Graduate Theses & Dissertations

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Effects of Intensive Agriculture on Stream Nutrient Export in East-Central Ontario, Canada
Recent agricultural land use change in east-central Ontario, including the expansion of intensive agriculture (corn and soybean crops) and tile drainage (TD) infrastructure, may alter the fluxes of both phosphorus (P) and nitrogen (N) to the Lower Great Lakes. Through intensive monitoring of several sub-watersheds that encompassed a range of row crop and TD extents, this study examined differences in stream N and P concentrations both seasonally and during variable flow conditions, to better understand land use/land cover (LULC) relationships with nutrient export. There was no clear relationship between total P (TP; concentration or export) and agricultural LULC, and instead, TP delivery was highly sensitive to flow events, and TP concentrations (especially particulate P; PP) were significantly higher during event flow compared with baseflow. In contrast, the dissolved fraction of P (total dissolved P; TDP) and dissolved nitrogen as nitrate (NO3-N) were not sensitive to flow, but were instead positively related to row crop agriculture, and associations between NO3-N concentrations/export and tile-drained row crop area were particularly strong (concentration r2 = 0.93; export r2 = 0.88). Regression relationships showed that with every 10% increase in row crop area in watersheds, NO3-N and TDP flow-weighted concentrations increased by 0.34 mg/L and 1.5 µg/L, respectively. As well, the same 10% increase in row crop agriculture translated to an increase of NO3-N export of as much as 130 kg/km2. Geospatial records of TD are incomplete in east-central Ontario, which presents challenges for evaluating the contribution of TD to nutrient export. Understanding the response of nutrients to changes in agriculture and agricultural practices is an integral part of watershed management as rapid changes in both urban and agricultural LULC continue to put pressure on water quality in the Lower Great Lakes. Author Keywords: East-Central Ontario, Nutrient Export, Row crops, Streams, Tile Drainage, Water Quality
Assessing Brook Trout (Salvelinus fontinalis) Seasonal Occupancy in Haliburton County, ON Using Environmental DNA
Brook trout (Salvelinus fontinalis) are declining across Ontario in both numbers and distribution, prompting concern for their future. Here, conventional, emerging, and predictive tools were combined to document brook trout occupation across seasons using streams in Haliburton County, ON as model systems. By using the Ontario Ministry of Natural Resources and Forestry’s (OMNRFs) Aquatic Ecosystem Classification (AEC) system variables with environmental DNA (eDNA) sampling and backpack electrofishing, my research supports the development of species occupancy models (SOMs) and eDNA as tools to document brook trout occurrence. To do this, eDNA sampling was validated in Canadian Shield stream environments by comparison with single-pass backpack electrofishing before seasonally sampling two river systems across their main channel and tributaries to assess occupancy. Streams were classified as potential high, moderate, and low-quality brook trout habitats using indicator variables within the AEC and sampled seasonally with eDNA to quantify occupancy and relate it to habitat potential at the county scale. Results showed eDNA to be an effective tool for monitoring fish across Canadian Shield landscapes and that brook trout occupancy varied seasonally within and across watersheds, suggesting that habitat and fish management strategies need to consider seasonal movement and spatial connectivity. Using these tools will enable biologists to efficiently predict and document brook trout occurrences and habitat use across the landscape. Author Keywords: Aquatic Ecosystem Classification, brook trout, Canadian Shield, connectivity, environmental DNA, seasonal occupation
Understanding Angler Dynamics in a Recreational Lake Trout (Salvelinus namaycush) Fishery in Algonquin Provincial Park Using Long-Term Access Creel Data
In order to effectively manage recreational fisheries, it is important to understand how the resource is being used. In this thesis, long-term creel census data, collected on Lake Opeongo in Algonquin Provincial Park, Ontario, Canada was used to assess fine-scale angler dynamics within a recreational Lake Trout (Salvelinus namaycush) fishery. The spatial distribution of angler reported catch locations of Lake Trout within the lake, was assessed using an Optimized Hotspot Analysis in ArcGIS. Areas of significant clustering of catch locations were revealed during all time periods and varied in size and location both seasonally and temporally. Cormack-Jolly-Seber models were used to evaluate the probability of individual angling boats persisting in the regional fishery and being detected on Lake Opeongo through time, as well as to examine the effect of angler travel distance and gas prices on participation parameters. Time-varying models revealed that the probability of an angler persisting in the fishery varied, while detection estimates remained stable. Travel distance had a negative effect on both parameters while increased gas prices only had a slight negative effect on detection estimates. Additionally, among Lake Opeongo anglers, angling avidity varied as did lake specific fishing experience. Average CUE was found to be higher among angling parties who visited the lake more often than fishing parties who visited relatively few times. Author Keywords:
Wastewater Impacts on Freshwater Mussels and Water Quality in a Tributary of the Lower Grand River in Southwestern Ontario, Canada
The main goal of this thesis was to assess the potential impacts of discharges of treated effluent from a small facultative sewage lagoon serving approximately 300 residents of the Mississaugas of the Credit First Nation to freshwater mussel populations in Boston Creek, a small tributary of the lower Grand River. The current resident mussel populations inhabiting Boston Creek were assessed using semi-qualitative visual surveying methods. In addition to various population level observations, other possible point and non-point influences on water quality in Boston Creek were identified. Following this, Lasmigona costata mussels were deployed as biomonitoring organisms alongside passive samplers during the October 2017 lagoon discharge period. Time weighted average (TWA) concentrations of select Contaminants of Emerging Concern (CECs) and Polycyclic Aromatic Hydrocarbons (PAHs) were estimated from levels of these compounds accumulated on passive samplers to understand the influence of wastewater on water quality in Boston Creek. Finally, mussel tissues were analyzed for various biomarkers of exposure to contaminants. Population surveys indicated that Boston Creek supports a plentiful and diverse community of freshwater mussels and may be a refuge for the Species of Special Concern, Villosa iris. Passive sampling revealed that most PAHs measured were present at concentrations below detection limits, while CECs were typically detected at relatively low concentrations (ng/L) directly downstream of the lagoon discharge. Biomarker responses detected in Lasmigona costata generally could not be attributed to exposure to the lagoon effluent but these data may indicate response to other point and non-point sources of pollution that could be affecting resident freshwater mussel populations in Boston Creek. The mussels surveyed in Boston Creek may be displaying community level effects of exposure to other sources of pollution in the area. The results of this thesis will help in establishing water quality guidelines in the lower Grand River watershed that will assist in the recovery strategy for freshwater mussel species at risk in Ontario. Author Keywords: Biomarkers, Biomonitoring, CECs, First Nations, Freshwater Mussels, SAR
Potential for Greenhouse Gas Emissions from Sediments of Agricultural Streams and Lake Erie
This thesis examines how dissolved organic matter quantity and quality and nutrients influence the flux potential of greenhouse gases (GHG) from sediments collected from streams across southern Ontario as well as Lake Erie. Sediments were collected and incubated in a laboratory setting where headspace gases and interstitial waters were analyzed. Results demonstrated that nutrients (dissolved organic carbon (DOC), total dissolved phosphorous (TDP) and total dissolved nitrogen (TDN)) were commonly significant predictors of CO2, CH4, and N2O fluxes, but spatial discrepancies were observed for the significance of DOM quality and sedimentary characteristics. Land use was not found to be directly related to gas flux potential. Different relationships were observed between the streams and lake, and between the basins of Lake Erie. Overall, results from this study suggest that sediments from freshwater systems have the potential to be sources of GHG, the degree of which depends on nutrient concentrations and DOM structure from watershed inputs. Author Keywords: dissolved organic matter, greenhouse gases, Lake Erie, nutrients, sediment, streams
Effects of Silver Nanoparticles on Lower Trophic Levels in Aquatic Ecosystems
Due to their effective antibacterial and antifungal properties, silver nanoparticles (AgNPs) have quickly become the most commonly used nanomaterial, with applications in industry, medicine and consumer products. This increased use of AgNPs over the past decade will inevitably result in an elevated release of nanoparticles into the environment, highlighting the importance of assessing the environmental impacts of these nanomaterials on aquatic ecosystems. Although numerous laboratory studies have already reported on the negative effects of AgNPs to freshwater organisms, only a handful of studies have investigated the impacts of environmentally relevant levels of AgNPs on whole communities under natural conditions. This thesis examines the effects of chronic AgNP exposure on natural freshwater littoral microcrustacean, benthic macroinvertebrate and pelagic zooplankton communities. To assess the responses of these communities to AgNPs, I focused on a solely field-based approach, combining a six-week mesocosm study with a three-year whole lake experiment at the IISD – Experimental Lakes Area (Ontario, Canada). Our mesocosm study tested the effects of AgNP concentration (low, medium and high dose), surface coating (citrate- and polyvinylpyrrolidone [PVP]-coated AgNPs), and type of exposure (chronic and pulsed addition) on benthic macroinvertebrates in fine and stony sediments. Relative abundances of metal-tolerant Chironomidae in fine sediments were highest in high dose PVP-AgNP treatments; however, no negative effects of AgNP exposure were seen on biodiversity metrics or overall community structure throughout the study. I observed similar results within the whole lake study that incorporated a long-term addition of low levels of AgNPs to an experimental lake. Mixed-effects models and multivariate methods revealed a decline in all species of the littoral microcrustacean family Chydoridae in the final year of the study within our experimental lake, suggesting that this taxon may be sensitive to AgNP exposure; however, these effects were fairly subtle and were not reflected in the overall composition of littoral communities. No other negative effects of AgNPs were observed on the pelagic zooplankton or benthic macroinvertebrate communities. My results demonstrate that environmentally relevant levels of AgNPs have little impact on natural freshwater microcrustacean and benthic macroinvertebrate communities. Instead, biodiversity metrics and community structure are primarily influenced by seasonal dynamics and nutrient concentrations across both lakes. This thesis highlights the importance of incorporating environmental conditions and the natural variability of communities when examining the potential risks posed by the release of AgNPs into the environment, as simplistic laboratory bioassays may not provide an adequate assessment of the long-term impacts of AgNPs on freshwater systems. Author Keywords: Benthic macroinvertebrates, IISD - Experimental Lakes Area, Littoral microcrustaceans, Silver nanoparticles, Whole lake experiment, Zooplankton
Protecting Sources of Drinking Water for the M'Chigeeng First Nation, Manioulin Island, Ontario
The potential impacts of domestic wastewater (DWW) on the source of drinking water for the M’Chigeeng First Nation were monitored as part of the development of a Source Water Protection plan. During a period of continuous overflow of the Gaaming Wastewater Lagoon serving the community, the chemical tracers, caffeine and sucralose were tracked in West Bay with Passive Organic Chemical Integrative Samplers (POCIS). From the results, we speculated that DWI impacts could have been from three possible DWW sources. POCIS deployed above and below the thermocline indicated a higher mean sucralose concentration of 2.52 ± 1.83 ng/L in the hypolimnion of West Bay relative to mean epilimnetic sucralose concentrations of 0.56 ± 0.02 ng/L, suggesting possible wastewater percolation with an estimated time of travel of 61.5 days. Microbial loads of 200 CFU/100 ml E. coli from the lagoon overflow into Mill Creek decreased to 60 CFU/100 ml before entering West Bay. West Bay’s wastewater assimilative capacity met Provincial Water Quality Objectives in the epilimnion and hypolimnion except for dissolved oxygen in the hypolimnion at 4.16 ± 1.86 mg/L, which is a threat to the onset of hypoxia for fish (i.e. <5 mg/L). Assimilative capacity results support a Fall lagoon discharge. Author Keywords: caffeine, drinking water, Passive Organic Chemical Integrative Samplers (POCIS), sucralose, thermocline, wastewater
Fate and Effects of Silver Nanoparticle Addition in a Lake Ecosystem
The potential release of nanoparticles into aquatic environments is raising global concerns. As antimicrobials, silver nanoparticles (AgNPs) are among the most prominent form in use. Despite this, their fate, long-term toxicity, and ecological relevance have yet to be investigated largely under natural settings with seasonality and environmental complexity. To better understand the environmental significance, we released AgNPs into Lake 222 at the Experimental Lakes Area over two years. AgNPs remained suspended in the water column and were detected throughout the lake and in the lower food web. Total Ag concentrations ranged from below 0.07 to 18.9 μg L-1 in lake water, and were highly dynamic seasonally both in the epilimnion and hypolimnion depending on the physical, chemical and biological conditions of the lake. Approximately 60% of the measured Ag mass in October was present in the sediment in 2014 and 50% in 2015 demonstrating relatively high sedimentation and removal from the water column. During winter months, Ag was largely absent in the water column under the ice. After ice melt and before summer stratification, Ag concentrations increased in the lake suggesting AgNPs may not be tightly bound to the sediment and are able re-enter the water column during spring mixing events. Despite temporal variation, total Ag was highly synchronous across spatial locations for both years, indicating rapid dispersal upon lake entry. When investigating AgNP sizes using spICPMS, size distributions were similar across spatial locations, with the 40-60 nm size class constituting approximately 60% of all particles identified. Large aggregates (>100 nm) and dissolved Ag were infrequently detected within the lake. Ag accumulated in the lower food web ranging from 0.27-16.82 μg Ag mg C-1 in the bacterioplankton and 0.17-6.45 μg Ag mg C-1 in algae (particulate fraction). Partial least squares models revealed the highest predictors of Ag accumulation were dissolved nutrients including DOC, TDN, TDP in bacterioplankton. Major predictors for particulate Ag included temperature, dissolved oxygen, and sampling date. The diversity of predictors among biological compartments emphasizes the importance of understanding the role of environmental complexity within the lower food web. Despite Ag accumulation we did not detect strong negative effects on the lake food web. An increase in particulate and bacterioplankton chlorophyll-a occurred after addition in contrast to reference lakes, which may indicate a hormetic response to low dose AgNP concentrations. Our findings provide the first whole-lake perspective regarding Ag fate and toxicity, suggesting small scale experiments may overestimate environmental responses. Author Keywords: Ecotoxicity, Fate, Lower food web, Silver Nanoparticles, Whole-lake addition
Comparing Biological Responses to Contaminants in Darters (Etheostoma spp.) Collected from Rural and Urban Regions of the Grand River Watershed, Ontario
Urban and agricultural activities may introduce chemical stressors, including contaminants of emerging concern (CECs) and current use pesticides (CUPs) into riverine systems. The objective of this study was to determine if fish collected from sites in a river show biomarkers of exposure to these classes of contaminants, and if the biomarker patterns vary in fish collected from urbanized and agricultural sites. The watershed selected for this study was the Grand River in southern Ontario, which transitions from areas dominated by agricultural land use in the north to highly urbanized locations in the southern part of the watershed. Rainbow darters (Etheostoma caerluem) and fantail darters (Etheostoma flabellare) were collected from the Grand River in June, 2014 for biomarker analysis from two urbanized sites and three agricultural sites (n=20 per site). Over the same period of time, Polar Organic Chemical Integrative Samplers (POCIS) were deployed for 2 weeks at each site to monitor for the presence of CUPs and CECs. The amounts of the target compounds accumulated on POCIS, determined using LC-MS/MS were used to estimate the time weighted average concentrations of the contaminants at each site. Data on the liver somatic index for darters indicate site-specific differences in this condition factor (p<0.05). Significant differences in the concentrations of thiobarbituric acid reactive substances (TBARS) in gill tissue (p<0.05) indicate differences in oxidative stress in fish collected from the various sites. Measured concentrations of ethoxyresorufin-O-deethylase (EROD) in liver tissue were significantly different between sites (p<0.05), indicating differences in CYP1A metabolic activity. Finally, acetylcholinesterase (AChE) activity in brain tissue was significantly different between fish from rural and urban sites (p<0.05). The analysis of these biomarkers indicates that fish may be experiencing different levels of biological stress related to different land uses. These data may be useful in developing mitigation strategies to reduce impacts on fish and other aquatic organisms in the watershed. Author Keywords: AChE, Biomarker, Darter, EROD, POCIS, TBARS
effects of parasitism on consumer-driven nutrient recycling
Daphnia are keystone consumers in many pelagic ecosystems because of their central role in nutrient cycling. Daphnia are also frequently infected, and the parasites causing these infections may rival their hosts in their ability to regulate ecosystem processes. Therefore, parasitic exploitation of Daphnia may alter nutrient cycling in pelagic systems. This thesis integrates existing knowledge regarding the exploitation of Daphnia magna by 2 endoparasites to predict parasite-induced changes in the nutrient cycling of infected hosts and ecosystems. In chapter 1, I I contextualizing the integration of these themes by reviewing the development of the fields of elemental stoichiometry and parasitology. In chapter 2, we show how the bacterial parasite, Pasteuria ramosa, increased the nitrogen (N) and phosphorus (P) release rates of D. magna fed P-poor diets. We used a mass-balance nutrient release model to show that parasite-induced changes in host nutrient accumulation rates and diet-specific changes in host ingestion rates were responsible for the accelerated nutrient release rates that we observed. In chapter 3, we extended our examination of the nutrient mass balance of infected D. magna to include another parasite, the microsporidian H. tvaerminnensis. We found differences in the effects of these two parasites on host nutrient use as well as support for the hypothesis that parasite-induced changes in Daphnia N release are caused by the effects of infection on Daphnia fecundity. In chapter 4, we examined the relationship between P concentrations and the presence and prevalence of H. tvaerminnensis in rock pools along the Baltic Sea. We found that particulate P concentrations were negatively associated with the prevalence of this parasite, a result that is consistent with the increase in P sequestration of H. tvaerminnensis-infected Daphnia that we observed in chapter 3. I discuss the potential implications of the work presented in chapters 2-4 for other parasite-host systems and ecosystems in chapter 5. Overall, the research presented here suggests that parasite-induced changes in host nutrient use may affect the availability of nutrients in the surrounding environment, and the magnitude of this effect may be linked to parasite-induced reductions in fecundity for many invertebrate hosts. Author Keywords: consumer, ingestion rates, mass-balance, nutrient-recycling, parasitism, phosphorus
Bioremoval of copper and nickel on living and non-living Eugelna gracilis
This study assesses the ability of a unicellular protist, Euglena gracilis, to remove Cu and Ni from solution in mono- and bi-metallic systems. Living Euglena cells and non-living Euglena biomass were examined for their capacity to sorb metal ions. Adsorption isotherms were used in batch systems to describe the kinetic and equilibrium characteristics of metal removal. In living systems results indicate that the sorption reaction occurs quickly (<30 min) in both Cu (II) and Ni (II) mono-metallic systems and adsorption follows a pseudo-second order kinetics model for both metals. Sorption capacity and intensity was greater for Cu than Ni (p < 0.05) and were described by the Freundlich model. In bi-metallic systems sorption of both metals appears equivalent. In non-living systems sorption occurred quickly (10-30 min) and both Cu and Ni equilibrium uptake increased with a concurrent increase of initial metal concentrations. The pseudo-first-order model was applied to the kinetic data and the Langmuir and Freundlich models effectively described single-metal systems. The biosorption capacity of Cu (II) and) was 3x times greater than that of Ni (II). Sorption of one metal in the presence of relatively high concentrations of the other metal was supressed. Generally, it was found that living Euglena remove Cu and Ni more efficiently than non-living Euglena biomass in both mono- and bi-metallic systems. It is anticipated that this work should contribute to the identification of baseline uptake parameters and capacities for Cu and Ni by Euglena as well as to the increasing amount of research investigating sustainable bioremediation. Author Keywords: accumulation, biosorption, Cu, Euglena gracilis, kinetics, Ni
THE LIFE HISTORY STRATEGY, GROWTH, BODY CONDITION, AND DIET OF STOCKED AMERICAN EEL (Anguilla rostrata) IN THE UPPER ST. LAWRENCE RIVER AND LAKE ONTARIO
My study was primarily focused on the comparison of life history traits between stocked American eel and their naturally recruited conspecifics in Lake Ontario and the upper St. Lawrence River (USLR/LO). I found that stocked eels experienced faster annual growth than their naturally recruited conspecifics and were comprised of a greater proportion of males. These findings indicate that the life history patterns of American eel may be genetically predisposed. Additionally, my study served to characterize the diets of stocked American eel and examine possible associations between eel and prey size. The eels consumed a number of macroinvertebrate prey orders as well as fishes and macrocrustaceans, with the latter prey items being more prevalent in the diets of larger eel specimens. A disparity in eel growth and body condition was observed between two primary stocking locations and were likely attributable to differences in available forage and habitat. Lastly, growth, body condition, and stocked eel diet were compared between lentic and lotic habitats. Eels from lotic streams experienced slower annual growth and had reduced body condition, and their diets were comprised of smaller prey items. The results of this study suggest that the current stocking methods employed in the USLR/LO are not suitable to restore the natural recruitment of individuals that will exhibit desired life history traits. Author Keywords:

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