Polychlorinated biphenyls and organochlorine pesticides concentration patterns and trends in top predator fish of Laurentian Great Lakes from 1999 to 2014

Concentration patterns and temporal trends of legacy persistent, bioaccumulative and toxic (PBT) contaminants were determined using the Great Lake Fish Monitoring and Surveillance Program (GLFMSP) top predator fish data from 1999 to 2014 and applying Kendall-Theil robust regression after cluster-based age normalization. For most Great Lakes sites, significant decreasing concentration trends ranging from ?4.1% to ?21.6% per year (with the only exception being mirex in Lake Erie walleye) were found for PBTs including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichlorethane (DDTs), dieldrin, endrin, chlordane, oxychlordane, nonachlor, mirex, and hexachlorobenzene (HCB) reflecting the successful historical and ongoing reduction of fugitive releases and remediation efforts in the U.S. and Canada including physical removal (dredging) coupled with sediment sequestration. Generally, lower concentrations and faster decreasing trends are observed in western/northern sampling sites compared to eastern/southern sites as the former sites are generally more remote from population centers and industrial activities. PCBs, which can be released from ongoing sources, have the highest concentration, the second slowest decreasing trend, and increasing mass fractions of the contaminants studied suggesting that they will continue to be the legacy contaminant of greatest concern into the future.     

U.S. EPA Great Lakes National Program Office monitoring of the Laurentian Great Lakes: Insights from 40 years of data collection

The U.S. EPA Great Lakes National Program Office (GLNPO) implements long-term monitoring programs to assess Great Lakes ecosystem status and trends for many interrelated ecosystem components, including offshore water quality as well as offshore phytoplankton, zooplankton and benthos; chemical contaminants in air, sediments, and predator fish; hypoxia in Lake Erie's central basin; and coastal wetland health. These programs are conducted in fulfillment of Clean Water Act mandates and Great Lakes Water Quality Agreement commitments. This special issue presents findings from GLNPO's Great Lakes Biology Monitoring Program, Great Lakes Water Quality Monitoring Program, Lake Erie Dissolved Oxygen Monitoring Program, Integrated Atmospheric Deposition Network, Great Lakes Fish Monitoring and Surveillance Program, and Great Lakes Sediment Surveillance Program. These GLNPO programs have generated temporal and spatial datasets for all five Great Lakes that form the basis for assessment of the state of these lakes, including trends in nutrients, key biological indicators, and contaminants in air, sediments and fish. These datasets are used by researchers and managers across the Great Lakes basin for investigating physical, chemical and biological drivers of ongoing ecosystem changes; some of these analyses are presented in this special issue, along with discussion of new methods and approaches for monitoring.     

Beach science in the Great Lakes

Monitoring beach waters for human health has led to an increase and evolution of science in the Great Lakes, which includes microbiology, limnology, hydrology, meteorology, epidemiology, and metagenomics, among others. In recent years, concerns over the accuracy of water quality standards at protecting human health have led to a significant interest in understanding the risk associated with water contact in both freshwater and marine environments. Historically, surface waters have been monitored for fecal indicator bacteria (fecal coliforms, Escherichia coli, enterococci), but shortcomings of the analytical test (lengthy assay) have resulted in a re-focusing of scientific efforts to improve public health protection. Research has led to the discovery of widespread populations of fecal indicator bacteria present in natural habitats such as soils, beach sand, and stranded algae. Microbial source tracking has been used to identify the source of these bacteria and subsequently assess their impact on human health. As a result of many findings, attempts have been made to improve monitoring efficiency and efficacy with the use of empirical predictive models and molecular rapid tests. All along, beach managers have actively incorporated new findings into their monitoring programs. With the abundance of research conducted and information gained over the last 25 years, “Beach Science” has emerged, and the Great Lakes have been a focal point for much of the ground-breaking work. Here, we review the accumulated research on microbiological water quality of Great Lakes beaches and provide a historic context to the collaborative efforts that have advanced this emerging science.     

A brief history of the U.S. EPA Great Lakes National Program Office's water quality survey

The U.S. Environmental Protection Agency Great Lakes National Program Office (GLNPO) water quality survey (WQS) constitutes the longest-running, most extensive monitoring of water quality and the lower trophic level biota of the Laurentian Great Lakes, and has been instrumental in tracking shifts in nutrients and the lower food web over the past several decades. The initial impetus for regular monitoring of the Great Lakes was provided by the 1972 Great Lakes Water Quality Agreement (GLWQA) which asked the parties to develop monitoring and surveillance programs to ensure compliance with the goals of the agreement. The resulting monitoring plan, eventually known as the Great Lakes International Surveillance Plan (GLISP), envisioned a nine-year rotation of intensive surveys of the five lakes. A broadening of the scope of the GLWQA in 1978 and the completion of the first nine-year cycle of sampling, prompted reappraisals of the GLISP. During this pause, and using knowledge gained from GLISP, GLNPO initiated an annual WQS with the narrower focus of tracking water quality changes and plankton communities in the offshore waters of the lakes. Beginning in 1983 with lakes Erie, Huron, and Michigan, the WQS added Lake Ontario in 1986 and Lake Superior in 1992, evolving into its current form in which all five lakes are sampled twice a year. The WQS is unique in that all five lakes are sampled by one agency, using one vessel and one principal laboratory for each parameter group, and represents an invaluable resource for managing and understanding the Great Lakes.     

Widespread prevalence of hypoxia and the classification of hypoxic conditions in the Laurentian Great Lakes

Aquatic hypoxia within the Laurentian Great Lakes has contributed to various adverse ecological consequences and stimulated research interest in recent decades. An analysis of published peer-reviewed journal articles from 2000 to 2020 demonstrates an increasing trend of studies related to hypoxia in the Laurentian Great Lakes. However, the majority of these studies (78%) focus on Lake Erie and in particular the well-documented hypolimnetic hypoxic conditions that develop in the central basin of Lake Erie. This hypoxic zone is relatively large (up to 1.5 million ha), has substantial ecological effects, and motivates monitoring programs and water quality improvement initiatives. Nonetheless, the hypoxic zone in the central basin of Lake Erie is only one of over twenty documented hypoxic zones in the Laurentian Great Lakes. Moreover, hypoxic conditions in the Great Lakes are quite diverse. Here, we define and characterize a four-fold classification of Great Lakes hypoxic conditions: 1) hypolimnetic hypoxia, 2) over-winter hypoxia, 3) diel hypoxia, and 4) episodic hypoxia. We suggest that Great Lakes research and monitoring programs should seek to more broadly document hypoxic conditions and develop models to predict the temporal and spatial occurrence of hypoxia. Such efforts are particularly timely as future climatic conditions contributing to warmer temperatures, longer and more intense stratified periods, increased spring nutrient loading and more variable allocthonous inputs are expected to exacerbate three of the four hypoxic conditions described for the Great Lakes (hypolimnetic, diel, and episodic hypoxia).     

Cumulative Habitat Impacts of Nearshore Engineering

A multi-disciplinary, multi-institutional research team evaluated a broad range of physical and biological characteristics at six Great Lakes nearshore sites in order to develop and test a conceptual modeling framework to assess linkages between bluff erosion, sediment supply, coastal processes, and biological utilization of nearshore and coastal habitats. The sites were chosen to represent a broad range of hydrogeomorphic conditions, with the objective of assessing the response of these nearshore systems to anthropogenic modifications and coastal change. As a result of this 2-year field effort, new methods and integrated approaches were developed to characterize, map, and assess the dynamic nature of the nearshore zone (area generally less than 10 m water depth). Thus, these data provide an initial quantitative assessment of nearshore change. In addition, our data indicate that shoreline modifications have led to cumulative impacts that have irreversibly modified Great Lakes nearshore coastal habitats and the processes that create and maintain them. Of special note is our observation that altered nearshore substrate dynamics resulting from shoreline modifications may enhance the colonization success of lithophilic aquatic invasive species in nearshore areas of the Great Lakes. Continued development of the shoreline may exacerbate changes in Great Lakes nearshore food-web structures and ecosystem services. Further study and monitoring of these phenomena are needed, and our work suggests that a holistic, multidisciplinary approach is necessary to develop effective management strategies to address these and other issues affecting nearshore areas of the Great Lakes.     

Tributary phosphorus monitoring in the U.S. portion of the Laurentian Great Lake Basin: Drivers and challenges

This paper examines the tributary monitoring network currently in place for sampling the amount of phosphorus entering the U.S. Great Lakes, focusing on the challenges faced by the agencies and organizations responsible for maintaining the network. The tributaries that are monitored vary in terms of flow, the size and terrain of the watershed being drained, and patterns of land use. Data generated by this network are used by researchers to compute lake-wide phosphorus loads. In this work, the primary drivers and challenges associated with operating an effective phosphorus tributary monitoring program were investigated through interviews with stakeholders responsible for managing a portion of the existing network. Based on these interviews, the authors identify three recommendations that policy makers interested in maintaining an effective phosphorus monitoring network in the Great Lakes should consider. The first is to provide states with incentives to support the long-term monitoring that is required to estimate phosphorus loads in tributaries to the Great Lakes; currently, most states design their programs to meet the requirements of the Clean Water Act, which results in patterns of sampling that are not necessarily useful for computing loads. The second recommendation is to facilitate the creation of a monitoring protocol that generates enough samples to identify trends and quantify loads at a level of certainty necessary for use in statistical models and load control programs. Finally, funding mechanisms capable of supporting long-term monitoring programs need to be established, with programs in Michigan and Minnesota serving as potential models.     

A pound of prevention,plus a pound of cure: Early detection and eradication of invasive species in the Laurentian Great Lakes

Ballast water regulations implemented in the early 1990s appear not to have slowed the rate of new aquatic invasive species (AIS) establishment in the Great Lakes. With more invasive species on the horizon, we examine the question of whether eradication of AIS is a viable management strategy for the Laurentian Great Lakes, and what a coordinated AIS early detection and eradication program would entail. In-lake monitoring would be conducted to assess the effectiveness of regulations aimed at stopping new AIS, and to maximize the likelihood of early detection of new invaders. Monitoring would be focused on detecting the most probable invaders, the most invasion-prone habitats, and the species most conducive to eradication. When a new non-native species is discovered, an eradication assessment would be conducted and used to guide the management response. In light of high uncertainty, management decisions must be robust to a range of impact and control scenarios. Though prevention should continue to be the cornerstone of management efforts, we believe that a coordinated early detection and eradication program is warranted if the Great Lakes management community and stakeholders are serious about reducing undesired impacts stemming from new AIS in the Great Lakes. Development of such a program is an opportunity for the Laurentian Great Lakes resource management community to demonstrate global leadership in invasive species management.     

Associations between Breeding Marsh Bird Abundances and Great Lakes Hydrology

We used Great Lakes hydrologic data and bird monitoring data from the Great Lakes Marsh Monitoring Program from 1995–2002 to: 1) evaluate trends and patterns of annual change in May-July water levels for Lakes Ontario, Erie, and Huron-Michigan, 2) report on trends of relative abundance for birds breeding in Great Lakes coastal marshes, and 3) correlate basin-wide and lake-specific annual indices of bird abundance with Great Lakes water levels. From 1995–2002, average May, June, and July water levels in all lake basins showed some annual variation, but Lakes Erie and Huron-Michigan had identical annual fluctuation patterns and general water level declines. No trend was observed in Lake Ontario water levels over this period. Abundance for five of seven marsh birds in Lake Ontario wetlands showed no temporal trends, whereas abundance of black tern (Chlidonias niger) declined and that of swamp sparrow (Melospiza georgiana) increased from 1995–2002. In contrast, abundances of American coot (Fulica americana), black tern, common moorhen (Gallinula chloropus), least bittern (Ixobrychus exilis), marsh wren (Cistorthorus palustris), pied-billed grebe (Podilymbus podiceps), sora (Porzana carolina), swamp sparrow, and Virginia rail (Rallus limicola) declined within marshes at Lakes Erie and Huron/Michigan from 1995–2002. Annual abundances of several birds we examined showed positive correlations with annual lake level changes in non-regulated Lakes Erie and Huron/Michigan, whereas most birds we examined in Lake Ontario coastal wetlands were not correlated with suppressed water level changes of this lake. Overall, our results suggest that long-term changes and annual water level fluctuations are important abiotic factors affecting abundance of some marsh-dependent birds in Great Lakes coastal marshes. For this reason, wetland bird population monitoring initiatives should consider using methods in sampling protocols, or during data analyses, to account for temporal and spatial components of hydrologic variability that affect wetlands and their avifauna.     

St. Clair-Detroit River system: Phosphorus mass balance and implications for Lake Erie load reduction,monitoring, and climate change

To support the 2012 Great Lakes Water Quality Agreement on reducing Lake Erie's phosphorus inputs, we integrated US and Canadian data to update and extend total phosphorus (TP) loads into and out of the St. Clair-Detroit River System for 1998–2016. The most significant changes were decreased loads from Lake Huron caused by mussel-induced oligotrophication of the lake, and decreased loads from upgraded Great Lakes Water Authority sewage treatment facilities in Detroit. By comparing Lake St. Clair inputs and outputs, we demonstrated that on average the lake retains 20% of its TP inputs. We also identified for the first time that loads from resuspended Lake Huron sediment were likely not always detected in US and Canadian monitoring programs due to mismatches in sampling and resuspension event frequencies, substantially underestimating the load. This additional load increased over time due to climate-induced decreases in Lake Huron ice cover and increases in winter storm frequencies. Given this more complete load inventory, we estimated that to reach a 40% reduction in the Detroit River TP load to Lake Erie, accounting for the missed load, point and non-point sources other than that coming from Lake Huron and the atmosphere would have to be reduced by at least 50%. We also discuss the implications of discontinuous monitoring efforts.     

Initial insights into the development and implementation of a citizen-science drone-based coastal change monitoring program in the Great Lakes region

High-resolution spatio-temporal data are needed to improve coastal management programs, particularly along the Great Lakes where lake level fluctuations pose challenges to coastal decision-making and planning. Unfortunately, there is a paucity of coastal change monitoring datasets, particularly those that document event-scale changes over a large spatial scale. This paucity of data is compounded by the large size and range of shore types throughout the region.Unoccupied aerial vehicle (UAV) or drone data collected by citizen scientists are a potential solution to this challenge. However, no citizen science coastal change monitoring program exists in the Great Lakes region, nor does a comprehensive drone-based coastal change monitoring programs exist anywhere in the United States. To inform the development of drone-based citizen science programs, the goal of this paper is to describe the development and implementation of a citizen science coastal change monitoring program along the Great Lakes shores of Michigan. The citizens participating in this project generate imagery in two ways: (1) the submission of photos of coastal changes or hazards via a web app developed for the project called PicShores and (2) drone collection of survey-quality aerial imagery for use in the generation of orthomosaic images and digital elevation models (DEMs). This paper presents the methods utilized to develop the citizen science monitoring program, some initial findings from the citizen science monitoring, and explores some challenges and next steps for the program.     

Significance of toxaphene in Great Lakes fish consumption advisories

Fish consumption advisories have been issued for the Great Lakes generally based on the most restrictive contaminant. For the Canadian waters of the Great Lakes, toxaphene causes minor restrictions only in Lake Superior, i.e., 3% of the total (restrictive + unrestrictive) advisories issued. However, the significance of the hazard posed by toxaphene in fish is not clear since more restrictive advisories due to other priority contaminants may be masking the less restrictive advisories. We simulated fish consumption advisories for the Toxaphene-only scenario by neglecting the presence of contaminants other than toxaphene, and compared with the issued advisories as well as with the published simulated Mercury-only scenario. Restrictive advisories under the Toxaphene-only scenario compared to the issued toxaphene related advisories would increase from 3% to 14%, < 1% to 4%, and 0% to 2% for Lakes Superior, Huron and Ontario, respectively, and remain at 0% for Lake Erie. For Lake Superior, most of the restrictive Toxaphene-only advisories would be for fatty fish. Overall, the Toxaphene-only advisories would be significantly less restrictive compared to the issued advisories, and also generally less restrictive compared to the Mercury-only scenario. These results suggest that toxaphene is less of a concern than PCBs (including dioxin-like PCBs), dioxins–furans and mercury from the perspective of health risk to humans consuming Great Lakes fish; elevated toxaphene is mainly a concern for human consumers of Lake Superior fatty fish. Our results suggest that the routine monitoring of toxaphene in other Canadian waters of the Great Lakes and Lake Superior lean/pan fish could be discontinued.     

Vessel-Based Education Programs in the Great Lakes: An Evaluation of Effects on Student Knowledge and Attitudes

Vessel-based education programs are found throughout the Great Lakes region, yet they have received little quantitative evaluation attention. The focus of this research was to measure the impacts of one such multi-disciplinary program, the Great Lakes Education Program (GLEP), on changes in Great Lakes knowledge and attitudes of fourth grade students. A valid and reliable written survey was developed from eight pre-existing instruments. The study incorporated a quasi-experimental, pre- and post-test design involving 39 fourth grade classrooms (945 students). As a result of the GLEP vessel experience, students exhibited a highly significant increase in Great Lakes knowledge, and girls experienced a statistically significant increase in positive attitudes toward the Great Lakes. Boys had significantly more Great Lakes and aquatic experiences than girls. Recommendations for vessel-based education programs include conducting rigorous evaluations with reliable and valid measurements for knowledge and attitudes, using research designs with controls for threats to validity, conducting longerterm follow-up evaluations with students, and strengthening cruise and classroom curricula.     

Contaminant Analysis of Fillets from Great Lakes Coho Salmon, 1980

Analyses of coho salmon from each of the Great Lakes by a single laboratory produced residue data on the accumulation of environmental contaminants which have been banned, severely restricted, or are currently permitted in the basin. Coho salmon from Lake Superior contained only trace amounts or low levels of most toxic substances quantified; Lake Erie fish were contaminated with low levels of a number of pesticides and industrial compounds; relatively higher residues were detected in coho from Lake Huron and Lake Michigan; and the highest concentrations for a number of compounds were found in fillets from coho from Lake Ontario. Contaminant concentrations in migratory coho salmon indicate open lake contaminant problems rather than point source or nearshore conditions. Tissue residues were less than USFDA action levels, used by many agencies in assessing the severity of fish contaminant problems. Only mirex concentrations in fish collected from Lake Ontario exceeded a USFDA action level. The data reported in this study generally agree with recent findings from individual state contaminant monitoring programs. Problems with varying analytical and sampling techniques preclude direct comparisons with previously published data of other studies.     

Trends in Water Clarity of the Lower Great Lakes from Remotely Sensed Aquatic Color

Satellite observations of aquatic colour enable environmental monitoring of the Great Lakes at spatial and temporal scales not obtainable through ground-based monitoring. By merging data from the Coastal Zone Color Scanner (CZCS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), monthly binned images of water-leaving radiance over the Great Lakes have been produced for the periods 1979–1985 and 1998–2006. This time-series can be interpreted in terms of changes in water clarity, showing seasonal and inter-annual variability of bright-water episodes such as phytoplankton blooms, re-suspension of bottom sediments, and whiting events. Variations in Secchi disk depth over Lakes Erie and Ontario are predicted using empirical relationships from coincident measurements of water transparency and remotely-sensed water-leaving radiance. Satellite observations document the extent to which the water clarity of the lower Great Lakes has changed over the last three decades in response to significant events including the invasion of zebra mussels. Results confirm dramatic reductions in Lake Ontario turbidity in the years following mussel colonization, with a doubling of estimated Secchi depths. Evidence confirms a reduction in the frequency/intensity of whiting events in agreement with suggestions of the role of calcium uptake by mussels on lake water clarity. Increased spring-time water clarity in the eastern basin of Lake Erie also corroborates previous observations in the region. Despite historical reports of localised increases in transparency in the western basin immediately following the mussel invasion, image analysis shows a significant increase in turbidity between the two study periods, in agreement with more recent reports of longer term trends in water clarity. Through its capacity to provide regular and readily interpretable synoptic views of regions undergoing significant environmental change, this work illustrates the value of remotely sensing water colour to water clarity monitoring in the lower Great Lakes.     

Mean Circulation in the Great Lakes

In this paper new maps are presented of mean circulation in the Great Lakes, employing long-term current observations from about 100 Great Lakes moorings during the 1960s to 1980s. Knowledge of the mean circulation in the Great Lakes is important for ecological and management issues because it provides an indication of transport pathways of nutrients and contaminants on longer time scales. Based on the availability of data, summer circulation patterns in all of the Great Lakes, winter circulation patterns in all of the Great Lakes except Lake Superior, and annual circulation patterns in Lakes Erie, Michigan, and Ontario were derived. Winter currents are generally stronger than summer currents, and, therefore, annual circulation closely resembles winter circulation. Circulation patterns tend to be cyclonic (counterclockwise) in the larger lakes (Lake Huron, Lake Michigan, and Lake Superior) with increased cyclonic circulation in winter. In the smaller lakes (Lake Erie and Lake Ontario), winter circulation is characterized by a two-gyre circulation pattern. Summer circulation in the smaller lakes is different; predominantly cyclonic in Lake Ontario and anticyclonic in Lake Erie.     

Do existing ecological classifications characterize the spatial variability of stream temperatures in the Great Lakes Basin,Ontario?

Ecological classifications of stream ecosystems have been used to develop monitoring programs, identify reference and impacted systems, and focus conservation efforts. One of the most influential, but highly variable, components of stream ecosystems is water temperature but few geographically broad-scale and long-term programs exist to assess and monitor temperatures. This study evaluated if existing ecological classifications could be used to categorize the similarities and differences in stream temperatures across the Ontario portion of the Great Lakes Basin. Concordance between the spatial variability in temperatures and an existing ecological classification would support the use of that classification to define areas with similar temperatures, guide the development of a monitoring program, and inform management programs. The five classifications evaluated were the ecoregions and ecodistricts defined in the National Ecological Framework for Canada, the ecoregions and ecodistricts defined in the Ecological Land Classification of Ontario, and the aquatic ecosystem units defined in the Aquatic Ecosystem Classification (AEC) for the Ontario portion of the Great Lakes Basin. Hierarchical linear modelling and corrected Akaike Information Criterion indicated that the ecodistrict classifications characterized more of the spatial variability in temperatures than the ecoregion and AEC classification but temperatures were more variable among sites within classes than between classes. Therefore, none of the existing ecological classifications could be used to characterize thermal variability. Future research should examine if the inability of the existing classifications to capture the thermal variability translates into inaccurate classification of other ecosystem components such as water quality, and macroinvertebrate and fish assemblages.     

The Great Lakes Region and Bulk Water Exports

Abstract

The article provides an overview of the latest developments in the debate concerning the bulk water export of Great Lakes water. It examines the policy and legal dimensions of this new debate. The policy dimension focuses on the public attention and concern, in Canada, regarding bulk water removals from the Great Lakes basin. This concern has triggered the new Canadian federal legislation banning water exports from the region (Bill C-15). Is this a sign that the Canadian government now embraces a water conservation ethic? Is its position in line with the recent recommendations on the issue of the International Joint Commission (IJC), the joint body created by the United States and Canada to manage its shared waters? The attempt by investors to export water from the Great Lakes basin raises issues regarding Canada's obligations under international and regional trade agreements, most notably the General Agreement on Tariffs and Trade (GATT) and the North American Free Trade Agreement (NAFTA). The article examines the provisions of those two trade agreements in the context of the water export debate in Canada and concludes that increased clarity on Canada/US transboundary water issues is required.