Landscape ecotoxicology is the study of dose-response relationships to toxicants and integrating environmental factors across a defined landscape. In this thesis, I contributed new knowledge to the field of landscape ecotoxicology by adapting analytical methods to assess spatial patterns of chemical exposure among different wildlife keystone species, quantify the relationships between contaminant sources and exposures, and quantify dose-response relationships across large landscapes. Currently, there are few landscape ecotoxicology tools available for quantifying geospatial patterns of environmental toxicology data. To address this gap, I adapted spatial and statistical methods and demonstrated how they can be used to 1) integrate data and assess spatial patterns of contaminant exposure; 2) assess spatial patterns of exposure to complex mixtures; and 3) examine dose-response patterns across landscapes. I developed fur Hg as a biomarker medium as a non-invasive biomonitoring tool in river otter (Lontra canadensis) and mink (Neovison vison) by developing conversion factors that can be used to estimate internal organ Hg from fur Hg, using a meta-regression approach. Based on these results, I suggest that the fur Hg screening guideline be reduced from 20 ug/g to 15 ug/g to be more conservative. I also quantified how the distribution of fur Hg changes across the pelt of river otters. Results from this study indicate that topcoat should be used for biomonitoring as it is less variable than the undercoat and samples should be taken from the forebody (head and legs) for the most accurate organ Hg estimation. Using biomarkers of exposure, I quantified the relationship between sources of Hg and factors that promote Hg bioaccumulation with dietary Hg from stomach contents and fur Hg to establish fur as a proxy for bioavailability of environmental Hg. I also assessed spatial dose-response patterns between fur Hg and fur cortisol using a geographically weighted regression (GWR). Based on these results I use my proposed fur screening guideline of 15 µg/g to categorize fur Hg exposures and demonstrate that at low exposures (<15 µg/g) in fur, Hg has a positive relationship with cortisol. Conversely, at high exposures (>15 µg/g) in fur, Hg has a negative relationship with cortisol. This research provides a field example of heterogeneous dose-response relationships. Finally, I assessed spatial patterns of complex metal exposures in a variety of biomonitoring datasets. I used normalization and transformation techniques to effectively combine datasets comprised of different species and life stages. I then used a spatial principal components analysis (sPCA) to exemplify clusters of complex exposures associated with oil and gas development in regions of Alberta, Canada. These advancements in the field of landscape ecotoxicology will help advance evidence-based long-term ecological monitoring programs.

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Over the last decade the development and use of nanomaterials (NMs) and nanoparticles (NPs) has increased at a great rate. As a result there is an ever increasing risk of exposing humans and wildlife to these potentially harmful materials. Titanium dioxide nanoparticles (TiO2 NPs) and carbon nanotubes (CNTs) are two of the most widely used NMs at present. Their potentially harmful effects on organisms and physicochemical properties have been investigated in a growing number of scientific studies. However understanding the level of risk they may pose is far from satisfactory. The present body of work has addressed various aspects of this field. In order to better quantify the fate of TiO2 NPs in the environment the methodology of measuring Ti from TiO2 NPs was improved using ICP-OES and single particle ICP-MS was demonstrated to provide the first steps towards characterising the nature of TiO2 NPs in liquid-phase media. The potential harm of TiO2 NPs and single walled carbon nanotubes (SWCNTs) to zebrafish was investigated in two separate studies. Little evidence of physiological toxicity was found and the only nano-scale effect of note was an increase in total glutathione of zebrafish exposed to TiO2 NPs. More subtle effects in reproductive studies were further investigated using the three-spined stickleback in a longer term investigation. Similarly to the zebrafish there was little evidence of any physiological disturbances and the well documented reproductive behaviour of the stickleback was not significantly altered as a result of TiO2 NP exposure. This body of work has added to the understanding of the potential toxic effects caused by exposure to both TiO2 NPs and SWCNTs. Improved methods for the detection and characterisation of TiO2 NPs have been demonstrated and the most sensitive tools for ecotoxicological assessments of NP toxicity have been elucidated.

This study involved the development and evaluation of a number of biomonitoring techniques for use with members of the Ulvaceae, Enteromorpha intestinalis (L.) Link, and Viva iactuca (L.). The techniques included both previously established ones and those which required development. The two main procedures developed for these algae were the neutral red retention technique (making use of a vital stain) and the ion leakage Health Index (based upon electrolyte leakage). Following optimisation both were used to produce quantitative structure-activity relationships (QSARs) for a series of n-alcohols using log Kow as the physicochemical parameter. The resultant QSARs were statistically indistinguishable with line equations of -0.88 log Kow + 2.87 and -0.95 log Kow + 2.83 respectively, with r values of 0.98, suggesting that both reflect the same non-specific narcotic effect on membrane integrity. However the neutral red retention technique was less useful than the Health Index with low reproducibility and is therefore unsuitable for use as an environmental biomonitor. The effects of other compounds with specific modes of action were established using the ion leakage technique, the high toxicity of the antifouling compound tributyltin being reflected in the Health Index. Further development of the ion leakage technique involved inductively coupled - plasma mass spectrometry (ICP/MS) in the identification of ions lost during leakage. Synergistic toxicity was investigated exposing the algae to UV light and anthracene, simulating photo-induced toxicity. No photo-induced toxicity was observed although UV exposure did reduce the Health Index. An environmental assessment was carried out for algae from clean sites and organically and inorganically polluted sites, comparing the Health Index with other measures of health and bioaccumulation data. A long term study of a clean site showed the algal Health Index to be influenced by seasonally dependent physical parameters, but reflected reduced health in algae exposed environmentally to organic pollutants. Algae exposed to long term heavy metal pollution in the Fal Estuary had 'normal',. Health Indices, however chlorophyll fluorescence induction techniques did highlight a reduced photosynthetic efficiency in these algae. The ion leakage technique has potentially a wide application in field and laboratory based biomonitoring and direct toxicity studies. Chlorophyll fluorescence analysis was also shown to be useful although it requires further investigation and evaluation.

The present study focused on methylmercury (MeHg) in emergent aquatic insects and spiders from human-made ponds. This dissertation addresses two main topics: (1) factors affecting variation in spider MeHg concentrations around human-made ponds and (2) the magnitude of MeHg transported out of human-made ponds by emergent aquatic insects (insect-mediated MeHg flux). Spiders were specifically targeted in this study because they have been proposed as sentinels of MeHg contamination (organism whose tissue concentrations reflect the level of MeHg in the environment). Spider MeHg concentrations were related to spider diet, size, and proximity to waterbody, but affected individual spider taxa differently. In a second study, I found that only "large" spiders within a taxa had tissue concentrations positively related to prey MeHg concentrations. These results indicate that the relationship between spider and prey MeHg could be size-dependent and that "large" spiders within a taxa may better reflect ambient MeHg contamination. Finally, I tested a conceptual model hypothesizing insect-mediated MeHg flux from human-made ponds is controlled by pond permanence and fish presence. In agreement with the conceptual model, insect-mediated MeHg flux from ponds was suppressed by the presence of fish, likely due to fish predation on emergent insect larvae. I found the mean aggregate MeHg flux was approximately 6 times higher from ponds without fish than from ponds with fish. The suppression of insect flux by fish was stronger for large insect taxa than small insect taxa. Results of this study indicate that community structure can influence the cross-system transport of contaminants, like MeHg, from ponds to terrestrial food webs.

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The Common tern (Sterna hirundo) is considered a sentinel wildlife species for monitoring mercury (Hg) and other contaminants within the St. Lawrence River Cornwall/Massena Areas of Concern (AOC). Here, I investigate the relationship between Hg bioaccumulation and diet using stable isotopes of carbon (δ13C) and nitrogen (δ15N) in adult and chick Common terns from three colonies along a 160 km transect of the upper St. Lawrence River. The foraging range of the colony furthest downstream (EMC) includes both the Massena and Cornwall AOC’s while the two upstream colonies (213 and Ice) are more removed from known point sources of Hg. I also sampled winter- and summer-grown breast feathers to compare diet and Hg exposure on the terns’ breeding ground vs. the terns’ wintering grounds. Hg exposure in summer-grown feathers was significantly higher than Hg exposure in winter grown feathers. Stable carbon (δ13C) and nitrogen (δ15N) isotopes revealed a switch from a marine-based diet during the winter months to a freshwater-based diet on the breeding grounds. Among colonies in summer-grown and chick feathers, the only significant difference in total mercury (THg) exposure was found in chick feathers where Hg was significantly lower at 213 than Ice – both of which are upstream from the AOC’s. However, THg was negatively correlated with δ13C in both winter and summer feathers, and the most parsimonious multi-regression model for winter and summer feathers indicated that δ13C explains 24 and 25% of the variation in Hg exposure, respectively. This suggests terns foraging offshore bioaccumulate more Hg than individuals foraging inshore or in freshwater (winter feathers), and that during the breeding period, terns foraging in pelagic habitats bioaccumulate more Hg than terns foraging in littoral habitats (summer feathers). For the upper St. Lawrence River, these results provide strong evidence that foraging habitat is more important than colony location in determining Hg exposure in a top trophic consumer. / Thesis (Master, Biology) -- Queen's University, 2013-06-01 19:35:59.665

The production of engineered nanomaterials is an emerging and rapidly expanding industry. It exploits the capacity for materials to be manufactured to present particular properties distinct from the bulk material, through tailoring of the particle size and surface functionality. This ability to fine tune particle properties at the nanoscale is responsible for the explosion in uses of engineered nanomaterials in industries as diverse as cosmetics and medicine, to “green” technologies and manufacturing. However, this increased reactivity at the nanoscale, defined as having at least one dimension < 100 nm in size, is also responsible for the increasing concern over their environmental safety. Material flows of engineered nanoparticles into the aquatic environment have been identified throughout their production, use and disposal, putting these ecosystems at potential risk of contamination. In particular, sediments are a likely sink of engineered nanomaterials in the aquatic environment due to their propensity to destabilise and settle out of suspension in natural freshwaters. An emerging body of literature has demonstrated toxicity of nanomaterials to aquatic species. In this thesis, the case is presented for using bioaccumulation as a first indicator of risk to aquatic organisms exposed to engineered nanomaterials. Using the sediment dwelling freshwater worm, Lumbriculus variegatus, this work investigates the factors which govern the bioaccumulation of cerium oxide and silver nanomaterials. It is hypothesised that the fate of these materials in sediments will be determined by their core composition, primary particle size and surface coating. A novel approach is presented to measure two biologically relevant fate parameters (persistence of particles and dissolved species in the sediment pore waters) and how particle properties affect the distribution of the nanomaterials between these phases of the sediment. This provides the context within which to interpret biological exposures assessing both the extent of uptake and how they are accumulated, whether through dietary uptake or across the skin. Understanding this route to uptake is important as the mechanism of toxicity may depend upon the point of contact of a material at the nano-bio interface. For example, a nanoparticle which comes into contact with biological material in the gut may exert a different effect upon an organism than one which is translocated directly across the skin. It is demonstrated that sediment properties determine the fate of engineered nano cerium oxide and silver to a greater extent than stabilising surfactants, with the majority of particles aggregating or associating with the solid constituents of the sediment > 200 nm in size. The dissolved fraction of the metal present in the pore waters was a better predictor of bioavailability than the persistence of particulate material < 200 nm in size, with partially soluble nanosilver being more available than insoluble cerium oxide. The route to metal nanoparticle uptake also differed with particle core, with electrostatically stabilised citrate and sterically stabilised polyethylene glycol (PEG) coated ceria available only through dietary uptake, whilst citrate and PEG coated silver was accumulated through transdermal uptake. Dynamic changes in the fate of silver nanoparticles were also observed for sterically stabilised polyvinylpyrrolidone (PVP) coated silver, resulting in the emergence of a colloidal pore water fraction of silver after 3 months aging in sediments. However, this colloidal silver was still not considered accumulated, indicating that low molecular weight species of silver, dissolving from the particle surface either during the exposure or upon contact with the worms’ surfaces was responsible for uptake of silver from the sediments. In conclusion, this work contributes towards our understanding of the factors which determine both the route and extent of biological uptake of engineered nanomaterials. It presents a novel combination of methods which allow for understanding bioaccumulation of these materials in the context of their fate and behaviour within sediments.