scholarly journals Laurentian 95800 expedition report, Lake Huron, Georgian Bay and Lake Michigan, Ontario, Canada and Michigan, U.S.A.

2018 ◽  
Author(s):  
D K Rea ◽  
B J Todd ◽  
C F M Lewis
Keyword(s):  
Lake Michigan ◽  
Lake Huron ◽  
Georgian Bay

Late Wisconsinan ice-flow reconstruction for the central Great Lakes region

1985 ◽  
Vol 22 (6) ◽  
pp. 935-940 ◽  
Author(s):  
Stephen Irving Dworkin ◽  
Grahame J. Larson ◽  
G. William Monaghan
Keyword(s):  
Lake Michigan ◽  
Source Area ◽  
Heavy Mineral ◽  
Lake Huron ◽  
Georgian Bay ◽  
South Central ◽  
Mineral Assemblages ◽  
Specific Source ◽  
Late Wisconsinan ◽  
Lake Michigan Lobe

Late Wisconsinan tills from the lower peninsula of Michigan can be differentiated with respect to the Lake Michigan, Saginaw, and Huron–Erie lobes on the basis of their heavy-mineral assemblages. Using discriminant analysis, the heavy-mineral assemblages can also be associated with specific source areas on the Canadian Shield. These associations suggest that (1) the Lake Michigan Lobe flowed southwestward across a region north of Lake Huron and then into southwestern Michigan; (2) the Saginaw Lobe flowed southwestward across a region northwest of Georgian Bay and then into south-central Michigan; and (3) the Huron–Erie Lobe flowed southwestward across a region north of Georgian Bay and then southward into southeastern Michigan.Comparison of the heavy-mineral assemblages of tills from southeastern Michigan with those from younger tills just south of Lake Huron indicates that a significant westward shift in source area occurred during the retreat of the Huron–Erie Lobe from southeastern Michigan.

Detection of spatial and temporal hydro-meteorological trends in Lake Michigan, Lake Huron and Georgian Bay

2019 ◽  
Vol 22 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Aisha Javed ◽  
Vincent Y. S. Cheng ◽  
George B. Arhonditsis
Keyword(s):  
Lake Michigan ◽  
Lake Huron ◽  
Georgian Bay

scholarly journals Toxins and Other Bioactive Metabolites in Deep Chlorophyll Layers Containing the Cyanobacteria Planktothrix cf. isothrix in Two Georgian Bay Embayments, Lake Huron

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 445
Author(s):  
Arthur Zastepa ◽  
Todd R. Miller ◽  
L. Cynthia Watson ◽  
Hedy Kling ◽  
Susan B. Watson
Keyword(s):  
Thermal Stratification ◽  
Chemical Defence ◽  
Euphotic Zone ◽  
Lake Huron ◽  
Metabolic Inhibitors ◽  
Bioactive Metabolites ◽  
Total Biomass ◽  
Key Factors ◽  
Georgian Bay ◽  
And Function

The understanding of deep chlorophyll layers (DCLs) in the Great Lakes—largely reported as a mix of picoplankton and mixotrophic nanoflagellates—is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile Bay (TMB) and South Bay (SB), along eastern Georgian Bay, Lake Huron (Ontario, Canada) in 2014, 2015, and 2018. Both embayments showed the annual formation of DCLs, present as dense, thin, metalimnetic plates dominated by the large, potentially toxic, and bloom-forming cyanobacteria Planktothrix cf. isothrix. The contribution of P. cf. isothrix to the deep-living total biomass (TB) increased as thermal stratification progressed over the ice-free season, reaching 40% in TMB (0.6 mg/L at 9.5 m) and 65% in South Bay (3.5 mg/L at 7.5 m) in 2015. The euphotic zone in each embayment extended down past the mixed layer, into the nutrient-enriched hypoxic hypolimnia, consistent with other studies of similar systems with DCLs. The co-occurrence of the metal-oxidizing bacteria Leptothrix spp. and bactivorous flagellates within the metalimnetic DCLs suggests that the microbial loop plays an important role in recycling nutrients within these layers, particularly phosphate (PO4) and iron (Fe). Samples taken through the water column in both embayments showed measurable concentrations of the cyanobacterial toxins microcystins (max. 0.4 µg/L) and the other bioactive metabolites anabaenopeptins (max. ~7 µg/L) and cyanopeptolins (max. 1 ng/L), along with the corresponding genes (max. in 2018). These oligopeptides are known to act as metabolic inhibitors (e.g., in chemical defence against grazers, parasites) and allow a competitive advantage. In TMB, the 2018 peaks in these oligopeptides and genes coincided with the P. cf. isothrix DCLs, suggesting this species as the main source. Our data indicate that intersecting physicochemical gradients of light and nutrient-enriched hypoxic hypolimnia are key factors in supporting DCLs in TMB and SB. Microbial activity and allelopathy may also influence DCL community structure and function, and require further investigation, particularly related to the dominance of potentially toxigenic species such as P. cf. isothrix.

Paleohydrology of the upper Laurentian Great Lakes from the late glacial to early Holocene

2009 ◽  
Vol 71 (3) ◽  
pp. 397-408 ◽  
Author(s):  
Andy Breckenridge ◽  
Thomas C. Johnson
Keyword(s):  
Great Lakes ◽  
Lake Michigan ◽  
Lake Superior ◽  
Late Glacial ◽  
Lake Huron ◽  
Michigan Basin ◽  
Great Lakes Basin ◽  
Lake Agassiz ◽  
Sharp Drop ◽  
Freshwater Fluxes

AbstractBetween 10,500 and 9000 cal yr BP, δ18O values of benthic ostracodes within glaciolacustrine varves from Lake Superior range from − 18 to − 22‰ PDB. In contrast, coeval ostracode and bivalve records from the Lake Huron and Lake Michigan basins are characterized by extreme δ18O variations, ranging from values that reflect a source that is primarily glacial (∼ − 20‰ PDB) to much higher values characteristic of a regional meteoric source (∼ − 5‰ PDB). Re-evaluated age models for the Huron and Michigan records yield a more consistent δ18O stratigraphy. The striking feature of these records is a sharp drop in δ18O values between 9400 and 9000 cal yr BP. In the Huron basin, this low δ18O excursion was ascribed to the late Stanley lowstand, and in the Lake Michigan basin to Lake Agassiz flooding. Catastrophic flooding from Lake Agassiz is likely, but a second possibility is that the low δ18O excursion records the switching of overflow from the Lake Superior basin from an undocumented northern outlet back into the Great Lakes basin. Quantifying freshwater fluxes for this system remains difficult because the benthic ostracodes in the glaciolacustrine varves of Lake Superior and Lake Agassiz may not record the average δ18O value of surface water.

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

2019 ◽  
Vol 27 (2-3) ◽  
pp. 207-221 ◽  
Author(s):  
J. Daniel Weller ◽  
Patricia Chow-Fraser
Keyword(s):  
Lake Huron ◽  
Georgian Bay ◽  
Marsh Habitat

Bioenergetic analysis of prey consumption by Bythotrephes cederstroemi in Lake Michigan

1995 ◽  
Vol 52 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Peder M. Yurista ◽  
Kimberly L. Schulz
Keyword(s):  
Body Weight ◽  
Consumption Rate ◽  
Lake Michigan ◽  
Food Resource ◽  
Lake Huron ◽  
Bioenergetic Model ◽  
Bioenergetic Analysis ◽  
Bythotrephes Cederstroemi ◽  
Resource Conditions ◽  
Predation Rates

A bioenergetic model for Bythotrephes cederstroemi was constructed using measured physiological parameters to predict predation rates. The model predicts that juvenile B. cederstroemi will consume approximately 150% of their body weight per day, while adults consume 118% of their body weight per day. These rates are consistent with those of other invertebrate crustaceans. The predicted rate was twice that of an experimental measurement reported for Lake Huron B. cederstroemi; this discrepancy is attributed to experimental artifacts and to differences between B. cederstroemi populations in Lake Michigan and those in Lakes Huron and Erie. The model was most sensitive to estimation of ingestion and assimilation efficiencies and, secondarily, respiration coefficients. This model estimates the consumption rate of B. cederstroemi in Lake Michigan under optimal food resource conditions, and may be useful in predicting the future impact of B. cederstroemi predation on the zooplankton assemblages of other lakes.

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