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<p>The spaceborne lidar Ice, Cloud, and land Elevation Satellite (ICESat)-2 provides the ATL13 data product for inland water bodies. However, its quality characteristics are not yet fully understood. This study presents a robust method for extracting lake water level data and makes a comprehensive evaluation on the determined water levels. The selected study areas are Lake Huron and Lake Superior, which are part of the Great Lakes. The extracted water levels from ATL13 over a period of four years are validated by using the field measurements at the closest NOAA hydrological stations. The evaluation is carried out in terms of data specifications, wind speed, frozen precipitation, distance of photon segments to hydrological stations, data acquisition time, and beam intensity. The determined water levels are then further used for seasonal monitoring and modeling of water surface. This work demonstrates the critical need for outlier removal and the capability of the ATL13 data. A total bias of 9 - 10 cm is found in the ATL13 product. It is found that frozen precipitation can lead to an overestimation (~ 5 cm) of the water level. However, the uncertainty of water level determination is not found to be significantly related to the laser beam intensity and data acquisition time. We expect that these findings will be valuable for users employing the ATL13 inland water body product and for developers producing future versions of the ATL13 product.</p>

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Annex 2 of the Great Lakes Water Quality Protocol calls for the collaborative development of a ‘nearshore framework’, but does not provide guidance with respect to nearshore governance. This thesis bridges this gap with a series of studies on the determinants for adaptive governance that will inform implementation of the Great Lakes Water Quality Protocol 2012. The principal focus of this work is on eutrophication, which is essentially a nearshore issue. The methodology includes a comprehensive literature review and 35 key informant interviews using a standardized questionnaire. The results assess Great Lakes governance, examine the strengths of the Great Lakes Water Quality Agreement Protocol 2012 and evaluate the effectiveness of the International Joint Commission. A major product of the research is the development of a framework for assessing adaptive capacity based on six determinants: public participation, science, networks, leadership, flexibility and resources. The framework is validated in the case study of eutrophication in Lake Erie and used to identify gaps in adaptive capacity for current eutrophication governance of Lake Erie. The framework was then tested on two additional case studies, the Chesapeake Bay and the Baltic Sea Region. These systems are both eutrophic and are similar in many other ways to the Great Lakes. This allowed exploration of issues of scale, from local (Chesapeake Bay) to binational (the Great lakes) to transnational (the Baltic Sea). The most important finding of this work is that the key barrier for building adaptive capacity for eutrophication governance in the Great Lakes is the lack of adequate leadership and resources. A key recommendation is therefore that the IJC be strengthened in its role to function as a collaborative leader to foster adaptive capacity. The findings from this research can inform the implementation of the Great Lakes Water Quality Protocol 2012. / Thesis / Doctor of Philosophy (PhD)

Though the water in eastern Georgian Bay is oligotrophic, some of the coastal embayments and wetlands have begun to show signs of water quality impairment that is thought to be related to human development along the shoreline. The primary objective of my thesis is to provide environmental agencies with the resources to effectively manage water quality in the coastal zone of eastern Georgian Bay. First, I evaluate the ability of the Lakeshore Capacity Model (LCM), developed for inland Precambrian Shield lakes, to predict the trophic status of coastal embayments. Finding that the LCM does not accurately predict trophic status, I develop the Anthro-geomorphic Model (AGM), which uses the level of human development and the degree of mixing between the embayment and open waters of Georgian Bay to predict embayment trophic status. Second, I explore the spatial association between densities of building, dock and road development and Water Quality Index (WQI) scores, an index designed to evaluate wetland condition, for wetlands in the Township of Georgian Bay. I found an inverse relationship between WQI scores and the density of these stressor variables inside wetland catchments, which indicates that these stressors have a negative impact on wetland water quality. I then created a series of mapping products that present building, dock and road densities, along with WQI scores for 61 wetlands in the Township of Georgian Bay, to determine how wetland water quality is spatially associated with densities of these stressor variables. I found that regions with high densities of building, dock and road development were associated with wetlands of lower quality, whereas wetlands in areas that had low densities of development were of higher quality. I used this information to identify areas of conservation priority for management in the Township of Georgian Bay. The results from this thesis will provide environmental managers with resources to protect the valuable coastal waters of eastern Georgian Bay. / Thesis / Master of Science (MSc) / A number of coastal embayments and wetlands of eastern Georgian Bay show signs of water quality impairment thought to be caused by cottage development. The objective of my thesis is to develop and evaluate models designed to measure the impact of human development on water quality in these coastal zones. First, finding that the Ontario Lakeshore Capacity Model, developed for Muskoka lakes, does not accurately predict trophic status in embayments, I develop the Anthro-geomorphic Model, which uses building density and basin morphometry to predict embayment trophic status. Second, I explore the appropriateness of using development densities (building, dock and road) to quantify anthropogenic stress in coastal wetlands. This thesis provides the scientific basis for choosing management practices to protect the coastal waters of Georgian Bay.

<p dir="ltr">Nutrients are essential to support fish production in aquatic systems but are detrimental in excess. To that end, the relationship between nutrient loading and fish biomass is hypothesized to be unimodal. In the mid-20^th century, numerous aquatic systems in North America and Europe were receiving excessive nutrients and were considered heavily degraded as a result. Since then, nutrient abatement programs have resulted in increased fish biomass in many systems throughout the two continents. However, few systems have complete records of fish biomass and nutrient loading to offer support for both sides of the unimodal fishery production curve. In Saginaw Bay, Lake Huron, total phosphorus estimates are available back to when nutrient abatement programs were first implemented in the system in the 1970s. In addition, a long-term fall bottom trawling dataset from an annual monitoring survey conducted by the Michigan Department of Natural Resources has indexed fish biomass and composition since 1970. In Chapter 2, we utilize these datasets to analyze trends in system-wide fish biomass as well as fish community trends since 1970 in response to continued nutrient abatement. We found increasing fish biomass from 1970 until the early 2000s concurrent with total phosphorus declines. However, more recently, we documented declines in system-wide fish biomass with reduced nutrient loads. We found planktivorous and benthivorous fish species displayed similar initial increases in biomass followed by more recent declines in biomass. However, we determined current total phosphorus loading was still sufficient to support piscivore biomass near peak levels.</p><p dir="ltr">While nutrients in Saginaw Bay are lower than at times in the past, the system is still highly productive. One consequence of productive systems is increased susceptibility to hypoxia, or low dissolved oxygen that can result from organic matter decomposition. Past studies have documented hypoxic conditions in Saginaw Bay in the summer and over-winter period. However, past studies have been limited in scale and have not estimated the extent or duration of hypoxia throughout the Saginaw Bay system. With climate change expected to increase the occurrence of hypoxia throughout the Laurentian Great Lakes, knowledge of dissolved oxygen dynamics in the system is becoming progressively more important. In Chapter 3, we used an array of high frequency data loggers deployed throughout inner Saginaw Bay over two summer and over-winter periods to document dissolved oxygen conditions. We also analyzed a time series dataset of bottom oxygen and environmental parameter measurements to determine the conditions that contribute to low dissolved oxygen in the bay. Further, through stable isotope analysis we investigated whether hypoxic conditions had an effect on the carbon and nitrogen (δ¹³C and δ¹⁵N) isotopic signatures of chironomid larvae, an important basal prey item in Saginaw Bay. We found instances of seasonal hypolimnetic hypoxia in the summers of 2021 and 2022 but normoxic conditions throughout the over-winter periods following each summer. We also determined bottom water and wind speed to be the most reliable predictors of low dissolved oxygen since 2011, indicating the temporary stratification that can occur during warm, calm summer periods likely precedes the development of hypoxic conditions in Saginaw Bay. Chironomid δ¹³C and δ¹⁵N values were highly variable, but some individuals displayed very low values, indicative of hypoxia exposure.</p>

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