Georgian Bay Research Articles

The inner shelf geology of Atlantic Canada compared with the North Sea and Atlantic United States: Insights for Atlantic Canadian offshore wind energy

The Quaternary history of the Atlantic Canadian inner shelf shares some similarities with the North Sea and northern United States of America (US) Atlantic coast, with the influence of large-scale glaciation and subsequent sea level transgression being the main drivers of seafloor morphology, sedimentology, and uppermost stratigraphy. The geology of the inner shelf, generally confined to 100 m water depth for this study, is an important constraint on the development of offshore renewables, in particular wind energy. Offshore wind has seen rapid growth, particularly in Europe and Asia, where the industry has now experienced decades of production. In the US, one small-scale production farm and many hundreds of MW are in the production pipeline. In contrast, offshore wind in Canada, despite onshore installed wind capacity that ranks highly globally, lacks any operating turbines and there are no plans for development in the wind resource-rich Atlantic Canadian region. In this study, the geological constraints on offshore wind in Atlantic Canada are explored. Generally, the available offshore wind resource is high, and thus the main geophysical constraint on the development of offshore wind energy converters is the inner shelf geology. Several sites with available high-resolution geophysical data are selected for in-depth analysis and comparison with production and planned offshore wind farm sites found elsewhere. In general, a lack of sufficiently thick Quaternary sedimentation—necessary for the most common bottom-fixed foundations for wind turbines—will make developing offshore wind in Atlantic Canada challenging when compared with North Sea and US Atlantic Coast locations. A few locations may be suitable geologically, such as Sable Island Bank in Nova Scotia (thick package of sands), Northumberland Strait between Prince Edward Island and Nova Scotia (shallow firm seabed and sandbanks), Baie des Chaleurs in New Brunswick/Québec (thick, low relief fine sediments), and St. George's Bay, Newfoundland (shallow, postglacially modified moraine).

Ecohydrological controls on lichen and moss CO2 exchange in rock barrens turtle nesting habitat

AbstractLichens and mosses are among the first organisms to colonize the open bedrock of eastern Georgian Bay, Ontario making them essential for primary soil formation and ecosystem succession, while also providing nesting habitat for turtle species‐at‐risk. However, the slow growing nature of lichen and moss makes them vulnerable to ecohydrological stresses caused by climate and land‐use change. In order to better understand how lichen and moss will respond to stressors, we examined which ecohydrological factors (e.g., near‐surface soil moisture and temperature) control the CO2 exchange of lichen (Cladonia spp.) and moss (Polytrichum spp.) on rock barrens, and the time of year growth primarily occurs. Net ecosystem productivity (NEP) was significantly greater in the wet period of the growing season than the dry, with an estimated difference of 0.7 μmol m−2 s−1 for lichen, 2.9 μmol m−2 s−1 for moss, and 2.5 μmol m−2 s−1 for a moss and lichen mix. These findings indicate that the wet portions of the growing season are critical for growth, while lichen and moss have little to no productivity during the dry period. Our results indicate that near‐surface soil moisture is an indicator of the CO2 exchange of lichen and moss, and this relationship varies among cover types. For the geographical regions where warm, dry conditions are expected to increase in duration and frequency with climate change, lichen and moss NEP will likely decrease, thus limiting the long‐term availability of nesting habitat for turtle species‐at‐risk.

Spatial Heterogeneity of Surface Topography in Peatlands: Assessing Overwintering Habitat Availability for the Eastern Massasauga Rattlesnake

The eastern massasauga rattlesnake (Sistrurus catenatus) relies on small-scale differences in peatland surface elevation to survive harsh overwintering conditions at the northern limit of its range. We characterized the spatial heterogeneity of surface topography in peatlands within the eastern Georgian Bay rock barrens landscape of Ontario, Canada, to assess available snake overwintering habitat. At six peatlands, we used a differential global positioning system to collect surface-elevation data. We created spatially-explicit surface models to map peatland surface topography, quantify habitat that was likely to remain unflooded during the overwintering period, and identify key characteristics associated with greater habitat availability. While surface elevations were spatially heterogeneous within and among sites, larger peatlands were associated with greater surface spatial variability relative to the lowest elevation measured within each site. However, even peatlands with very little spatial heterogeneity (average of 0.24 m above lowest elevation), provided unflooded overwintering habitat. Inter-annual weather conditions and peatland and watershed characteristics likely control the availability and distribution of unflooded overwintering habitat. We found that trees, specifically white pine (Pinus strobus) and maple (Acer spp.), were spatially associated with higher surface elevations and could be used to identify areas of unflooded winter habitat. Our findings are useful for landscape-scale assessments of available overwintering habitat to prioritize conservation and management efforts.

Species distribution models for the eastern blacklegged tick, Ixodes scapularis, and the Lyme disease pathogen, Borrelia burgdorferi, in Ontario, Canada.

The blacklegged tick, Ixodes scapularis, is established in several regions of Ontario, Canada, and continues to spread into new geographic areas across the province at a rapid rate. This poses a significant public health risk since I. scapularis transmits the Lyme disease-causing bacterium, Borrelia burgdorferi, and other pathogens of potential public health concern. The objective of this study was to develop species distribution models for I. scapularis and B. burgdorferi to predict and compare the potential distributions of the tick vector and the Lyme disease pathogen as well as the ecological factors most important for species establishment. Ticks were collected via tick dragging at 120 sites across southern, central, and eastern Ontario between 2015 and 2018 and tested for tick-borne pathogens. A maximum entropy (Maxent) approach was used to model the potential distributions of I. scapularis and B. burgdorferi. Two independent datasets derived from tick dragging at 25 new sites in 2019 and ticks submitted by the public to local health units between 2015 and 2017 were used to validate the predictive accuracy of the models. The model for I. scapularis showed high suitability for blacklegged ticks in eastern Ontario and some regions along the shorelines of the Great Lakes, and moderate suitability near Algonquin Provincial Park and the Georgian Bay with good predictive accuracy (tick dragging 2019: AUC = 0.898; ticks from public: AUC = 0.727). The model for B. burgdorferi showed a similar predicted distribution but was more constrained to eastern Ontario, particularly between Ottawa and Kingston, and along Lake Ontario, with similarly good predictive accuracy (tick dragging 2019: AUC = 0.958; ticks from public: AUC = 0.863. The ecological variables most important for predicting the distributions of I. scapularis and B. burgdorferi included elevation, distance to deciduous and coniferous forest, proportions of agricultural land, water, and infrastructure, mean summer/spring temperature, and cumulative annual degree days above 0°C. Our study presents a novel application of species distribution modelling for I. scapularis and B. burgdorferi in Ontario, Canada, and provides an up to date projection of their potential distributions for public health knowledge users.

Bluewater Beach, Georgian Bay, Ontario, Canada, May-June 1987; 1988

Bluewater Beach, Georgian Bay, Ontario, Canada, May-June 1987; 1988

Bluewater Beach, Georgian Bay, Ontario, Canada, May-June 1987

Bluewater Beach, Georgian Bay, Ontario, Canada, May-June 1987

Wymbolwood Beach, Georgian Bay, Ontario, Canada, May-June 1982

Wymbolwood Beach, Georgian Bay, Ontario, Canada, May-June 1982

Basin-Specific Pollutant Bioaccumulation Patterns Define Lake Huron Forage Fish.

The Lake Huron ecosystem is unique among the Laurentian Great Lakes (USA/Canada) in that its surface area encompasses 3 distinct basins. This ecosystem recently experienced significant ecological restructuring characterized by changes in primary production, species dominance and abundances, and top predator energy dynamics. However, much of the evidence for this restructuring has been largely derived from biomonitoring data obtained from long-term sampling of the lake's Main Basin. We examined polychlorinated biphenyl (PCB) concentrations and the stable isotopes of carbon (δ13 C) and nitrogen (δ15 N) in rainbow smelt (Osmerus mordax), bloater (Coregonus hoyi), and round goby (Neogobius melanostomus) to determine spatial variability in these environmental markers as indicators of the ubiquity of trophic restructuring throughout Lake Huron. Stable isotopes indicated that North Channel fish occupied trophic positions between 0.5 and 1.0 lower relative to Main Basin and Georgian Bay conspecifics, respectively. Sum PCB concentrations for 41 congeners were highest for fish from the Main Basin (27.5 ± 3.0 ng g-1 wet wt) and Georgian Bay (26.3 ± 3.4 ng g-1 wet wt) relative to North Channel (13.6 ± 1.2 ng g-1 wet wt) fish. Discriminant functions analysis demonstrated basin-specific PCB congener profiles with individual species also having distinct profiles dependent on their basin of collection. These bioaccumulation patterns among Lake Huron forage fish mirror those reported for lake trout in this lake and indicate that the degree of food-web ecological restructuring in Lake Huron is not equivalent across the basins. Specifically, basin-specific PCB congener profiles demonstrated that differences among Lake Huron secondary and top predator consumer species are likely dictated by cross-basin differences in zooplankton community ecology and trophodynamics that can regulate the efficiencies of prey energy transfer and PCB congener bioaccumulation patterns in aquatic food webs. Environ Toxicol Chem 2020;39:1712-1723. © 2020 SETAC.

Initial Effects of Wildfire on Freshwater Turtle Nesting Habitat

ABSTRACTNatural wildfire regimes are important for ecosystem succession but can have negative ecological effects depending on fire characteristics. A portion of a granite rock barrens landscape that extends along the eastern shoreline of Georgian Bay, Lake Huron to eastern Ontario, Canada, burned in 2018 during a wildfire that affected >11,000 ha. This landscape is a biodiversity hotspot providing habitat for many species at risk where freshwater turtles nest in soil deposits in cracks and crevices in the bedrock dominated by moss (Polytrichum spp.) and lichen (Cladonia spp.) cover. To assess the initial effect of wildfire on freshwater turtle nesting habitat, we measured soil depths and estimated moss, lichen, and vascular plant cover at 2 morphology types (crevice, flat) in burned and unburned areas of the landscape. The probability that burned flat plots supported soil was near zero; the burned flat plots had 98% less soil volume compared to unburned flat plots. Although crevices were more resistant to soil loss, burned crevices still had a 15% lower probability of having soil and 35% less soil volume compared to unburned crevice plots. We estimated nest site availability by calculating the number of locations with shallow (5–10 cm), intermediate (10–20 cm), and deep (>20 cm) soils required for a small (5 cm × 5 cm) or medium (10 cm × 10 cm) nest chamber. Overall, the burned open rock barrens had 71–73% fewer sites with suitable soil depth and volume for a nest chamber of either size. Furthermore, burned plots had almost no lichen and moss cover but were dominated by bare soil, forbs, and jack pine (Pinus banksiana) seedlings. Although the loss of tree cover in previously forested areas may increase nest site availability for freshwater turtles in newly open areas, we suggest that organic soil combustion and soil erosion may require restoration activities in the post‐fire landscape to support successful nesting of at‐risk turtles. © 2020 The Wildlife Society.

Distribution and diagenesis of trace metals in marine sediments of a coastal Mediterranean area: St Georges Bay (Lebanon)

St Georges Bay of Lebanon's coast is an open bay to the Mediterranean Sea. It is exposed to numerous anthropogenic activities such as industrial effluent, untreated wastewater discharge and maritime activities resulting in increasing chemical contamination, especially with trace metals. Contamination with trace metals (Cu, Cd, Co, Pb, As, Ag and Hg) and the influence of early diagenesis on their distribution were studied on both sediments and waters. For this purpose, sediment cores were collected, then treated under inert atmosphere to retrieve pore waters and solid fraction. The area appears to be seriously impacted by the materials transported by the Beirut River and/or by direct inputs, and recent land reclamation using dumpsite material. The sediments showed a significant level of contamination. Element mobility was studied by selective extraction on sediments. The mobility of trace elements from solid fraction to pore waters is controlled by the Fe/Mn cycle and organic matter.

Challenging the Bleak Climate Forecast for Georgian Bay (Updated)

‘State of the Bay’ is an initiative of the Georgian Bay Biosphere Reserve (GBBR) which has forecast that water temperatures in Georgian Bay Ontario “are warming” and could rise by “10°C this century within coastal ecosystems”, and warns of “catastrophic events”. These claims are evaluated herein from year-round government records at 11 weather stations surrounding Georgian Bay, and June-October records at the two moored buoys in the water. [Note: Since this paper was first published in 2020 some GBBR claims have been moderated but claims of ‘warming’ have been retained. Air and water temperatures in this study are now updated to include 2020.] From the mid-1940s, Georgian Bay waterfront towns have followed a cycle of cooling to about 1980, warming to the mid-2000s, and then cooling in the last 15-20 years. A rough estimate of cooling rates of air temperatures is -0.20°C/decade since 2005 and -0.40°C/decade since 2010. Surface water in northern Georgian Bay has cooled at -0.10°C/decade since 2005. In the south, cooling was -0.24°C/decade since 2004-2006, cooling in June - July, warming in August - September, and constant in October. ‘Extreme highs’ and ‘extreme lows’ in Wiarton show cooling of -0.31°C/decade and -0.36°C/decade for 2000-2020, and extreme temperatures in Collingwood and Parry Sound have cooled since 2000 and 2005 respectively. There is no sign of warming of air or water over the last 15 years. Forecasts are inherently difficult for natural rhythms, and are critically flawed when linear trends through non-linear cyclical data are extrapolated into the future.

Effects of vessel size and trawling on estimates of pelagic fish backscatter in Lake Huron

Integrated acoustic and netting surveys are conducted in marine and freshwater environments to assess the status of fisheries resources and study fish population dynamics. Vessel avoidance by fish, due to noise generated by the survey vessel or from simultaneous trawl operations, can bias acoustic estimates of fish density. Unlike in marine systems, few studies have assessed vessel avoidance in freshwaters, including the Laurentian Great Lakes. Annual acoustic and netting surveys have been conducted in Parry Sound, a coastal embayment of Georgian Bay, Lake Huron (Ontario, Canada). Parry Sound supports one of the lake’s few rehabilitated native lake trout Salvelinus namaycush populations, as well as abundant pelagic prey fish. In 2014–2017, night-time fisheries acoustic surveys were conducted with a 120 kHz transducer while intermittently deploying a pelagic trawl from an 18.9 m long vessel, a typical size of vessel used for acoustic surveying on the Laurentian Great Lakes. In 2017, a simultaneous acoustic survey was conducted from a 7 m long vessel with a 120 kHz transducer. To assess potential bias associated with trawling, fish backscatter was compared before, during, and after trawl operation. Furthermore, to assess potential bias associated with vessel size, fish backscatter was compared between the large and small vessel surveys. Fish backscatter was significantly lower and deeper during and after trawl deployment compared to immediately before, suggesting fish avoided the trawling vessel. In contrast, there was no significant difference in fish backscatter between the large and small vessel, although mean backscatter depth was slightly deeper from the large vessel. These results show bias from avoidance is possible in the fish density estimates obtained from hydroacoustic and trawling surveys in large freshwater ecosystems.

(En)gendering Shoreline Law: Nishnaabeg Relational Politics Along the Trent Severn Waterway

This article examines the colonization of Michi Saagiig Nishnaabeg territory by the Trent Severn Waterway. By examining legal bracketing as a process within Canadian common law alongside prevailing Nishnaabeg philosophy and legal thought, I consider how the construction of a canal system connecting Lake Ontario to Georgian Bay disrupted practices integral to Nishnaabeg law. I offer up the concept of shoreline law as a way to understand particular place-based relationships that Mississaugas hold with water and land and other beings with which they share territory. In particular, I show how colonial domination of Nishnaabeg territory resulted in a gendered dispossession of land that continues to have reverberations throughout Nishnaabeg political systems today. Shoreline law offers up a way to rethink international relations by showing the importance of multiple relationships within the shared space of the shoreline.

Simulated changes in extent of Georgian Bay low-marsh habitat under multiple lake levels

The extent of coastal wetlands in Georgian Bay is controlled primarily by the water level of Lake Huron, which directly affects the amount of critical habitat available for fish and wildlife communities. Lake-levels have historically fluctuated by nearly 2 m and that range could increase in the future. This prompted us to investigate how quantity and quality of wetland habitat in Georgian Bay may be affected by different lake-level scenarios. The extent of low-marsh habitat was modeled with a generalized linear model that used hydrogeomorphic features (i.e. depth, slope, and exposure) as predictors. We simulated lake levels between 175.5 m and 177.5 m at 0.5 m-increments, and found that the total area of low marsh peaked at 176.0 m (7113 ha) and declined sharply as lake levels increased or decreased. In contrast, low-marsh volume was highest at 176.5 m (3.84 × 107 m3) but remained relatively stable across all modeled lake levels. We derived an average elevation profile for low-marsh habitat across the study area that showed a shallow “step” between 175.5 and 176.0 m, flanked by steeper upslope and downslope sections. At historically low lake levels low-marsh habitat would have been dominated by shallow water (< 0.5 m), whereas at higher lake levels it would have been dominated by deeper (0.5–2.0 m) water. The geomorphology at low lake levels (i.e. 176.0 m) appears to favour large areas of shallow habitat at the expense of deeper habitats that could have supported more structurally complex, submersed aquatic vegetation.

Three-dimensional visualization of top-down superimposed thrust sheets in the SW Grenville Province, Ontario

AbstractTo properly understand the tectonic history of the Grenville Province it is necessary to have a reliable, scientifically based understanding of the present-day three-dimensional (3D) structure of the orogen. Based on detailed Nd isotope mapping of surface boundaries and Lithoprobe seismic sections, this study provides the first detailed visualization of the 3D structure of the Grenville gneiss belt in Ontario using the SketchUp software package. The 3D visualization supports a model in which thrust geometry was imposed from the top downwards, controlled by the NW boundary of the Central Metasedimentary Belt that originated as a failed back-arc rift zone. The Central Metasedimentary Belt boundary controlled the trajectory of the Allochthon Boundary Thrust, its underlying tectonic duplex and, ultimately, the Grenville Front. This process of superimposed thrusting explains the large-scale change in the trajectory of the Grenville Front north of Georgian Bay that has been called the ‘Big Bend’. To assist in visualizing the 3D model, a fly-through animation is provided in the supplementary material.

Spatial patterns of rainbow smelt energetic condition in Lakes Huron and Erie in 2017: Evidence for Lake Huron resource limitation

Rainbow smelt (Osmerus mordax) is a key planktivore and prey fish in Lake Huron. Given the declining offshore productivity in the lake since the early 2000s, we described the energy content of rainbow smelt in 2017 across five different regions (North Channel, Georgian Bay, Saginaw Bay, northern main basin, southern main basin) where phytoplankton and zooplankton productivity likely varied. To increase contrast across the productivity gradient, rainbow smelt energy content was also estimated from western Lake Erie. Within the North Channel where large fish (≥90 mm, total length) were sampled most frequently, mean energy density (kJ/g wet weight) varied seasonally: 4.29 in April (month of spawning), 3.86 in June, 3.99 in July, and up to 4.35 in September. Energy density of rainbow smelt from higher productivity western Lake Erie was 37% (large fish ≥90 mm) to 60% higher (small fish <90 mm) than that of fish from Lake Huron. Within Lake Huron, energy density of rainbow smelt from North Channel was slightly higher than those from other regions; rainbow smelt from Georgian Bay generally had the lowest energy density. Across regions, including western Lake Erie, energy density increased with chlorophyll a concentration. Compared with Lake Huron studies prior to 2004, when oligotrophication had not yet accelerated, energy density of rainbow smelt in 2017 was up to 31% lower. The decline in rainbow smelt energy density is likely the result of declining primary and secondary pelagic production and increased resource limitation for planktivorous fish.

Rainbow Trout Migration and Use of a Nature‐Like Fishway at a Great Lakes Tributary

AbstractRainbow Trout Oncorhynchus mykiss were monitored over two consecutive vernal migration periods at a nature‐like fishway on the Beaver River, Ontario, to assess attraction efficiency, passage efficiency, multiple fish passage metrics, and interannual return rates from Georgian Bay, Lake Huron. Fishway evaluations have shifted to fill knowledge gaps related to the passage of nonsalmonids; however, surprisingly little work has been conducted with Rainbow Trout, with no known study assessing attraction or passage at a nature‐like fishway. Attraction efficiency was 53% and passage efficiency was 100% in 2017; only two of the radio‐tagged fish returned to the fishway in 2018. Upstream passage through the fishway required an average time of 152 ± 122 min. Fish spent 19–43 d upstream before returning to Lake Huron, where downstream passage required as little as 15 min. Overall, there were no significant relationships between any of the fish passage metrics and fish size or condition. These results can be used as a foundation for anadromous O. mykiss subspecies passage research and suggest that fisheries managers may need to adjust annual fishway counts. Future research should focus on developing methods to directly integrate temporal passage metrics into estimates of fishway efficiency.

A Multitracer Approach to Quantifying Resource Utilization Strategies in Lake Trout Populations in Lake Huron.

Lake ecosystems are threatened by an array of stressors. An understanding of how food webs and bioaccumulation dynamics respond to these challenges requires the quantification of energy flow. We present a combined, multitracer approach using both polychlorinated biphenyls (PCBs) and stable isotopes to trace energy flow, and to quantify how lake trout feeding strategies have adapted to changes in food web structure in 3 basins of Lake Huron (ON, Canada). This combined tracer approach allows the quantification of dietary proportions (using stable isotopes), which are then integrated using a novel PCB tracer approach that employs knowledge of PCB bioaccumulation pathways, to estimate consumption and quantify energy flow between age cohorts of individual fish across Lake Huron. We observed basin-specific differences in ultimate energy sources for lake trout, with Georgian Bay lake trout deriving almost 70% of their energy from benthic resources compared with 16 and 33% for Main Basin and North Channel lake trout, respectively. These differences in resource utilization are further magnified when they are contrasted with age. The dependency on pelagic energy sources in the Main Basin and North Channel suggests that these populations will be the most negatively affected by the ongoing trophic collapse in Lake Huron. Our study demonstrates the utility of a multitracer approach to quantify the consequences of food web adaptations to changes in aquatic ecosystems. Environ Toxicol Chem 2019;38:1245-1255. © 2019 SETAC.

Development of a multi-scale wetland Resilience Index from muskellunge nursery habitat in Georgian Bay, Lake Huron

In a 2012 study, no age-0 muskellunge (Esox masquinongy) were found in any of 16 historic nursery sites in coastal marshes of southeastern Georgian Bay (SEGB), and this was attributed to sustained low water levels (1999–2013) that had altered the vegetation structure of nursery habitat. In the same study, age-0 muskellunge were found in 16 coastal marshes surveyed in northern Georgian Bay (NGB), even though these sites had been subjected to the same water-level conditions. We hypothesize that hydrogeomorphic features of NGB sites made them resilient to effects of sustained low lake levels that made the SEGB sites unsuitable for age-0 muskellunge. Compared to their SEGB counterparts, the NGB nursery sites were significantly steeper, deeper, and less sheltered under low water levels. We used these hydrogeomorphic features to develop a multi-scale Resilience Index (RI) for identifying coastal wetlands that are resilient to stable low lake levels. The RI correctly classified the NGB and SEGB nursery sites, with an area-under-the-curve score of 0.973. Coarser-scale variants of the RI provide a regional screening tool in the identification of resilient wetland habitat (e.g. potential muskellunge nursery habitat), and a basin-wide approach to identify vulnerable wetland habitats. This multi-scale index, in conjunction with targeted field surveys, should provide managers a useful tool in the face of uncertain water level forecasts.

Hydrogeomorphic modeling of low-marsh habitat in coastal Georgian Bay, Lake Huron

Potential impacts of global climate change on the amount of low-marsh habitat in coastal wetlands of the Great Lakes are unknown, which may have important implications for the Great Lakes fish community that use such habitat. We developed a generalized linear model that uses only hydrogeomorphic (HGM) features and lake elevations to predict the extent of low marsh in coastal wetlands of eastern and northern Georgian Bay. The McMaster Coastal Wetland Inventory was used as a reference dataset to train the model, while best available data were assembled to create a digital elevation model that was used to derive all HGM features at a lake elevation of 176.17 m (International Great Lakes Datum 1985). The best predictive model included depth, slope, and exposure as HGM variables, yielding an area under the curve (AUC) score of 0.83. We classified the model output into low-marsh and open-water habitat using a threshold value identified by maximizing the true skill statistic. The classified model output had sensitivity and specificity scores of 0.80 and 0.75, respectively, and correctly identified 81% of the low-marsh units present in the reference dataset with an average 60% areal overlap between the model prediction and reference dataset. We applied the model to two external datasets to check model performance, and found the lowest AUC to be 0.79, with associated sensitivity and specificity scores of 0.65 and 0.77, respectively. Applying this model with future water-level scenarios should provide a cost-effective alternative for forecasting changes in the amount of low marsh-habitat in Georgian Bay.