Lake Huron Basin Research Articles

Winter/Spring Runoff Is Earlier, More Protracted, and Increasing in Volume in the Laurentian Great Lakes Basin

AbstractWinter/spring runoff has changed in streams worldwide due to climate change, particularly in temperate areas where winter/spring streamflow depends on snowmelt. Such changes potentially affect receiving waters through altered nutrient loading and mixing patterns. The Laurentian Great Lakes are an important freshwater resource and have experienced a myriad of impacts due to climate change. We analyzed 70 years of stream gauge data in the Great Lakes Basin to test for changes in timing, duration, and amount of winter/spring runoff during the period 1950–2019. We found strong evidence for earlier runoff in each of the Great Lakes except Lake Erie, protracted winter/spring runoff throughout the Great Lakes Basin, and a higher runoff depth during the winter‐spring period over time for all watersheds except Lake Superior. Lake Ontario had the greatest change in the date by which 50% of the Jan–May runoff had been discharged (6 days earlier from 1950 to 2019). For winter/spring runoff duration, the most extreme change was observed in Lake Erie (increase of 19 days), and for runoff depth, the greatest change was in the Lake Huron Basin (increase of 3.3 cm). Results were similar for natural and impacted streams. Our results demonstrate dramatic changes in runoff patterns over the last seven decades in the Great Lakes Basin concomitant with previously published changes in precipitation and snowpack. Shifts toward earlier, more protracted, and more voluminous runoff likely change nutrient loading and mixing patterns that influence primary producers, particularly in the nearshore areas of the Great Lakes.

Investigating relationships between climate controls and nutrient flux in surface waters, sediments, and subsurface pathways in an agricultural clay catchment of the Great Lakes Basin

Water quality within agricultural catchments is governed by management practices and climate conditions that control the transport, storage, and exchange of nutrients between components of the hydrologic cycle. This study aims to improve knowledge of nitrogen (N) and phosphorus (P) transport in low permeability agricultural watersheds by considering spatial and temporal trends of surface water nutrient concentrations in relation to hydroclimatic drivers, sediment quality, shallow hyporheic exchange, groundwater quality, and tile drain discharge over a 14-month field study in a clay hydrosystem of the Lake Huron basin, one of the five Great Lakes. Results found that events of varying magnitude and intensity enhanced nutrient release from overland flow and subsurface pathways. Tile drain discharge was found to be a consistent and elevated source of P and N to surface waters when flowing, mobilizing both diffuse nutrients from fertilizer application and legacy stores in the vadose zone. Surface water quality was temporally variable at the seasonal and event scale. Targeted sampling following fertilization periods, snowmelt, and moderate precipitation events revealed catchment wide elevated nutrient concentrations, emphasizing the need for targeted sampling regimes. Controls other than discharge magnitude and overland flow were found to contribute to peak nutrient concentrations, including internal nitrate loading, soil-snowmelt interaction, catchment wetness, and freeze thaw cycles. Sediments were found to store P in calcium minerals and have a high P storage capacity. Instream mechanisms such as sediment P fixation and hyporheic exchange may play a role in mediating surface water quality, but currently have no discernable benefit to year-round surface water nutrient concentrations. Best management practices need to focus on reducing sources of agricultural nutrients (e.g., field phosphorus concentrations and tile drain discharge loading) at the watershed scale to reduce nutrient concentrations and export in flashy clay catchments.

Sediment sequences and palynology of outer South Bay, Manitoulin Island, Ontario: Connections to Lake Huron paleohydrologic phases and upstream Lake Agassiz events

South Bay on the southern coast of Manitoulin Island is a fjord-like embayment connected to Lake Huron by a natural narrow gap in the bay's outer sill 6.5–14 m above the lake. A seismic profile, pollen, plant macrofossil, grain size analyses, and other sediment properties of two piston cores from a shallow outer basin of the bay document a 9 m-thick sediment section comprising rhythmically laminated clay under silty clay containing zones with small molluscan shells and marsh detritus. A sandy pebbly layer under soft silty clay mud overlies these sediments. This stratigraphy represents inundation by deep glacial Lake Algonquin followed by the shallowing Post Algonquin series of lakes, and exposure in the early Holocene by 5 Lake Stanley lowstands in the Lake Huron basin separated by 4 Lake Mattawa highstands. Overflow from South Bay in the first lowstand is thought to have eroded the outer sill gap. Marsh environments are inferred to have formed in the bay during subsequent lowstands. The Lake Mattawa highstands are attributed to outburst floods mainly from glacial Lake Agassiz. Palynological evidence of increased spruce occurrence, an apparent regional climate reversal, during the dry pine period is attributed to cold northwest winds from the Lake Superior basin and a lake effect from the Mattawa highstands in the Lake Huron basin. Lake waters transgressed South Bay following the pine period to form the Nipissing shore on Manitoulin Island. Transfer of Lake Huron basin drainage to southern outlets and continued glacioisostatic uplift of the region led to the present configuration of South Bay and Lake Huron.

Novel Large Sulfur Bacteria in the Metagenomes of Groundwater-Fed Chemosynthetic Microbial Mats in the Lake Huron Basin.

Little is known about large sulfur bacteria (LSB) that inhabit sulfidic groundwater seeps in large lakes. To examine how geochemically relevant microbial metabolisms are partitioned among community members, we conducted metagenomic analysis of a chemosynthetic microbial mat in the Isolated Sinkhole, which is in a deep, aphotic environment of Lake Huron. For comparison, we also analyzed a white mat in an artesian fountain that is fed by groundwater similar to Isolated Sinkhole, but that sits in shallow water and is exposed to sunlight. De novo assembly and binning of metagenomic data from these two communities yielded near complete genomes and revealed representatives of two families of LSB. The Isolated Sinkhole community was dominated by novel members of the Beggiatoaceae that are phylogenetically intermediate between known freshwater and marine groups. Several of these Beggiatoaceae had 16S rRNA genes that contained introns previously observed only in marine taxa. The Alpena fountain was dominated by populations closely related to Thiothrix lacustris and an SM1 euryarchaeon known to live symbiotically with Thiothrix spp. The SM1 genomic bin contained evidence of H2-based lithoautotrophy. Genomic bins of both the Thiothrix and Beggiatoaceae contained genes for sulfur oxidation via the rDsr pathway, H2 oxidation via Ni-Fe hydrogenases, and the use of O2 and nitrate as electron acceptors. Mats at both sites also contained Deltaproteobacteria with genes for dissimilatory sulfate reduction (sat, apr, and dsr) and hydrogen oxidation (Ni-Fe hydrogenases). Overall, the microbial mats at the two sites held low-diversity microbial communities, displayed evidence of coupled sulfur cycling, and did not differ largely in their metabolic potentials, despite the environmental differences. These results show that groundwater-fed communities in an artesian fountain and in submerged sinkholes of Lake Huron are a rich source of novel LSB, associated heterotrophic and sulfate-reducing bacteria, and archaea.

Archaeological Landscapes during the 10–8 ka Lake Stanley Lowstand on the Alpena‐Amberley Ridge, Lake Huron

Archaeologists have long been interested in the Lake Stanley lowstand event (∼10–8 ka) in the Lake Huron basin, as archaeological sites from the Late Paleoindian/Early Archaic cultural periods were inundated by subsequent high water levels. Recent archaeological and paleoenvironmental investigations of this submerged landscape have documented stone structures that were likely utilized for caribou hunting by these cultural groups during the late Lake Stanley lowstand phase of Lake Huron. In 2011 and 2012, a total of 67 core, sediment, and rock samples were collected in a 50 km2 area by divers and a ponar sampler deployed from a survey vessel. These samples were analyzed for sediment size, sorting, morphology and source, organic and carbonate content, testate amoebae, and organic materials. A series of indicators, including distinct microfossil assemblages (such as species only found in sphagnum moss and boggy arctic ponds), rooted trees (tamarack and spruce), and charcoal (ca. 8–9000 yr old) reveal a series of microenvironments that are consistent with a subarctic climate. The analysis of the Alpena‐Amberley Ridge provides a detailed picture of the environment exploited by ancient peoples during the Lake Stanley lowstand period. The methodologies employed in this study can in turn help identify other unique microregions that may yield more archaeological sites with less obvious archaeological footprints.

Glaciolacustrine history of the Huron-Erie lowland in the southeastern Great Lakes region (USA) revisited

Abstract The glaciolacustrine history of the Huron-Erie lowland is reinterpreted using a closed basin model (CBM), based on ground surveys, LiDAR imagery, and digital elevation mapping (DEM). According to the CBM, paleolakes Utica, St. Clair, and Rouge were formed about 13,813 cal yr BP in closed depressions as the level of glacial Lake Elkton dropped below that of bounding morainal swells. The CBM explains why no physical connections could be established previously between paleolakes Algonquin and St. Clair, or between paleolakes St. Clair and Rouge. The CBM obviates the need for a spillway at Port Huron during the time of early Lake Algonquin. The Port Huron spillway is reinterpreted as having first formed about 5,728 cal yr BP simply as a consequence of early Holocene glacial rebound, southward tilting of the Lake Huron basin, and rising water level during the Nipissing transgression. LiDAR and DEM maps suggest that spillway development in the Port Huron moraine caused catastrophic flooding during initial formation of the St. Clair River channel. Channeled scablands-like topography in the form of braided scour channels, streamlined erosional residuals, and boulder lag deposits downriver from Detroit suggest that the Detroit River may have formed by outburst flooding as the Detroit moraine was breached by the rising water level of paleolake St. Clair.

Lobal affinity of Late Wisconsin tills at St. Marys in southwestern Ontario, Canada

The exposures at the St. Marys Cement Inc. quarry at St. Marys, Ontario, have been studied by geologists since the mid-1950s. This paper summarizes previous and new information collected in 2009, 2010, and 2012 and discusses the record of sediments resting on the bedrock surface that have been exposed during quarry operations. The exposed sediments illustrate the dynamic behavior of the Laurentide Ice Sheet in this area during the Late Wisconsin. Evidence for subglacial meltwater activity, shifting ice-flow directions during till deposition, a local or regional erosion event, possible subaerial exposure, and ice-marginal sedimentation is observed in the sequence of tills and stratified sediments exposed in the quarries. It also highlights how rapid lateral facies changes, complex contact relationships, and steep erosional contacts can prove to be challenging for correlation and extrapolation of subsurface units into three-dimensional stratigraphic models. Fourteen units were identified of which the lower six were deposited during the Nissouri age (Catfish Creek Drift). This included five layers of till deposited by a glacier that alternated from flowing out of the Lake Huron basin to that of a regional flow to the south-southwest. An angular unconformity cuts into these sediments and separates them from a finer-grained sediment sequence (primarily of Port Bruce age) consisting of glaciofluvial gravel, two fine-textured till layers, and rhythmically bedded glaciolacustrine sediments, all overlain by the uppermost till, the Rannoch Till, and Mitchell Moraine ice-marginal fan sediments.

Postglacial lake shoreline surveys and lacustrine paleobiotic records in northern Bruce and Grey counties, Ontario, Canada

Northern Grey and Bruce counties are situated centrally in the Lake Huron basin of the Great Lakes area of North America and are similarly central to the area of glacial Lake Algonquin, the largest glacial lake of the Great Lakes area. Ten survey traverses at sites in northern Grey and Bruce counties have documented the continuation of Lake Algonquin and Nipissing phase shorelines onto the Bruce Peninsula from previous work to the east. The Algonquin shoreline near 240m ASL (above sea level) rises northward above land high enough to record it near Lion's Head. The Nipissing shoreline at 191m ASL defines a shallow strait across the Bruce Peninsula near Ferndale, which was flooded temporarily at the maximum of the Nipissing transgression, separating northern Bruce Peninsula from the mainland. Uplift and Port Huron outlet downcutting later rejoined the island to the mainland as it is today. Raised beaches define Algonquin and Nipissing regressions by uplift using the Port Huron outlet. Paleobiotic records in a sand dune at Oliphant (molluscs), a Nipissing shorebluff along Sucker Creek (molluscs) and several sites in the former Nipissing shallow water strait near Ferndale (molluscs, ostracodes, plant macrofossils), provide paleoenvironmental data and supplement prior pollen studies at Lake Charles, Slough of Despond, and Hope Bay. Lake Algonquin deep water rhythmite clays are barren of fossils, whereas Nipissing shallow water silts are fossiliferous.

Rock drumlins and megaflutes of the Niagara Escarpment, Ontario, Canada: a hard bed landform assemblage cut by the Saginaw–Huron Ice Stream

The late Wisconsin (c. 18,000 ybp) Saginaw–Huron Ice Stream (SHIS) of the Laurentide Ice Sheet was as much as 800 km long and 250 km wide in the Great Lakes basin of mid-continent North America. In its onset zone in the upper Lake Huron basin of Ontario, Canada it flowed south from the high standing Canadian Shield to move over gently dipping Ordovician and Silurian dolostones devoid of glacial sediment cover. The onset zone is recorded by a distinct ‘hard bed landform assemblage’ across ∼3000 km2 of north-facing escarpments (Niagara, Fossil Hill, and Kagawong) and dip slope pavements on the Bruce Peninsula and Manitoulin Island, and the adjacent floor of Lake Huron. A wide range of glacially-streamlined rock landforms were carved into dolostones below fast flowing ice. The largest are 30 km-wide bullet-shaped escarpment ‘promontories’ that face upglacier. Superposed on these are swarms of rock drumlins up to 5 km wide with downglacier lengths of as much as 10 km. Promontories and drumlins record streaming of dirty basal ice around escarpment highs and create a distinct ‘zig-zag’ planform to the escarpments. In turn, down-dip, trailing-edge dolostone pavements are corrugated by kilometre-long megagrooves and megaflutes cut by basal ice flowing around resistant high-standing bioherm mounds on dolostone bedding planes. The geomorphology of the Niagara Escarpment does not primarily reflect a lengthy history of preglacial Cenozoic fluvial erosion as classically argued, but geologically-brief episodes of accelerated abrasion and quarrying below ice streams within successive Pleistocene ice sheets.

Deep karst system research, Michigan, USA

At least three major evaporite dissolution events have developed deep karst in two zones of the northern Michigan basin. Dissolution of outer margin Silurian evaporites resulted in the Mackinac Breccia during the early Devonian. This rebound and exposure or a later, brief basin rebound also caused the development of surficial evaporate epikarst in the middle Detroit River Group before the next subsidence and new deposition. Pleistocene glaciation pumped fresh water into shallow Silurian and Devonian carbonate aquifers and stressed the formations by repeated loading and unloading. Buried early Devonian paleokarst in the Detroit River Group was affected by hydrostatic pressure from the glacial waters and exposure along hydraulically open faults and fractures which developed the ancient karst. The current karsted zone varies from totally removed evaporites and collapsed formations along the northern margin of the Detroit River Group subcrop, to an irregular active evaporite dissolution front 29–39 km further basinward. The last glacial retreat from the Lake Huron basin approximately 10,000 years before present (ybp), opened and flooded the basin, The level dropped approximately 150 m in the Lake Huron basin to Lake Stanley stage at 10,000–7,500 ybp to approximately 58 m compared to the present 177 m above sea level of Lake Huron. This is likely the time when most of the visible collapse sinkholes in Northern Michigan formed. Some of these sinkholes have been identified in Lake Huron recently by subbottom profiling. Water venting from them into the lake has conductivity values ranging from 123 to 1,821 μS/cm, attributed to high levels of chloride and sulfate. A benthic ecosystem of anoxic chemosynthetic bacteria is established in mat and bacteria filament forms at the vents. There are no land springs from this system which has hundreds of square kilometers of active swallow area.

Contemporary gene flow between “paired” silver (Ichthyomyzon unicuspis) and northern brook (I. fossor) lampreys: implications for conservation

In most lamprey genera, “paired” species exist in which the larvae are morphologically similar or indistinguishable but, following metamorphosis, one species becomes parasitic while the other bypasses the adult feeding phase and rapidly becomes sexually mature. Since DNA barcoding and similar studies using short segments of the mitochondrial genome do not provide sufficient resolution to distinguish between recent divergence and a lack thereof, the current study examined the relationship between the parasitic silver lamprey (Ichthyomyzon unicuspis) and nonparasitic northern brook lamprey (I. fossor) using up to 10,230 bp from the mitochondrial genome to make phylogenetic inferences and mitochondrial restriction fragment length polymorphism (RFLP) and microsatellite markers to test for significant differences in allele frequencies. We found that silver and northern brook lampreys are not reciprocally monophyletic; two lineages were observed but each occurred within both species. There also were no significant range-wide differences in RFLP haplotype or microsatellite allele frequencies between the species, nor were there significant differences where they occurred sympatrically within the Lake Huron basin. Significant genetic differentiation was found only within the Lake Michigan basin where the results were potentially confounded by geographic separation. Our results thus support suggestions that silver and northern brook lampreys represent ecotypes of a single species since, where they are sympatric, they appear to be experiencing ongoing gene flow. However, alternative life history strategies can be important for a species’ long-term persistence, and critical data are needed to decide whether these two feeding types should be managed as a single unit.

Variations in the oxygen-isotope composition of ancient Lake Superior between 10,600 and 8,800 cal BP

Variations in the oxygen-isotope composition of paleo-water bodies in the Lake Superior Basin provide information about the timing and pathways of glacial meltwater inflow into and within the Lake Superior Basin. Here, the oxygen-isotope compositions of Lake Superior have been determined using ostracodes from four sediment cores from across the Basin (Duluth, Caribou and Ile Parisienne sub-basins, Thunder Bay trough). The δ18O values indicate that lake water (Lake Minong) at ~10,600–10,400 cal [~9,400–9,250] BP was dominated by glacial meltwater derived from Lake Agassiz and the Laurentide Ice Sheet (LIS). From that time to ~9,000 cal [~8,100] BP, a period associated with formation of thick varves across the Lake Superior Basin, the δ18O values of Lake Minong decreased even further (−24 to −28‰), symptomatic of an increasing influx of glacial meltwater. Its supply was reduced between ~9,000 and ~8,900 cal [~8,100–8,000] BP, and lake water δ18O values grew higher by several per mil during this period. Between ~8,900 and ~8,800 cal [~8,000–7,950] BP, there was a return to δ18O values as low as −29‰ in some parts of the Lake Superior Basin, indicating a renewed influx of glacial meltwater before its final termination at ~8,800–8,700 cal [~7,950–7,900] BP. The sub-basins in the Lake Superior Basin generally displayed very similar patterns of lake water δ18O values, typical of a well-mixed system. The final stage of glacial meltwater input, however, was largely expressed near its input (Thunder Bay trough) and recognizable in dampened form mainly in the Duluth sub-basin to the west. Water in the easternmost Ile Parisienne sub-basin was enriched in 18O relative to the rest of the lake, particularly after ~10,000 cal [~8,900] BP, probably because of a strong influence of local precipitation/runoff, and perhaps also enhanced evaporation. By ~9,200 cal [~8,250] BP, lake water δ18O values in the Ile Parisienne sub-basin were similar to the adjacent Lake Huron Basin, suggesting a strong hydraulic connection between the two water bodies, and common responses to southern Ontario’s shift to warmer and dry climatic conditions after ~9,000 cal [~8,100] BP.

Glacial landsystems and dynamics of the Saginaw Lobe of the Laurentide Ice Sheet, Michigan, USA

The surficial terrain of the Saginaw Lobe in southern Michigan is divided into 4 landsystems, numbered sequentially from southwest to northeast, containing related assemblages of sediments and landforms, two of which appear to have a genetic relationship with the bedrock units over which they lie. Landsystem 1 consists of the Sturgis Moraine, a terminal/recessional moraine, and an adjacent drumlin field. The moraine is a high-relief ridge with hummocky topography and ice-walled lake plains at its crest, and thick, coarse outwash fans on its distal margin. The drumlin field extends up-glacier from the Sturgis Moraine across the subcrop of the Mississippian Coldwater Shale to the subcrop of the overlying Marshall Sandstone. The low permeability of the shale may have increased basal pore pressures into a range in which deformation of basal sediment into drumlins occurred. Landsystem 2 overlies the subcrop of the Marshall Sandstone. Stagnation of the lobe behind a discontinuous moraine in this area is indicated by high relief, collapse topography, composed of kames, eskers, and ice-walled lake plains. A system of tunnel valleys terminates and merges in this landsystem with large outwash fans and plains sloping away from the margin. High basal drainage into the sandstone may have facilitated stagnation across a broad area to form this landsystem. Landsystem 3 may have also developed during stagnation of the lobe, but it differs from landsystem 2 by its more subdued relief. It contains a network of evenly spaced, southwest-trending open tunnel valleys that contain discontinuous esker segments. Landsystem 4 consists of till plains and low recessional moraines formed as the Saginaw Lobe retreated downslope into Saginaw Bay of the Lake Huron Basin. Tunnel valleys are absent in this area.

Palaeoenvironmental reconstruction at an oxbow lake situated at the lower Nottawasaga River, southern Ontario, Canada

The purpose of this investigation at the lower Nottawasaga River in southern Ontario, Canada, was to reconstruct the impact of base level on fluvial stability and human occupation during the Holocene in a topographically confined section, where the river cuts through the Edenvale Moraine. Three cores were extracted from an oxbow lake (Doran Lake) and a ground-penetrating radar survey was executed in its vicinity to study wider subsurface alluvial architecture. Radiocarbon dating suggests that the Nottawasaga River became entrenched in the Edenvale Moraine early in the Holocene, with base-level lowering in the Lake Huron basin, and that Doran Lake formed towards the middle Holocene as a meander cutoff when water levels in the Lake Huron basin increased, leading to a period of fluvial instability, enhanced flow and floodplain aggradation. Fluctuating lake levels would have affected human settlement as well as the preservation and visibility of archaeological remains predominantly through vertical accretion.

A late Lake Minong transgression in the Lake Superior basin as documented by sediments from Fenton Lake, Ontario

The evolution of the early Great Lakes was driven by changing ice sheet geometry, meltwater influx, variable climate, and isostatic rebound. Unfortunately none of these factors are fully understood. Sediment cores from Fenton Lake and other sites in the Lake Superior basin have been used to document constantly falling water levels in glacial Lake Minong between 9,000 and 10,600 cal (8.1–9.5 ka) BP. Over three meters of previously unrecovered sediment from Fenton Lake detail a more complex lake level history than formerly realized, and consists of an early regression, transgression, and final regression. The initial regression is documented by a transition from gray, clayey silt to black sapropelic silt. The transgression is recorded by an abrupt return to gray sand and silt, and dates between 9,000 and 9,500 cal (8.1–8.6 ka) BP. The transgression could be the result of increased discharge from Lake Agassiz overflow or the Laurentide Ice Sheet, and hydraulic damming at the Lake Minong outlet. Alternatively ice advance in northern Ontario may have blocked an unrecognized low level northern outlet to glacial Lake Ojibway, which switched Lake Minong overflow back to the Lake Huron basin and raised lake levels. Multiple sites in the Lake Huron and Michigan basins suggest increased meltwater discharges occurred around the time of the transgression in Lake Minong, suggesting a possible linkage. The final regression in Fenton Lake is documented by a return to black sapropelic silt, which coincides with varve cessation in the Superior basin when Lake Agassiz overflow and glacial meltwater was diverted to glacial Lake Ojibway in northern Ontario.

The Saint-Narcisse morainic complex and early Younger Dryas events on the southeastern margin of the Laurentide Ice Sheet

The Saint-Narcisse morainic complex extends over 750 km along the southern margin of the Laurentian Highlands in Québec, north of the St. Lawrence Valley, between the Ottawa and Saguenay Rivers. To the east, the Laurentide Ice Sheet margin was located in the present St. Lawrence Estuary. To the west, the morainic complex is extended 235 km west of the Ottawa River to the Algonquin Highlands, in Ontario. The general outline of the morainic complex comprises large lobes and reentrants, related to major topographic features. In the lower Saint-Maurice River area, the moraine is composed of reworked clay and till and proximal glaciomarine deposits (Yamachiche Diamicton) and melt-out till and ice-marginal outwash (Charette Drift). The Saint-Narcisse Event can be subdivided in several phases: local readvance in low areas, main phase at the origin of the Saint-Narcisse Moraine s.s., melting-out of the marginal ice with compressive structures and large proglacial outwash features, and slow retreat with secondary ridges. The accuracy of the chronological data is limited by several factors: and a floating chronology is proposed. Two landmarks constrain the age and range of duration of the main Saint-Narcisse phase. The main ridge deposition occured after the onset, ca. 12.9 cal ka, of Champlain Sea in the St. Lawrence Valley, and a rapid ice retreat on the southern edge of the Laurentians. It ended before the drawdowm, in the Lake Huron basin, of Glacial Lake Algonquin ca. 12.5 cal ka. The Saint-Narcisse Event is related to the early cold phase of Younger Dryas, as evidenced by other YD ice readvances in Maine, Nova Scotia, and ice cover on the Gaspé Peninsula. It corresponds to a positive change of the budget of the Laurentide Ice Sheet as a result of climate forcing. After a slow ice front retreat during about 900-700 yr, the final phase of YD is marked by the Mars-Batiscan Moraine, located 17 to 70 km north of the Saint-Narcisse Moraine.

Evidence for early hunters beneath the Great Lakes

Scholars have hypothesized that the poorly understood and rarely encountered archaeological sites from the terminal Paleoindian and Archaic periods associated with the Lake Stanley low water stage (10,000-7,500 BP) are lost beneath the modern Great Lakes. Acoustic and video survey on the Alpena-Amberley ridge, a feature that would have been a dry land corridor crossing the Lake Huron basin during this time period, reveals the presence of a series of stone features that match, in form and location, structures used for caribou hunting in both prehistoric and ethnographic times. These results present evidence for early hunters on the Alpena-Amberley corridor, and raise the possibility that intact settlements and ancient landscapes are preserved beneath Lake Huron.

Editorial

The papers contained in this issue constitute the second installment of articles which originated from the conference “State of Lake Huron (SOLH): Ecosystem change, habitat and management” held at Honey Harbour on the shores of scenic Georgian Bay (October 2006). The conference was jointly sponsored by the Aquatic Ecosystem Health and Management Society (AEHMS) and the Lake Huron Binational Partnership. Details about the conference are included in an earlier issue published in 2008 (see volume 11, issue 2).The first installment of Lake Huron articles consisted mainly of papers focusing on the physical aspects of the lake. However, this current group of papers are mostly biological in nature. These articles deal with diverse topics such as benthos, fish diversity, lake whitefish, deepwater demersal forage fishes, aquatic birds, coastal wetlands, ecological indicators, and islands. One of the papers deals with mercury/lead sediment contamination. Additional papers currently under preparation are expected to be published in future issues of the journal.Many thanks are due to the authors for their contributions, as well as for their hard work in the revisions of their manuscripts. Once again we sincerely thank various committee members listed below for their assistance and guidance. Finally, the financial support of Environment Canada and US Environmental Protection Agency is gratefully acknowledged. We hope that the publication of the two groups of papers will be useful to students, researchers and managers working on the Lake Huron basin in enhancing our current understanding of the state of this lake. Mohiuddin Munawar Chief Editor, Aquatic Ecosystem Health and Management

Review of fish diversity in the Lake Huron basin

Lake Huron has a rich aquatic habitat diversity that includes shallow embayments, numerous tributaries, shallow mid-lake reef complexes, archipelagos, and profundal regions. These habitats provide support for warm, cool, and cold water fish communities. Diversity of fishes in Lake Huron reflects post-glaciation colonization events, current climate conditions, accidental and intentional introductions of non-indigenous species, and extinctions. Most extinction events have been largely associated with habitat alterations, exploitation of fisheries, and interactions with non-indigenous species. The most recent historical survey of extirpated and imperiled species conducted in the late 1970s identified 79 fish species in Lake Huron proper and about 50 additional species in tributaries. Of those 129 species, 20 are now considered extirpated or imperiled. Extirpated species include Arctic grayling, paddlefish, weed shiner, deepwater cisco, blackfin cisco, shortnose cisco, and kiyi. Six species have declined appreciably due to loss of clear-water stream habitat: the river redhorse, river darter, black redhorse, pugnose shiner, lake chubsucker, redside dace, eastern sand darter, and channel darter. While numerous agencies, universities, and other organizations routinely monitor nearshore and offshore fish distribution and abundance, there is a need for more rigorous examination of the distribution and abundance of less-common species to better understand their ecology. This information is critical to the development of management plans aimed at ecosystem remediation and restoration.

The Stanley unconformity in Lake Huron basin: evidence for a climate-driven closed lowstand about 7900 14C BP, with similar implications for the Chippewa lowstand in Lake Michigan basin

J.L. Hough in 1962 recognized an erosional unconformity in the upper section of early postglacial lake sediments in northwestern Lake Huron. Low-level Lake Stanley was defined at 70 m below present water surface on the basis of this observation, and was inferred to follow the Main Algonquin highstand and Post-Algonquin lake phases about 10 14C ka, a seminal contribution to the understanding of Great Lakes history. Lake Stanley was thought to have overflowed from the Huron basin through the Georgian Bay basin and the glacio-isostatically depressed North Bay outlet to Ottawa and St. Lawrence rivers. For this overflow to have occurred, Hough assumed that post-Algonquin glacial rebound was delayed until after the Lake Stanley phase.