers due to varying catchability of species for each gear type. No significant difference was found between the three methods of IBI calculation. IBI score variance determined that current sampling protocols reduce the variance of mean IBI scores within a river by ~75%.M.Sc
Effects of multiple stressors on historical changes in the fish communities of the Credit River watershed
Get PDFWatersheds in southern Ontario are of high conservation concern due to their diverse fish communities, productive environments, and threats from numerous anthropogenic stressors. The Credit River watershed, located west of the Greater Toronto Area, has 63 fish species and multiple stressors, including urbanization, climate change, and aquatic invasive species (AIS). This research examines fish community change in the Credit River watershed in relation to these multiple stressors. Historical fish datasets collected in the watershed from 1954 to present were analyzed to examine richness patterns and homogenization at the site and subwatershed levels. Richness and faunal homogenization increased at the site and subwatershed level over time. AIS and temperature were responsible for causing the most variation in the fish communities over time. The cumulative effects of AIS and temperature also caused increased variation in the communities over time.M.Sc
Exploring Spatiotemporal Community Assembly using Taxonomic and Functional Dimensions of Biodiversity
No full textDetermining how diversity is generated and maintained in ecological communities is a central goal of community ecology and conservation. Ecologists have long aimed to explain the processes responsible for the assembly of communities and although many hypotheses have been proposed, understanding what makes a non-native species successful continues to be the principal question in invasion ecology. Addressing these topics is inherently complex given that the mechanisms that regulate diversity are often dependent on the spatial and temporal scale at which they are quantified and are further complicated by pervasive context dependence. This thesis examines the spatiotemporal changes in, and community assembly processes governing, functional and taxonomic dimensions of biodiversity in fish communities of the Laurentian Great Lakes in response to the establishment of non-native species and extirpation of native species. I show that both taxonomic and functional dimensions of local and regional diversity are increasing over time. Between-community diversity has increased and decreased for functional and taxonomic dimensions of diversity, respectively, indicating the presence of both biotic differentiation and homogenization that is temporally dynamic. Environmental filtering selects for similar species due to a shared affinity for local conditions and explains establishment success of non-native species as well as local and regional patterns of diversity. Community assembly and composition is also highly regulated by dispersal and historical effects due to the glacial history of the region.Ph.D
Acoustic and Strobe-light Behavioural Barriers: Examining Behavioural and Movement Responses of Common Carp (Cyprinus carpio) at Laboratory and Mesocosm Scales
No full textAcoustic and strobe-light behavioral barriers have been recognized as tools to limit the spread of Asian carps in the Great Lakes. Urgent research is needed to understand how these stimuli impact behaviour, and to evaluate barrier efficacy within realistic canal environments. In a laboratory study, Common Carp responses to stimuli were recorded with video trials (n=44). There were no differences in behavioural responses to acoustic, strobe-light, or combined stimuli. The stimulus period increased durations of carp movement, and the post-stimulus period had increases in movement duration and barrier passes. In a mesocosm study, Common Carp (n=6) and buffalo (n=3) were exposed to the same stimuli, and movement was analyzed using acoustic telemetry. Acoustic stimuli did not produce significant movement responses. Strobe lights (n=12) produced smaller utilization distributions, a decrease in relocations, and an increase in travel velocity near the stimuli (M.Sc
Quantifying the Effect of Sampling Gear and Effort on the Index of Biotic Integrity in two Huron-Erie Corridor Areas of Concern
No full textThe Detroit and St. Clair rivers were identified as Areas of Concern (AOC) in response to losses in critical fish and wildlife habitat. Implementation of remedial action plans required aquatic monitoring of AOCs using the Index of Biotic Integrity (IBI), a multi-metric index for biological assessment. In this study, three methods of calculating the IBI were applied to fish communities sampled using two different gears to determine the influence of scoring and sampling methods on IBI scores. IBI score variance between sites was also examined to determine the influence of sample effort. The results revealed that the IBI was not sensitive to gear type in either rivers due to varying catchability of species for each gear type. No significant difference was found between the three methods of IBI calculation. IBI score variance determined that current sampling protocols reduce the variance of mean IBI scores within a river by ~75%.M.Sc
Exploring Spatiotemporal Community Assembly using Taxonomic and Functional Dimensions of Biodiversity
Get PDFDetermining how diversity is generated and maintained in ecological communities is a central goal of community ecology and conservation. Ecologists have long aimed to explain the processes responsible for the assembly of communities and although many hypotheses have been proposed, understanding what makes a non-native species successful continues to be the principal question in invasion ecology. Addressing these topics is inherently complex given that the mechanisms that regulate diversity are often dependent on the spatial and temporal scale at which they are quantified and are further complicated by pervasive context dependence. This thesis examines the spatiotemporal changes in, and community assembly processes governing, functional and taxonomic dimensions of biodiversity in fish communities of the Laurentian Great Lakes in response to the establishment of non-native species and extirpation of native species. I show that both taxonomic and functional dimensions of local and regional diversity are increasing over time. Between-community diversity has increased and decreased for functional and taxonomic dimensions of diversity, respectively, indicating the presence of both biotic differentiation and homogenization that is temporally dynamic. Environmental filtering selects for similar species due to a shared affinity for local conditions and explains establishment success of non-native species as well as local and regional patterns of diversity. Community assembly and composition is also highly regulated by dispersal and historical effects due to the glacial history of the region.Ph.D
Science in support of policy: Assessment and recovery of fish species at risk in the Sydenham River
No full textPassage of the Canadian 'Species at Risk Act' created a need for improved scientific tools to assess and recover fish species at risk. The Sydenham River was used as a test case to address these needs because of the large number (n = 8) of species at risk found there. The objectives were to: (1) compare the efficiency of electrofishing and seining for sampling fish species at risk, and, (2) develop and test a science-based framework to decide between three recovery planning approaches. Fishes were sampled at 75 sites throughout the watershed. Geomorphology, substrate, and water quality were measured at each site and their relationship with species at risk was examined. Based on the results of this study, assessment and recovery of fish species at risk in the Sydenham River would be best served by a standardized sampling methodology focused on backpack electrofishing, and a recovery plan using an ecosystem-based approach
Acoustic and Strobe-light Behavioural Barriers: Examining Behavioural and Movement Responses of Common Carp (Cyprinus carpio) at Laboratory and Mesocosm Scales
Get PDFAcoustic and strobe-light behavioral barriers have been recognized as tools to limit the spread of Asian carps in the Great Lakes. Urgent research is needed to understand how these stimuli impact behaviour, and to evaluate barrier efficacy within realistic canal environments. In a laboratory study, Common Carp responses to stimuli were recorded with video trials (n=44). There were no differences in behavioural responses to acoustic, strobe-light, or combined stimuli. The stimulus period increased durations of carp movement, and the post-stimulus period had increases in movement duration and barrier passes. In a mesocosm study, Common Carp (n=6) and buffalo (n=3) were exposed to the same stimuli, and movement was analyzed using acoustic telemetry. Acoustic stimuli did not produce significant movement responses. Strobe lights (n=12) produced smaller utilization distributions, a decrease in relocations, and an increase in travel velocity near the stimuli (M.Sc
- …
