Lake Michigan Shoreline Research Articles

Observing low-altitude features in ozone concentrations in a shoreline environment via uncrewed aerial systems

Abstract. Ozone is a pollutant formed in the atmosphere by photochemical processes involving nitrogen oxides (NOx) and volatile organic compounds (VOCs) when exposed to sunlight. Tropospheric boundary layer ozone is regularly measured at ground stations and sampled infrequently through balloon, lidar, and crewed aircraft platforms, which have demonstrated characteristic patterns with altitude. Here, to better resolve vertical profiles of ozone within the atmospheric boundary layer, we developed and evaluated an uncrewed aircraft system (UAS) platform for measuring ozone and meteorological parameters of temperature, pressure, and humidity. To evaluate this approach, a UAS was flown with a portable ozone monitor and a meteorological temperature and humidity sensor to compare to tall tower measurements in northern Wisconsin. In June 2020, as a part of the WiscoDISCO20 campaign, a DJI M600 hexacopter UAS was flown with the same sensors to measure Lake Michigan shoreline ozone concentrations. This latter UAS experiment revealed a low-altitude structure in ozone concentrations in a shoreline environment showing the highest ozone at altitudes from 20–100 m a.g.l. These first such measurements of low-altitude ozone via a UAS in the Great Lakes region revealed a very shallow layer of ozone-rich air lying above the surface.

Unconsolidated sediment thickness mapping by waterborne geophysics along the Lake Michigan shoreline

Mapping unconsolidated sediment at the Illinois Lake Michigan shoreline (ILMS) is complex but vital for sustainable management and use of this dynamic system which undergoes significant redistribution of sand in the littoral transport system over time. To understand erosion and accretion processes it is critical to map the ILMS sediments at high spatiotemporal resolution. Here we used two geophysical methods, waterborne electrical resistivity imaging (wERI) and sub-bottom profiling (SBP), ground-truthed by hydraulic jet probing and historic borings, to map the thickness of unconsolidated sediments along two reaches of the ILMS. These geophysical surveys show that the sediments have not undergone deformation, and the thickness of the unconsolidated sandy material ranges between 4 and 5 m over semiconsolidated clay and bedrock. Both geophysical methods agree with jet probe results which provide direct evidence of loose, sandy sediments up to depths of 4 to 5 m below the lakebed. The wERI shows more detailed variation in the sediment and bedrock topography than the other methods. Overall, the geophysical methods, particularly the wERI, appear to be effective tools to map the sediment structure along the ILMS at high spatial resolution. Considering the relatively low cost of the operation of geophysical surveys, simplicity of operation and data analyses, wERI and SBP show promising potential for comprehensive mapping of the ILMS. The methods supplement the limited extent of direct sampling and the lower spatial resolution but great extent of airborne geophysics, and provide the information needed for better understanding of sediment transport mechanisms.

Land cover and water quality of drowned river mouths: Evidence of an environmental gradient along the eastern Lake Michigan shoreline

Lake Michigan’s drowned river mouths (DRM) are hydrologically unique systems with both riverine and large-lake influences. Serving as focal points for human development, DRMs have experienced a history of industrialization, urbanization, and are now moving towards an era of restoration and revitalization. The goal of this study was to examine water quality in 12 DRMs along Lake Michigan’s eastern shoreline. We hypothesized that there is a latitudinal gradient in indicators of water quality in these DRM lakes, which is the result of natural land cover, anthropogenic land use, and underlying geology. We identified a latitudinal gradient in land use/land cover with developed land area more abundant in southern DRMs and forest more abundant in northern land area; this distinction was evident at both the local and whole watershed geographic scales but was more distinct at the local scale. Water quality followed suit with specific conductance, chlorophyll-a, and total phosphorus (TP) concentrations higher in southern DRMs and lower in northern DRMs; whereas, Secchi disk depth showed the opposite trend. Multivariate analysis results were consistent with the relationship of water quality and latitudinal gradient. Thermal stratification and low dissolved oxygen (DO) concentrations in the hypolimnion were more common in deeper (i.e., greater than 4 m) areas of DRMs; low DO in the hypolimnion was more likely in southern DRMs than in northern DRMs. These results provide a foundation for future research initiatives in helping separate anthropogenic vs. natural stress in these systems, which provide critical ecosystem services for their surrounding communities.

A reduced-complexity shoreline model for coastal areas with large water level fluctuations

A new reduced-complexity, 1-D shoreline model has been developed, calibrated, and tested with a set of shoreline positions detected from high-resolution satellite images. Motivated by recent large interannual water level fluctuations and associated shoreline changes in the Great Lakes, the model is built on previous models that are based on the disequilibrium concept, with extensions for water level effects. Unlike other shoreline models, the model includes two different sources of disequilibrium, wave disequilibrium and water level disequilibrium. The model also includes a passive flooding term to account for the instantaneous effect of the water level changes on the shoreline position. Case studies forced by seasonally-varying waves and water levels varying on seasonal and interannual timescales highlight the model's ability to enhance wave-driven shoreline change when water level variations are additionally present. The model was applied to two sites along the Lake Michigan shoreline, Jeorse Park and West Beaches, with shoreline time series extracted from multispectral satellite imagery. When calibrated and applied to an eleven year period of decreasing water levels, the new model shows significant skill in simulating and forecasting the shoreline position in the two study areas, with modest improvement over existing models. The simulation results additionally highlight the dominance of water level disequilibrium over wave disequilibrium for the study sites. When applied to a nearly forty year simulation of West Beach, the new model shows excellent ability to model the shoreline response to water level and wave fluctuations over a range of timescales. Comparison models are seen to be incapable of capturing the water level effects, particularly when water level trends differ from the calibration period. Overall, the model results and parameters show the importance of the newly introduced water level disequilibrium in modulating wave-driven shoreline change. Finally, while the shoreline model was motivated by Great Lakes coastal processes, it may provide new predication abilities for coastlines where water level fluctuations and trends play a role in shoreline changes. • A new shoreline model is developed, tested, and compared to existing models. • The model is based on the concept of combined wave and water level disequilibrium. • The model is applied to two case studies along the Lake Michigan shoreline. • The model successfully simulates shoreline changes enhanced by water level changes.

Improving coastal resilience planning with respect to long-term water level fluctuations by examining decadal coastal profile behavior at sandy, harbor filet beaches along Lake Michigan in the Great Lakes of North America

Resilient planning for coastal hazards requires an understanding of both short-term and long-term coastal change dynamics. Numerous studies have been conducted throughout the Great Lakes of North America on processes and responses associated with short-term coastal changes, such as storms and seasonal fluctuations in lake level; however, few datasets exist that can capture long-term coastal morphodynamics in this region. Lack of data and knowledge creates a barrier for accurately modeling future coastal change, which underpins proactive coastal management. This is particularly problematic at sites adjacent to coastal infrastructure, such as those near harbors. To address this, we utilize a 32-year record of coastal profile change from several sites along the Lake Michigan shoreline of Michigan to examine profile evolution in response to changing lake levels and human disturbance. These data reveal that coastal sites without shoreline armoring can recover from erosive high lake level phases if lake level remains low for an extended period. However, if sites are armored, or if future climate conditions result in more frequent or more extreme lake level fluctuations, full recovery of the coastal profile is unlikely. Managers and decisionmakers can utilize this information to evaluate their site conditions and proactively plan for future coastal changes.

Effects of magnetite on phosphorus storage and carbon cycling in Lake Michigan shoreline sediments

Lake Michigan, one of the Laurentian Great Lakes, hosts the world's largest freshwater sand dune system and is ecologically and economically important. Phosphorus (P) plays a key role in the lake biota, while industrial P runoff, pollution controls, and invasive species add to the complexity of P dynamics in the shoreline ecosystem. Rich in iron oxide minerals, the Lake Michigan shoreline has been little studied with respect to P bioavailability and cycling. In this study, we analyzed magnetite concentrations in samples collected from 19 beach and sand dune sites located along the eastern shore of Lake Michigan, and we examined the mineral effects on P bioavailability through adsorption experiments, sediment fractionation and extraction, and microcosm incubations. We find that magnetite is widely distributed in the sand dune ecosystem and its content can reach very high levels (>30% dry weight) in natural beach sediments. P has the strongest adsorption affinity to magnetite when compared to prominent sediment minerals calcite and quartz, and the native magnetite holds up to 10 and 28 times more moderately and strongly bound P, respectively, than the bulk sediments. Microcosm incubations with native sediments showed that the addition of P significantly increased microbial decomposition of labile organic carbon, whereas the added synthetic magnetite did not significantly reduce the P bioavailability or decrease the carbon degradation. This research highlights the multiple effects of magnetite on P storage, bioavailability, and labile organic carbon degradation in the shoreline sand dunes, which may provide new insights into understanding nutrient and carbon cycling in the Great Lakes ecosystem.

Using sUAS-Acquired Imagery to Map Landslide Susceptibility along the Lake Michigan Shoreline of Wisconsin

Bluffs along the Wisconsin shoreline of Lake Michigan frequently collapse, and this collapse often occurs due to saturation and weakness in a sand layer present in the bluffs. We used an sUAS to collect visible and thermal imagery of bluffs along Lake Michigan in Kewaunee County, WI. We then proceeded to classify this imagery in ArcGIS Pro to determine whether the program’s classification tools could locate the sand layer. Furthermore, we examined imagery before and after a major storm to determine the storm’s effect on water content in the sand layer. Our results indicate that we can use automated computer programs to classify the sand layer based on a combination of visible and thermal imagery. Additionally, we found that large summer storms do not significantly alter the saturation of the sand layer and infer that their effect on bluff collapse is minimal.

A Simple, Fully Automated Shoreline Detection Algorithm for High-Resolution Multi-Spectral Imagery

This paper develops and validates a new fully automated procedure for shoreline delineation from high-resolution multispectral satellite images. The model is based on a new water–land index, the Direct Difference Water Index (DDWI). A new technique based on the buffer overlay method is also presented to determine the shoreline changes from different satellite images and obtain a time series for the shoreline changes. The shoreline detection model was applied to imagery from multiple satellites and validated to have sub-pixel accuracy using beach survey data that were collected from the Lake Michigan (USA) shoreline using a novel backpack-based LiDAR system. The model was also applied to 132 satellite images of a Lake Michigan beach over a three-year period and detected the shoreline accurately, with a >99% success rate. The model out-performed other existing shoreline detection algorithms based on different water indices and clustering techniques. The resolution shoreline position timeseries is the first satellite image-extracted dataset of its kind in terms of its high spatial and temporal resolution, and paves the road to obtaining other high-temporal-resolution datasets to refine models of beaches worldwide.

Repeat photography of Lake Michigan coastal dunes: Expansion of vegetation since 1900 and possible drivers

Coastal dunes are prominent features along the Lake Michigan shoreline, especially along Michigan’s Lower Peninsula. Numerous studies in recent years have reconstructed the geomorphic history of these dune systems, from their initial formation in the mid-Holocene to about 300 years ago. These studies have suggested linkages between past dune behavior and climatic variability and fluctuating lake levels. Less is known, however, about how these dune systems change on shorter-temporal scales in the modern era and the potential drivers of that change. Using repeat photography, this paper attempts to demonstrate how the coastal dunes of Lake Michigan’s eastern shore have changed since the 19th century. We collected hundreds of photographs of these dunes, taken between the years 1885 and 2018, from archives and citizen scientists. In the spring and summer of 2019, we took ∼70 new photographs replicating the original images. The changes between coastal dune conditions in the original photographs and in the 2019 photographs show a general expansion of vegetation across formerly barren and active surfaces along the entire shoreline. Although human development has also played a role in reshaping the coastal dune systems, the most pronounced difference between historical and current dune conditions where repeat photography was conducted is the expansion of vegetation – grasses, shrubs, and even trees. Here, we present the 20 photograph pairs most representative of these trends, explore these changes, and discuss the likely causes, including the increase in precipitation in Michigan in the past ∼80 years.

Rapid lake Michigan shoreline changes revealed by UAV LiDAR surveys

The recent record-breaking Laurentian Great Lakes water levels have led to severe erosion along many shorelines, but quantification of this erosion has not yet been widely reported. In this paper, novel shoreline measurements of Lake Michigan erosion, using a LiDAR-equipped unmanned aerial vehicle (UAV). The vehicle surveyed two beaches, Dune Acres and Beverly Shores, along the Indiana shoreline of southern Lake Michigan over the period 2018–2019, which are compared to existing aircraft-based LiDAR surveys. The UAV surveys reveal extensive shoreline erosion and recession at both beaches since the low water conditions of 2012–2013, with both beaches losing 70.7 and 64.8 m3/m of dry beach volume. Shoreline recession over this period was nearly 35 m for both beaches. In the period 2018–2019, the UAV measurements reveal continued beach erosion and the transition of beach topography to a steep, actively eroding foredune. Storm erosion resolved by short-interval surveys highlight the episodic nature of shoreline erosion, with 8 m3/m of material lost over a stormy two-week period at Dune Acres. While large, the erosion and recession observed at both beaches is in keeping with limited historical observations of shoreline change during high water episodes. However, the observed overall shoreline recession slopes of 1:29 (water level rise : recession) are much less than historical slopes, suggesting that the beaches are not yet in equilibrium with the high water levels and that erosion will continue in the foreseeable future while lake levels remain high.

Delineating spatial distribution and thickness of unconsolidated sand along the southwest Lake Michigan shoreline using TEM and ERT geophysical methods

Erosion and accretion of various magnitudes occur along the southwest Lake Michigan shoreline. These processes are triggered by natural events and human activities, which affect the distribution and thickness of sand on the nearshore lake bottom. Significant erosion along the Illinois coastline has highlighted the need for a large-scale means of acquiring spatially rich data to build models of sand distribution along the entire shoreline. Thus, we implemented a high-resolution airborne transient electromagnetic (TEM) method, coupled with a ground-based electrical resistivity tomography (ERT) method to determine the sand distribution and thickness along the shore from the beach to ~1 km into the lake. From Kenosha, Wisconsin, to Chicago, Illinois, we acquired 1049 line-km of TEM data, and 13.43 line-km of ERT data. Our results indicated a distinct, uneven distribution and thickness of the unconsolidated sand unit covering the southwestern Lake Michigan shoreline. The unconsolidated sand unit was found to range in thickness from 0 to ~12 m. This unconsolidated sand unit was shown to be thickest (4.5 to ~10 m) in the northern part of the study site. In southern Wisconsin and Chicago, the sand layer beneath the water column was found to be very thin, ≤1 m. We propose, based on our analysis, that lake-bed conditions and wind direction are the main factors that limit southward littoral transport. Our data suggest that the current state of the shoreline is relatively analogous to how it has always behaved; however, anthropogenic disturbance has exacerbated the natural patterns of erosion and accretion.

A Geological Understanding of Lake Michigan’s Shoreline Behavior

The profile of Indiana’s shoreline with Lake Michigan changes dramatically from year to year and systematically within a year. Sediment is always moving in the nearshore system of Lake Michigan. As a result, the onshore-offshore profile of Indiana's Lake Michigan shoreline changes seasonally and annually.

Geological Understanding of Lake Michigan's High Lake Levels

Crashing waves, eroding seawalls, collapsing roads, and disappearing beaches have become a common sight along the Lake Michigan shoreline during the past months. Research studies conducted on the changing levels of the Great Lakes by Todd Thompson, Director of the Indiana Geological and Water Survey, and his colleagues can help evaluate recent changes to the coast in the context of long-term lake-level change.

Improving ozone simulations in the Great Lakes Region: The role of emissions, chemistry, and dry deposition

The Great Lakes Region of the US continues experiencing exceedances of the ozone (O3) standards, despite years of emissions controls. In part, this is due to interactions between emissions from surrounding large cities (e.g., Chicago) and meteorology, which is heavily influenced by the presence of the Great Lakes. These complex meteorology-emissions interactions pose a challenge to fully capture O3 dynamics, particularly near shores of the lakes, where high O3 levels are often experienced. In a simulation with the Community Multiscale Air Quality (CMAQ) model, using inputs as typically constructed, the model tends to be biased high. A literature review indicated that NOx emissions from mobile sources, possibly overestimated in the 2011 National Emission Inventory (NEI), or the version of the Carbon Bond chemical mechanism used in CMAQ could be responsible for high biases of O3. As such, a series of sensitivity tests was conducted to identify potential causes for this bias, including emissions biases (e.g., biogenic VOCs, anthropogenic NOx), chemical mechanism choice, and O3 dry deposition to fresh water, for high O3 periods in July 2011. The base model/emissions configuration used the following: Carbon Bond mechanism CB05, biogenic emissions using Biogenic Emission Inventory System (BEIS), and anthropogenic emissions from the 2011 National Emissions Inventory (NEI). Meteorological inputs were developed using the Weather Research and Forecasting (WRF) model (version 3.8.1). Simulated daily maximum 8-h average O3 without and with a cutoff of 60 ppb (referred to as MDA8 O3 and elevated MDA8 O3 hereafter, respectively) were evaluated against measurements. The evaluation showed a high bias in MDA8 O3 across the domain, particularly at coastal sites (by ∼6 ppb), while elevated MDA8 O3 (i.e., greater than 60 ppb) was biased low, with exceptions centered along the shore of Lake Michigan. Using the CB6 chemical mechanism or 50% reduction of NOx emissions from on-road mobile sources led to substantial domain-wide decreases in O3 from the base case, and the model performance improved, particularly along the Lake Michigan shoreline and for the western domain. However, elevated MDA8 O3 was more biased against measurements, compared to the model performance in the base case, except at a few sites along the shoreline. Using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) instead of BEIS to estimate biogenic emissions, or increasing dry deposition of O3 to fresh water by a factor of ten (which is unrealistic), had minor impacts on simulated O3 over land. But, combining MEGAN with CB6 resulted in improved elevated MDA8 O3 simulation along the western coast of Lake Michigan. Finally, using CB6 combined with a 30% reduction of on-road mobile NOx emissions and MEGAN led to the best performance. Two companion papers investigate how meteorological modeling can be improved. Together, the recommended modeling system could serve as a starting point for future O3 modeling in the region.

Tracking the distribution of microfiber pollution in a southern Lake Michigan watershed through the analysis of water, sediment and air.

Microplastic waste is a worldwide problem, heavily afflicting marine and freshwater environments; the loading of this pollution in water, sediment and living organisms continues to escalate. Synthetic microfibers, resulting from the release of microscopic fibers from synthetic textiles, constitute the most prevalent type of microplastics pollution in aquatic environments. This study investigated the origin and distribution of synthetic microfibers in a representative Lake Michigan watershed in Indiana (USA) by analyzing water, sediment and air samples above and below wastewater treatment plant discharges, downstream in the watershed and water from the Lake Michigan shoreline. Synthetic microfibers were also quantified in wastewater from a local wastewater treatment plant (WWTP) and in laundry effluent. Laboratory testing of numerous fabrics suggests that Fenton oxidation, used to break down natural fibers, effectively eliminates non-polluting, natural fibers from the samples. However, the hydroxyl radical-mediated oxidation bleaches the dye from certain synthetic microfibers, which likely leads to under-reported values for these microplastics in natural samples. The data collected from the watershed samples indicate that approximately 4 billion synthetic microfibers are transported daily through the Lake Michigan tributary. Wastewater effluent is not the only source of synthetic microfibers, since surface water samples above the WWTP contained a similar load to downstream samples. Repeated sampling exhibited variability in the number of microfibers detected, substantiating the heterogeneous distribution of these pollutants and the requirement for multiple samples for a given site. The average load of synthetic microfibers from water sampled at the Lake Michigan shoreline was higher than the tributary water, suggesting the shoreline functions as a repository for the microfibers. Given the extent and potential consequences of this pollution, quantification of the ubiquitous plastic fibers can be instituted as part of the traditional total suspended solids (TSS) water quality monitoring parameter.

Rapid Expansion of Banded Killifish Fundulus diaphanus across Northern Illinois: Dramatic Recovery or Invasive Species?

The distribution of the Illinois state-threatened Banded Killifish Fundulus diaphanus has remained largely unchanged in Illinois from 1880 to 2000, being restricted mainly to the northeastern corner of the state. One population identified as Western Banded Killifish F. d. menona has remained stable in the glacial lakes region along the southeastern Wisconsin–northeastern Illinois border. Starting in 2001 a second population began to spread and become more common along the Lake Michigan shoreline. From there the population expanded through the Chicago Area Waterway System into the Des Plaines River and eventually the Illinois River. Historical museum specimens from this region are identified as F. d. menona, but recent specimens are identified as hybrids between F. d. menona and Eastern Banded Killifish F. d. diaphanus. Subsequently, a third population appeared in the Mississippi River near the mouth of the Rock River in 2009 and has spread from there. These individuals are also identified as F. d. menona. The rapid expansion of Banded Killifish from Lake Michigan to the Illinois River appears to be an invasion of the Eastern subspecies F. d. diaphanus and the subsequent hybridization with the native Western subspecies. It is unknown where the Banded Killifish in the Mississippi River originated, possibly from populations 160 kilometers upstream or human introductions. As the Illinois River and Mississippi River populations continue to expand their ranges, their ecological impacts are unknown at this time.

Analysis of a sudden bluff failure along the southwest Lake Michigan shoreline

Elevated lake levels in the Lake Michigan-Huron basin have resulted in erosion at the bases of coastal bluffs composed of unconsolidated glacial deposits. Base erosion leads to a general steepening of the bluff face that can cause the bluffs to suddenly fail, transporting sediment into the nearshore hydrodynamic system. Sudden bluff failure impacts infrastructure built near the bluffs and the sediment budget of the coastal region. A better understanding of the mechanics that govern bluff failure will improve predictions of bluff retreat and sediment budgets. Here we present findings collected from a set of newly developed in-situ monitoring devices that record and measure several properties of the bluff leading up to and during a sudden failure. The devices are capable of accurately measuring, amongst other properties, displacement of the failing bluff at the millisecond sampling rate needed to capture sudden changes. A bluff failure was recorded on December 13, 2016, which prior to failure underwent an elevated creep rate for approximately 1.5 days and a highly-accelerated creep rate for the final 2.5 h. A creep to failure technique was used to analyze the displacement record and substantiated that the bluff failure was likely caused by the formation of segregation ice within the bluff as temperatures dropped from − 1 to − 12 °C over a 40-hour period prior to failure. Finally, a time to failure prediction estimate provided an upper bound for the time until ultimate failure from any one instance of time depending on the instantaneous creep rate.

Environmental drivers of shell shape in a freshwater gastropod from small and large lakes

AbstractElimia livescens (Menke 1830) is a freshwater gastropod common in the Laurentian Great Lakes region. Geometric morphometric analysis was conducted to determine the variation in shell shape among sites along the shoreline of Lake Michigan (4 sites) and 3 inland lakes on Beaver and Manitou Islands (8 sites) in Michigan, USA. Canonical Variates Analysis (CVA) showed significant variation in shell shape among the sites at inland lakes and those on the Lake Michigan shoreline. Based on shell shape, 82.5% of individual snails could be correctly assigned to their lake of origin, and 62.8% could be correctly assigned to their site of origin. CVA axes were tested for correlations with the environmental variables. Shell shape in E. livescens was correlated most strongly with fetch length and specific conductance. Higher fetch lengths produce higher-energy wave action and may select for individuals with a larger aperture, more globose shape, and lower spire (better for anchorage). Lower fetch lengths produce...

Zebra mussels (Dreissena polymorpha) as a biomonitor of trace elements along the southern shoreline of Lake Michigan.

The invasive zebra mussel (Dreissena polymorpha) has become an accepted biomonitor organism for trace elements, but it has yet to be studied along the Lake Michigan shoreline. Likewise, the relationships between tissue concentrations of elements, organism size, and sediment concentrations of elements have not been fully explained. The present study found that a variety of allometric variables such as length, dry tissue mass, shell mass, organism condition indices, and shell thickness index were useful in explaining intrasite variability in elemental concentrations. The flesh condition index (grams of tissue dry mass per gram of shell mass) explained variability at the most sites for most elements. Once allometric intrasite variability was taken into account, additional significant differences were found between sites, although the net effect was small. Significant positive relationships between sediment and tissue concentrations were found for Pb and Zn, with a significant negative relationship for Cd. It was also found that Cu and Zn concentrations in tissues increased significantly along the shoreline in the southeasterly direction, whereas Hg increased in a northwesterly direction. Opportunistic sampling found that zebra mussels accumulate significantly higher concentrations of nearly all elements analyzed compared to Asian clams (Corbicula fluminea) at the same site. The present study demonstrates the need to fully explain natural sources of variability before using biomonitors to explain spatial distributions of trace elements.

Helminths of the American Toad,Anaxyrus americanus americanus, and Fowler's Toad,Anaxyrus fowlerifrom the Silver Creek Area and Lake Michigan Shoreline in Western Michigan, U.S.A

In total, 105 toads (71 American toads, Anaxyrus americanus americanus Holbrook, 1836; 31 Fowler's toads, Anaxyrus fowleri (Hinckley, 1882); and 3 A. a. americanus × A. fowleri hybrids) were collected in 2011 and 2012 from the lower Silver Creek area and Lake Michigan shoreline (LMS) in western lower Michigan and examined for helminths. Five helminth species (1 Digenea, Gorgoderina sp.; 1 Cestoda, Mesocestoides sp.; and 3 Nematoda,-Cosmocercoides variabilis, Oswaldocruzia pipiens, and Rhabdias americanus) were found in American toads. Mesocestoides sp. and R. americanus were the most common helminths of American toads. Four helminth species (1 Digenea, Haematoloechus sp.; 1 Cestoda, Mesocestoides sp.; and 2 Nematoda, C. variabilis and O. pipiens) infected Fowler's toad, with Mesocestoides sp. being most common. Anaxyrus a. americanus × A. fowleri hybrids were infected with Mesocestoides sp., R. americanus, and C. variabilis. The prevalences and intensities of helminth species found in both toad species and the mean numbers of helminth species in infected toads and in all examined toads were always higher in American toads than in Fowler's toads. Although C. variabilis and R. americanus infected American toads and C. variabilis and O. pipiens infected Fowler's toads on the LMS, it is believed that they were not infected there. The occurrence of these nematodes in toads on the LMS reflects infections that occurred in their breeding ponds and other moist areas. This is the first survey on the helminths of Fowler's toads from Michigan and from a shoreline dune area for both toad species.