Evolutionary history has been recognized as an important factor in studying ecological communities. Lake fish communities have had limited consideration from a community phylogenetics perspective and present the opportunity to include trophic interactions in the analysis. For the species under study, I used known phylogenies from the literature and genetic information to determine relative branch lengths and phylogenetic relationships by Bayesian inference. Using the resultant phylogenetic tree and fish community data, the phylogenetic community structure was determined for the lakes in the Manitoulin Island and LaCloche regions of Ontario, Canada. Evidence of phylogenetic structuring was found, particularly associated with piscivory, winter hypoxia tolerance, and thermal preferences for deep coldwater lakes. Although the majority of the lakes were weakly structured from a phylogenetic perspective, significant trends were nonetheless apparent; especially when further informed by examining species-specific trends, demonstrating that evolutionary history can play a role in structuring freshwater fish communities.

Over the next three decades, there are many predicted disturbances to Earth’s oceans, such as El Nino and hurricanes, which will lead to mass coral bleaching effects. Marine protected areas have been utilized worldwide to maintain coral population sizes and remediate external stressors, such as overfishing or mining. Using a series of modeling techniques, this thesis will propose an experiment that will determine the optimal distance and location for a future MPA in New Zealand. It will also be measuring whether one large reserve or a network of smaller MPAs are more effective in the regeneration of stony corals. These models will be based on Solemosmilia variabilis, the most common stony coral in the region. Based on past studies, it is hypothesized that there will be a significant positive increase with the metapopulation growth of corals in both protected areas. It is also predicted that there will be a higher rate of connectivity within a network of smaller marine protected areas if the MPAs are less than 2 km apart. If the distance is greater, one larger MPA will be more effective due to the lower rates of genetic drift.

Rivers are hierarchical networks that integrate both large and small scale processes within catchments. They are highly influenced by variation in flow and are characterised by strong longitudinal movement of materials. I conducted an extensive literature review that indicated braided rivers lie at the upper end of the river complexity gradient due to the addition of strong lateral and vertical connectivity with their floodplains. The management of these rivers requires an understanding of the connective linkages that drive complexity, however in developed regions few braided river systems remain intact. The large number of relatively pristine braided rivers in New Zealand provided a unique opportunity to study physical and biotic patterns in these large dynamic systems. Initially I examined horizontal connectivity through patterns in regional and local diversity in eleven braided rivers in the North and South islands of New Zealand. Subsequently, the next component of my thesis focused on vertical connectivity through intensive investigations of energy pathways and the recipient spring stream food-webs. The eleven river survey included sampling of multiple reaches and habitats (main channels, side braids, spring sources, spring streams and ponds) and confirmed the importance of lateral habitats to invertebrate diversity. However, I found that large spatial scales made a greater contribution to diversity than small scales, such that major differences occurred between rivers rather than habitats. This result suggested either a role for catchment-scale factors, such as flow, or biogeographic patterning. Subsequent analysis of the relationships between invertebrate diversity and the physical environment indicated strong regulation by flow variability, but also biogeographic community patterns. Braided rivers are clearly disturbance dominated ecosystems, however the effects of disturbance are manifest in different ways across the riverscape. The role of vertical hydrological connectivity in linking the different components of the floodplain was investigated by tracing carbon pathways from the terrestrial floodplain to spring-fed streams and their communities. Using δ13C isotope signatures it was possible to show that inorganic carbon in groundwater was derived from terrestrial vegetation and subsequently incorporated into spring stream food-webs. However, the degree to which a stream community uses groundwater as opposed to allochthonous carbon is affected by the successional stage of riparian vegetation, a function of the shifting habitat mosaic that is regulated primarily by flow variation and sediment dynamics. In summary, the structure of braided river ecosystems is regulated primarily at the catchment scale, but connectivity at smaller scales plays an important role in determining ecological structure and function.

Recent studies within the past decade or so have shown the importance of algae in geomorphic and hydrologic processes of lotic systems. However, the ecohydraulic role of algae in bedrock systems has largely been ignored. In addition, the utility of algae as indicators of channel dynamics have often been assumed by geomorphologists, but relatively few studies have examined this relationship. The purpose of this study was to determine whether algae, specifically diatoms, are useful indicators of channel geomorphological dynamics, and to examine if distinct habitats or biotopes typical in fluviokarst and bedrock systems provide unique habitat space for diatoms, and to address the potential ecohydraulic implications. The investigation was performed in a 100 m reach of Shawnee Run, a limestone, fluviokarst tributary to the Kentucky River in Mercer County, KY. The results of the study showed that periphyton are not useful indicators of channel dynamics, and that biotopes and other distinct habitats, including riffles, bedforms, and fine sediment, do not provide unique habitat in terms of diatom community composition.

No description available.

Over the past two decades, Lake Winnipeg has been experiencing increasingly rapid eutrophication, and large cyanobacterial blooms now form in the North Basin in most years in late summer or fall. Cyanobacteria are considered a relatively poor food source compared with other phytoplankton, but the impacts of these blooms upon the primary consumers in the lake have not previously been researched. A microscopic analysis of whole water samples found cyanobacteria to be scarcely present in summer 2012, with nitrogen-fixing and non-fixing cyanobacteria comprising 11.2% and 8.4% of the basin-wide biovolume, respectively, and all but absent in fall. Gut content analysis of chironomids found that cyanobacteria made up an almost negligible part of their diet. Stable isotope analysis revealed that nitrogen-fixing cyanobacteria reduced phytoplankton δ15N values, and that this same reduction could be traced through the zooplankton, but not down to the sediments or chironomids.

The phytotoxicities of monensin, the 10:2 saturated fluorotelomer carboxylic acid (10:2 FTCA), and atrazine to freshwater macrophytes were investigated in three microcosm-based assessments. Both responses of plants grown as individuals in “cone-tainers” and those grown in mixed and monocultures were examined to permit comparison of the toxicological sensitivities of macrophytes under each planting design, and investigation of whether interactions between neighbours may modify plant response to an environmental contaminant. Exposures of monensin and the 10:2 FTCA at environmentally relevant concentrations were found to produce few significant effects in the higher aquatic plants across all growth conditions, thus direct comparisons of effective concentrations were not conducted. Significant differences between relative growth rates (RGR) of plant grown in assemblages versus individually indirectly indicate that over longer exposure durations toxicity may be underestimated using the individual “cone-tainer” method. RGRs and sensitivities of plants to atrazine were found to be in the same range across planting methods, demonstrating that responses of aquatic plants in the individual-test system reflected those observed in model populations and two-species communities. A lack of observed relations between plants in the mixed and monoculture tests, however, meant that the potential for modification of toxicity through plant interactions was not investigated.

This project examines the spatial relationships that exist between Winnipeg, Canada and Tokyo, Japan, with the intent to develop an understanding of the preciseness of the world. Different site-specific systemic conditions were used as critical tools to explore the implication of distinct design catalysts and inhibitors. I have concentrated on the relationships that exist between time and space, to identify and displace localized, momentary events that exist in one site to the other. Familiarities of my local surroundings were deliberately obscured to make explicit a heightened awareness of my position on the planet. This helps to facilitate discussions. I have created a space that is dissembled through abstract understandings of displaced elements in the environment. It is my intention for this space to be experienced in a different way each time we come across it, by shifting and changing ones perception of their character in the world.

To assess the affects of permafrost degradation on key components of the aquatic food web, an in situ manipulative mesocosm experiment was performed in an upland, unslumped Arctic lake located near Inuvik, Northwest Territories. In total, twelve replicate mesocosms were established, 3 control and 3 replicates of 3 treatment levels each dosed with differing amounts of sediments sourced from a nearby thermokarst slumped lake. Findings from the experiment showed that pelagic autotrophic processes had the greatest potential to contribute to higher trophic levels regardless of treatment. Even in the high sediment treatment level, which showed the least pelagic autotrophic production, pelagic autotrophic production was two orders of magnitude greater than pelagic heterotrophic production and 5 times greater than benthic autotrophic or heterotrophic production. Sediment treatment had no significant effect on benthic primary productivity; however, a 500% increase in benthic heterotrophic production was observed. This raises the possibility that increased activity in benthic heterotrophic production is the first step in thermokarst-affected lake ecosystem succession leading to the proliferation of benthic primary production observed in many slumped lakes in the western Canadian Arctic. Water column phosphorus concentrations increased with increasing sediment treatment while pelagic primary production decreased and zooplankton biomass increased. These results suggest that the initial effect of thermokarst disturbance is an enrichment of the system and that top-down predation from zooplankton regulate the abundance of phytoplankton in these systems. If incidences of thermokarst disturbance continue to increase as predicted by current climate models/scenarios, results from this study suggest that the structure and function of Arctic aquatic ecosystems will be significantly impacted. This study highlights the need for further research to obtain a better mechanistic and predictive understanding of the potential effects of thermokarst disturbance on the geochemistry and ecology of Arctic lakes at relevant spatial and temporal scales. / Graduate

This thesis reviews literature relating both to the treatment of metal rich wastewaters by the use of constructed wetlands and the use of slurry analytical procedures for the determination of heavy metals in environmental micro-samples. A survey of metal contaminated wetland sites showed that aquatic plants maintain low levels of metals in aerial parts despite some very elevated sediment metal concentrations and extreme acidity. A series of greenhouse trials investigated the uptake of metals into aerial sections of Typha, Phragmites and Equisetum in long term hydroponic experiments. Phragmites was shown to accumulate zinc to a higher level than Typha. The toxicity of zinc supplied in the nutrient solution at 5 mg.dm-3 over long periods was found to limit the viability of such non-sediment based systems. A reliable routine analytical procedure was developed along with a program of quality control for the study of metal uptake into aquatic plants. A micro sampling technique, eminently suited for the analysis of small plant sections was developed. This technique uses ozone to ash the plant samples at a low temperature and following suspension in a liquid medium provides a sample ready for slurry determinations by a variety of analytical instrumentation. It is proposed that this method may also be suitable for the determination of metals in individual invertebrates and other zoological micro-samples as well as potential applications in the medical field.