Laurentian Great Lakes System Research Articles

A temporal record of microplastic accumulation in sediment cores of the Great Lakes, North America, reflects macroeconomic and regional influences

Documented plastic pollution throughout the Laurentian Great Lakes system prompted investigation of microplastics (MPs) in sediment cores. We examined offshore sediment cores from Lake Huron (LH43) and Lake Ontario (403A) to understand temporal trends and changes in microplastic (MP) pollution in the size range 53 µm to 2 mm. MP abundances varied from 18.1 to 280.1 particles per g of dry weight sediment ( N g−1 dw) in LH43, and 8.2–488.4 g−1 dw in core 403A. The 15 cm cores are equivalent to 56 years of accumulation in Lake Huron and 72 years of accumulation in Lake Ontario. Analysis of the two cores shows an increasing trend in MP accumulation from 1964 to 1989, which mirrors the global plastic production rate. Subsequent peaks and troughs in the MP abundance profiles reflect macroeconomic changes and regional controls. These results show how changing abundances of MPs in lake sediment cores can act as proxies for global perturbations in oil supply as well as national economic shifts.

Categorization of plastic debris on sixty-six beaches of the Laurentian Great Lakes, North America

The Laurentian Great Lakes system is a major global sink for plastic debris. An area of 10 m2 on each of sixty-six Great Lakes beaches was sampled for large micro-, meso- and macroplastic items. A total of 21 592 plastic items were collected and categorized. Pre-production plastic pellets were the most abundant debris type, accounting for 58.3% of the total count. The remaining 42.7% of the debris items are the focus of this study. Detailed, multi-step characterization was performed with the plastics being categorized using physical identification, known usage, and Fourier transform infrared spectroscopy (FTIR). Values of 805.5 items m−2 at Baxter Beach in Sarnia, Ontario, Canada, and 688.1 items m−2 at Bronte Beach in Oakville, Ontario, Canada are the highest of all sampling locations. Sampling sites on only three beaches contained no plastic debris: Bay City in Michigan, U.S.A., Presque Isle State Park in Erie, Pennsylvania, U.S.A. and Pebble Beach in Marathon, Ontario, Canada. The plastic items sampled were mainly large microplastics (68.4% of total) with a total of 1477.5 items m−2, followed by mesoplastics (27.3% of total) with 598.8 items m−2, and macroplastics (4.3% of total) with 91.9 items m−2. By mass, the microplastic fraction accounted for 25.61 g m2 (14.1%), the mesoplastic for 47.06 g m2 (25.9%), and macroplastic for 109.3 g m2 (60.1%). A total of 3004 items were determined as specific polymers based on physical properties, known polymer usage, Resin Identification Code, and FTIR. A total of 1227 plastic items (40.8% of total) were identified as expanded polystyrene. The 49 most common items, excluding pellets, were scored using a matrix scoring technique to determine their potential general origin. It was determined that these items mostly originated from shoreline and urban sources, whereas pellets originated from the plastics industry.

Social-Ecological Risk and Vulnerability to Flooding and Erosion along the Ohio Lake Erie Shoreline

The Laurentian Great Lakes system holds approximately 20% of the world’s available surface freshwater and represents an immense economic engine for the region. Lake Erie, one of the five North American Great Lakes is classified as highly stressed and deteriorating with significant flooding and erosion issues stemming from record-high water levels. This study adapts a well-established oceanic coastal vulnerability index to estimate impacts and risks of lake-level rise on the Ohio portion of Lake Erie coastal social-ecological system. The authors worked closely with coastal engineers, planners, and other practitioners associated with the Ohio Department of Natural Resources (ODNR) and the Office of Coastal Management (OCM) to help adapt a scientifically-grounded framework for natural resource and policy decision making. Overall, place-based risk and vulnerability to flooding and erosion necessitates an integrated approach that combines socio-economic, built-environment, political boundaries, and bio-physical characteristics. While most of the integrated methodologies are focused on the oceanic coasts at the county scale, this research presents a model for Lake Erie-relevant variables at the higher-resolution census-tract unit of analysis and a coastal vulnerability index at 100-foot intervals along the coastline for four decades and each season. The result is both a foundation for Ohio’s Department of Natural Resources, Office of Coastal Management to identify scientifically-informed, place-based priority management areas for flooding and erosion, as well as a methodological roadmap to adapt the Coastal and Place Vulnerability Indices to the other Great Lakes’ states and provincial shorelines.

Fate and transport of tritium in the Laurentian Great Lakes system

A mass balance modelling approach was used to help understand the movement and impacts of tritium discharged from Canada Deuterium Uranium (CANDU) reactor facilities into Lake Ontario. A concentration-time model, previously developed, is updated in this study. Historical and projected tritium concentrations for Lake Ontario waters are presented. A model calculated accident scenario (10 times highest accidental release) indicates the importance of dilution to the dispersion of tritium; a “modelled” release in 2016 has tritium levels declining by the year 2030 to “previous 2016 levels”. As part of the mass balance approach, lake-bottom sediments were considered as potential radionuclide “sinks”. Tritium porewater results were noted as perturbations at depth in both short (30–50 cm cores) and long sediment core profiles (to 300 cm). These change in tritium concentrations with depth may have been due to CANDU emissions (as the most likely source) over time, based on records of accidental releases of tritiated coolant water. However, the exact process (advection and/or diffusion) responsible for the penetration of tritium into the lake bottom requires additional physical and hydrogeological characterization of the lake bottom sediments.

Transitions in microbial communities along a 1600 km freshwater trophic gradient

Abstract This study examined vertically-resolved patterns in microbial community structure across a freshwater trophic gradient extending 1600 km from the oligotrophic waters of Lake Superior to the eutrophic waters of Lake Erie, the most anthropogenically influenced of the Laurentian Great Lakes system. Planktonic bacterial communities clustered by Principal Coordinates Analysis (PCoA) on UniFrac distance matrices into four groups representing the epilimnion and hypolimnion of the upper Great Lakes (Lakes Superior and Huron), Lake Superior's northern bays (Nipigon and Black bays), and Lake Erie. The microbes within the upper Great Lakes hypolimnion were the most divergent of these groups with elevated abundance of Planctomycetes and Chloroflexi compared to the surface mixed layer. Statistical tests of the correlation between distance matrices identified temperature and sample depth as the most influential community structuring parameters, reflecting the strong UniFrac clustering separating mixed-layer and hypolimnetic samples. Analyzing mixed-layer samples alone showed clustering patterns were correlated with nutrient concentrations. Operational taxonomic units (OTU) which were differentially distributed among these conditions often accounted for a large portion of the reads returned. While limited in coverage of temporal variability, this study contributes a detailed description of community variability that can be related to other large freshwater systems characterized by changing trophic state.

Huron-to-Erie Water Quality Data Platform

To address the challenges of environmental degradation, creation of a sustainable urban environment, and increased public engagement and awareness, a mass-oriented, user-friendly and cloud-based data platform has been developed and deployed to provide integrative water quality data in one of the most critical urban corridors of the Laurentian Great Lakes system. In this paper, we describe the data platform developed for the watershed and connecting channels between Lake Huron and Lake Erie, including the St. Clair River, Lake St. Chair, and the Detroit River. This data platform greatly facilitates the access of data across data providers and agencies. Several example applications are provided of platform use for temporal and spatial characterization of intake water source quality and urban beach health through consideration of Escherichia coli, Dissolved Oxygen, pH, and blue-green algae detections along the Huron-to-Erie corridor. Although data collection for each of these parameters was designed for unique purposes and supported through varied agencies, this paper shows the collective advantages of applying the data beyond the original scope of collection.

Early onset of a microcystin-producing cyanobacterial bloom in an agriculturally-influenced Great Lakes tributary

In late May 2016, a cyanobacterial harmful algal bloom (cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identified Planktothrix agardhii as the dominant cyanobacterium with cell abundance exceeding 1.7×109 cells/L and total microcystins (MC) reaching 19 μg/L MC-LR equivalents, a level over 10-fold higher than the 2015 revised U.S. Environmental Protection Agency (EPA) national health advisory levels for drinking water exposure to adults. Low river discharge coincident with negligible precipitation through the latter half of May coincided with an 80% decline in river turbidity that likely favored bloom formation by a low-light adapted P. agardhii population. Also contributing to the cHAB were high initial nutrient loads and an increase of the river temperature from 13°C to 26°C over this same period. The bloom persisted through 5 June with microcystins exceeding 22 μg/L MC-LR equivalents at the bloom peak. By 6 June, the river had returned to its muddy character following a rain event and sampling on 7 June detected only low levels of toxin (<0.6 μg/L) at public water systems located near the bloom origin. The elevated toxin production associated with this early onset bloom was without precedent for the Maumee River and an unique attribute of the cHAB was the high proportion of potentially-toxic genotypes. Whereas Planktothrix spp. is common in lotic environments, and has been previously detected in the Maumee, blooms are not commonly reported. This early onset, microcystin-producing cHAB provided a rare opportunity to glean insights into environmental factors that promote bloom development and dominance by Planktothrix in lotic environments.

Identification, enumeration and diversity of nitrifying planktonic archaea and bacteria in trophic end members of the Laurentian Great Lakes

Oligotrophic Lake Superior and mesotrophic Lake Erie are trophic end members of the hydrologically connected Laurentian Great Lakes system, and as such exhibit different profiles of dissolved nitrogen species. Nitrification in Lake Superior has led to increasing nitrate concentrations over the past century, as opposed to Erie, where nitrate inventories have declined due to denitrification. In this study, we examined the abundance and diversity of nitrifying microbes involved in the oxidation of ammonia to nitrite, and nitrite to nitrate. By in situ hybridization methods, we enumerated the major planktonic ammonia oxidizing bacteria (AOB) and archaea (AOA) during a July 2011 cruise from Lake Superior to Lake Erie. In Lake Superior, AOA dominated compared to AOB, typically exceeding 5 × 103 mL− 1, whereas in Erie, AOB were more abundant than AOA. These data parallel prior work on Lake Superior and Lake Erie sediments, in which AOA are far more abundant in Superior, but AOB dominate in Erie. The lakes were sampled during stratification, and AOA and AOB were largely restricted to the hypolimnion, consistent with the observation that ammonia oxidizers are photoinhibited in surface waters. In Lakes Superior and Erie, we also detected nitrite oxidizing bacteria (NOB) in a pattern paralleling AOA/AOB abundance. Phylogenetic analysis of archaeal 16S rRNA revealed that the planktonic archaea of Lake Superior are members of the ammonia oxidizing Group I.1a Thaumarchaeota most closely related to Nitrosoarchaeum limnia. These AOA are distinct from the Group I.1a AOA in Lake Superior sediments. The major AOB of Lake Erie form a subcluster within the genus Nitrosospira.

Phylogenies of microcystin-producing cyanobacteria in the lower Laurentian Great Lakes suggest extensive genetic connectivity.

Lake St. Clair is the smallest lake in the Laurentian Great Lakes system. MODIS satellite imagery suggests that high algal biomass events have occurred annually along the southern shore during late summer. In this study, we evaluated these events and tested the hypothesis that summer bloom material derived from Lake St. Clair may enter Lake Erie via the Detroit River and represent an overlooked source of potentially toxic Microcystis biomass to the western basin of Lake Erie. We conducted a seasonally and spatially resolved study carried out in the summer of 2013. Our goals were to: 1) track the development of the 2013 summer south-east shore bloom 2) conduct a spatial survey to characterize the extent of toxicity, taxonomic diversity of the total phytoplankton population and the phylogenetic diversity of potential MC-producing cyanobacteria (Microcystis, Planktothrix and Anabaena) during a high biomass event, and 3) compare the strains of potential MC-producers in Lake St. Clair with strains from Lake Erie and Lake Ontario. Our results demonstrated a clear predominance of cyanobacteria during a late August bloom event, primarily dominated by Microcystis, which we traced along the Lake St. Clair coastline downstream to the Detroit River's outflow at Lake Erie. Microcystin levels exceeded the Province of Ontario Drinking Water Quality Standard (1.5 µg L−1) for safe drinking water at most sites, reaching up to five times this level in some areas. Microcystis was the predominant microcystin producer, and all toxic Microcystis strains found in Lake St. Clair were genetically similar to toxic Microcystis strains found in lakes Erie and Ontario. These findings suggest extensive genetic connectivity among the three systems.

An Ecological Network Analysis of nitrogen cycling in the Laurentian Great Lakes

As water moves through the Laurentian Great Lakes system, it experiences a steep gradient in physical and chemical conditions between oligotrophic Lake Superior and eutrophic Lake Erie, likely affecting stocks and flows of nitrogen (N) across these lakes. We used published rates, supplemented by measurements conducted during a series of research cruises from 2010 to 2012, to construct three coupled 4-compartment N models for Lakes Superior, Huron, and Erie. Linear Inverse Modeling was used to identify plausible solutions to this model, and subsequent analysis focused on the most parsimonious model solution. For the most parsimonious model solution, we used Ecological Network Analysis (ENA) to analyze N flow and cycling in this steady-state model, and to examine the ultimate source of the N removed via denitrification within each lake. We also calculated denitrification efficiencies for each lake (the fraction of N removed through denitrification relative to all N exported) for 10,000 possible solutions to the underdetermined model. The average path length of N atoms in Lake Superior was 47.4, compared to 25.7 in Lake Huron and 15.2 in Lake Erie. Lake Superior's long (191 years) hydrologic residence time and relatively high N cycling rates allow for N atoms to have multiple opportunities to enter the sediment N pool and ultimately be removed through denitrification. Despite having a low areal denitrification rate, Lake Superior had a higher denitrification efficiency (86±1%; mean±95% CI) compared to Lake Huron (64±12%), and Lake Erie (48±7%). This long residence time also makes Lake Superior highly sensitive to changes in loading rates and internal processes, probably contributing to the steady nitrate rise over the past century.

Coupling Socioeconomic and Lake Systems for Sustainability: A Conceptual Analysis Using Lake St. Clair Region as a Case Study

Applying sustainability at an operational level requires understanding the linkages between socioeconomic and natural systems. We identified linkages in a case study of the Lake St. Clair (LSC) region, part of the Laurentian Great Lakes system. Our research phases included: (1) investigating and revising existing coupled human and natural systems frameworks to develop a framework for this case study; (2) testing and refining the framework by hosting a 1-day stakeholder workshop and (3) creating a causal loop diagram (CLD) to illustrate the relationships among the systems’ key components. With stakeholder assistance, we identified four interrelated pathways that include water use and discharge, land use, tourism and shipping that impact the ecological condition of LSC. The interrelationships between the pathways of water use and tourism are further illustrated by a CLD with several feedback loops. We suggest that this holistic approach can be applied to other case studies and inspire the development of dynamic models capable of informing decision making for sustainability.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-013-0432-4) contains supplementary material, which is available to authorized users.

Eating the Invaders: The Prevalence of Round Goby (Apollonia melanostomus) in the Diet of Double-Crested Cormorants on the Niagara River

Abstract. The Round Goby (Apollonia melanostomus) is a small benthic fish, native to the Eurasian Ponto-Caspian region, that has rapidly spread through the entire Laurentian Great Lakes system since its 1990 discovery in Lake St. Clair. Tolerant of high population densities, the exotic Round Goby competes aggressively with native fish for food and habitat, and has increasingly been exploited by endemic Great Lakes predators. A management program for the Upper Niagara River, initiated in 2004, has provided an opportunity to study the interactions between these invaders and the Double-crested Cormorant (Phalacrocoiax auritus), a native top predator. The gut contents of 1,119 cormorants nesting at two sites in the Upper Niagara River from 2004 to 2007 were examined, and the species composition of ingested prey (by number and weight) was quantified for the 600 stomachs that contained identifiable prey. Results of these analyses indicate that Round Goby can constitute up to 85% of the biomass in cormorant diet...

An assessment of long-term trends in hydrologic components and implications for water levels in Lake Superior

The combination of climate change and natural periodicities in meteorological variables are demonstrating significant impacts on the water resources of Lake Superior within the Laurentian Great Lakes system of North America. Statistical analyses of long-term records are used to demonstrate how changes over time may be interpreted very differently, depending upon the timeframe over which the analyses are made. Non-linear regression modelling shows that, while increasing trends in overland and overlake precipitation, flows and runoff occurred during the first decades of the twentieth century, very different trends are apparent for the period 1970–2005. For this latter period, increasing rates of air overlake temperature and lake evaporation are occurring but all other parameters are demonstrating decreasing trends. The result is a decline in water levels in Lake Superior at the rate of approximately 1 cm per year over the last 35 years. The results are used to show that to avoid decreasing water levels in Lake Superior, the discharge through St Mary's River must be decreased to approximately one-half the long-term annual average, the results of which will have dramatic implications for ships' cargo levels and hydroelectric energy generation.

Formation of the St. Clair River Delta in the Laurentian Great Lakes System

The St. Clair River delta, the largest in the Laurentian Great Lakes system, is located in Lake St. Clair at the mouth of the St. Clair River. It straddles the border between the state of Michigan in the USA and the province of Ontario in Canada. The current study aims at characterizing and explaining the formation and evolution of the distributary channels in the St. Clair River delta and the delta itself. The delta is classified as a river dominated feature with classic “bird's foot” structure similar to the Mississippi delta model. The delta is composed of two surfaces. The older surface at the delta apex was deposited at a higher lake level some 3,500 to 5,000 years B.P. The current delta started to form following a drop in lake level some 3,500 years B.P. and continues to build to the present day. The delta consists of seven active deep channels averaging 11 m in depth entering a lake with a mean depth of 3 m with much shallower water in the delta front region. The channels are stable and are actively eroding into the sediments of the lake creating both sub-aqueous and sub-aerial levee deposits with crevasses. The interdistributary bays are being filled with sandy deposits created by wave energy and by crevasse deposits. At the erosional front of each distributary a narrow erosional notch “leading channel” is being formed which appears to control the direction of lakeward erosion of each deep distributary channel. The emplacement of the delta body in the shallow receiving water body has been termed “burrowing” delta formation and is the mechanism controlling the formation of this sedimentary feature.

The Expansion of White Perch,Morone Americana, In the Lower Great Lakes

White perch, Morone Americana, first appeared in the Laurentian Great Lakes system in 1951 and flourished in the Bay of Quinte, Lake Ontario throughout the 1950s and 1960s. The species extended its range to Lake Erie and Lake St. Clair and more recently (1983) to Saginaw Bay, Lake Huron. Self sustaining populations of white perch are now established in western Lake Erie (1974) and Lake St. Clair (1979). Factors contributing to successful colonization by white perch include: suitability of habitat within the range, ability to spawn over a variety of substrates, and high egg production.

Surface water temperature and ice regimes of Georgian Bay

Data from 38 airborne radiation thermometer (Art) surveys of Georgian Bay (a part of the Laurentian Great Lakes system) over a 4‐year period have been used to determine the areal patterns of surface water temperature and their seasonal variation. Although the limited observational period makes the resulting maps tentative, nevertheless definitive patterns have emerged. Of particular interest are the marked control of surface water temperature by water depth and the influx of cool surface water from Lake Huron during July and August. Ice is found on Georgian Bay from about mid‐December through to late April; the areal extent showed wide year to year variation with the maximum area ranging from 40 to 90% of the whole.