In insects, flight energetics varies greatly among species but the source of this variation remains unknown. This thesis addresses phenotypic plasticity and matching of cellular and whole-animal metabolism in a bumblebee (Bombus impatiens). Bumblebees begin flying prior to full metabolic maturation, suggesting a window of greater metabolic plasticity. Bees were induced to fly before fully maturing, but although flight training resulted in elevated metabolic rates compared to controls, there was no change in biochemical activities of any tested enzymes. Similarly, while statistical models of flight parameters explained the majority of inter-individual variation in measures such as metabolic rate and wing beat frequency, there was no direct link between whole-animal metabolism and cellular energy production pathways. This suggests that muscle energy production and whole-animal metabolic demands are not plastically synchronised, and that inter-specific variation is likely not solely the result of phenotypic plasticity.

Unlike the clear causal relationship between acute pesticide exposure and mortality in non-target wildlife, the association between sub-lethal pesticide exposure and chronic health problems (e.g., cancer, birth defects, endocrine disruption) are not as easily established. Studies that have reported relationships between pesticide exposure and chronic health issues are often surrounded by controversy and scientific debate. As a result of the uncertain relationship between pesticide exposure and human and wildlife health, and likely due to the direct alarm of their constituents, many municipal governments throughout Canada are implementing bylaws that regulate the use of pesticides. In some cases, pesticide use on public and private golf courses also falls under the newly created bylaws. One of the main arguments of those opposed to these restrictions is that there is a lack of scientific evidence linking pesticide exposure to poor human and environmental health. With municipalities planning pesticide control in order to protect human and environmental health, and with the controversial debate around pesticide exposure and the onset of health problems, it seemed timely to examine some of the potential effects of exposure to commonly used golf course pesticides. The purpose of this doctoral thesis was to perform a detailed review of the carcinogenic and genotoxic potential of the most common pesticides used on golf courses of the Ottawa/Gatineau region, focusing on epidemiological and in vivo and in vitro mammalian laboratory evidence, and to conduct a non-lethal biomonitoring study to provide scientifically based measures of some possible consequences of repeated pesticide exposure on non-target animals living in areas of regular pesticide use. Specifically, genetic (e.g., DNA strand breaks and chromosomal damage), developmental (e.g., skeletal birth defects and asymmetry) and organismal effects (e.g., changes in clinical haematology, body condition, blood parasite load) were assessed in meadow voles (Microtus pennsylvanicus) living in golf course ecosystems of the Ottawa/Gatineau region of Canada. In general, voles from golf courses did not appear to differ in their asymmetry, skeletal birth defects, blood parameters, parasite load, body condition or level of chromosomal damage when compared to voles from reference sites. However, voles from golf courses did appear to experience significantly greater DNA damage expressed as single or double strand breaks. The comet assay showed that two parameters of DNA damage (e.g., tail length and moment) significantly decreased in relation to days since last application of a pesticide, and to days since the last application of a specific fungicide (DaconilRTM ) containing a potentially genotoxic active ingredient (chlorothalonil). The slopes of these exponential curves were not significantly different than the half-life decay curve of chlorothalonil on vegetation (half-life data obtained from another study). Moreover, both parameters appeared to increase in a dose-dependent manner with the amount of the last application of Daconil RTM.

This thesis describes investigations into the energy store (defined as the size of lipid stores) dynamics in breeding Arctic seabirds. The first chapter compares three species feeding at similar trophic levels but with different life history, physiological and foraging strategies, and breeding strategies. They managed their stores differently during poor environmental conditions. Though lipids were the primary tissue driving changes in body composition in Thick-billed Murres and Northern Fulmars, lean tissues were most dynamic in Black-legged Kittiwakes. Chapter two presents a method for evaluating the size of lipid stores non-lethally in Thick-billed Murres and Northern Fulmars using plasma fatty acid composition and concentration. Traditional (morphometric) tools had less predictive ability (especially for Thick-billed Murres) than plasma fatty acids. In Chapter three, I show that the plasma fatty acid signatures of Thick-billed Murres breeding at low and high Arctic colonies differ; likely an effect of differing diets. In addition, the concentration of plasma fatty acids increases during the breeding season, and is highest during chick-rearing. It is proposed that this may reflect a greater need for metabolic fuels as chick-rearing is likely the period of greatest energy expenditure. In Chapter four, the results of an egg replacement study are presented. Thick-billed Murres were made to lay a replacement egg following the removal of the first laid egg. The fatty acid signatures of the female and male plasma and of the first and replacement eggs were identified. Fatty acid signatures of eggs were highly conserved and those fatty acids found in the highest concentration in eggs were depleted in females after laying the replacement egg. In addition, from comparisons of the fatty acid signatures of eggs and potential prey species, I suggest that local sources of fatty acids could be utilised for the production of the replacement egg. In Chapter five, the way in which breeding adults manage an increase in the cost of diving is examined. In two experiments, conducted during two breeding seasons, the chick growth and plasma fatty acid concentrations of handicapped versus control adults were compared. Generally, adults passed on the increase in cost of diving to their chicks as chick mass gain was significantly less in some of the treatment groups. In addition, a feeding watch study suggests that this was because handicapped adults fed their chicks less frequently than control groups. This thesis represents the most physiologically intensive studies that have been conducted to date on wild breeding auks and is presented in the context of the potential effects of environmental change.

Sexual dimorphism in traits such as colour, size, and shape is very ubiquitous in animals. The direction and intensity of sexual dimorphism, however, varies between species and understanding the causes for the evolution and maintenance of sexual dimorphism has been a central quest in evolutionary biology. The purpose of my thesis was to explore the ecological causes and consequences of sexual dimorphism in northern map turtles. I integrated a variety of approaches to test hypotheses associated with sexual size dimorphism (SSD) as well as sexual dimorphism in trophic morphology. In my first chapter provided evidence through dietary and functional analysis that dimorphism in feeding structures has evolved to increase the energy intake of females to fuel egg production. In my second chapter, I investigated factors contributing to sex differences in diet and habitat use. I found no sex differences in habitat despite marked differences in prey distribution. Using stable isotopes analysis and fecal analysis, I found a large dietary overlap between males and females, indicating no intersexual competition for food. Patterns of prey selection in females, however, were again concordant with the reproductive role hypothesis. In my third chapter, I studied SSD from an ontogenetic perspective. I investigated sexual bimaturation (sex differences in age at maturity) and its relation to the operational sex ratio. Females take twice as long as males to reach sexual maturitd but the estimated operational sex ratio was even in my study population contrary to a male bias sex ratio as predicted by the pattern of maturation in this species. I also tested if fast growing juvenile females incur the metabolic cost of growth compared to similar size non-growing males. Based on respirometry, I found no evidence of such metabolic cost. In my fourth chapter, I investigated thermoregulatory implications of sexual size dimorphism. I showed that large females have a more limited range of daily body temperature than small turtles. This difference appears to lead to a lower accuracy of thermoregulation in large females. Maturation in males, however, does not appear to involve a thermoregulatory cost that could lead to a decrease in growth rate.

Size spectra in aquatic systems have shown a strong consistency of shape across a range of environmental conditions and among different groups of organisms, with higher normalized biomass of small organisms than large. Two main hypotheses have been proposed to explain this consistency in patterns. The energy hypothesis states that because of the inefficient transfer of energy between trophic levels, large organisms (as predators) have less energy available to them per unit habitat than small organisms. The habitat hypothesis states that space availability in the habitat shapes size spectra because small organisms perceive greater habitat space due to the presence of crevices and interstitial spaces that large organisms cannot access. My research examined body size spectra of organisms in 17 stream sites, testing both the energetic and habitat hypotheses for macroinvertebrates, crayfish, and fish. Body size research in lotic systems has rarely included all three groups of organisms, despite the potential importance of large organisms to ecosystem function. I developed a sampling method (electrobugging) to improve collection of large mobile macroinvertebrates; this method collected additional taxa and size classes not sampled by traditional methods. Slopes of size spectra including macroinvertebrates, crayfish, and fish were similar among sites. Large macroinvertebrates, crayfish, and fish contributed approximately half or more of the biomass in each site, while the contribution of small macroinvertebrates was negligible. To examine the habitat hypothesis, I developed a method to estimate habitat space from digital photographs of stream substrates by fitting organisms of different sizes to profiles extracted from the photos. Stable nitrogen isotopes were used to estimate trophic position and test the energetic hypothesis. The results of the test of both hypotheses suggested that both energy availability and space availability affected the normalized biomass of organisms in our study sites, although energy availability explained more of the variation in normalized biomass. The strong relationship between normalized biomass and delta15N suggested that energy availability contributed to primary structuring of size spectra, controlling the negative linear relationship of normalized biomass with size. Space availability had a weaker effect on normalized biomass, and may have contributed to secondary structuring of size spectra, controlling deviations from linearity in the normalized biomass-body size relationship.

The purpose of this research was to examine in detail indicators related to biodiversity in the Frontenac Axis region. The Frontenac Axis, south-eastern Ontario, is of unique conservation potential because it is a mainly undeveloped, forested region surrounded by cleared agricultural and urban land. The first chapter explores whether potential anthropogenic stressors such as roads, buildings, human population and deforestation affect forest biodiversity. The second chapter examines coarse woody debris and its contribution to biodiversity, in particular, the diversity of ferns. I used biodiversity indicators at three taxonomic levels: a complete taxonomic group; functional groups within a taxonomic group; and individual large carnivore species. Species presence data were taken from the 'Atlas of the Mammals of Ontario', the 'Atlas of the Breeding Birds of Ontario', and the 'Herptile Atlas of Ontario'. (Abstract shortened by UMI.)

In this study, I examined the occurrence of polygyny in marsh wrens (Cistothorus palustris) in Delta, B.C. Using four field seasons of data, I found in this population that males were moderately (19%) to highly (66%) polygynous, that in three years of the study (1979, 1992, 1993) polygynous males fledged more young than did monogamous males, and that the breeding sex ratio was female biased in three out of the four years of the study (1979, 1982, 1993). In order to examine if the observed male reproductive success was an accurate measure of male fecundity, I used DNA fingerprinting to assess paternity and therefore male realized reproductive success for the 1992 and 1993 breeding seasons. In order to ascertain the importance of predation of breeding nests on female choice of a breeding situation and male and female reproductive success, I compared predation rates on polygynous and monogamous nests. In order to test all of the possible reasons for polygyny occurring simultaneously I used a multi-modeled approach. I found that the skewed sex ratio model explained the occurrence of polygyny in 1979, 1982, and 1993. Additionally in 1979, 1982, and 1992, the polygyny threshold model also explained polygyny in the Delta population. In 1993, I found that the random settlement model was also supported by the results of this study. Overall in this population of marsh wrens the largest factors affecting the occurrence of polygyny was the skewed sex ratio of the breeding population in favor of females. Secondly, determination of which males became polygynous was most likely affected by female choice of a breeding situation, with females apparently preferring males whose territories were further from the upland edge of the marsh.

Water, algae and invertebrates colonizing navigational buoys at 18 sites in the Montreal area of the St. Lawrence River were sampled during the spring, summer and fall of 1995 to assess which measures of invertebrate assemblages (density, biomass, size distribution, and taxonomic composition) best respond to wastewater discharge and to compare invertebrate responses among sampling dates. Increases of up to five orders of magnitude in fecal coliforms, 2-fold increases in TP and PO$\sb4,$ 20-fold increases in NH$\sb4$ concentration and 2-3-fold decreases in water clarity (Secchi depth, suspended matter) were found downstream of point sources of urban wastewater discharge. Despite these physico-chemical changes, invertebrate assemblages were only weakly related to wastewater exposure, since DFA on composition and size distribution only correctly classified 44-61% of sites into groups based on fecal coliform concentration for all four sampling dates. Fecal coliforms were best predicted by Chironomidae, other Diptera and Nematoda density in the fall (mult. reg. adj.r$\sp2$ = 0.69, p $$ 0.001), density of invertebrates in the size class 4-8 $\mu$g in the fall (adj.r$\sp2$ = 0.65, p $$ 0.001), and total invertebrate density (adj.r$\sp2$ = 0.75, p = 0.002) in the spring. Periphyton biomass, suspended matter concentration and current velocity were the main environmental correlates of invertebrate composition and size distribution patterns in the fall. In the second chapter, spatio-temporal patterns of buoy invertebrate and algal size distributions were investigated, in relation to trophic gradients in the river. The size distributions were not significantly related to physico-chemical parameters of the river, although variability in the data may have been too high to detect trophic effects. Size spectra on buoys, despite the fact that protozoans were not accounted for, had striking similarities with other complete size distributions (containing algae, protozoans and invertebrates) from stream, lake and marine littoral zones. (Abstract shortened by UMI.)

The taxonomic composition and size structure of benthic macroinvertebrate assemblages from twelve streams were studied in relation to differences in trophic conditions. Orthocladiinae (Diptera: Chironomidae) were numerically dominant at 11 of the 12 sites, however the Hydropsychidae (Trichoptera) attained the highest biomass. Principal component analysis revealed differences in the composition of assemblages among rural and urban sites. Rural sites had higher densities of sensitive taxa such as Ephemeroptera, Chironominae and Simuliidae, while urban sites had higher densities of tolerant taxa such as Oligochaeta. Site scores on the first principal component, explaining the most taxonomic variability between regions, were significantly related to the nutrient differences between the rural and urban streams. The mean annual spectrum for the entire assemblage followed a unimodal distribution peaking at the 8 $\mu$g (dry mass) size class. Polynomial regression models fitted to the abundance per size class for the entire assemblage revealed a weak positive relationship with total phosphorus (TP). Subsequent analyses on the mean size spectra of seven dominant taxa revealed that the Oligochaeta and Hydroptilidae have significantly higher densities in the urban sites, which contain high TP, while the Ephemeroptera and Chironominae have significantly lower densities in these sites. The three other dominant taxa, including the Hydropsychidae, Tanypodinae and Orthocladiinae showed less obvious differences in densities per size class between regions. These results demonstrate that although the size spectra of the entire community may not be greatly influenced by differences in stream eutrophication, the spectra of certain key taxa do show responses of a higher magnitude. This discrepancy in detecting responses suggests that the size distribution of entire benthic assemblages is resilient to differences in stream productivity, despite significant changes in the taxonomic composition.

American eels (Anguilla rostrata) are known to leave the water for excursions onto land despite lacking specialized air breathing organs. Other studies have established that the eel suffers from acidosis and hypoxemia as a result of this air exposure, but the survival of the eels despite these conditions demonstrates a large degree of tolerance to these effects. This thesis will investigate the changes in tissue enzymes of the American eel as a result of air exposure. It is the hypothesis of this experiment that conditions of air exposure eels will undergo a metabolic reorganization including an initial Pasteur effect and metabolic depression indicated by changes in enzyme activities and metabolite concentrations. Eels were air exposed for 3, 5 or 10 days in boxes ensuring constant temperature and humidity. Maximal activities were determined in white muscle, gill and posterior kidney tissues harvested immediately following the particular air exposure period; as a result of technical difficulties, liver was unavailable for study. Enzymes assayed included those key in glycolysis (PFK, PK, LDH), glycogen metabolism (GPase and GSase) and gluconeogenesis (GDH, AspAT, AlaAT, and PEPCK). In addition, kinetic analysis was undertaken for PFK and PK in harvested posterior kidney. Blood collected at the time of harvest was analyzed for glucose, lactate and cortisol to determine circulating levels. Muscle samples were also analyzed for glycogen content. Although changes in enzyme rates, enzyme kinetics and metabolites were observed to result from the air exposure, it could not be concluded that the changes were part of a concerted metabolic depression.