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.     

Great Lakes and Inland Sport Fish Consumption by Licensed Anglers in Two Ontario Communities

Risk assessments for potential health effects associated with consumption of contaminated Great Lakes (GL) sport fish (SF) rely heavily on estimated human consumption and preparation practices. The mid-1990s study reported here used a two stage sampling approach based on selection of high GL fish consumers among licensed Ontario anglers. Mean GL fish consumption (meals/year), meal size (g/meal) and estimated grams/day in two Ontario GL communities were: 34.2, 186.1, and 19.9 in Cornwall and 10.9, 331.9, and 12.3 in Mississauga respectively, in the same range as U.S. Environmental Protection Agency (EPA) estimates used in the development of water quality criteria. Yet different species preferences, awareness of advisories and other sport and commercial fish consumption by participating anglers have implications for overall contaminant intake, suggesting the continued need for site-specific consumption surveys.     

An Examination of the Plasticity of Gonad Development in Sea Lampreys,Petromyzon marinus: Observations through Gonadal Biopsies

Observations of larvae with atypical gonads led to this study to determine the extent of the plasticity of gonad development in larval, metamorphosing, and juvenile sea lampreys. Larval and early metamorphosing, sea lampreys underwent microsurgery to remove a biopsy of gonadal tissue. These biopsies were examined quantitatively and were categorized as ovaries, presumptive testes, or as atypical gonads. After a period of approximately 8 to 10 months, the larvae and subsequent juveniles were killed and the gonads were re-examined, again quantitatively, for any changes in gonad development. There was no significant change in the number of larvae with typical ovaries as a direct result of sex reversals and oocyte atresia. None of the metamorphosing lampreys initially biopsied had atypical gonads and no sex reversals were observed in this group. Oocyte number in typical ovaries of the larvae and metamorphosing lampreys did not change over the course of the study; however germ cell number increased significantly in typical testes of both larvae and metamorphosing lampreys. The results of the study confirm that the lability of sex in larval sea lampreys is much greater than previously thought; however, it is clear that sex is defined and does not appear to change once the lampreys have entered the juvenile period.     

The Lake Ontario Great Lakes Science Practicum: A Model for Training Limnology Students on How to Conduct Shipboard Research in the Great Lakes

The authors designed and led an 8-day limnology practicum conducted on the R/V Lake Guardian that focused on classical and emerging technologies in a series of four inter-dependent teaching modules. The practicum was tied together by a general research question (Are spatial patterns of Lake Ontario productivity a function of distance from the shoreline?), and a guided inquiry approach was used to help students frame testable hypotheses to address this question. Students collected a research-quality data set while participating in the practicum's teaching models, and subsequent to the cruise presented their results as oral papers at research conferences and as research papers. The design of this practicum may provide a useful model for other educators who wish to train the next generation of Great Lakes limnologists by conducting courses on a research vessel.     

Fisheries: Past,Present, and Future in the Great Lakes

Against the background of (1) some major shifts in fisheries research, (2) past use of science in fisheries management, and (3) what society considers valuable, the importance of effective communications and science transfer emerges. These issues are critical to future progress in fisheries and ecosystem management.     

Predicted Atrazine Concentrations in the Great Lakes: Implications for Biological Effects

Atrazine is an herbicide used extensively throughout the Midwest corn belt, including the agricultural regions within the Great Lakes basin watershed. Measurements of atrazine concentrations in the Great Lakes are few, however, so knowledge of its current concentrations, persistence, and trends in this ecosystem is limited. A dynamic annual time step model was used to predict atrazine concentrations over time in the Great Lakes based on varied atrazine loading rates to the lakes (“most-likely” and “high” loading conditions). Four degradation scenarios were evaluated: no degradation, and atrazine degradation with half-lives of 2 years, 5 years, and 10 years. Predicted steady-state concentrations for all of the scenarios and all the Great Lakes ranged from 0.0024 to 0.88 μg/L. The number of years until steady-state conditions were achieved ranged from 4 to over 400 years. The most-likely loading rate and two-year half-life scenario had the lowest concentrations (0.0024 to 0.13 μg/L) and the fewest years (4 to 13 years) to achieve steady-state conditions. Available monitored atrazine concentrations in the Great Lakes are very similar to the most-likely loading rate and 2-year half-life scenario predicted values. Monitored and predicted concentrations in the Great Lakes indicate atrazine does not currently pose a toxicological risk to humans or aquatic organisms, and under current and expected lower loading rates should remain well below criteria values.     

The Great Lakes Cladophora Model: Development,testing, and application to Lake Michigan

A recent review of the Great Lakes Water Quality Agreement has concluded that while controls on phosphorus inputs to Lake Michigan achieved the desired effect in offshore waters, the nearshore region continues to suffer from elevated phosphorus levels. Failure to achieve trophic state goals in the nearshore is manifested in nuisance growth of Cladophora and attendant impacts on property owners, utilities, and the public health and welfare. This study focuses on a site in Lake Michigan near Milwaukee, Wisconsin, where nuisance growth of Cladophora and associated beach fouling occur regularly. A mechanistic model simulating Cladophora growth, suitable for guiding nutrient management in the Great Lakes nearshore, is presented. The model represents an update of the Canale and Auer framework, reflecting current understandings of Cladophora ecology and offering a user-friendly interface making the software more widely available to decision makers. This Great Lakes Cladophora Model (GLCM) is first validated for the Auer/Canale data set collected in 1979 at a site on Lake Huron and then for a data set developed in 2006 for a site on Lake Michigan. Model performance under the strikingly different forcing conditions (depth, light, phosphorus levels) characteristic of these two sites affirms the widespread applicability of the tool. The GLCM is then extended to examine the impacts of ecosystem perturbation (dreissenid colonization) on Cladophora growth and to future approaches to monitoring and management.     

Alkalinity,pH, and pCO2 in the Laurentian Great Lakes: An initial view of seasonal and inter-annual trends

Ongoing human perturbations to the global inorganic carbon cycle can cause various changes in the pH and alkalinity of aquatic systems. Here seasonal and inter-annual trends in these variables were investigated in the five Laurentian Great Lakes using data from the U.S. EPA GLENDA database. These observations, along with temperature, were also used to predict the partial pressure of carbon dioxide in surface water (pCO₂). There are strong seasonal differences in pH in all five lakes, with higher pH levels in summer than in spring. All lakes show significantly higher pCO₂ values in spring than in summer. Michigan and Ontario show higher alkalinity values in spring; Huron shows lower spring values. Inter-annually, open-lake pH shows the highest values in all lakes around 2010, the time frame of lowest lake water levels, though only lakes Superior and Erie show statistically significant inflection points at that time. Inter-annual alkalinity trends differ considerably from those of pH. Superior’s alkalinity increases until ～2008 and then begins dropping; Ontario’s alkalinity decreases until ～2004 and then begins increasing, with the decrease coinciding with the introduction and establishment of Dreissenid mussels. The other lakes show much less clear inter-annual alkalinity trends. For pCO₂, inter-annual trends in each lake show either increases from 1992 to 2019 (for Superior, Michigan, and Huron) or shifts from slightly decreasing values to increasing values for the other lakes. The timing of this shift is from 2008 to 2010.     

Assessing Contamination in Great Lakes Sediments Using Benthic Invertebrate Communities and the Sediment Quality Triad Approach

Sediments in many Great Lakes harbors and tributary rivers are contaminated. As part of the USEPA's Assessment and Remediation of Contaminated Sediment (ARCS) program, a number of studies were conducted to determine the nature and extent of sediment contamination in Great Lakes Areas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a series of papers describing studies conducted to evaluate sediment toxicity from three AOC's (Buffalo River, NY; Indiana Harbor, IN; Saginaw River, MI), as part of the ARCS Program. Oligochaeta (worms) and Chironomidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consisted of taxa identified as primarily contaminant tolerant organisms. Structural deformities of mouthparts in midge larvae were pronounced in many of the samples. Good concurrence was evident between measures of laboratory toxicity, sediment contaminant concentration, and benthic invertebrate community composition in extremely contaminated samples. However, in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxicity test results or sediment contaminant concentration. Laboratory sediment toxicity tests may better identify chemical contamination in sediments than many commonly used measures of benthic invertebrate community composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are needed to better interpret the response of benthic invertebrates to sediment contamination.     

An alternative hypothesis to invasional meltdown in the Laurentian Great Lakes region: General facilitation by Dreissena

Invasional meltdown, where established non-indigenous species facilitate the establishment and spread of newly arriving non-indigenous species, may contribute to the increasing rate of biological invasions. The Laurentian Great Lakes have been used as an example of invasional meltdown, but our results suggest that this may not be the case. We propose that the increased numbers of facilitative interactions are not due to an invasion meltdown, but rather a strongly interacting species, such as Dreissena, promoting population level changes in both native and non-indigenous species. Dreissena are the facilitator in the majority of reported facilitations of non-indigenous species, and those non-indigenous species have not yet led to more invasions. Further, our results show that Dreissena facilitate non-indigenous and native species similarly. Literature reviews showed little evidence that Dreissena facilitate fish or are facilitated by phytoplankton. Consequently, the observed pattern of species interactions in the Great Lakes does not conform to the definition of invasional meltdown. We suggest that Dreissena cause strong interactions and change the benthos in a way that facilitates many organisms (native and non-indigenous), but that system-wide invasional meltdown is not occurring in the Great Lakes.     

Distribution of nuisance Cladophora in the lower Great Lakes: Patterns with land use, near shore water quality and dreissenid abundance

Selected shorelines and offshore shoals in Lakes Erie, Huron and Ontario were surveyed with a high frequency hydroacoustic system to investigate current spatial patterns of nuisance benthic filamentous algal (e.g., Cladophora) cover and stand height. Cladophora reached nuisance levels at all sites in Lakes Erie and Ontario, but not in Lake Huron or Georgian Bay. Despite clear gradients in coastal land cover, near shore water quality gradients were generally weak, and for Lakes Erie and Ontario, measures of near shore water quality were similar to that at offshore shoals. Hierarchical partitioning analysis suggested that while dreissenid mussel abundance appeared to be important in determining the magnitude of Cladophora standing crop, the joint contribution of catchment land cover, near shore water quality (nutrient levels and suspended matter) and dreissenid mussel abundance explained nearly 95% of the total variance in nuisance Cladophora standing crop observed in this study. Although the results from this study are necessarily correlative in nature and definition of causal relationships is not possible, these results provide corroborating evidence from sites across a gradient within and across the lower Great Lakes that is consistent with the operation of the near shore shunt model.     

Impacts on biodiversity and species changes in the lower Great Lakes

The Great Lakes basin ecosystem evolved after the retreat of the last ice sheet, about 10 000 years ago. Today, the complex of species present in the Great Lakes and much of the visible landscape bears little resemblance to that found some 400 years ago. Rather, the effects of various aspects of human development have caused major changes in the natural biodiversity. Lessons learned in the lower Great Lakes are applicable to many lakes around the world that have undergone agricultural, industrial and urban development in their drainage basins and have become managed, artificial ecosystems.     

Sustainable fisheries management in the Great Lakes: Scientific and operational challenges

Fisheries managers seek to sustain Great Lakes' fish populations in a large, complex lake‐watershed ecosystem responding to often competing issues: non‐indigenous species, resource allocation and environmental quality. Within the past 200 years, human activity has caused dramatic changes in the character of this ecosystem. Before the 1900s, the offshore fish communities in each of the Great Lakes were dominated by the piscivorous lake trout and burbot. The current fish fauna of the Great Lakes' basin includes 179 species representing 29 families in 18 orders and two classes of fish. Twenty‐five non‐indigenous fish species have established populations in the Great Lakes' ecosystem. Sustainable management of Great Lakes' fisheries depends on social, economic and ecological factors. Hundreds of millions of dollars are spent annually to protect and preserve Great Lakes' fisheries and their associated ecosystems. Management of Great Lakes' fisheries on a species‐by‐species basis is pointless. Recreational fishing provides larger economic benefits on the Great Lakes, compared to commercial fisheries. Further, quota management, even when practiced at levels well below maximum sustainable yield, does not lead to stable fish communities. Management will be constrained more by ecological reality than by economic forces, but ultimately a managed system comprised of both indigenous and non‐indigenous fishes is a logical objective.     

Classifying Sea Lamprey Marks on Great Lakes Lake Trout: Observer Agreement,Evidence on Healing Times between Classes,and Recommendations for Reporting of Marking Statistics

In 1997 and 1998 two workshops were held to evaluate how consistent observers were at classifying sea lamprey (Petromyzon marinus) marks on Great Lakes lake trout (Salvelinus namaycush) as described in the King classification system. Two trials were held at each workshop, with group discussion between trials. Variation in counting and classifying marks was considerable, such that reporting rates for A1–A3 marks varied two to three-fold among observers of the same lake trout. Observer variation was greater for classification of healing or healed marks than for fresh marks. The workshops highlighted, as causes for inconsistent mark classification, both departures from the accepted protocol for classifying marks by some agencies, and differences in how sliding and multiple marks were interpreted. Group discussions led to greater agreement in classifying marks. We recommend ways to improve the reliability of marking statistics, including the use of a dichotomous key to classify marks. Laboratory data show that healing times of marks on lake trout were much longer at 4°C and 1°C than at 10°C and varied greatly among individuals. Reported A1–A3 and B1–B3 marks observed in late summer and fall collections likely result from a mixture of attacks by two year classes of sea lamprey. It is likely that a substantial but highly uncertain proportion of attacks that occur in late summer and fall lead to marks that are classified as A1–A3 the next spring. We recommend additional research on mark stage duration.     

Research on Great Lakes Algal Communities: Problems from the Past,Lessons for the Future

Review of research on algal communities in the Laurentian Great Lakes shows significant progress in delineating this component of the biota and understanding the factors which regulate its composition and distribution. Unaddressed or poorly addressed problems remain in certain fundamental research areas and future progress will depend largely on how quickly and thoroughly these problems are reduced. It is clear that there is no useful distinction between basic and applied research in this area and best progress will be achieved through a balanced approach.     

Evaluating the Effects of Habitat Patchiness on Small Fish Assemblages in a Great Lakes Coastal Marsh

Wetlands are naturally heterogeneous ecosystems with resident species adapted to patchy environments. We measured how assemblages of small fish varied among four natural patches of coastal marsh in Mismer Bay, Lake Huron, USA. We sampled patches continuously for extensive time periods to describe both spatial and temporal fish distribution patterns. Fish richness and distribution varied spatially with some species restricted to one or two patches, such as Phoxinus eos and Margariscus margarita, and others widely distributed, such as Pimephales notatus and Culaea inconstans. For ubiquitous species, patch utilization varied temporally, which was explained by variation in habitat characteristics, such as macrophyte richness and growth form diversity, emergent macrophyte stem density, water temperature and depth. Northern Great Lakes coastal marshes are not static environments, and intensive sampling illustrates the dynamic interactions between fishes and this successional marsh environment. We conclude that extended sampling protocols in patchy, temperate wetlands are preferable to short surveys for making accurate evaluations about the spatio-temporal habitat utilization of fishes.     

Metals and Essential Elements in Herring Gulls from the Great Lakes, 1983

Adult and prefledged herring gulls were collected from one location each in Lakes Ontario, Erie, Huron, and Superior. Composite samples of liver, kidney, and feather were analyzed for 24 elements and composite samples of bone for 22 elements. After consideration of quality assurance results, concentrations of 16 elements (Al, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, P, Pb, Sr, Ti, Zn) in liver, kidney, and feather were accepted for presentation while 6 elements were accepted from bone (Ca, Cd, Hg, P, Pb, Zn). Only lead, cadmium, and mercury values were of toxicological interest. Data on other trace elements are presented as baseline values among locations for each tissue and age class. Concentrations of Cd, Pb, and Hg were higher in adults than in prefledged young. Metal levels varied among different tissues with Cd highest in kidney (2.16 μg/g; Hamilton Harbour, Lake Ontario), Pb highest in bone (30.0 μg/g; Double Island, Lake Huron), and Hg highest in feather (6.11 μg/g; Middle Island, Lake Erie). Lead levels in both age classes were generally higher in tissues from the two upper lakes colonies than in samples from the lower lakes. Cadmium and mercury levels did not vary greatly among locations. Levels found are below those associated with metal toxicoses in laboratory studies with other avian species.