The active synthetic constituent of oral contraceptives 17α- ethinylestradiol (EE2) and its natural steroidal estrogen analogues are being released into the aquatic environment mainly via wastewater treatment plants (WWTPs). Although steroidal estrogens have been frequently reported in very low concentrations in the environment, they have been placed at the top of the list of endocrine disrupting chemicals (EDCs) for their high estrogenic activity in non-target aquatic species like fish and frogs. Almost 30 years worth of intensive research has moved the problem of endocrine disruption in the aquatic environment from being a hypothesis to a well-known cause-and-effect story. However, the fate and effects of many pharmaceuticals, including EE2, remain poorly understood. Thus, the main objective of this thesis was to investigate EE2 bioaccumulation in fish by field and laboratory studies. An optimized sample preparation and analytical method protocol was achieved to detect EE2 in its biologically active form in whole fish tissue at trace levels (ng/g). Shorthead redhorse suckers (ShRHS) (Moxostoma macrolepidotum) collected in proximity to a WWTP in the St. Clair River have significantly accumulated EE2 with an average of 1.5 ng/g. EE2 bioaccumulation was limited to fish exhibiting intersex and with induced vitellogenin (VTG). EE2 was absent in fish from a reference site. Positive correlations between EE2 and lipid content as well as "15N supported the hypothesis of EE2 bioaccumulation in wild ShRHSs. A wider survey was carried out to explore patterns of EE2 bioaccumulation in the pelagic and benthic food-wed of the St. Clair IV River, Ontario. In the WWTP effluents and nearby surface waters, EE2 levels were extremely low and below our method detection limits. All of the seven sampled species from different trophic levels and the sediment samples collected from the impacted sites and the reference sites did not have any measurable EE2 concentrations. A laboratory controlled study where male goldfish (Carassius auratus) were exposed to EE2 via water versus food demonstrated that fish can rapidly accumulate EE2 by both routes of exposure. The uptake constant for water was 45 h-1 and the bioconcentration factor for EE2 in fish was 377. The fast uptake rate of EE2 via water coincided with a much slower elimination rate constant of 0.0786 h-1. The assimilation efficiency of 0.106 for EE2 by goldfish was determined by EE2 dietary exposure, which was used to predict EE2 accumulation under different exposure scenarios. The work presented here was the first demonstration of EE2 bioaccumulation in wild fish and the first to model EE2 bioaccumulation from water and dietary exposure in laboratory-exposed fish.

Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus) were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated lakes in other Arctic regions and more temperate locations. For example, concentrations of Hg and Ni were 175 ng/g and 250 ng/g dry weight, respectively, in Feniak Lake surface sediment. If any anthropogenic enrichment has occurred, it is not distinguishable from background variability based on surface sediment to down core comparisons. With the exception of Hg, the site rank order of metal concentrations (Cu, Cd, Ni, Pb, and Zn) in sediment and freshwater fish tissue among lakes is not consistent. This suggests that a number of physical, chemical, and physiological parameters mediate metal bioavailability and uptake in these systems. Maximum concentrations of most metals in fish from this study are equal to or higher than those collected from remote Arctic lakes and rivers in Canada, Finland, and Russia. Muscle Hg concentrations in excess of 1 μg/g wet weight were observed in lake trout from Fenink Lake, which has no identified Hg source other than naturally Hg enriched sediments. Fish diet seems to influence some heavy metal burdens, as evidenced by the higher concentrations of some metals in lake trout compared to grayling, and differences among lakes for lake trout. Cadmium, Cu, and Zn burdens were higher in lakes where snails were consumed by trout compared to lakes without snails.

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Aquatic vegetation provides important habitats for fish, but these habitats are increasingly being altered anthropogenically. My research evaluated the movement and habitat use of three small rare fish species, the blackchin shiner Notropis heterodon (BCS), blacknose shiner Notropis heterolepis (BNS), and banded killifish Fundulus diaphanous, in a Minnesota lake. BCS and BNS traveled farther in spring than summer, but selection of habitat based upon macrophyte biovolume did not explain these differences. All three fish species traveled long distances (> 1,800 m) and were capable of reaching all available habitats in Square Lake. Macrophyte species richness and prey (zooplankton) abundance were not correlated with fish abundance; however, ordination techniques suggested several macrophyte species were important to the habitat use of these fishes in Square Lake. Proactive management for the conservation of these sensitive fish species in Square Lake should focus on protecting vegetated habitats and preserving water quality

The overall objective of this study was to provide a spatial pattern analysis offish distribution in the Great Lakes and to relate these patterns to shoreline features such as coastal wetlands, tributaries and substrate type. Very little is known regarding the distribution patterns of fish in the Great Lakes at the geographical scale of each lake basin. I first explored whether there were systematic patterns in distribution offish and coastal wetlands by looking at density maps of each and calculating nearest neighbor distances. I used three different classification schemes to sort the 139 fish taxa into functional categories to produce ecologically meaningful distribution maps. There were striking differences in the overall distribution pattern of nursery and spawning habitat in the five Great Lakes when data were compared for Jude and Pappas' classification taxocenes: open-water, intermediate and coastal. Overall, open-water species were the most abundant, and were also widely distributed throughout all five lakes. Coastal species were the least abundant and appeared to be restricted to the two lower lakes. The distribution pattern of coastal and intermediate taxa overlapped a great deal; both taxocenes made extensive use of the two lower lakes for spawning and nursery habitat during this synoptic survey, especially in western Lake Erie and eastern Lake Ontario. Fish distribution patterns sorted by thermal preference and by reproductive guild were compared with those sorted by taxocene. Results from a chi-square analysis indicated a high degree of overlap between thermal classes and taxocenes. There were also positive associations between many reproductive guilds and the three taxocenes, although these were not as strong as the previous comparison. I then examined spatial association between distributions of fish and coastal wetlands and other geomorphic features by testing the distribution offish along the shore of the Great Lakes and calculating the correlation between fish and coastal wetlands of Lake Ontario. A chi-square goodness-of-fit test indicated strong associations between the distribution offish and three shoreline classes: (wetland, sandy beach/dunes and bluff) and fish used coast~cl wetlands preferentially for spawning and nursery habitat at a basin-wide scale. Bivariate pattern analysis indicated that occurrences offish in L. Ontario were positively associated with both coastal wetlands and tributaries, although the relationship was considerably weaker for tributaries than for wetlands. Results from this study indicated that 1) Fish have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 2) Coastal wetlands have an aggregated distribution pattern along the shores of Great Lakes and L. Ontario; 3) Spatial distribution offish and wetlands is positively associated; 4) The preferred utilization of coastal wetlands by majority of the Great Lakes fishes is consistent across geographic scales, from the site level to that of the entire Great Lakes basin. / Thesis / Master of Science (MSc)

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Trait-based approaches are useful in ecological research because of their potential ability to predict species responses from patterns present in the community and to infer mechanisms driving community assembly. Current approaches for fishes are lacking traits across all five fundamental niche dimensions (i.e. habitat, life history, trophic, metabolic and defense). This study quantified a broad range of fish functional traits across all five niche dimensions (commonly used traits and novel traits), quantified intra- and interspecific variation for each trait, tested for relationships among traits within and among niche dimensions, tested for phylogenetic conservatism of traits and assessed trait-environment relationships for a subset of these traits under two different contexts. Approximately one third of the quantified traits exhibited greater intraspecific variation than interspecific variation and were not included in subsequent analyses. There were similarities between phylogeny and trait dendrograms for all traits, and habitat, metabolic and defense traits. The traits identified in chapter 2 were able to explain species responses during different flow periods in two intermittent streams as well as species-specific differences in host microbiome at the onset of drought in one intermittent stream. The novel traits identified in chapter 2 did contribute to our understanding of the community assembly dynamics in chapter 3.