Applications of Geographic Information Systems in Landscape Ecotoxicology

Abstract

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.