The Laurentian Great Lakes are the largest system of freshwater on earth containing 22% of the world’s supply. Although part of a single system, each lake shows substantial variation regarding physical, chemical and biological parameters. The main goals of this thesis were to characterize the nutrient status of natural phytoplankton communities while comparing several commonly used measurements of nutrient status and Chlorophyll a (Chl a) fluorescence measurements. The study sites include the western basin (WB), west-central basin (WCB), and central basin (CB) of Lake Erie, the Bay of Quinte in Lake Ontario, and Colpoys Bay in Lake Huron. Independent measures of nutrient status were assessed by measurements of nitrogen (N) debt, phosphorus (P) debt, particulate C:N:P ratios, and alkaline phosphatase activity (APA). Variable fluorescence of chlorophyll a was measured by pulse amplitude modulated (PAM) fluorometry and fast repetition rate (FRR) fluorometry in parallel with the independent measures. In 2005, the phytoplankton communities in Lake Erie were generally N deficient in May, P deficient in June, and neither N nor P deficient in September. The maximum dark adapted quantum yield (Fv/Fm) measured by PAM or FRRF was lower in May and June, and maximal in September, while the functional absorption cross section of photosystem II (σPSII) was maximal in May and June, and minimal in September. Relationships between the variable fluorescence indicators and independent measures of nutrient status showed strong associations with N or P deficient sites having low Fv/Fm and high σPSII. In 2006, the electron transport rate (ETR) and the initial slope (α) derived from the PAM fluorescence rapid light-response curves (RLC) were compared to independent measures and Fv/Fm measurements in Lake Erie. Relationships between ETR, α, independent measures of nutrient status, and Fv/Fm measurements revealed strong associations with nutrient status. Confirming previous reports, N deficiency was highest in the WB during isothermal conditions while P deficiency was highest in the CB during summer stratification. The fluorescence parameters generally decreased as the severity of N and P deficiency increased. N and P enrichment assays also revealed increased values of Fv/Fm, ETR, and α from N and P deficient samples over twenty-four hours. Additionally, spatial variability of P status was evaluated during summer stratification. Colpoys Bay, the most oligotrophic site, had the strongest P deficiency, and evidence for existence of P deficiency was weakest in the Bay of Quinte, the most eutrophic site. Nutrient enrichment assays revealed that all fluorescence parameters showed a positive response to P additions in oligotrophic sites, with no response in eutrophic sites. Community structure was also associated with nutrient status and Chl a fluorescence at all locations. In P deficient sites, nano-flagellates such as chrysophytes and cryptophytes were prevalent; cyanobacteria were dominant at sites that displayed N deficiency.

The Laurentian Great Lakes are the largest system of freshwater on earth containing 22% of the world’s supply. Although part of a single system, each lake shows substantial variation regarding physical, chemical and biological parameters. The main goals of this thesis were to characterize the nutrient status of natural phytoplankton communities while comparing several commonly used measurements of nutrient status and Chlorophyll a (Chl a) fluorescence measurements. The study sites include the western basin (WB), west-central basin (WCB), and central basin (CB) of Lake Erie, the Bay of Quinte in Lake Ontario, and Colpoys Bay in Lake Huron. Independent measures of nutrient status were assessed by measurements of nitrogen (N) debt, phosphorus (P) debt, particulate C:N:P ratios, and alkaline phosphatase activity (APA). Variable fluorescence of chlorophyll a was measured by pulse amplitude modulated (PAM) fluorometry and fast repetition rate (FRR) fluorometry in parallel with the independent measures. In 2005, the phytoplankton communities in Lake Erie were generally N deficient in May, P deficient in June, and neither N nor P deficient in September. The maximum dark adapted quantum yield (Fv/Fm) measured by PAM or FRRF was lower in May and June, and maximal in September, while the functional absorption cross section of photosystem II (σPSII) was maximal in May and June, and minimal in September. Relationships between the variable fluorescence indicators and independent measures of nutrient status showed strong associations with N or P deficient sites having low Fv/Fm and high σPSII. In 2006, the electron transport rate (ETR) and the initial slope (α) derived from the PAM fluorescence rapid light-response curves (RLC) were compared to independent measures and Fv/Fm measurements in Lake Erie. Relationships between ETR, α, independent measures of nutrient status, and Fv/Fm measurements revealed strong associations with nutrient status. Confirming previous reports, N deficiency was highest in the WB during isothermal conditions while P deficiency was highest in the CB during summer stratification. The fluorescence parameters generally decreased as the severity of N and P deficiency increased. N and P enrichment assays also revealed increased values of Fv/Fm, ETR, and α from N and P deficient samples over twenty-four hours. Additionally, spatial variability of P status was evaluated during summer stratification. Colpoys Bay, the most oligotrophic site, had the strongest P deficiency, and evidence for existence of P deficiency was weakest in the Bay of Quinte, the most eutrophic site. Nutrient enrichment assays revealed that all fluorescence parameters showed a positive response to P additions in oligotrophic sites, with no response in eutrophic sites. Community structure was also associated with nutrient status and Chl a fluorescence at all locations. In P deficient sites, nano-flagellates such as chrysophytes and cryptophytes were prevalent; cyanobacteria were dominant at sites that displayed N deficiency.

I investigated whether Neogobius melanostomus, an invader of biodiversity “hot-spots” in Ontario facilitates or inhibits unionid mussel recruitment by serving as a host or as a sink for their parasitic larvae (glochidia). Infestation and metamorphosis rates of four mussel Species at Risk (Epioblasma torulosa rangiana, Epioblasma triquetra, Lampsilis fasciola, and Villosa iris) and one common species (Actinonaias ligamentina) on N. melanostomus were compared to rates on known hosts in the laboratory. All species successfully infested N. melanostomus, but only E. triquetra, V. iris, and A. ligamentina successfully metamorphosed, albeit at low rates. Neogobius melanostomus collected from areas of unionid occurrence in the Grand and Sydenham rivers exhibited body burdens of 39.4% and 5.1%, respectively. Analyses indicate that N. melanostomus serves more as a sink for glochidia than as a host for unionids, thereby limiting recruitment, which is a novel way by which N. melanostomus is affecting native mussel species.

Alternative reproductive tactics (ARTs), occur where members of one sex of a species have two or more strategies of obtaining fertilization. The tactics differ in behavioural approaches to reproduction, but also commonly differ in physiological and morphological traits. The round goby, Neogobius melanostomus, is a globally invasive species with male ARTs. How behaviour may influence invasiveness in round goby has been of recent interest, but researchers have not considered the role or impact that male ARTs may have. I compared guarder and sneaker male round goby, assessing differences in their boldness, activity, exploration, sociality, aggression, startle responses, and dispersal tendencies. Sneaker males were more bold, active, and explorative while guarder males were more aggressive. In addition, I studied whether more guarders or sneakers are caught in a population survey study and how variation in a common round goby trapping method, minnow traps, may create catch biases. Two commonly employed minnow trap models include a black vinyl plastic coated metal trap (black traps) and a galvanized metal steel trap (silver traps). I investigated whether these black and silver traps and baited (corn) and unbaited traps differ in terms of the numbers, ART ratios, and sizes of round goby captured. I found silver traps captured 1.7 times more round goby than black traps, while baited traps captured 3.4 times more round goby than unbaited traps. Baited traps captured larger round goby and tended to capture more guarders than unbaited traps. I also found black traps captured larger males, but there was no difference in the size of females captured. Taken together my results indicate that care needs to be applied when making estimates of round goby populations in terms of the types of individuals present and the trapping method used. / Thesis / Master of Science (MSc)

No description available.

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.

No description available.

No description available.

<p>Seasonal and annual water-level fluctuation is a primary mechanism that maintains high aquatic biodiversity in coastal marshes of the Laurentian Great Lakes by preventing formation of dense mono-cultures of emergent or submergent plants. The past 14 years of sustained low water levels in Georgian Bay (Lake Huron) have prompted proposals to impound coastal wetlands as a way to mitigate against desiccation. We hypothesize that a loss of hydrological connection with the Great Lakes would lead to altered water chemistry and an expansion of emergent vegetation at the expense of aquatic habitat. This could result in a fish community with reduced diversity which may positively impact the larval amphibian community. On the other hand, bird communities may respond with only short-term gains, and may not demonstrate long-term benefits without active management. We investigate how long-term severance of hydrological connection between coastal marshes and Georgian Bay affect ecosystem functions. We compare food web components of a chain of three coastal wetlands in Tadenac Bay that were sequentially impounded by beaver activities over the past 5 decades. We also surveyed the food web of Wye Marsh, which was impounded over 80 years ago, and compare it with that of Matchedash Bay, which had never been impounded. In both cases, there were negative impacts of impoundment on water chemistry, vegetation and fish communities. Bird communities showed no significant differences but larval amphibian diversity was greater in the beaver impoundments than in the hydrologically connected coastal wetland. Based on our results, we do not recommend impounding Georgian Bay wetlands as a means to restore and maintain water levels.</p> / Master of Science (MSc)

No description available.