North American Great Lakes Basin Research Articles

Hydrologic implications of projected changes in rain-on-snow melt for Great Lakes Basin watersheds

Abstract. Rain-on-snow (ROS) melt events reduce the amount of water stored in the snowpack while also exacerbating flooding. The hydrologic implications of changing ROS events in a warming climate, however, are still uncertain. This research used a calibrated and validated Soil and Water Assessment Tool (SWAT) hydrologic model, modified with energy budget equations to simulate ROS melt and forced with a climate model ensemble representing moderate greenhouse gas concentrations, to simulate changes to ROS melt in the North American Great Lakes Basin from 1960–2069. The changes to ROS events between the historic period (1960–1999) and mid-century (2040–2069) represent an approximately 30 % reduction in melt in warmer, southern subbasins but less than 5 % reduction in melt in colder, northern subbasins. Additionally, proportionally more rainfall reduces the formation of snowpacks, with area-weighted combined winter and spring rain-to-snow ratios rising from approximately 1.5 historically to 1.9 by the mid-21st century. Areas with historic mean combined winter and spring air temperatures lower than −2 ∘C have ROS regimes that are resilient to mid-21st century warming projections, but ROS occurrence in areas that have mean combined winter and spring temperatures near the freezing point are sensitive to changing air temperatures. Also, relationships between changes in the timing of ROS melt and water yield endure throughout spring but become weak by summer. As the influence of ROS melt events on hydrological systems is being altered in a changing climate, these conclusions are important to inform adaptive management of freshwater ecosystems and human uses in regions of the globe that are sensitive to changes in ROS events.

Indigenous Peoples‐related environmental research within the basin of the Laurentian Great Lakes: A systematic map protocol

Abstract The North American Great Lakes Basin is the homeland for many First Nations, Métis and Native American Tribes. The terrestrial and aquatic ecological systems within this multinational region, which is of spiritual, cultural and subsistence significance to a diversity of Indigenous Peoples, are facing several natural and anthropogenic pressures. While there are many current and past research efforts and projects to address those pressures, the nature and range of environment‐related projects involving Indigenous Peoples or organizations remains unknown. This gap in knowledge presents a unique opportunity to identify and map past and current environmental and ecological research within the Great Lakes involving Indigenous Peoples. A systematic search strategy will be applied to identify and capture peer‐reviewed publications that pertain to past and current environmental research within the Great Lakes basin that involve or are connected to Indigenous Peoples, following the procedures outlined in this systematic mapping protocol. Publications that pertain to environmental and ecological research with, for and by Indigenous Peoples within the Great Lakes, as determined by the use of suitable keywords, will be retrieved from four proposed online bibliographic platforms and databases. Searches will only include peer‐reviewed publications in the English language. Final captures of the search results will be screened in two stages to identify potentially relevant papers. This will take place through (1) title and abstract screening and (2) full‐text analysis. Following the completion of the screening process, remaining papers will be coded and analysed through a narrative synthesis approach and descriptive statistics will be conducted. Environmental research captured through this systematic protocol will be geospatially mapped using the ArcGIS mapping software. It is anticipated that the information obtained from the resulting systematic map will be beneficial for identifying gaps in environmental research to support and inform future initiatives for environmental research planning, policy and decision‐making with, for and by Indigenous Communities within the Great Lakes basin.

Evaluation of gridded precipitation datasets over international basins and large lakes

Reliable precipitation estimates are a crucial component for hydrologic modeling and hydro-climate applications. However, watersheds that extend across international boundaries or those that contain large bodies of water pose particular challenges to the acquisition of consistent and accurate precipitation estimates. The North American Great Lakes basin is characterized by both of these features, which has led to long-standing challenges to water budget analysis and hydrologic prediction. In order to provide optimal conditions for hydrologic model calibration, retrospective analyses, and real-time forecasting, this study comprehensively evaluates four gridded datasets over the Great Lakes basin, including the Analysis of Record for Calibration (AORC), Canadian Precipitation Analysis (CaPA), Multi-sensor Precipitation Estimate (MPE), and a merged CaPA-MPE. These products are analyzed at multiple spatial (overland, overlake, sub-basin, country) and temporal (daily, monthly, annual) scales using station observations and a statistical water balance model. In comparison with gauge observations from the Global Historical Climatology Network Daily (GHCN-D), gridded datasets generally agree with ground observations, however the international border clearly delineates a decrease in gridded precipitation accuracy over the Canadian portion of the basin. Analysis reveals that rank in gridded precipitation accuracy differs for overland and overlake regions, and between colder and warmer months. Overall, the AORC has the lowest variance compared to gauge observations and has greater performance over temporal and spatial scales. While CaPA and AORC may better capture atmospheric dynamics between land and lake regions, comparison with a statistical water balance model suggests that AORC and MPE provide the best estimates of monthly overlake precipitation.

Loads and elimination of trace elements in wastewater in the Great Lakes basin

The growing use of trace elements in industrialized societies is driving an increase in the occurrence of trace elements in anthropogenic waste streams globally. Yet, the large-scale sources of many trace elements to wastewater and their elimination during treatment remain poorly understood and potential environmental impacts on freshwater systems therefore unclear. We screened 42 wastewater treatment facilities in the North American Great Lakes basin and deployed a black-box approach to calculate representative estimates for average per-capita trace element loads and basin-scale effluent discharge rates, as well as trace element removal efficiencies across different treatment technologies. Our results show different removal of specific groups of trace elements during wastewater treatment: average removal efficiencies were 25% for alkali metals, 50% for alkaline earth metals, 74% for transition metals, and 85% for rare earth elements. Higher elimination of the majority of trace elements was generally achieved by more advanced, tertiary treatment types. Elemental loads generally followed natural abundance patterns, but anomalous loading rates were observed for various trace elements across the sampled facilities. By examining geospatial attributes of the sampled sewersheds, trends in select trace element loads were qualitatively tied to possible point sources and diffuse sources. Overall, these results illustrate the potential of wastewater surveillance to inform environmental management of emerging trace element contaminants.

Incorporating rain-on-snow into the SWAT model results in more accurate simulations of hydrologic extremes

In many cold climates, rain-on-snow (ROS) events are associated with severe snowmelt and flooding. ROS events also rapidly deplete snowpacks, reducing the potential for subsurface water storage later in the year. We incorporated a simple, easily transferable energy-balance ROS model into the Soil and Water Assessment Tool (SWAT) to assess how ROS melt affects winter floods and summer hydrological drought over a large area such as the North American Great Lakes Basin, where ROS is associated with severe snowmelt events. Using 504 random parameter sets, the modification consistently improved simulations and led to higher winter flows and lower summer flows compared with the unmodified SWAT. The SWAT ROS model also had improved performance for simulating daily streamflow in 501 (99.4%) of the 504 random parameter sets and improved performance for simulating daily snowpack in 504 (100%) of the sets, compared to the unmodified SWAT. We then used streamflow and snow water equivalent as the objectives in a multivariable, multi-site calibration to compare SWAT ROS with the unmodified SWAT. The SWAT ROS model simulated 51% larger peak (0.95 quantile) daily flows during winter and spring and 58% lower daily summer low (0.05 quantile) flows across the Great Lakes Basin, compared to the unmodified SWAT. We also used observed snowpack data to demonstrate how the unmodified SWAT can miss daily ROS melt events, delaying snowmelt to later in the season. Thus, the unmodified SWAT model appears to be misrepresenting the streamflow distribution in areas where ROS events occur, which is particularly important for modeling extreme events. When simulating conditions in cold climates at diverse scales up to large basins or continents, hydrological models such as SWAT must incorporate ROS, as many other models already do. This has implications for water resources management confronted with hydrological extremes in ROS-prone areas around the world, especially where climate change is altering ROS melt events.

The changing nature of ablation-inducing synoptic weather types in the North American Great Lakes basin

The runoff generated by snow cover ablation dominates regional hydrology in the North American Great Lakes basin, while rapid events can represent a physical hazard due to flooding. In determining the likelihood and magnitude of an ablation event, both the presence of snow cover and the synoptic-scale atmospheric environment should be considered, where the atmospheric environment provides the meteorological characteristics and surface energy fluxes necessary for ablation. Pending snowpack availability, variations or changes in the frequency of ablation-inducing synoptic types, and/or varying suitability of meteorological characteristics for snowmelt, can alter the frequency of ablation events. In light of a changing global climate, it is unclear if and how ablation-inducing synoptic types in the Great Lakes basin have transformed in recent decades as from 1960 to 2009, the interannual frequency of snow cover ablation events in the Great Lakes basin has significantly decreased. This study uses synoptic classification as a mechanism for identifying ablation-inducing synoptic weather types and for determining if changes to the frequency and inherent meteorological characteristic of the type are occurring. For a majority of the ten most impactful ablation-inducing synoptic weather types examined, significant trends are noted in their interannual frequencies, which can be partially explained by variations and trends in the phases of common teleconnection indices, such as the North Atlantic and Arctic Oscillations. Collectively, inherent meteorological characteristics of particular weather types in the basin are becoming more suitable for ablation, with increases in surface air temperatures, more southerly wind flow, and less cloud cover, plus increases in liquid precipitation rates during rain-on-snow synoptic types. Independent of snow cover, atmospheric environments suitable for ablation are becoming more frequent and generally more favorable for ablation.

Atmospheric concentrations of hexabromocyclododecane (HBCDD) diastereomers in the Great Lakes region

The concentrations of α-, β-, and γ-hexabromocyclododecane (HBCDD) diastereomers in atmospheric particle phase samples were determined at four United States Integrated Atmospheric Deposition Network (IADN) sites located in the North American Great Lakes basin collected between 1 January and 31 December 2014. The concentrations ranged from 0.37 to 8.9 pg/m3, 0.12–4.0 pg/m3, and 0.26–22 pg/m3 for α-, β-, and γ-HBCDD, respectively among the four sampling sites. The median ΣHBCDD concentrations for the four sites were 2.0 pg/m3, 2.1 pg/m3, 1.7 pg/m3 and 5.2 pg/m3 for Chicago, Cleveland, Sturgeon Point and Sleeping Bear Dunes, respectively. Higher levels of ∑HBCDD were observed at the remote site of Sleeping Bear Dunes with comparable levels at the remaining three sites. α-HBCDD and γ-HBCDD were the dominant isomers with an average contribution of about 40% and 50% to ΣHBCDD concentrations, respectively. These HBCDD concentrations were compared with the levels of other brominated flame retardants measured in these samples, including polybrominated diphenyl ethers (PBDEs), 2,3,4,5-tetrabromoethylhexyl benzoate (EHTBB), bis(2-ethylhexyl) tetrabromophthalate (BEHTBP), and decabromodiphenylethane (DBDPE). ∑HBCDD concentrations were significantly lower than or indistinguishable from those of PBDEs, EHTBB, BEHTBP, and DBDPE at all sites except Sleeping Bear Dunes. No significant correlations were found between ΣHBCDD and ΣPBDE, EHTBB, BEHTBP, and DBDPE concentrations, suggesting a different source of HBCDD contamination. This is the first study reporting concentrations of HBCDD isomers in the Great Lakes ambient air, and our results indicate that HBCDD is ubiquitous in the Great Lakes basin, including at remote sites.

The Role of Transnational Municipal Networks in Transboundary Water Governance

The transboundary nature of stressors impacting shared water bodies has been traditionally recognized in agreements between nation states. Several developments have led to new layers of cross border environmental actors, including regional and city level interactions. This proliferation of non-state actors is witnessed in two large water bodies, the Baltic Sea and the North American Great Lakes. In both regions, transboundary water governance was led by nation states in agreements to improve heavily contaminated waters, the Helsinki Convention (1974) and the North American Great Lakes Water Quality Agreement (1972), respectively. Whilst there has been much research on transnational regional networks, especially in Europe, there has been less theoretical work done on transnational municipal transboundary water networks due to the delay of recognition of the legitimacy of these local government actors. This paper aims to examine the role of the transnational municipal networks in transboundary water governance by looking at the case studies of the Union of Baltic cities in the Baltic Sea region and the Great Lakes and St. Lawrence Cities Initiative in the North American Great Lakes Basin. It does this by assessing the role of these transnational municipal networks in bridging water governance gaps in these regions.

Spatial and Temporal Trends of Particle Phase Organophosphate Ester Concentrations in the Atmosphere of the Great Lakes.

The concentrations of six organophosphate esters (OPEs) in atmospheric particle phase samples collected once every 12 days at five sites in the North American Great Lakes basin over the period of March 2012 to December 2014, inclusive, are reported. These OPEs include tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP), tri-n-butyl phosphate (TNBP), triphenyl phosphate (TPHP), and 2-ethylhexyl diphenyl phosphate (EHDP). Median total OPE concentrations (∑OPE) ranged from 93 pg/m3 at Sleeping Bear Dunes to 1046 pg/m3 at Chicago. The ∑OPE levels were significantly (P < 0.05) higher at Chicago and Cleveland, our urban sites, than at our rural and remote sites. The composition profiles were dominated by chlorinated OPEs at the urban and rural sites and by nonchlorinated OPEs at the remote sites. The concentrations of all OPEs were significantly (P < 0.001) correlated to one another, suggesting that these compounds share similar sources. Most atmospheric ∑OPE concentrations were significantly (P < 0.05) decreasing over time, with halving times of about 3.5 years at the urban sites and about 1.5 years at the rural and remote sites. Interestingly, TCEP and EHDP concentrations were increasing over time at the rural and remote sites with doubling times of 2.2 and 3.7 years, respectively.

High Levels of Organophosphate Flame Retardants in the Great Lakes Atmosphere

Levels of 12 organophosphate flame retardants (OPs) were measured in particle phase samples collected at five sites in the North American Great Lakes basin from March 2012 to December 2012 (inclusive). The target compounds were three chlorinated OPs [tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP)], three alkyl phosphates [tri-n-butyl phosphate (TnBP), tris(butoxyethyl) phosphate (TBEP), and tris(2-ethylhexyl) phosphate (TEHP)], and six aryl phosphates [triphenyl phosphate (TPP), tri-o-tolyl phosphate (TOTP), tri-p-tolyl phosphate (TPTP), tris(3,5-dimethylphenyl) phosphate (TDMPP), tris(2-isopropylphenyl) phosphate (TIPPP), and tris(4-butylphenyl) phosphate (TBPP)]. Total OP (ΣOP) atmospheric concentrations ranged from 120 ± 18 to 2100 ± 400 pg/m3 at the five sites, with the higher ΣOP levels detected at Cleveland and Chicago. ΣOP concentrations at these urban sites were dominated by the chlorinated OPs (TCEP, TCPP, and TDCPP), with the sum of these three compounds comprising 51 ± 6 and 65 ± 12% of ΣOP concentrations at these two sites, respectively. Nonhalogenated OP compounds were major contributors to ΣOP concentrations at the remote sites, with the sum of all nine nonhalogenated OP concentrations comprising 70 ± 21 and 85 ± 13% of the ΣOP concentrations at Eagle Harbor and Sleeping Bear Dunes, respectively. On average, these ΣOP concentrations are about 2–3 orders of magnitude higher than the concentrations of brominated flame retardants in similar samples.

Restoring aquatic ecosystem connectivity requires expanding inventories of both dams and road crossings

A key challenge in aquatic restoration efforts is documenting locations where ecological connectivity is disrupted in water bodies that are dammed or crossed by roads (road crossings). To prioritize actions aimed at restoring connectivity, we argue that there is a need for systematic inventories of these potential barriers at regional and national scales. Here, we address this limitation for the North American Great Lakes basin by compiling the best available spatial data on the locations of dams and road crossings. Our spatial database documents 38 times as many road crossings as dams in the Great Lakes basin, and case studies indicate that, on average, only 36% of road crossings in the area are fully passable to fish. It is therefore essential that decision makers account for both road crossings and dams when attempting to restore aquatic ecosystem connectivity. Given that road crossing structures are commonly upgraded as part of road maintenance, many opportunities exist to restore connections within aquatic ecosystems at minimal added cost by ensuring upgrade designs permit water flow and the passage of fish and other organisms. Our findings highlight the necessity for improved dam and road crossing inventories that traverse political boundaries to facilitate the restoration of aquatic ecosystem connectivity from local to global scales.

Low dissolved ions may limit secondary invasion of inland waters by exotic round gobies and dreissenid mussels in North America

Round gobies and dreissenid mussels, exotic species in the North American Great Lakes basin, are euryhaline organisms whose geographic spread and ecological impacts in freshwaters may be limited by low levels of dissolved ions such as calcium (Ca). We measured source populations of these exotics in the St. Lawrence River and found population densities of dreissenids (range of ~1,000–6,400 individuals m−2) and round gobies (6–32 individuals m−2) similar to those in other Great Lake locations from which they have spread inland. However, we found little evidence for their secondary invasion of inland tributary rivers and lakes of northern New York State. Using natural waters collected from inland ecosystems, we ran laboratory bioassays of reproduction, growth, and survival of several life stages of zebra and quagga mussels as well as the round goby. We found little difference in the responses of zebra and quagga mussels, with each species showing moderate reproductive success, growth, and survival at Ca concentrations > 13 mg L−1 and dramatic improvements at >18 mg L−1. Round gobies showed moderate survival in waters with Ca concentrations > 8 mg L−1 and high survival > 18 mg L−1. These bioassays are the first such experiments for quagga mussels and round gobies and show how all three species may be similarly restricted in their ability to invade and permanently colonize significant geographic regions of New York State and perhaps the US.

A multi-modeling approach to evaluating climate and land use change impacts in a Great Lakes River Basin

River ecosystems are driven by linked physical, chemical, and biological subsystems, which operate over different temporal and spatial domains. This complexity increases uncertainty in ecological forecasts, and impedes preparation for the ecological consequences of climate change. We describe a recently developed “multi-modeling” system for ecological forecasting in a 7600 km2 watershed in the North American Great Lakes Basin. Using a series of linked land cover, climate, hydrologic, hydraulic, thermal, loading, and biological response models, we examined how changes in both land cover and climate may interact to shape the habitat suitability of river segments for common sport fishes and alter patterns of biological integrity. In scenario-based modeling, both climate and land use change altered multiple ecosystem properties. Because water temperature has a controlling influence on species distributions, sport fishes were overall more sensitive to climate change than to land cover change. However, community-based biological integrity metrics were more sensitive to land use change than climate change; as were nutrient export rates. We discuss the implications of this result for regional preparations for climate change adaptation, and the extent to which the result may be constrained by our modeling methodology.

Genetic analysis across different spatial scales reveals multiple dispersal mechanisms for the invasive hydrozoan Cordylophora in the Great Lakes

Discerning patterns of post-establishment spread by invasive species is critically important for the design of effective management strategies and the development of appropriate theoretical models predicting spatial expansion of introduced populations. The globally invasive colonial hydrozoan Cordylophora produces propagules both sexually and vegetatively and is associated with multiple potential dispersal mechanisms, making it a promising system to investigate complex patterns of population structure generated throughout the course of rapid range expansion. Here, we explore genetic patterns associated with the spread of this taxon within the North American Great Lakes basin. We collected intensively from eight harbours in the Chicago area in order to conduct detailed investigation of local population expansion. In addition, we collected from Lakes Michigan, Erie, and Ontario, as well as Lake Cayuga in the Finger Lakes of upstate New York in order to assess genetic structure on a regional scale. Based on data from eight highly polymorphic microsatellite loci we examined the spatial extent of clonal genotypes, assessed levels of neutral genetic diversity, and explored patterns of migration and dispersal at multiple spatial scales through assessment of population level genetic differentiation (pairwise F(ST) and factorial correspondence analysis), Bayesian inference of population structure, and assignment tests on individual genotypes. Results of these analyses indicate that Cordylophora populations in this region spread predominantly through sexually produced propagules, and that while limited natural larval dispersal can drive expansion locally, regional expansion likely relies on anthropogenic dispersal vectors.

Tracking Toxaphene in the North American Great Lakes Basin. 1. Impact of Toxaphene Residues in United States Soils

A coupled atmospheric transport model was employed to study six scenarios to assess the contribution of reemission and long-range transport of toxaphene from different sources in the United States to its environmental fate in the Great Lakes ecosystem in the year 2000. Modeled air concentrations at the first model level (1.5 m) range from less than 5 pg m(-3) over the upper Great lakes (Lakes Superior and Huron) to several tens of picograms per cubic meter over the lower Great Lakes (Lakes Erie and Ontario) in the summer but drop off to the range from 0.05 to 2 pg m(-3) in the wintertime. The modeled toxaphene depositions to the lakes suggest a decreasing trend from the mid-1990s to 2000. Modeling results showed that, on an annual basis, for the Great Lakes basin as a whole, the southeast U.S. sources made the largest contribution to the toxaphene air concentrations and dry and wet depositions at 72%, 78%, and 88% respectively. The model results also showed that a significant proportion of these contributions occur during relatively short episodic events due primarily to the interseasonal changes in atmospheric circulation patterns.

Contaminants programs in the North American Great Lakes Basin

Contaminants programs in the North American Great Lakes Basin